Fiber-optic voltage sensor with cladded fiber and evanescent wave variation detection

DOEpatents

Wood, Charles B.

1992-01-01

A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent wave in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities.

Fiber-optic voltage sensor with cladded fiber and evanescent wave variation detection

DOEpatents

Wood, C.B.

1992-12-15

A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent wave in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities. 3 figs.

Side-emitting fiber optic position sensor

DOEpatents

Weiss, Jonathan D [Albuquerque, NM

2008-02-12

A side-emitting fiber optic position sensor and method of determining an unknown position of an object by using the sensor. In one embodiment, a concentrated beam of light source illuminates the side of a side-emitting fiber optic at an unknown axial position along the fiber's length. Some of this side-illuminated light is in-scattered into the fiber and captured. As the captured light is guided down the fiber, its intensity decreases due to loss from side-emission away from the fiber and from bulk absorption within the fiber. By measuring the intensity of light emitted from one (or both) ends of the fiber with a photodetector(s), the axial position of the light source is determined by comparing the photodetector's signal to a calibrated response curve, look-up table, or by using a mathematical model. Alternatively, the side-emitting fiber is illuminated at one end, while a photodetector measures the intensity of light emitted from the side of the fiber, at an unknown position. As the photodetector moves further away from the illuminated end, the detector's signal strength decreases due to loss from side-emission and/or bulk absorption. As before, the detector's signal is correlated to a unique position along the fiber.

Fiber optic sensor system for detecting movement or position of a rotating wheel bearing

DOEpatents

Veeser, Lynn R.; Rodriguez, Patrick J.; Forman, Peter R.; Monahan, Russell E.; Adler, Jonathan M.

1997-01-01

An improved fiber optic sensor system and integrated sensor bearing assembly for detecting movement or position of a rotating wheel bearing having a multi-pole tone ring which produces an alternating magnetic field indicative of movement and position of the rotating member. A magneto-optical material, such as a bismuth garnet iron (B.I.G.) crystal, having discrete magnetic domains is positioned in the vicinity of the tone ring so that the domains align themselves to the magnetic field generated by the tone ring. A single fiber optic cable, preferably single mode fiber, carries light generated by a source of light to the B.I.G. crystal. The light passes through the B.I.G. crystal and is refracted at domain boundaries in the crystal. The intensity of the refracted light is indicative of the amount of alignment of the domains and therefore the strength of the magnetic field. The refracted light is carried by the fiber optic cable to an optic receiver where the intensity is measured and an electrical signal is generated and sent to a controller indicating the frequency of the changes in light intensity and therefore the rotational speed of the rotating wheel bearing.

Optical inverse-square displacement sensor

DOEpatents

Howe, R.D.; Kychakoff, G.

1989-09-12

This invention comprises an optical displacement sensor that uses the inverse-square attenuation of light reflected from a diffused surface to calculate the distance from the sensor to the reflecting surface. Light emerging from an optical fiber or the like is directed onto the surface whose distance is to be measured. The intensity I of reflected light is angle dependent, but within a sufficiently small solid angle it falls off as the inverse square of the distance from the surface. At least a pair of optical detectors are mounted to detect the reflected light within the small solid angle, their ends being at different distances R and R + [Delta]R from the surface. The distance R can then be found in terms of the ratio of the intensity measurements and the separation length as given in an equation. 10 figs.

A Novel Design of an Automatic Lighting Control System for a Wireless Sensor Network with Increased Sensor Lifetime and Reduced Sensor Numbers

PubMed Central

Mohamaddoust, Reza; Haghighat, Abolfazl Toroghi; Sharif, Mohamad Javad Motahari; Capanni, Niccolo

2011-01-01

Wireless sensor networks (WSN) are currently being applied to energy conservation applications such as light control. We propose a design for such a system called a Lighting Automatic Control System (LACS). The LACS system contains a centralized or distributed architecture determined by application requirements and space usage. The system optimizes the calculations and communications for lighting intensity, incorporates user illumination requirements according to their activities and performs adjustments based on external lighting effects in external sensor and external sensor-less architectures. Methods are proposed for reducing the number of sensors required and increasing the lifetime of those used, for considerably reduced energy consumption. Additionally we suggest methods for improving uniformity of illuminance distribution on a workplane’s surface, which improves user satisfaction. Finally simulation results are presented to verify the effectiveness of our design. PMID:22164114

A novel design of an automatic lighting control system for a wireless sensor network with increased sensor lifetime and reduced sensor numbers.

PubMed

Mohamaddoust, Reza; Haghighat, Abolfazl Toroghi; Sharif, Mohamad Javad Motahari; Capanni, Niccolo

2011-01-01

Wireless sensor networks (WSN) are currently being applied to energy conservation applications such as light control. We propose a design for such a system called a lighting automatic control system (LACS). The LACS system contains a centralized or distributed architecture determined by application requirements and space usage. The system optimizes the calculations and communications for lighting intensity, incorporates user illumination requirements according to their activities and performs adjustments based on external lighting effects in external sensor and external sensor-less architectures. Methods are proposed for reducing the number of sensors required and increasing the lifetime of those used, for considerably reduced energy consumption. Additionally we suggest methods for improving uniformity of illuminance distribution on a workplane's surface, which improves user satisfaction. Finally simulation results are presented to verify the effectiveness of our design.

Fiber optic sensor based on reflectivity configurations to detect heart rate

NASA Astrophysics Data System (ADS)

Yunianto, M.; Marzuki, A.; Riyatun, R.; Lestari, D.

2016-11-01

Research of optical fiber-based heart rate detection sensor has been conducted using the reflection configurationon the thorax motion modified. Optical fiber used in this research was Plastic Optical Fiber (POF) with a diameter of 0.5. Optical fiber system is made with two pieces of fiber, the first fiber is to serve as a transmitter transmitting light from the source to the reflector membrane, the second fiber serves as a receiver. One of the endsfrom the two fibersis pressed and positioned perpendicular of reflector membrane which is placed on the surface of the chest. The sensor works on the principle of intensity changes captured by the receiver fiber when the reflector membrane gets the vibe from the heart. The light source used is in the form of Light Emitting Diode (LED) and Light Dependent Resistor (LDR) as a light sensor. Variations are performed on the reflector membrane diameter. The light intensity received by the detector increases along with the increasing width of the reflector membrane diameter. The results show that this sensor can detect the harmonic peak at a frequency of 1.5 Hz; 7.5 Hz; 10.5 Hz; and 22.5 Hz in a healthy human heart with an average value of Beat Per Minute (BPM) by 78 times, a prototype sensor that is made can work and function properly.

Quantum noise reduction in intensity-sensitive surface-plasmon-resonance sensors

NASA Astrophysics Data System (ADS)

Lee, Joong-Sung; Huynh, Trung; Lee, Su-Yong; Lee, Kwang-Geol; Lee, Jinhyoung; Tame, Mark; Rockstuhl, Carsten; Lee, Changhyoup

2017-09-01

We investigate the use of twin-mode quantum states of light with symmetric statistical features in their photon number for improving intensity-sensitive surface plasmon resonance (SPR) sensors. For this purpose, one of the modes is sent into a prism setup where the Kretschmann configuration is employed as a sensing platform and the analyte to be measured influences the SPR excitation conditions. This influence modifies the output state of light that is subsequently analyzed by an intensity-difference measurement scheme. We show that quantum noise reduction is achieved not only as a result of the sub-Poissonian statistical nature of a single mode, but also as a result of the nonclassical correlation of the photon number between the two modes. When combined with the high sensitivity of the SPR sensor, we show that the use of twin-mode quantum states of light notably enhances the estimation precision of the refractive index of an analyte. With this we are able to identify a clear strategy to further boost the performance of SPR sensors, which are already a mature technology in biochemical and medical sensing applications.

Automatic Suppression of Intense Monochromatic Light in Electro-Optical Sensors

PubMed Central

Ritt, Gunnar; Eberle, Bernd

2012-01-01

Electro-optical imaging sensors are widely distributed and used for many different tasks. Due to technical improvements, their pixel size has been steadily decreasing, resulting in a reduced saturation capacity. As a consequence, this progress makes them susceptible to intense point light sources. Developments in laser technology have led to very compact and powerful laser sources of any wavelength in the visible and near infrared spectral region, offered as laser pointers. The manifold of wavelengths makes it difficult to encounter sensor saturation over the complete operating waveband by conventional measures like absorption or interference filters. We present a concept for electro-optical sensors to suppress overexposure in the visible spectral region. The key element of the concept is a spatial light modulator in combination with wavelength multiplexing. This approach allows spectral filtering within a localized area in the field of view of the sensor. The system offers the possibility of automatic reduction of overexposure by monochromatic laser radiation. PMID:23202039

Plastic Optical Fibre Sensor for Spine Bending Monitoring with Power Fluctuation Compensation

PubMed Central

Zawawi, Mohd Anwar; O'Keeffe, Sinead; Lewis, Elfed

2013-01-01

This paper presents the implementation of power fluctuation compensation for an intensity-based optical fibre bending sensor aimed at monitoring human spine bending in a clinical environment. To compensate for the light intensity changes from the sensor light source, a reference signal was provided via the light reflection from an aluminum foil surface fixed at a certain distance from the source fibre end tips. From the results, it was found that the investigated sensor compensation technique was capable of achieving a 2° resolution for a bending angle working range between 0° and 20°. The study also suggested that the output voltage ratio has a 0.55% diversion due to input voltage variation between 2.9 V and 3.4 V and a 0.25% output drift for a 2 h measurement. With the achieved sensor properties, human spine monitoring in a clinical environment can potentially be implemented using this approach with power fluctuation compensation. PMID:24233073

Designing Light Beam Transmittance Measuring Tool Using a Laser Pointer

NASA Astrophysics Data System (ADS)

Nuroso, H.; Kurniawan, W.; Marwoto, P.

2016-08-01

A simple instrument used for measuring light beam transmittance percentage made of window film has been developed. The instrument uses a laser pointer of 405 nm and 650 nm ±10% as a light source. Its accuracy approaches 80%. Transmittance data was found by comparing the light beam before and after passing the window film. The light intensity measuring unit was deleted by splitting the light source into two beams through a beam splitter. The light beam was changed into resistance by a NORP12 LDR sensor designed at a circuit of voltage divider rule of Khirchoff's laws. This conversion system will produce light beam intensity received by the sensor to become an equal voltage. This voltage will, then, be presented on the computer screen in the form of a real time graph via a 2.0 USB data transfer.

In situ calibration of a light source in a sensor device

DOEpatents

Okandan, Murat; Serkland, Darwin k.; Merchant, Bion J.

2015-12-29

A sensor device is described herein, wherein the sensor device includes an optical measurement system, such as an interferometer. The sensor device further includes a low-power light source that is configured to emit an optical signal having a constant wavelength, wherein accuracy of a measurement output by the sensor device is dependent upon the optical signal having the constant wavelength. At least a portion of the optical signal is directed to a vapor cell, the vapor cell including an atomic species that absorbs light having the constant wavelength. A photodetector captures light that exits the vapor cell, and generates an electrical signal that is indicative of intensity of the light that exits the vapor cell. A control circuit controls operation of the light source based upon the electrical signal, such that the light source emits the optical signal with the constant wavelength.

Sunlight Intensity Based Global Positioning System for Near-Surface Underwater Sensors

PubMed Central

Gómez, Javier V.; Sandnes, Frode E.; Fernández, Borja

2012-01-01

Water monitoring is important in domains including documenting climate change, weather prediction and fishing. This paper presents a simple and energy efficient localization strategy for near surface buoy based sensors. Sensors can be dropped randomly in the ocean and thus self-calibrate in terms of geographic location such that geo-tagged observations of water quality can be made without the need for costly and energy consuming GPS-hardware. The strategy is based on nodes with an accurate clock and light sensors that can regularly sample the level of light intensity. The measurements are fitted into a celestial model of the earth motion around the sun. By identifying the trajectory of the sun across the skies one can accurately determine sunrise and sunset times, and thus extract the longitude and latitude of the sensor. Unlike previous localization techniques for underwater sensors, the current approach does not rely on stationary or mobile reference points. PMID:22438746

Sunlight intensity based global positioning system for near-surface underwater sensors.

PubMed

Gómez, Javier V; Sandnes, Frode E; Fernández, Borja

2012-01-01

Water monitoring is important in domains including documenting climate change, weather prediction and fishing. This paper presents a simple and energy efficient localization strategy for near surface buoy based sensors. Sensors can be dropped randomly in the ocean and thus self-calibrate in terms of geographic location such that geo-tagged observations of water quality can be made without the need for costly and energy consuming GPS-hardware. The strategy is based on nodes with an accurate clock and light sensors that can regularly sample the level of light intensity. The measurements are fitted into a celestial model of the earth motion around the sun. By identifying the trajectory of the sun across the skies one can accurately determine sunrise and sunset times, and thus extract the longitude and latitude of the sensor. Unlike previous localization techniques for underwater sensors, the current approach does not rely on stationary or mobile reference points.

Optical-Fiber Leak Detector

NASA Technical Reports Server (NTRS)

Workman, Gary L.; Kosten, Susan E.

1994-01-01

Proposed optical-fiber sensor detects small changes in pressure in elastomeric O-ring or similar pressure seal, which may indicate deterioration of seal and interpreted as indications of incipient failure. According to concept, length of optical fiber embedded in seal. Light-emitting diode illuminates one end of fiber; photodetector measures intensity of light emerging from other end. Pressure-induced changes in seal bend fiber slightly, altering microbending-induced loss of light from fiber and alter intensity of light at photodetector. Change in intensity approximately proportional to change in pressure.

Wavefront image sensor chip

PubMed Central

Cui, Xiquan; Ren, Jian; Tearney, Guillermo J.; Yang, Changhuei

2010-01-01

We report the implementation of an image sensor chip, termed wavefront image sensor chip (WIS), that can measure both intensity/amplitude and phase front variations of a light wave separately and quantitatively. By monitoring the tightly confined transmitted light spots through a circular aperture grid in a high Fresnel number regime, we can measure both intensity and phase front variations with a high sampling density (11 µm) and high sensitivity (the sensitivity of normalized phase gradient measurement is 0.1 mrad under the typical working condition). By using WIS in a standard microscope, we can collect both bright-field (transmitted light intensity) and normalized phase gradient images. Our experiments further demonstrate that the normalized phase gradient images of polystyrene microspheres, unstained and stained starfish embryos, and strongly birefringent potato starch granules are improved versions of their corresponding differential interference contrast (DIC) microscope images in that they are artifact-free and quantitative. Besides phase microscopy, WIS can benefit machine recognition, object ranging, and texture assessment for a variety of applications. PMID:20721059

Analyzing spatial coherence using a single mobile field sensor.

PubMed

Fridman, Peter

2007-04-01

According to the Van Cittert-Zernike theorem, the intensity distribution of a spatially incoherent source and the mutual coherence function of the light impinging on two wave sensors are related. It is the comparable relationship using a single mobile sensor moving at a certain velocity relative to the source that is calculated in this paper. The auto-corelation function of the electric field at the sensor contains information about the intensity distribution. This expression could be employed in aperture synthesis.

A compact multi-channel fluorescence sensor with ambient light suppression

NASA Astrophysics Data System (ADS)

Egly, Dominik; Geörg, Daniel; Rädle, Matthias; Beuermann, Thomas

2012-03-01

A multi-channel fluorescence sensor has been developed for process monitoring and fluorescence diagnostics. It comprises a fiber-optic set-up with an immersion probe and an intensity-modulated high power ultraviolet light-emitting diode as a light source for fluorescence excitation. By applying an electronic lock-in procedure, fluorescence signals are selectively detectable at ambient light levels of 1000 000 times higher intensity. The sensor was designed to be compact, low cost and easily adaptable to a wide field of application. The set-up was used to simultaneously monitor three important metabolic fluorophores: NAD(P)H, flavins and porphyrins during the cultivation of a baker's yeast. Moreover, the accumulation and degradation kinetics of protoporphyrin IX induced by 5-aminolevulinic acid on the skin could be recorded by the sensor. The detection limit for protoporphyrin IX was determined to be 4 × 10-11 mol L-1. The linear signal amplification of the sensor and time courses of fluorescence signals monitored during yeast fermentations were validated using a commercial CCD spectrometer. The robust and flexible set-up of the fiber-optic measurement system promises easy implementation of this non-invasive analytical tool to fluorescence monitoring and diagnostics in R&D and production.

Self-calibrating solar position sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxey, Lonnie Curt

A sun positioning sensor and method of accurately tracking the sun are disclosed. The sensor includes a position sensing diode and a disk having a body defining an aperture for accepting solar light. An extension tube having a body that defines a duct spaces the position sensing diode from the disk such that the solar light enters the aperture in the disk, travels through the duct in the extension tube and strikes the position sensing diode. The extension tube has a known length that is fixed. Voltage signals indicative of the location and intensity of the sun are generated bymore » the position sensing diode. If it is determined that the intensity values are unreliable, then historical position values are used from a table. If the intensity values are deemed reliable, then actual position values are used from the position sensing diode.« less

Seeing Chemistry through Sound: A Submersible Audible Light Sensor for Observing Chemical Reactions for Students Who Are Blind or Visually Impaired

ERIC Educational Resources Information Center

Supalo, Cary A.; Kreuter, Rodney A.; Musser, Aaron; Han, Josh; Briody, Erika; McArtor, Chip; Gregory, Kyle; Mallouk, Thomas E.

2006-01-01

In order to enable students who are blind and visually impaired to observe chemical changes in solutions, a hand-held device was designed to output light intensity as an audible tone. The submersible audible light sensor (SALS) creates an audio signal by which one can observe reactions in a solution in real time, using standard laboratory…

Full spectrum optical safeguard

DOEpatents

Ackerman, Mark R.

2008-12-02

An optical safeguard device with two linear variable Fabry-Perot filters aligned relative to a light source with at least one of the filters having a nonlinear dielectric constant material such that, when a light source produces a sufficiently high intensity light, the light alters the characteristics of the nonlinear dielectric constant material to reduce the intensity of light impacting a connected optical sensor. The device can be incorporated into an imaging system on a moving platform, such as an aircraft or satellite.

Optical sensor of magnetic fields

DOEpatents

Butler, M.A.; Martin, S.J.

1986-03-25

An optical magnetic field strength sensor for measuring the field strength of a magnetic field comprising a dilute magnetic semi-conductor probe having first and second ends, longitudinally positioned in the magnetic field for providing Faraday polarization rotation of light passing therethrough relative to the strength of the magnetic field. Light provided by a remote light source is propagated through an optical fiber coupler and a single optical fiber strand between the probe and the light source for providing a light path therebetween. A polarizer and an apparatus for rotating the polarization of the light is provided in the light path and a reflector is carried by the second end of the probe for reflecting the light back through the probe and thence through the polarizer to the optical coupler. A photo detector apparatus is operably connected to the optical coupler for detecting and measuring the intensity of the reflected light and comparing same to the light source intensity whereby the magnetic field strength may be calculated.

Silicon-Etalon Fiber-Optic Temperature Sensor

NASA Technical Reports Server (NTRS)

Beheim, Glenn; Fritsch, Klaus; Flatico, Joseph M.; Azar, Massood Tabib

1993-01-01

Developmental temperature sensor consists of silicon Fabry-Perot etalon attached to end of optical fiber. Features immunity to electrical interference, small size, light weight, safety, and chemical inertness. Output encoded in ration of intensities at two different wavelengths, rather than in overall intensity, with result that temperature readings not degraded much by changes in transmittance of fiber-optic link.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, Raoul; Tan, Weihong; Shi, Zhong-You

1997-01-01

This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor (50). An optical fiber micro-light source (50) is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors (22) in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material (60). This process allows significant control of the size of the micro light source (50). Furthermore, photo-chemically attaching an optically active material (60) enables the implementation of the micro-light source in a variety of sensor applications.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, R.; Tan, W.; Shi, Z.Y.

1997-05-06

This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications. 10 figs.

Capillary waveguide optrodes: an approach to optical sensing in medical diagnostics

NASA Astrophysics Data System (ADS)

Lippitsch, Max E.; Draxler, Sonja; Kieslinger, Dietmar; Lehmann, Hartmut; Weigl, Bernhard H.

1996-07-01

Glass capillaries with a chemically sensitive coating on the inner surface are used as optical sensors for medical diagnostics. A capillary simultaneously serves as a sample compartment, a sensor element, and an inhomogeneous optical waveguide. Various detection schemes based on absorption, fluorescence intensity, or fluorescence lifetime are described. In absorption-based capillary waveguide optrodes the absorption in the sensor layer is analyte dependent; hence light transmission along the inhomogeneous waveguiding structure formed by the capillary wall and the sensing layer is a function of the analyte concentration. Similarly, in fluorescence-based capillary optrodes the fluorescence intensity or the fluorescence lifetime of an indicator dye fixed in the sensing layer is analyte dependent; thus the specific property of fluorescent light excited in the sensing layer and thereafter guided along the inhomogeneous waveguiding structure is a function of the analyte concentration. Both schemes are experimentally demonstrated, one with carbon dioxide as the analyte and the other one with oxygen. The device combines optical sensors with the standard glass capillaries usually applied to gather blood drops from fingertips, to yield a versatile diagnostic instrument, integrating the sample compartment, the optical sensor, and the light-collecting optics into a single piece. This ensures enhanced sensor performance as well as improved handling compared with other sensors. waveguide, blood gases, medical diagnostics.

Fiber optic Cerenkov radiation sensor system to estimate burn-up of spent fuel: characteristic evaluation of the system using Co-60 source

NASA Astrophysics Data System (ADS)

Shin, S. H.; Jang, K. W.; Jeon, D.; Hong, S.; Kim, S. G.; Sim, H. I.; Yoo, W. J.; Park, B. G.; Lee, B.

2013-09-01

Cerenkov radiation occurs when charged particles are moving faster than the speed of light in a transparent dielectric medium. In optical fibers, the Cerenkov light also can be generated due to their dielectric components. Accordingly, the radiation-induced light signals can be obtained using optical fibers without any scintillating material. In this study, to measure the intensities of Cerenkov radiation induced by gamma-rays, we have fabricated the fiber-optic Cerenkov radiation sensor system using silica optical fibers, plastic optical fibers, multi-anode photomultiplier tubes, and a scanning system. To characterize the Cerenkov radiation generated in optical fibers, the spectra of Cerenkov radiation generated in the silica and plastic optical fibers were measured. Also, the intensities of Cerenkov radiation induced by gamma-rays generated from a cylindrical Co-60 source with or without lead shielding were measured using the fiberoptic Cerenkov radiation sensor system.

Solid State pH Sensor Based on Light Emitting Diodes (LED) As Detector Platform

PubMed Central

Lau, King Tong; Shepherd, R.; Diamond, Danny; Diamond, Dermot

2006-01-01

A low-power, high sensitivity, very low-cost light emitting diode (LED)-based device developed for low-cost sensor networks was modified with bromocresol green membrane to work as a solid-state pH sensor. In this approach, a reverse-biased LED functioning as a photodiode is coupled with a second LED configured in conventional emission mode. A simple timer circuit measures how long (in microsecond) it takes for the photocurrent generated on the detector LED to discharge its capacitance from logic 1 (+5 V) to logic 0 (+1.7 V). The entire instrument provides an inherently digital output of light intensity measurements for a few cents. A light dependent resistor (LDR) modified with similar sensor membrane was also used as a comparison method. Both the LED sensor and the LDR sensor responded to various pH buffer solutions in a similar way to obtain sigmoidal curves expected of the dye. The pKa value obtained for the sensors was found to agree with the literature value.

Arduino-based experiment demonstrating Malus’s law

NASA Astrophysics Data System (ADS)

Freitas, W. P. S.; Cena, C. R.; Alves, D. C. B.; Goncalves, A. M. B.

2018-05-01

Malus’s law states that the intensity of light after passing through two polarizers is proportional to the square of the cosine of the angle between the polarizers. We present a simple setup demonstrating this law. The novelty of our work is that we use a multi-turn potentiometer mechanically linked to one of the polarizers to measure the polarizer’s rotation angle while keeping the other polarizer fixed. Both the potentiometer and light sensor used to measure the transmitted light intensity are connected to an Arduino board so that the intensity of light is measured as a function of the rotation angle.

Dynamic Optical Filtration

NASA Technical Reports Server (NTRS)

Chretien, Jean-Loup (Inventor); Lu, Edward T. (Inventor)

2005-01-01

A dynamic optical filtration system and method effectively blocks bright light sources without impairing view of the remainder of the scene. A sensor measures light intensity and position so that selected cells of a shading matrix may interrupt the view of the bright light source by a receptor. A beamsplitter may be used so that the sensor may be located away from the receptor. The shading matrix may also be replaced by a digital micromirror device, which selectively sends image data to the receptor.

Dynamic optical filtration

NASA Technical Reports Server (NTRS)

Chretien, Jean-Loup (Inventor); Lu, Edward T. (Inventor)

2005-01-01

A dynamic optical filtration system and method effectively blocks bright light sources without impairing view of the remainder of the scene. A sensor measures light intensity and position so that selected cells of a shading matrix may interrupt the view of the bright light source by a receptor. A beamsplitter may be used so that the sensor may be located away from the receptor. The shading matrix may also be replaced by a digital micromirror device, which selectively sends image data to the receptor.

Low-Light Image Enhancement Using Adaptive Digital Pixel Binning

PubMed Central

Yoo, Yoonjong; Im, Jaehyun; Paik, Joonki

2015-01-01

This paper presents an image enhancement algorithm for low-light scenes in an environment with insufficient illumination. Simple amplification of intensity exhibits various undesired artifacts: noise amplification, intensity saturation, and loss of resolution. In order to enhance low-light images without undesired artifacts, a novel digital binning algorithm is proposed that considers brightness, context, noise level, and anti-saturation of a local region in the image. The proposed algorithm does not require any modification of the image sensor or additional frame-memory; it needs only two line-memories in the image signal processor (ISP). Since the proposed algorithm does not use an iterative computation, it can be easily embedded in an existing digital camera ISP pipeline containing a high-resolution image sensor. PMID:26121609

Fourier optics analysis of grating sensors with tilt errors.

PubMed

Ferhanoglu, Onur; Toy, M Fatih; Urey, Hakan

2011-06-15

Dynamic diffraction gratings can be microfabricated with precision and offer extremely sensitive displacement measurements and light intensity modulation. The effect of pure translation of the moving part of the grating on diffracted order intensities is well known. This study focuses on the parameters that limit the intensity and the contrast of the interference. The effects of grating duty cycle, mirror reflectivities, sensor tilt and detector size are investigated using Fourier optics theory and Gaussian beam optics. Analytical findings reveal that fringe visibility becomes <0.3 when the optical path variation exceeds half the wavelength within the grating interferometer. The fringe visibility can be compensated by monitoring the interfering portion of the diffracted order light only through detector size reduction in the expense of optical power. Experiments were conducted with a grating interferometer that resulted in an eightfold increase in fringe visibility with reduced detector size, which is in agreement with theory. Findings show that diffraction grating readout principle is not limited to translating sensors but also can be used for sensors with tilt or other deflection modes.

Design of a Programmable Star Tracker-Based Reference System for a Simulated Spacecraft

DTIC Science & Technology

2014-03-27

This reduces the overall light intensity hitting the sensor, as indicated by the darker color. However, the red and green circles are also forming...may be beneficial on SimSat since we can control the light output depending on the source chosen. It is possible to sacrifice some star light intensity ...could be done to improve accuracy based on what could be controlled and changed easily. 3.2.3.1 Focal Length. The optics portion of the light collection

Design of Automatic Intensity Varying Smart Street Lighting System

NASA Astrophysics Data System (ADS)

Gupta, Ashutosh; Gupta, Shipra

2017-08-01

The paper is proposed with an aim of power conservation. In this era of development, it is essential to develop a streetlight that turns on and off automatically without human interference. To achieve this light sensor have been placed in each panel which turns the street light on and off automatically. For energy conservation cool-white LED’s have been used in street light panel and dimmer modules have been installed which changes the intensity of the streetlight depending on the darkness.

Polythiophene-fullerene based photodetectors: tuning of spectral response and application in photoluminescence based (bio)chemical sensors.

PubMed

Nalwa, Kanwar S; Cai, Yuankun; Thoeming, Aaron L; Shinar, Joseph; Shinar, Ruth; Chaudhary, Sumit

2010-10-01

A photoluminescence (PL)-based oxygen and glucose sensor utilizing inorganic or organic light emitting diode as the light source, and polythiophene: fullerene type bulk-heterojunction devices as photodetectors, for both intensity and decay-time based monitoring of the sensing element's PL. The sensing element is based on the oxygen-sensitive dye Pt-octaethylporphyrin embedded in a polystyrene matrix.

Performance analysis of photoresistor and phototransistor for automotive’s halogen and xenon bulbs light output

NASA Astrophysics Data System (ADS)

Rammohan, A.; Kumar, C. Ramesh

2017-11-01

Illumination of any light is measured using a different kind of calibrated equipment’s available in the market such as a goniometer, spectral radiometer, photometer, Lux meter and camera based systems which directly display the illumination of automotive headlights light distribution in the unit of lux, foot-candles, lumens/sq. ft. and Lambert etc., In this research, we dealt with evaluating the photo resistor or Light Dependent Resistor (LDR) and phototransistor whether it is useful for sensing light patterns of Automotive Halogen and Xenon bulbs. The experiments are conducted during night hours under complete dark space. We have used the headlamp setup available in TATA SUMO VICTA vehicle in the Indian market and conducted the experiments separately for Halogen and Xenon bulbs under low and high beam operations at various degrees and test points within ten meters of distance. Also, we have compared the light intensity of halogen and xenon bulbs to prove the highest light intensity between halogen and Xenon bulbs. After doing a rigorous test with these two sensors it is understood both are good to sensing beam pattern of automotive bulbs and even it is good if we use an array of sensors or a mixed combination of sensors for measuring illumination purposes under perfect calibrations.

Hopfield neural network and optical fiber sensor as intelligent heart rate monitor

NASA Astrophysics Data System (ADS)

Mutter, Kussay Nugamesh

2018-01-01

This paper presents a design and fabrication of an intelligent fiber-optic sensor used for examining and monitoring heart rate activity. It is found in the literature that the use of fiber sensors as heart rate sensor is widely studied. However, the use of smart sensors based on Hopfield neural networks is very low. In this work, the sensor is a three fibers without cladding of about 1 cm, fed by laser light of 1550 nm of wavelength. The sensing portions are mounted with a micro sensitive diaphragm to transfer the pulse pressure on the left radial wrist. The influenced light intensity will be detected by a three photodetectors as inputs into the Hopfield neural network algorithm. The latter is a singlelayer auto-associative memory structure with a same input and output layers. The prior training weights are stored in the net memory for the standard recorded normal heart rate signals. The sensors' heads work on the reflection intensity basis. The novelty here is that the sensor uses a pulse pressure and Hopfield neural network in an integrity approach. The results showed a significant output measurements of heart rate and counting with a plausible error rate.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, Raoul; Tan, Weihong; Shi, Zhong-You

1994-01-01

This invention relates generally to the development of and a method of fabricating a micro optical fiber light source. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications.

Micro optical fiber light source and sensor and method of fabrication thereof

DOEpatents

Kopelman, R.; Tan, W.; Shi, Z.Y.

1994-11-01

This invention relates generally to the development of and a method of fabricating a micro optical fiber light source. An optical fiber micro-light source is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material. This process allows significant control of the size of the micro light source. Furthermore, photo-chemically attaching an optically active material enables the implementation of the micro-light source in a variety of sensor applications. 4 figs.

Comparison of sensitivity and resolution load sensor at various configuration polymer optical fiber

NASA Astrophysics Data System (ADS)

Arifin, A.; Yusran, Miftahuddin, Abdullah, Bualkar; Tahir, Dahlang

2017-01-01

This study uses a load sensor with a macro-bending on polymer optical fiber loop model which is placed between two plates with a buffer spring. The load sensor with light intensity modulation principle is an infrared LED emits light through the polymer optical fiber then received by the phototransistor and amplifier. Output voltage from the amplifier continued to arduino sequence and displayed on the computer. Load augment on the sensor resulted in an increase of curvature on polymer optical fibers that can cause power losses gets bigger too. This matter will result in the intensity of light that received by phototransistor getting smaller, so that the output voltage that ligable on computer will be getting smaller too. The sensitivity and resolution load sensors analyzed based on configuration with various amount of loops, imperfection on the jacket, and imperfection at the cladding and core of polymer optical fiber. The results showed that the augment on the amount of load, imperfection on the jacket and imperfection on the sheath and core polymer optical fiber can improve the sensitivity and resolution of the load sensor. The best sensors resolution obtained on the number of loops 4 with imperfection 8 on the core and cladding polymer optical fiber that is 0.037 V/N and 0,026 N. The advantages of the load sensor based on polymers optical fiber are easy to make, low cost and simple to use measurement methods.

Intensity-based fibre-optic sensing system using contrast modulation of subcarrier interference pattern

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Sherer, T. N.; Maitland, D. J.

1989-01-01

A novel technique to compensate for unwanted intensity losses in a fiber-optic sensing system is described. The technique involves a continuous sinusoidal modulation of the light source intensity at radio frequencies and an intensity sensor placed in an unbalanced interferometer. The system shows high sensitivity and stability.

Analysis of the reflection of a micro drop fiber sensor

NASA Astrophysics Data System (ADS)

Sun, Weimin; Liu, Qiang; Zhao, Lei; Li, Yingjuan; Yuan, Libo

2005-01-01

Micro drop fiber sensors are effective tools for measuring characters of liquids. These types of sensors are wildly used in biotechnology, beverage and food markets. For a fiber micro drop sensor, the signal of the output light is wavy with two peaks, normally. Carefully analyzing the wavy process can identify the liquid components. Understanding the reason of forming this wavy signal is important to design a suitable sensing head and to choose a suitable signal-processing method. The dripping process of a type of liquids is relative to the characters of the liquid and the shape of the sensing head. The quasi-Gauss model of the light field from the input-fiber end is used to analyse the distribution of the light field in the liquid drop. In addition, considering the characters of the liquid to be measured, the dripping process of the optical signal from the output-fiber end can be expected. The reflection surface of the micro drop varies as serials of spheres with different radiuses and global centers. The intensity of the reflection light changes with the shape of the surface. The varying process of the intensity relates to the tense, refractive index, transmission et al. To support the analyse above, an experimental system is established. In the system, LED is chosen as the light source and the PIN transform the light signal to the electrical signal, which is collected by a data acquisition card. An on-line testing system is made to check the theory discussed above.

Laser pulse detection method and apparatus

NASA Technical Reports Server (NTRS)

Goss, W.; Janesick, J. R. (Inventor)

1984-01-01

A sensor is described for detecting the difference in phase of a pair of returned light pulse components, such as two components of a light pulse of an optical gyro. In an optic gyro, the two light components have passed in opposite directions through a coil of optical fiber, with the difference in phase of the returned light components determining the intensity of light shining on the sensor. The sensor includes a CCD (charge coupled device) that receives the pair of returned light components to generate a charge proportional to the number of photons in the received light. The amount of the charge represents the phase difference between the two light components. At a time after the transmission of the light pulse and before the expected time of arrival of the interfering light components, charge accumulating in the CCD as a result of reflections from components in the system, are repeatedly removed from the CCD, by transferring out charges in the CCD and dumping these charges.

Characterization of modulated time-of-flight range image sensors

NASA Astrophysics Data System (ADS)

Payne, Andrew D.; Dorrington, Adrian A.; Cree, Michael J.; Carnegie, Dale A.

2009-01-01

A number of full field image sensors have been developed that are capable of simultaneously measuring intensity and distance (range) for every pixel in a given scene using an indirect time-of-flight measurement technique. A light source is intensity modulated at a frequency between 10-100 MHz, and an image sensor is modulated at the same frequency, synchronously sampling light reflected from objects in the scene (homodyne detection). The time of flight is manifested as a phase shift in the illumination modulation envelope, which can be determined from the sampled data simultaneously for each pixel in the scene. This paper presents a method of characterizing the high frequency modulation response of these image sensors, using a pico-second laser pulser. The characterization results allow the optimal operating parameters, such as the modulation frequency, to be identified in order to maximize the range measurement precision for a given sensor. A number of potential sources of error exist when using these sensors, including deficiencies in the modulation waveform shape, duty cycle, or phase, resulting in contamination of the resultant range data. From the characterization data these parameters can be identified and compensated for by modifying the sensor hardware or through post processing of the acquired range measurements.

Oxygen detection using evanescent fields

DOEpatents

Duan, Yixiang [Los Alamos, NM; Cao, Weenqing [Los Alamos, NM

2007-08-28

An apparatus and method for the detection of oxygen using optical fiber based evanescent light absorption. Methylene blue was immobilized using a sol-gel process on a portion of the exterior surface of an optical fiber for which the cladding has been removed, thereby forming an optical oxygen sensor. When light is directed through the optical fiber, transmitted light intensity varies as a result of changes in the absorption of evanescent light by the methylene blue in response to the oxygen concentration to which the sensor is exposed. The sensor was found to have a linear response to oxygen concentration on a semi-logarithmic scale within the oxygen concentration range between 0.6% and 20.9%, a response time and a recovery time of about 3 s, ant to exhibit good reversibility and repeatability. An increase in temperature from 21.degree. C. to 35.degree. C. does not affect the net absorption of the sensor.

Dynamic Control of Adsorption Sensitivity for Photo-EMF-Based Ammonia Gas Sensors Using a Wireless Network

PubMed Central

Vashpanov, Yuriy; Choo, Hyunseung; Kim, Dongsoo Stephen

2011-01-01

This paper proposes an adsorption sensitivity control method that uses a wireless network and illumination light intensity in a photo-electromagnetic field (EMF)-based gas sensor for measurements in real time of a wide range of ammonia concentrations. The minimum measurement error for a range of ammonia concentration from 3 to 800 ppm occurs when the gas concentration magnitude corresponds with the optimal intensity of the illumination light. A simulation with LabView-engineered modules for automatic control of a new intelligent computer system was conducted to improve measurement precision over a wide range of gas concentrations. This gas sensor computer system with wireless network technology could be useful in the chemical industry for automatic detection and measurement of hazardous ammonia gas levels in real time. PMID:22346680

An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique.

PubMed

Battista, L; Sciuto, S A; Scorza, A

2013-03-01

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10(-4) m(3)∕s (18.0 l∕min) for the mono-directional sensor and a measurement range of ±3.00 × 10(-4) m(3)∕s (±18.0 l∕min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the coefficient of determination r(2) is equal to 0.997; for the bi-directional configuration, the coefficient of determination r(2) is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty δQ of air flow rate has been evaluated by means of the propagation of distributions and the percentage error in the arrangement of bi-directional sensor ranges from a minimum of about 0.5% at -18.0 l∕min to a maximum of about 9% at -12.0 l∕min.

An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique

NASA Astrophysics Data System (ADS)

Battista, L.; Sciuto, S. A.; Scorza, A.

2013-03-01

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10-4 m3/s (18.0 l/min) for the mono-directional sensor and a measurement range of ±3.00 × 10-4 m3/s (±18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the coefficient of determination r2 is equal to 0.997; for the bi-directional configuration, the coefficient of determination r2 is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty δQ of air flow rate has been evaluated by means of the propagation of distributions and the percentage error in the arrangement of bi-directional sensor ranges from a minimum of about 0.5% at -18.0 l/min to a maximum of about 9% at -12.0 l/min.

Explosively pumped laser light

DOEpatents

Piltch, Martin S.; Michelotti, Roy A.

1991-01-01

A single shot laser pumped by detonation of an explosive in a shell casing. The shock wave from detonation of the explosive causes a rare gas to luminesce. The high intensity light from the gas enters a lasing medium, which thereafter outputs a pulse of laser light to disable optical sensors and personnel.

Fabrication of a miniaturized capillary waveguide integrated fiber-optic sensor for fluoride determination.

PubMed

Xiong, Yan; Wang, Chengjie; Tao, Tao; Duan, Ming; Tan, Jun; Wu, Jiayi; Wang, Dong

2016-05-10

Fluoride concentration is a key aspect of water quality and essential for human health. Too much or too little fluoride intake from water supplies is harmful to public health. In this study, a capillary waveguide integrated fiber-optic sensor was fabricated for fluoride measurement in water samples. The sensor was modularly designed with three parts, i.e., a light source, capillary flow cell and detector. When light propagated from a light emitting diode (LED) to the capillary waveguide cell through an excitation fiber, it interacted with the sensing reagent, and its intensity changed with different fluoride concentrations. Then, the light propagated to the detector through a detection fiber for absorption determination of fluoride according to Beer's law. This miniaturized sensor showed advantages of fast analysis (9.2 s) and small reagent demand (200 μL) per sample, and it also had a low detection limit (8 ppb) and high selectivity for fluoride determination. The sensor was applied to fluoride determination in different water samples. The results obtained were compared with those obtained by conventional spectrophotometry and ion chromatography, showing agreement and validating the sensor's potential application.

Study of a high-precision SAW-MOEMS strain sensor with laser optics

NASA Astrophysics Data System (ADS)

Liu, Xinwei; Chen, Shufen; Li, Honglang; Zou, Zhengfeng; Fu, Lei; Meng, Yanbin

2015-02-01

A novel structure design of a surface acoustic wave (SAW) micro-optic-electro-mechanical-system (MOEMS) strain sensor with a light readout unit is presented in this paper. By measuring the polarization intensity ratio of the TE/TM mode outputted from the waveguide, the strain produced from an object can be measured precisely. The basic working principle of the SAW MOEMS strain sensor is introduced and the mathematical model of the strain sensor system is established. The SAW characteristics effected by the strain sensor are mathematically deduced. The coupling coefficient between the SAW modes and light modes can be calculated based on the theory of coupling modes. The conversion coefficient of polarized light modes is obtained. Due to the restrictions of the specific parameters of the device, the level of technology and the material characteristics, the sensitivity of the strain sensor system is calculated through simulation as 0.1 μɛ, with a dynamic range of 0 ~ ±50 μɛ.

Sound intensity probe for ultrasonic field in water using light-emitting diodes and piezoelectric elements

NASA Astrophysics Data System (ADS)

Zeng, Xi; Mizuno, Yosuke; Nakamura, Kentaro

2017-12-01

The sound intensity vector provides useful information on the state of an ultrasonic field in water, since sound intensity is a vector quantity expressing the direction and magnitude of the sound field. In the previous studies on sound intensity measurement in water, conventional piezoelectric sensors and metal cables were used, and the transmission distance was limited. A new configuration of a sound intensity probe suitable for ultrasonic measurement in water is proposed and constructed for trial in this study. The probe consists of light-emitting diodes and piezoelectric elements, and the output signals are transmitted through fiber optic cables as intensity-modulated light. Sound intensity measurements of a 26 kHz ultrasonic field in water are demonstrated. The difference in the intensity vector state between the water tank with and without sound-absorbing material on its walls was successfully observed.

Non-cladding optical fiber is available for detecting blood or liquids.

PubMed

Takeuchi, Akihiro; Miwa, Tomohiro; Shirataka, Masuo; Sawada, Minoru; Imaizumi, Haruo; Sugibuchi, Hiroyuki; Ikeda, Noriaki

2010-10-01

Serious accidents during hemodialysis such as an undetected large amount of blood loss are often caused by venous needle dislodgement. A special plastic optical fiber with a low refractive index was developed for monitoring leakage in oil pipelines and in other industrial fields. To apply optical fiber as a bleeding sensor, we studied optical effects of soaking the fiber with liquids and blood in light-loss experimental settings. The non-cladding optical fiber that was used was the fluoropolymer, PFA fiber, JUNFLON™, 1 mm in diameter and 2 m in length. Light intensity was studied with an ordinary basic circuit with a light emitting source (880 nm) and photodiode set at both terminals of the fiber under certain conditions: bending the fiber, soaking with various mediums, or fixing the fiber with surgical tape. The soaking mediums were reverse osmosis (RO) water, physiological saline, glucose, porcine plasma, and porcine blood. The light intensities regressed to a decaying exponential function with the soaked length. The light intensity was not decreased at bending from 20 to 1 cm in diameter. The more the soaked length increased in all mediums, the more the light intensity decreased exponentially. The means of five estimated exponential decay constants were 0.050±0.006 standard deviation in RO water, 0.485±0.016 in physiological saline, 0.404±0.022 in 5% glucose, 0.503±0.038 in blood (Hct 40%), and 0.573±0.067 in plasma. The light intensity decreased from 5 V to about 1.5 V above 5 cm in the soaked length in mediums except for RO water and fixing with surgical tape. We confirmed that light intensity significantly and exponentially decreased with the increased length of the soaked fiber. This phenomena could ideally, clinically be applied to a bleed sensor.

A CMOS Luminescence Intensity and Lifetime Dual Sensor Based on Multicycle Charge Modulation.

PubMed

Fu, Guoqing; Sonkusale, Sameer R

2018-06-01

Luminescence plays an important role in many scientific and industrial applications. This paper proposes a novel complementary metal-oxide-semiconductor (CMOS) sensor chip that can realize both luminescence intensity and lifetime sensing. To enable high sensitivity, we propose parasitic insensitive multicycle charge modulation scheme for low-light lifetime extraction benefiting from simplicity, accuracy, and compatibility with deeply scaled CMOS process. The designed in-pixel capacitive transimpedance amplifier (CTIA) based structure is able to capture the weak luminescence-induced voltage signal by accumulating photon-generated charges in 25 discrete gated 10-ms time windows and 10-μs pulsewidth. A pinned photodiode on chip with 1.04 pA dark current is utilized for luminescence detection. The proposed CTIA-based circuitry can achieve 2.1-mV/(nW/cm 2 ) responsivity and 4.38-nW/cm 2 resolution at 630 nm wavelength for intensity measurement and 45-ns resolution for lifetime measurement. The sensor chip is employed for measuring time constants and luminescence lifetimes of an InGaN-based white light-emitting diode at different wavelengths. In addition, we demonstrate accurate measurement of the lifetime of an oxygen sensitive chromophore with sensitivity to oxygen concentration of 7.5%/ppm and 6%/ppm in both intensity and lifetime domain. This CMOS-enabled oxygen sensor was then employed to test water quality from different sources (tap water, lakes, and rivers).

Measurement of Cerenkov radiation induced by the gamma-rays of Co-60 therapy units using wavelength shifting fiber.

PubMed

Jang, Kyoung Won; Shin, Sang Hun; Kim, Seon Geun; Kim, Jae Seok; Yoo, Wook Jae; Ji, Young Hoon; Lee, Bongsoo

2014-04-21

In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at wavelengths of 500 and 510 nm, respectively, and the intensity of transmitted light output of the wavelength shifting fiber was 22.2 times higher than that of the plastic optical fiber. Also, electron fluxes and total energy depositions of gamma-ray beams generated from a Co-60 therapy unit were calculated according to water depths using the Monte Carlo N-particle transport code. The relationship between the fluxes of electrons over the Cerenkov threshold energy and the energy depositions of gamma-ray beams from the Co-60 unit is a near-identity function. Finally, percentage depth doses for the gamma-ray beams were obtained using the fiber-optic Cerenkov radiation sensor, and the results were compared with those obtained by an ionization chamber. The average dose difference between the results of the fiber-optic Cerenkov radiation sensor and those of the ionization chamber was about 2.09%.

Fabrication and Analysis Signal Optical Fiber Sensor Based On Bend Loss for Weight in Motion Applications

NASA Astrophysics Data System (ADS)

Aftah Syukron, Ahmad; Marzuki, Ahmad; Setyawan, Ary

2017-11-01

Road network plays very important role in economic development. Overweight is one of the main factors contributing to road damage. To minimize this factor, road authority has to make sure that all vehicles operate in according to maximum vehicle regulation set by the government. The one solution can use from this problem is Weight in motion (WIM) technology. WIM technology allows measuring vehicle weight quickly. The sensor is one of the important components in the WIM system. This paper presents a model of WIM fiber sensor work based on bend loss. Fiber sensor has made by coiling optical fiber. Coiling optical fiber has managed in the elliptical shape rubber coil. Rubber coil then is planted in the pad of sensor. The principle of this sensor is a detecting of the shift light intensity output of optical fiber when the vehicles a passing through on fiber sensor. Loading was carried out using loaded truck model. Data was carried out with variations of load and load positions in the truck. The results can be concluded that the shift light intensity is greater with the more shift loads. The loader of the truck has also resulted in the greater loss. Loads in the truck distributed on the axles due to the position of loads.

Split-spectrum intensity-based optical fiber sensors for measurement of microdisplacement, strain, and pressure

NASA Astrophysics Data System (ADS)

Wang, Anbo; Miller, Mark S.; Plante, Angela J.; Gunther, Michael F.; Murphy, Kent A.; Claus, Richard O.

1996-05-01

A self-referencing technique compensating for fiber losses and source fluctuations in reflective air-gap intensity-based optical fiber sensors is described. A dielectric multilayer short-wave-pass filter is fabricated onto or attached to the output end face of the lead-in-lead-out multimode fiber. The incoming broadband light from a white light or a light-emitting diode is partially reflected at the filter. The transmitted light through the filter projects onto a mirror. The light returning from the reflecting mirror is recoupled into the lead-in-lead-out fiber. These two reflections from the filter and the reflecting mirror are spectrally separated at the detector end. The power ratio of these two reflections is insensitive to source fluctuations and fiber-bending loss. However, because the second optical signal depends on the air-gap separation between the end face of the lead-in-lead-out fiber and the reflecting mirror, the ratio provides the information on the air-gap length. A resolution of 0.13 mu m has been obtained over a microdisplacement measurement range of 0-254 mu m. The sensor is shown to be insensitive to both fiber-bending losses and variations in source power. Based on this approach, a fiber-strain sensor was fabricated with a multilayer interference filter directly fabricated on the end face of the fiber. A resolution of 13.4 microstrain was obtained over a measurement range of 0-20,000 microstrain with a gauge length of 10 mm. The split-spectrum method is also incorporated into a diaphragm displacement-based pressure sensor with a demonstrated resolution of 450 Pa over a measurement range of 0-0.8 MPa.

Fiber-Optic Strain Sensors With Linear Characteristics

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1993-01-01

Fiber-optic modal domain strain sensors having linear characteristics over wide range of strains proposed. Conceived in effort to improve older fiber-optic strain sensors. Linearity obtained by appropriate choice of design parameters. Pattern of light and dark areas at output end of optical fiber produced by interference between electromagnetic modes in which laser beam propagates in fiber. Photodetector monitors intensity at one point in pattern.

Highly accurate nephelometric titrimetry.

PubMed

Zhan, Xiancheng; Li, Chengrong; Li, Zhiyi; Yang, Xiucen; Zhong, Shuguang; Yi, Tao

2004-02-01

A method that accurately indicates the end-point of precipitation reactions by the measurement of the relative intensity of the scattered light in the titrate is presented. A new nephelometric titrator with an internal nephelometric sensor has been devised. The work of the titrator including the sensor and change in the turbidity of the titrate and intensity of the scattered light are described. The accuracy of the nephelometric titrimetry is discussed theoretically. The titration of NaCl with AgNO(3) serves as a model. A relative error as well as deviation is within 0.2% under the experimental conditions. The applicability of the titrimetry in pharmaceutical analyses, for example, phenytoin sodium and procaine hydrochloride, is generally illustrated. Copyright 2004 Wiley-Liss, Inc. and the American Pharmacists Association

Laser intensity modulated real time monitoring cell growth sensor for bioprocess applications

NASA Astrophysics Data System (ADS)

Kishore, P.; Babu, P. Ravindra; Devi, V. Rama; Maunika, T.; Soujanya, P.; Kishore, P. V. N.; Dinakar, D.

2016-04-01

This article proposes an optical method for monitoring the growth of Escherichia coli in Luria Bertani medium and Saccharomyces cereviciae in YPD. Suitable light is selected which on interaction with the analyte under consideration, gets adsorption / scattered. Required electronic circuitry is designed to drive the laser source and to detect the intensity of light using Photo-detector. All these components are embedded and arranged in a proper way and monitored the growth of the microbs in real time. The sensors results are compared with standard techniques such as colorimeter, Nephelometer and hemocytometer. The experimental results are in good agreement with the existed techniques and well suitable for real time monitoring applications of the growth of the microbs.

Development of a TiO2/SiO2 waveguide-mode chip for an ultraviolet near-field fluorescence sensor.

PubMed

Kuroda, Chiaki; Nakai, Midori; Fujimaki, Makoto; Ohki, Yoshimichi

2018-03-19

Aimed at detecting fluorescent-labeled biological substances sensitively, a sensor that utilizes near-field light has attracted much attention. According to our calculations, a planar structure composed of two dielectric layers can enhance the electric field of UV near-field light effectively by inducing waveguide-mode (WM) resonance. The fluorescence intensity obtainable by a WM chip with an optimized structure is 5.5 times that obtainable by an optimized surface plasmon resonance chip. We confirmed the above by making a WM chip consisting of TiO 2 and SiO 2 layers on a silica glass substrate and by measuring the fluorescence intensity of a solution of quantum dots dropped on the chip.

An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Battista, L.; Sciuto, S. A.; Scorza, A.

2013-03-15

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it;more » the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 Multiplication-Sign 10{sup -4} m{sup 3}/s (18.0 l/min) for the mono-directional sensor and a measurement range of {+-}3.00 Multiplication-Sign 10{sup -4} m{sup 3}/s ({+-}18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the coefficient of determination r{sup 2} is equal to 0.997; for the bi-directional configuration, the coefficient of determination r{sup 2} is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty {delta}Q of air flow rate has been evaluated by means of the propagation of distributions and the percentage error in the arrangement of bi-directional sensor ranges from a minimum of about 0.5% at -18.0 l/min to a maximum of about 9% at -12.0 l/min.« less

A virus resonance light scattering sensor based on mussel-inspired molecularly imprinted polymers for high sensitive and high selective detection of Hepatitis A Virus.

PubMed

Yang, Bin; Gong, Hang; Chen, Chunyan; Chen, Xiaoming; Cai, Changqun

2017-01-15

We described a novel resonance light scattering (RLS) sensor for the specific recognition of trace quantities of Hepatitis A Virus (HAV); the sensor was based on a mussel-inspired hepatitis molecularly imprinted polymer. As a recognition element, polydopamine (PDA)-coated totivirus-imprinted polymer was introduced on the surface of SiO 2 nanoparticles (virus-imprinted SiO 2 @PDA NPs) using an efficient one-step synthesis method. The target virus was selectively captured by the imprinted polymer films, thereby increasing the RLS intensity. A simple fluorescence spectrophotometer was employed to measure the changes in the intensity. The enhanced RLS intensity (∆I RLS ) was proportional to the concentration of HAV in the range of 0.04-6.0nmol∙L -1 , with a low limit of detection of 8.6pmol∙L -1 . The selectivity study confirmed that the resultant HAV-imprinted SiO 2 @PDA NPs possessed high selectivity for HAV. The sensor was successfully applied for the direct detection of additional HAV from a 20,000-fold dilution of human serum. The proposed strategy is simple, eco-friendly, highly selective, and sensitive. Copyright © 2016 Elsevier B.V. All rights reserved.

Decoding mobile-phone image sensor rolling shutter effect for visible light communications

NASA Astrophysics Data System (ADS)

Liu, Yang

2016-01-01

Optical wireless communication (OWC) using visible lights, also known as visible light communication (VLC), has attracted significant attention recently. As the traditional OWC and VLC receivers (Rxs) are based on PIN photo-diode or avalanche photo-diode, deploying the complementary metal-oxide-semiconductor (CMOS) image sensor as the VLC Rx is attractive since nowadays nearly every person has a smart phone with embedded CMOS image sensor. However, deploying the CMOS image sensor as the VLC Rx is challenging. In this work, we propose and demonstrate two simple contrast ratio (CR) enhancement schemes to improve the contrast of the rolling shutter pattern. Then we describe their processing algorithms one by one. The experimental results show that both the proposed CR enhancement schemes can significantly mitigate the high-intensity fluctuations of the rolling shutter pattern and improve the bit-error-rate performance.

Ambient light-based optical biosensing platform with smartphone-embedded illumination sensor.

PubMed

Park, Yoo Min; Han, Yong Duk; Chun, Hyeong Jin; Yoon, Hyun C

2017-07-15

We present a hand-held optical biosensing system utilizing a smartphone-embedded illumination sensor that is integrated with immunoblotting assay method. The smartphone-embedded illumination sensor is regarded as an alternative optical receiver that can replaces the conventional optical analysis apparatus because the illumination sensor can respond to the ambient light in a wide range of wavelengths, including visible and infrared. To demonstrate the biosensing applicability of our system employing the enzyme-mediated immunoblotting and accompanying light interference, various types of ambient light conditions including outdoor sunlight and indoor fluorescent were tested. For the immunoblotting assay, the biosensing channel generating insoluble precipitates as an end product of the enzymatic reaction is fabricated and mounted on the illumination sensor of the smartphone. The intensity of penetrating light arrives on the illumination sensor is inversely proportional to the amount of precipitates produced in the channel, and these changes are immediately analyzed and quantified via smartphone software. In this study, urinary C-terminal telopeptide fragment of type II collagen (uCTX-II), a biomarker of osteoarthritis diagnosis, was tested as a model analyte. The developed smartphone-based sensing system efficiently measured uCTX-II in the 0-5ng/mL concentration range with a high sensitivity and accuracy under various light conditions. These assay results show that the illumination sensor-based optical biosensor is suitable for point-of-care testing (POCT). Copyright © 2016 Elsevier B.V. All rights reserved.

Optical position sensor for determining the interface between a clear and an opaque fluid

DOEpatents

Weiss, Jonathan D [Albuquerque, NM

2006-05-23

An inexpensive, optical position sensor for measuring a position or length, x, along a one-dimensional curvilinear, coordinate system. The sensor can be used, for example, to determine the position of an interface between a clear and an opaque fluid (such as crude oil and water). In one embodiment, the sensor utilizes the principle of dual-fluorescence, where a primary fiber emits primary fluorescent light and a parallel secondary fiber collects a portion of the primary fluorescent light that is not blocked by the opaque fluid. This, in turn, excites secondary fluorescence in the secondary fiber at a longer wavelength. A light detector measures the intensity of secondary fluorescence emitted from an end of the secondary fiber, which is used to calculate the unknown position or length, x. Side-emitting fibers can be used in place of, or in addition to, fluorescent fibers. The all-optical sensor is attractive for applications involving flammable liquids.

Mechanisms and Methods for Selective Wavelength Filtering

NASA Technical Reports Server (NTRS)

Tuma, Margaret (Inventor); Brown, Thomas G. (Inventor); Gruhlke, Russell (Inventor)

2007-01-01

An optical filter includes a dielectric waveguide layer, supporting waveguide modes at specific wavelengths and receiving incident light, a corrugated film layer, composed of one of a metal and a semiconductor and positioned adjacent to a second surface of the waveguide layer and a sensor layer, wherein the sensor layer is capable of absorbing optical energy and generating a corresponding electrical signal. The metal film layer supports a plurality of plasmons, the plurality of plasmons producing a first field and is excited by a transverse mode of the waveguide modes at a wavelength interval. The first field penetrates the sensor layer and the sensor layer generates an electrical signal corresponding to an intensity of received incident light within the wavelength interval.

Optical fiber-based fluorescent viscosity sensor

NASA Astrophysics Data System (ADS)

Haidekker, Mark A.; Akers, Walter J.; Fischer, Derek; Theodorakis, Emmanuel A.

2006-09-01

Molecular rotors are a unique group of viscosity-sensitive fluorescent probes. Several recent studies have shown their applicability as nonmechanical fluid viscosity sensors, particularly in biofluids containing proteins. To date, molecular rotors have had to be dissolved in the fluid for the measurement to be taken. We now show that molecular rotors may be covalently bound to a fiber-optic tip without loss of viscosity sensitivity. The optical fiber itself may be used as a light guide for emission light (external illumination of the tip) as well as for both emission and excitation light. Covalently bound molecular rotors exhibit a viscosity-dependent intensity increase similar to molecular rotors in solution. An optical fiber-based fluorescent viscosity sensor may be used in real-time measurement applications ranging from biomedical applications to the food industry.

Optical fiber-based fluorescent viscosity sensor.

PubMed

Haidekker, Mark A; Akers, Walter J; Fischer, Derek; Theodorakis, Emmanuel A

2006-09-01

Molecular rotors are a unique group of viscosity-sensitive fluorescent probes. Several recent studies have shown their applicability as nonmechanical fluid viscosity sensors, particularly in biofluids containing proteins. To date, molecular rotors have had to be dissolved in the fluid for the measurement to be taken. We now show that molecular rotors may be covalently bound to a fiber-optic tip without loss of viscosity sensitivity. The optical fiber itself may be used as a light guide for emission light (external illumination of the tip) as well as for both emission and excitation light. Covalently bound molecular rotors exhibit a viscosity-dependent intensity increase similar to molecular rotors in solution. An optical fiber-based fluorescent viscosity sensor may be used in real-time measurement applications ranging from biomedical applications to the food industry.

Optically stimulated differential impedance spectroscopy

DOEpatents

Maxey, Lonnie C; Parks, II, James E; Lewis, Sr., Samuel A; Partridge, Jr., William P

2014-02-18

Methods and apparatuses for evaluating a material are described. Embodiments typically involve use of an impedance measurement sensor to measure the impedance of a sample of the material under at least two different states of illumination. The states of illumination may include (a) substantially no optical stimulation, (b) substantial optical stimulation, (c) optical stimulation at a first wavelength of light, (d) optical stimulation at a second wavelength of light, (e) a first level of light intensity, and (f) a second level of light intensity. Typically a difference in impedance between the impedance of the sample at the two states of illumination is measured to determine a characteristic of the material.

Optical and Electric Multifunctional CMOS Image Sensors for On-Chip Biosensing Applications.

PubMed

Tokuda, Takashi; Noda, Toshihiko; Sasagawa, Kiyotaka; Ohta, Jun

2010-12-29

In this review, the concept, design, performance, and a functional demonstration of multifunctional complementary metal-oxide-semiconductor (CMOS) image sensors dedicated to on-chip biosensing applications are described. We developed a sensor architecture that allows flexible configuration of a sensing pixel array consisting of optical and electric sensing pixels, and designed multifunctional CMOS image sensors that can sense light intensity and electric potential or apply a voltage to an on-chip measurement target. We describe the sensors' architecture on the basis of the type of electric measurement or imaging functionalities.

Automatic Lamp and Fan Control Based on Microcontroller

NASA Astrophysics Data System (ADS)

Widyaningrum, V. T.; Pramudita, Y. D.

2018-01-01

In general, automation can be described as a process following pre-determined sequential steps with a little or without any human exertion. Automation is provided with the use of various sensors suitable to observe the production processes, actuators and different techniques and devices. In this research, the automation system developed is an automatic lamp and an automatic fan on the smart home. Both of these systems will be processed using an Arduino Mega 2560 microcontroller. A microcontroller is used to obtain values of physical conditions through sensors connected to it. In the automatic lamp system required sensors to detect the light of the LDR (Light Dependent Resistor) sensor. While the automatic fan system required sensors to detect the temperature of the DHT11 sensor. In tests that have been done lamps and fans can work properly. The lamp can turn on automatically when the light begins to darken, and the lamp can also turn off automatically when the light begins to bright again. In addition, it can concluded also that the readings of LDR sensors are placed outside the room is different from the readings of LDR sensors placed in the room. This is because the light intensity received by the existing LDR sensor in the room is blocked by the wall of the house or by other objects. Then for the fan, it can also turn on automatically when the temperature is greater than 25°C, and the fan speed can also be adjusted. The fan may also turn off automatically when the temperature is less than equal to 25°C.

Inexpensive Meter for Total Solar Radiation

NASA Technical Reports Server (NTRS)

Laue, E. G.

1987-01-01

Pyranometer containing solar cells measures combined intensity of direct light from Sun and diffuse light from sky. Instrument includes polyethylene dome that diffuses entering light so output of light detectors does not vary significantly with changing angle of Sun during day. Not to be calibrated for response of each detector to Sun angle, and sensor outputs not corrected separately before summed and integrated. Aids in deciding on proper time to harvest crops.

Adaptive time-sequential binary sensing for high dynamic range imaging

NASA Astrophysics Data System (ADS)

Hu, Chenhui; Lu, Yue M.

2012-06-01

We present a novel image sensor for high dynamic range imaging. The sensor performs an adaptive one-bit quantization at each pixel, with the pixel output switched from 0 to 1 only if the number of photons reaching that pixel is greater than or equal to a quantization threshold. With an oracle knowledge of the incident light intensity, one can pick an optimal threshold (for that light intensity) and the corresponding Fisher information contained in the output sequence follows closely that of an ideal unquantized sensor over a wide range of intensity values. This observation suggests the potential gains one may achieve by adaptively updating the quantization thresholds. As the main contribution of this work, we propose a time-sequential threshold-updating rule that asymptotically approaches the performance of the oracle scheme. With every threshold mapped to a number of ordered states, the dynamics of the proposed scheme can be modeled as a parametric Markov chain. We show that the frequencies of different thresholds converge to a steady-state distribution that is concentrated around the optimal choice. Moreover, numerical experiments show that the theoretical performance measures (Fisher information and Craḿer-Rao bounds) can be achieved by a maximum likelihood estimator, which is guaranteed to find globally optimal solution due to the concavity of the log-likelihood functions. Compared with conventional image sensors and the strategy that utilizes a constant single-photon threshold considered in previous work, the proposed scheme attains orders of magnitude improvement in terms of sensor dynamic ranges.

Exploiting the speckle-correlation scattering matrix for a compact reference-free holographic image sensor.

PubMed

Lee, KyeoReh; Park, YongKeun

2016-10-31

The word 'holography' means a drawing that contains all of the information for light-both amplitude and wavefront. However, because of the insufficient bandwidth of current electronics, the direct measurement of the wavefront of light has not yet been achieved. Though reference-field-assisted interferometric methods have been utilized in numerous applications, introducing a reference field raises several fundamental and practical issues. Here we demonstrate a reference-free holographic image sensor. To achieve this, we propose a speckle-correlation scattering matrix approach; light-field information passing through a thin disordered layer is recorded and retrieved from a single-shot recording of speckle intensity patterns. Self-interference via diffusive scattering enables access to impinging light-field information, when light transport in the diffusive layer is precisely calibrated. As a proof-of-concept, we demonstrate direct holographic measurements of three-dimensional optical fields using a compact device consisting of a regular image sensor and a diffusor.

Performance of light sources and radiation sensors under low gravity realized by parabolic airplane flights

NASA Astrophysics Data System (ADS)

Hirai, Hiroaki; Kitaya, Yoshiaki; Hirai, Takehiro

A fundamental study was conducted to establish an experimental system for space farming. Since to ensure optimal light for plant cultivation in space is of grave importance, this study examined the performance of light sources and radiation sensors under microgravity conditions created during the parabolic airplane flight. Three kinds of light sources, a halogen bulb, a fluorescent tube, and blue and red LEDs, and ten models of radiation sensors available in the market were used for the experiment. Surface temperature of the light sources, output signals from the radiation sensors, spectroscopic characteristics were measured at the gravity levels of 0.01, 1.0 and 1.8 G for 20 seconds each during parabolic airplane flights. As a result, the performance of the halogen lamp was affected the most by the gravity level among the three light sources. Under the microgravity conditions which do not raise heat convection, the temperature of the halogen lamp rose and the output of the radiation sensors increased. Spectral distributions of the halogen lamp indicated that peak wavelength appeared the highest at the level of 0.01G, which contributed to the increase in light intensity. In the case of red and blue LEDs, which are promising light sources in space farming, the temperature of both LED chips rose but irradiance from red LED increased and that from blue LED decreased under microgravity conditions due to the different thermal characteristics.

Temperature Dependence of Brillouin Light Scattering Spectra of Acoustic Phonons in Silicon

NASA Astrophysics Data System (ADS)

Somerville, Kevin; Klimovich, Nikita; An, Kyongmo; Sullivan, Sean; Weathers, Annie; Shi, Li; Li, Xiaoqin

2015-03-01

Thermal management represents an outstanding challenge in many areas of technology. Electrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. Interest in non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report temperature dependent BLS spectra of silicon, with Raman spectra taken simultaneously for comparison. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons. We determine that the integrated BLS intensity can be used measure the temperature of specific acoustic phonon modes. This work is supported by National Science Foundation (NSF) Thermal Transport Processes Program under Grant CBET-1336968.

Clinical measuring system for the form and position errors of circular workpieces using optical fiber sensors

NASA Astrophysics Data System (ADS)

Tan, Jiubin; Qiang, Xifu; Ding, Xuemei

1991-08-01

Optical sensors have two notable advantages in modern precision measurement. One is that they can be used in nondestructive measurement because the sensors need not touch the surfaces of workpieces in measuring. The other one is that they can strongly resist electromagnetic interferences, vibrations, and noises, so they are suitable to be used in machining sites. But the drift of light intensity and the changing of the reflection coefficient at different measuring positions of a workpiece may have great influence on measured results. To solve the problem, a spectroscopic differential characteristic compensating method is put forward. The method can be used effectively not only in compensating the measuring errors resulted from the drift of light intensity but also in eliminating the influence to measured results caused by the changing of the reflection coefficient. Also, the article analyzes the possibility of and the means of separating data errors of a clinical measuring system for form and position errors of circular workpieces.

Active optical sensors for tree stem detection and classification in nurseries.

PubMed

Garrido, Miguel; Perez-Ruiz, Manuel; Valero, Constantino; Gliever, Chris J; Hanson, Bradley D; Slaughter, David C

2014-06-19

Active optical sensing (LIDAR and light curtain transmission) devices mounted on a mobile platform can correctly detect, localize, and classify trees. To conduct an evaluation and comparison of the different sensors, an optical encoder wheel was used for vehicle odometry and provided a measurement of the linear displacement of the prototype vehicle along a row of tree seedlings as a reference for each recorded sensor measurement. The field trials were conducted in a juvenile tree nursery with one-year-old grafted almond trees at Sierra Gold Nurseries, Yuba City, CA, United States. Through these tests and subsequent data processing, each sensor was individually evaluated to characterize their reliability, as well as their advantages and disadvantages for the proposed task. Test results indicated that 95.7% and 99.48% of the trees were successfully detected with the LIDAR and light curtain sensors, respectively. LIDAR correctly classified, between alive or dead tree states at a 93.75% success rate compared to 94.16% for the light curtain sensor. These results can help system designers select the most reliable sensor for the accurate detection and localization of each tree in a nursery, which might allow labor-intensive tasks, such as weeding, to be automated without damaging crops.

A novel inter-fibre light coupling sensor probe using plastic optical fibre for ethanol concentration monitoring at initial production rate

NASA Astrophysics Data System (ADS)

Memon, Sanober F.; Lewis, Elfed; Pembroke, J. Tony; Chowdhry, Bhawani S.

2017-04-01

A novel, low cost and highly sensitive optical fibre probe sensor for concentration measurement of ethanol solvent (C2H5OH) corresponding to bio-ethanol production rate by an algae is reported. The principle of operation of the sensor is based on inter-fibre light coupling through an evanescent field interaction to couple the light between two multimode fibres mounted parallel to each other at a minimum possible separation i.e. < 1mm. The sensor was fabricated using a low cost 1000um plastic optical fibre (POF) and was characterized for real time measurement in the broadband spectrum including visible and near infra-red. The wavelength dependency of this sensor design was also investigated by post processing analysis of real time data and hence the optimum wavelength range determined. The proposed sensor has shown significant response in the range of 0.005 - 0.1 %v/v (%volume/volume or volume concentration) which depicts the high sensitivity for monitoring very minute changes in concentration corresponding refractive index changes of the solution. Numerically, sensor has shown the sensitivity of 21945 intensity counts/%v/v or 109.7 counts per every 0.0050 %v/v.

UV-Assisted Alcohol Sensors using Gallium Nitride Nanowires Functionalized with Zinc Oxide and Tin Dioxide Nanoparticles

NASA Astrophysics Data System (ADS)

Bajpai, Ritu

The motivation behind this work has been to address two of the most challenging issues posed to semiconductor gas sensors--- tuning the device selectivity and sensitivity to a wide variety of gases. In a chemiresistor type nanowire sensor, the sensitivity and selectivity depend on the interaction of different chemical analytes with the nanowire surface. Constrained by the surface properties of the nanowire material, most nanowire sensors can detect only specific type of analytes. In order to make a nano-sensor array for a wide range of analytes, there is a need to tune the device sensitivity and selectivity towards different chemicals. Employing the inherent advantages of nanostructure based sensing such as large surface area, miniature size, low power consumption, and nmol/mol (ppb) sensitivity, an attempt has been made to propose a device with tunable selectivity and sensitivity. The idea proposed in this work is to functionalize GaN nanowires which have relatively inactive surface properties (i.e., with no chemiresistive sensitivity to different classes of organic vapors), with analyte dependent active metal oxides. The selectivity of the sensor devices is controlled independent of the surface properties of the nanowire itself. It is the surface properties of the functionalizing metal oxides which determine the selectivity of these sensors. Further facilitated by the proposed fabrication technique, these sensors can be easily tuned to detect different gases. The prototype developed in this work is that of a UV assisted alcohol sensor using GaN nanowires functionalized with ZnO and SnO2 nanoparticles. As opposed to the widely demonstrated metal oxide based sensors assisted by elevated temperature, the operation of photoconductive semiconductor sensor devices such as those fabricated in this work, can also be assisted by UV illumination at room temperature. Temperature assisted sensing requires an integrated on-chip heater, which could impose constraints on the device fabrication process conditions. Additionally, light assisted sensing can be employed to tailor device response towards an analyte as demonstrated in this work. Therefore, there are two control knobs available for these sensor devices which are independent of the nanowire surface properties: i) sensor selectivity, regulated by the nanoparticle material selection ii) percentage response, tuned by the intensity of the incident light. Due to the small magnitude of device operating current and sensor activation at low illumination intensity (375 nW/cm2 at 365 nm wavelength has been used in this work), these sensors have low power consumption which makes them suitable for portable battery assisted operation. A fabrication recipe for freely suspended two-terminal nanowire devices has been developed. The deposition of nanoparticles was performed using the sputter deposition technique. A change in device current was observed when the device was exposed to alcohol vapors (methanol, ethanol, propanol, and butanol) at room temperature under 215 nm--400 nm UV illumination at 365 nm wavelength. The sensor reproducibly responded to a wide range of alcohol vapor concentrations, from 5000 mumol/mol (ppm) down to 200 nmol/mol (ppb) in air. Notably, the devices show low sensitivity to acetone and hexane, which allows them to selectively detect the alcohol vapors mixed with these two common volatile organic compounds (VOCs). The sensor response was not observed without UV excitation. To make a simplified quantitative and qualitative study of the sensitivity variation with variation of light intensity, the behavior of ZnO nanowire sensor devices was investigated in addition to the hybrid metal-oxide nanoparticle/GaN nanowire devices. With an increase in the light intensity, a corresponding increase in the device sensitivity was observed. In addition to the proposed sensor fabrication technique being a highly suitable candidate for making nano-sensor arrays for detection of a wide range of gases, the alcohol sensors fabricated in this work have many practical applications such as monitoring air quality, and testing the blood alcohol content (BAC) for impaired drivers.

Au-Graphene Hybrid Plasmonic Nanostructure Sensor Based on Intensity Shift

PubMed Central

Alharbi, Raed; Irannejad, Mehrdad; Yavuz, Mustafa

2017-01-01

Integrating plasmonic materials, like gold with a two-dimensional material (e.g., graphene) enhances the light-material interaction and, hence, plasmonic properties of the metallic nanostructure. A localized surface plasmon resonance sensor is an effective platform for biomarker detection. They offer a better bulk surface (local) sensitivity than a regular surface plasmon resonance (SPR) sensor; however, they suffer from a lower figure of merit compared to that one in a propagating surface plasmon resonance sensors. In this work, a decorated multilayer graphene film with an Au nanostructures was proposed as a liquid sensor. The results showed a significant improvement in the figure of merit compared with other reported localized surface plasmon resonance sensors. The maximum figure of merit and intensity sensitivity of 240 and 55 RIU−1 (refractive index unit) at refractive index change of 0.001 were achieved which indicate the capability of the proposed sensor to detect a small change in concentration of liquids in the ng/mL level which is essential in early-stage cancer disease detection. PMID:28106850

Fiber optic laser-induced breakdown spectroscopy sensor for molten material analysis

DOEpatents

Zhang, Hansheng; Rai, Awadesh K.; Singh, Jagdish P.; Yueh, Fang-Yu

2004-07-13

A fiber optic laser-induced breakdown spectroscopy (LIBS) sensor, including a laser light source, a harmonic separator for directing the laser light, a dichroic mirror for reflecting the laser light, a coupling lens for coupling the laser light at an input of a multimode optical fiber, a connector for coupling the laser light from an output of the multimode optical fiber to an input of a high temperature holder, such as a holder made of stainless steel, and a detector portion for receiving emission signal and analyzing LIBS intensities. In one variation, the multimode optical fiber has silica core and silica cladding. The holder includes optical lenses for collimating and focusing the laser light in a molten alloy to produce a plasma, and for collecting and transmitting an emission signal to the multimode optical fiber.

Temperature dependence of Brillouin light scattering spectra of acoustic phonons in silicon

NASA Astrophysics Data System (ADS)

Olsson, Kevin S.; Klimovich, Nikita; An, Kyongmo; Sullivan, Sean; Weathers, Annie; Shi, Li; Li, Xiaoqin

2015-02-01

Electrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. The need for a better understanding of such non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report the measured BLS spectra of silicon at different temperatures. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons.

Impact damage monitoring in CFRP using fiber Bragg grating ultrasound sensors

NASA Astrophysics Data System (ADS)

Tsuda, Hiroshi; Lee, Jung-Ryul; Eguchi, Shunji

2006-03-01

Impact damage in CFRP was monitored by ultrasonic inspection method using small-diameter fiber Bragg grating (FBG) sensors. The FBG ultrasound detection system consisted of broadband light source, FBG sensor and tunable optical filter. Broadband light was launched into the FBG sensor. Light reflected from the FBG sensor was transmitted through the tunable optical filter whose transmissive wavelength range is comparable to the reflected wavelength range of the FBG sensor. The operating wavelength of tunable filter was set to optimize the sensitivity of ultrasound detection. Ultrasound vibration was converted into change in intensity of light transmitted through the filter. A cross-ply carbon fiber-reinforced plastic (CFRP) plate was used as a test specimen for impact damage monitoring. A 6.3 X 9mm2 impact damage was introduced by ball dropping. Both FBG ultrasound sensor and piezoelectric ultrasound transmitter were attached on the CFRP surface. The change in responses to ultrasound excited by either spike signal or toneburst signal before and after impact damage was investigated. In response to ultrasound excited by spike signal, the response after impact damage showed a scattered behavior where the period of response signal got longer. In response to ultrasound excited by toneburst signal, damage signal features scattered and distorted waveform. Experimental results proved that the FBG inspection system could monitor a 6.3 X 9mm2 impact damage in CFRP.

Distributed fluorescent optical fiber proximity sensor: Towards a proof of concept

NASA Astrophysics Data System (ADS)

Gălătuș, Ramona; Faragó, Paul; Miluski, Piotr; Valles, Juan-Antonio

2018-06-01

Fluorescent fibers are optical fibers which emit light as a response to an incident phenomenon, usually an incident light. Operation depends on the doping dyes, which determine specific fluorescence and optical characteristics useful in the development of optical sensors. In this work we propose a low-cost distributed proximity sensor implemented using a red fluorescent fiber, to provide a security option for a surface plasmon resonance system. Operation of the proposed sensor relies on having the incident illumination intensity varied by the presence or absence of an obstacle in the vicinity of the sensing element. This will influence the radiated fluorescence accordingly. The proposed setup for the implementation of the optical proximity sensor assumes having a high brightness LED deployed for axial fiber illumination and a blue LED for side illumination. Electronic processing then accounts for gain and digitization. Measurement results of the prototype validate the proposed concept.

Reduced Fluoresceinamine as a Fluorescent Sensor for Nitric Oxide

PubMed Central

Duarte, Abel J.; Esteves da Silva, Joaquim C.G.

2010-01-01

A new fluorescent sensor for nitric oxide (NO) is presented that is based on its reaction with a non fluorescent substance, reduced fluoresceinamine, producing the highly fluorescent fluoresceinamine. Using a portable homemade stabilized light source consisting of 450 nm LED and fiber optics to guide the light, the sensor responds linearly within seconds in the NO concentration range between about 10–750 μM with a limit of detection (LOD) of about 1 μM. The system generated precise intensity readings, with a relative standard deviation of less than 1%. The suitability of the sensor was assessed by monitoring the NO generated by either the nitrous acid decomposition reaction or from a NO-releasing compound. Using relatively high incubation times, the sensor also responds quantitatively to hydrogen peroxide and potassium superoxide, however, using transient signal measurements results in no interfering species. PMID:22294892

Improvement of plastic optical fiber microphone based on moisture pattern sensing in devoiced breath

NASA Astrophysics Data System (ADS)

Taki, Tomohito; Honma, Satoshi; Morisawa, Masayuki; Muto, Shinzo

2008-03-01

Conversation is the most practical and common form in communication. However, people with a verbal handicap feel a difficulty to produce words due to variations in vocal chords. This research leads to develop a new devoiced microphone system based on distinguishes between the moisture patterns for each devoiced breaths, using a plastic optical fiber (POF) moisture sensor. In the experiment, five POF-type moisture sensors with fast response were fabricated by coating swell polymer with a slightly larger refractive index than that of fiber core and were set in front of mouth. When these sensors are exposed into humid air produced by devoiced breath, refractive index in cladding layer decreases by swelling and then the POF sensor heads change to guided type. Based on the above operation principle, the output light intensities from the five sensors set in front of mouth change each other. Using above mentioned output light intensity patterns, discernment of devoiced vowels in Japanese (a,i,u,e,o) was tried by means of DynamicProgramming-Matching (DP-matching) method. As the result, distinction rate over 90% was obtained to Japanese devoiced vowels. Therefore, using this system and a voice synthesizer, development of new microphone for the person with a functional disorder in the vocal chords seems to be possible.

Non-enzymatic glucose detection based on phenylboronic acid modified optical fibers

NASA Astrophysics Data System (ADS)

Sun, Xiaolan; Li, Nana; Zhou, Bin; Zhao, Wei; Liu, Liyuan; Huang, Chao; Ma, Longfei; Kost, Alan R.

2018-06-01

A non-enzymatic, sensitive glucose sensor was fabricated based on an evanescent wave absorbing optical fiber probe. The optical fiber sensor was functionalized by fixing a poly (phenylboronic acid) (polyPBA) film onto the conical region of the single mode fiber. The reflected light intensity of the polyPBA-functionalized fiber sensor increased proportionally with glucose concentration in the range of 0-60 mM, and the sensor showed good reproducibility and stability. The developed sensor possessed a high sensitivity of 0.1787%/mM and good linearity. The measurement of glucose concentration in human serum was also demonstrated.

Dual-mode photosensitive arrays based on the integration of liquid crystal microlenses and CMOS sensors for obtaining the intensity images and wavefronts of objects.

PubMed

Tong, Qing; Lei, Yu; Xin, Zhaowei; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

2016-02-08

In this paper, we present a kind of dual-mode photosensitive arrays (DMPAs) constructed by hybrid integration a liquid crystal microlens array (LCMLA) driven electrically and a CMOS sensor array, which can be used to measure both the conventional intensity images and corresponding wavefronts of objects. We utilize liquid crystal materials to shape the microlens array with the electrically tunable focal length. Through switching the voltage signal on and off, the wavefronts and the intensity images can be acquired through the DMPAs, sequentially. We use white light to obtain the object's wavefronts for avoiding losing important wavefront information. We separate the white light wavefronts with a large number of spectral components and then experimentally compare them with single spectral wavefronts of typical red, green and blue lasers, respectively. Then we mix the red, green and blue wavefronts to a composite wavefront containing more optical information of the object.

Study of Submicron Particle Size Distributions by Laser Doppler Measurement of Brownian Motion.

DTIC Science & Technology

1984-10-29

o ..... . 5-1 A.S *6NEW DISCOVERIES OR INVENTIONS .. o......... ......... 6-1 APPENDIX: COMPUTER SIMULATION OF THE BROWNIAN MOTION SENSOR SIGNALS...scattering regime by analysis of the scattered light intensity and particle mass (size) obtained using the Brownian motion sensor . 9 Task V - By application...of the Brownian motion sensor in a flat-flame burner, the contractor shall assess the application of this technique for In-situ sizing of submicron

An optical fiber Bragg grating and piezoelectric ceramic voltage sensor

NASA Astrophysics Data System (ADS)

Yang, Qing; He, Yanxiao; Sun, Shangpeng; Luo, Mandan; Han, Rui

2017-10-01

Voltage measurement is essential in many fields like power grids, telecommunications, metallurgy, railways, and oil production. A voltage-sensing unit, consisting of fiber Bragg gratings (FBGs) and piezoelectric ceramics, based on which an optical over-voltage sensor was proposed and fabricated in this paper. No demodulation devices like spectrometer or Fabry-Perot filter were needed to gain the voltage signal, and a relatively large sensing frequency range was acquired in this paper; thus, the cost of the sensing system is more acceptable in engineering application. The voltage to be measured was directly applied to the piezoelectric ceramic, and deformation of the ceramics and the grating would be caused because of the inverse piezoelectric effect. With a reference grating, the output light intensity change will be caused by the FBG center wavelength change; thus, the relationship between the applied voltage and the output light intensity was established. Validation of the sensor was accomplished in the frequency range from 50 Hz to 20 kHz and switching impulse waves with a test platform; good linearity of the input-output characteristic was achieved. A temperature validation test was completed, showing that the sensor maintains good temperature stability. Experimental results show that the optical over-voltage sensor can be used for voltage monitoring, and if applied with a voltage divider, the sensor can be used to measure high voltage.

An optical fiber Bragg grating and piezoelectric ceramic voltage sensor.

PubMed

Yang, Qing; He, Yanxiao; Sun, Shangpeng; Luo, Mandan; Han, Rui

2017-10-01

Voltage measurement is essential in many fields like power grids, telecommunications, metallurgy, railways, and oil production. A voltage-sensing unit, consisting of fiber Bragg gratings (FBGs) and piezoelectric ceramics, based on which an optical over-voltage sensor was proposed and fabricated in this paper. No demodulation devices like spectrometer or Fabry-Perot filter were needed to gain the voltage signal, and a relatively large sensing frequency range was acquired in this paper; thus, the cost of the sensing system is more acceptable in engineering application. The voltage to be measured was directly applied to the piezoelectric ceramic, and deformation of the ceramics and the grating would be caused because of the inverse piezoelectric effect. With a reference grating, the output light intensity change will be caused by the FBG center wavelength change; thus, the relationship between the applied voltage and the output light intensity was established. Validation of the sensor was accomplished in the frequency range from 50 Hz to 20 kHz and switching impulse waves with a test platform; good linearity of the input-output characteristic was achieved. A temperature validation test was completed, showing that the sensor maintains good temperature stability. Experimental results show that the optical over-voltage sensor can be used for voltage monitoring, and if applied with a voltage divider, the sensor can be used to measure high voltage.

A plastic total internal reflection-based photoluminescence device for enzymatic biosensors

NASA Astrophysics Data System (ADS)

Thakkar, Ishan G.

Growing concerns for quality of water, food and beverages in developing and developed countries drive sizeable markets for mass-producible, low cost devices that can measure the concentration of contaminant chemicals in water, food, and beverages rapidly and accurately. Several fiber-optic enzymatic biosensors have been reported for these applications, but they exhibit very strong presence of scattered excitation light in the signal for sensing, requiring expensive thin-film filters, and their non-planar structure makes them challenging to mass-produce. Several other planar optical waveguide-based biosensors prove to be relatively costly and more fragile due to constituent materials and the techniques involved in their fabrication. So, a plastic total internal reflection (TIR)-based low cost, low scatter, field-portable device for enzymatic biosensors is fabricated and demonstrated. The design concept of the TIR-based photoluminescent enzymatic biosensor device is explained. An analysis of economical materials with appropriate optical and chemical properties is presented. PMMA and PDMS are found to be appropriate due to their high chemical resistance, low cost, high optical transmittance and low auto-fluorescence. The techniques and procedures used for device fabrication are discussed. The device incorporated a PMMA-based optical waveguide core and PDMS-based fluid cell with simple multi-mode fiber-optics using cost-effective fabrication techniques like molding and surface modification. Several techniques of robustly depositing photoluminescent dyes on PMMA core surface are discussed. A pH-sensitive fluorescent dye, fluoresceinamine, and an O2-sensitive phosphorescent dye, Ru(dpp) both are successfully deposited using Si-adhesive gel-based as well as HydroThane-based deposition methods. Two different types of pH-sensors using two different techniques of depositing fluoresceinamine are demonstrated. Also, the effect of concentration of fluoresceinamine-dye molecules on fluorescence intensity and scattered excitation light intensity is investigated. The fluorescence intensity to the scattered excitation light intensity ratio for dye deposition is found to increase with increase in concentration. However, both the absolute fluorescence intensity and absolute scatter intensity are found to decrease in different amounts with an increase in concentration. An enzymatic hydrogen peroxide (H2O2) sensor is made and demonstrated by depositing Ruthenium-based phosphorescent dye (Ru(dpp) 3) and catalase-enzyme on the surface of the waveguide core. The O 2-sensitive phosphorescence of Ru(dpp)3 is used as a transduction signal and the catalase-enzyme is used as a bio-component for sensing. The H2O2 sensor exhibits a phosphorescence signal to scattered excitation light ratio of 100+/-18 without filtering. The unfiltered device demonstrates a detection limit of (2.20+/-0.6) microM with the linear range from 200microM to 20mM. An enzymatic lactose sensor is designed and characterized using Si-adhesive gel based Ru(dpp)3 deposition and oxidase enzyme. The lactose sensor exhibits the linear range of up to 0.8mM, which is too small for its application in industrial process control. So, a flow cell-based sensor device with a fluid reservoir is proposed and fabricated to increase the linear range of the sensor. Also, a multi-channel pH-sensor device with four channels is designed and fabricated for simultaneous sensing of multiple analytes.

Monolithic LED arrays, next generation smart lighting sources

NASA Astrophysics Data System (ADS)

Lagrange, Alexandre; Bono, Hubert; Templier, François

2016-03-01

LED have become the main light sources of the future as they open the path for intelligent use of light in time, intensity and color. In many usages, strong energy economy is done by adjusting these properties. The smart lighting has three dimensions, energy efficiency brought by GaN blue emitting LEDs, integration of electronics, sensors, microprocessors in the lighting system and development of new functionalities and services provided by the light. Monolithic LED arrays allow two major innovations, the spatial control of light emission and the adjustment of the electrical properties of the source.

Multifuctional integrated sensors (MFISES).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Homeijer, Brian D.; Roozeboom, Clifton

2015-10-01

Many emerging IoT applications require sensing of multiple physical and environmental parameters for: completeness of information, measurement validation, unexpected demands, improved performance. For example, a typical outdoor weather station measures temperature, humidity, barometric pressure, light intensity, rainfall, wind speed and direction. Existing sensor technologies do not directly address the demand for cost, size, and power reduction in multi-paramater sensing applications. Industry sensor manufacturers have developed integrated sensor systems for inertial measurements that combine accelerometers, gyroscopes, and magnetometers, but do not address environmental sensing functionality. In existing research literature, a technology gap exists between the functionality of MEMS sensors and themore » real world applications of the sensors systems.« less

[Spectral analysis of fiber bragg grating modulated by double long period grating and its application in smart structure monitoring].

PubMed

Lu, Ji-Yun; Liang, Da-Kai; Zhang, Xiao-Li; Zhu, Zhu

2009-12-01

Spectrum of fiber bragg grating (FBG) sensor modulated by double long period grating (LPFG) is proposed in the paper. Double LPFG consists of two LPFGS whose center wavelengths are the same and reflection spectrum of FBG sensor is located in linear range of double LPFG transmission spectrum. Based on spectral analysis of FBG and double LPFG, reflection spectrum of FBG modulated by double LPFG is obtained and studied by use of band-hider filter characteristics for double LPFG. An FBG sensor is attached on the surface of thin steel beam, which is strained by bending, and the center wavelength of FBG sensor will shift. The spectral peak of FBG sensor modulated by double LPFG is changed correspondingly, and the spectral change will lead to variation in exit light intensity from double LPFG. Experiment demonstrates that the relation of filtering light intensity from double LPFG monitored by optical power meter to center wavelength change of FBG sensor is linear and the minimum strain of material (steel beam) detected by the modulation and demodulation system is 1.05 microepsilon. This solution is used in impact monitoring of optical fibre smart structure, and FBG sensor is applied for impulse response signal monitoring induced by low-velocity impact, when impact pendulum is loaded to carbon fiber-reinforced plastics (CFP). The acquired impact response signal and fast Fourier transform of the signal detected by FBG sensor agree with the measurement results of eddy current displacement meter attached to the FBG sensor. From the results, the present method using FBG sensor is found to be effective for monitoring the impact. The research provides a practical reference in dynamic monitoring of optical fiber smart structure field.

Exploiting the speckle-correlation scattering matrix for a compact reference-free holographic image sensor

PubMed Central

Lee, KyeoReh; Park, YongKeun

2016-01-01

The word ‘holography' means a drawing that contains all of the information for light—both amplitude and wavefront. However, because of the insufficient bandwidth of current electronics, the direct measurement of the wavefront of light has not yet been achieved. Though reference-field-assisted interferometric methods have been utilized in numerous applications, introducing a reference field raises several fundamental and practical issues. Here we demonstrate a reference-free holographic image sensor. To achieve this, we propose a speckle-correlation scattering matrix approach; light-field information passing through a thin disordered layer is recorded and retrieved from a single-shot recording of speckle intensity patterns. Self-interference via diffusive scattering enables access to impinging light-field information, when light transport in the diffusive layer is precisely calibrated. As a proof-of-concept, we demonstrate direct holographic measurements of three-dimensional optical fields using a compact device consisting of a regular image sensor and a diffusor. PMID:27796290

Development of an optical instrument to determine the pesticide residues in vegetables

NASA Astrophysics Data System (ADS)

Qiu, Zhengjun; Fang, Hui; Li, Weimin; He, Yong

2005-12-01

An optical instrument was developed to determine the pesticide residues in vegetables based on the inhibition rate of organophosphates against acrtyl-cholinesterase (AChE). The instrument consists mainly of a solid light source with 410nm wavelength, a sampling container to store the liquid, an optical sensor to test the intensity of transmission light, a temperature sensor, and a MCU based data acquisition board. The light illuminates the liquid in the sampling container, and the absorptivity was determined by the amount of the pesticide residues in the liquid. This paper involves the design of optical testing system, the data acquisition and calibration of the optical sensor, the design of microcontroller-based electrical board. Tests show that the absorption rate is related to the pesticide residues and it can be concluded that the pesticide residues exceed the normal level when the inhibition rate is over 50 percent.

Method and apparatus for optical temperature measurement

DOEpatents

O'Rourke, P.E.; Livingston, R.R.; Prather, W.S.

1994-09-20

A temperature probe and a method for using said probe for temperature measurements based on changes in light absorption by the probe are disclosed. The probe comprises a first and a second optical fiber that carry light to and from the probe, and a temperature sensor material, the absorbance of which changes with temperature, through which the light is directed. Light is directed through the first optical fiber, passes through the temperature sensor material, and is transmitted by a second optical fiber from the material to a detector. Temperature-dependent and temperature-independent factors are derived from measurements of the transmitted light intensity. For each sensor material, the temperature T is a function of the ratio, R, of these factors. The temperature function f(R) is found by applying standard data analysis techniques to plots of T versus R at a series of known temperatures. For a sensor having a known temperature function f(R) and known characteristic and temperature-dependent factors, the temperature can be computed from a measurement of R. Suitable sensor materials include neodymium-doped borosilicate glass, accurate to [+-]0.5 C over an operating temperature range of about [minus]196 C to 400 C; and a mixture of D[sub 2]O and H[sub 2]O, accurate to [+-]0.1 C over an operating range of about 5 C to 90 C. 13 figs.

Method and apparatus for optical temperature measurement

DOEpatents

O'Rourke, Patrick E.; Livingston, Ronald R.; Prather, William S.

1994-01-01

A temperature probe and a method for using said probe for temperature measurements based on changes in light absorption by the probe. The probe comprises a first and a second optical fiber that carry light to and from the probe, and a temperature sensor material, the absorbance of which changes with temperature, through which the light is directed. Light is directed through the first optical fiber, passes through the temperature sensor material, and is transmitted by a second optical fiber from the material to a detector. Temperature-dependent and temperature-independent factors are derived from measurements of the transmitted light intensity. For each sensor material, the temperature T is a function of the ratio, R, of these factors. The temperature function f(R) is found by applying standard data analysis techniques to plots of T versus R at a series of known temperatures. For a sensor having a known temperature function f(R) and known characteristic and temperature-dependent factors, the temperature can be computed from a measurement of R. Suitable sensor materials include neodymium-doped boresilicate glass, accurate to .+-.0.5.degree. C. over an operating temperature range of about -196.degree. C. to 400.degree. C.; and a mixture of D.sub.2 O and H.sub.2 O, accurate to .+-.0.1.degree. C. over an operating range of about 5.degree. C. to 90.degree. C.

Active Optical Sensors for Tree Stem Detection and Classification in Nurseries

PubMed Central

Garrido, Miguel; Perez-Ruiz, Manuel; Valero, Constantino; Gliever, Chris J.; Hanson, Bradley D.; Slaughter, David C.

2014-01-01

Active optical sensing (LIDAR and light curtain transmission) devices mounted on a mobile platform can correctly detect, localize, and classify trees. To conduct an evaluation and comparison of the different sensors, an optical encoder wheel was used for vehicle odometry and provided a measurement of the linear displacement of the prototype vehicle along a row of tree seedlings as a reference for each recorded sensor measurement. The field trials were conducted in a juvenile tree nursery with one-year-old grafted almond trees at Sierra Gold Nurseries, Yuba City, CA, United States. Through these tests and subsequent data processing, each sensor was individually evaluated to characterize their reliability, as well as their advantages and disadvantages for the proposed task. Test results indicated that 95.7% and 99.48% of the trees were successfully detected with the LIDAR and light curtain sensors, respectively. LIDAR correctly classified, between alive or dead tree states at a 93.75% success rate compared to 94.16% for the light curtain sensor. These results can help system designers select the most reliable sensor for the accurate detection and localization of each tree in a nursery, which might allow labor-intensive tasks, such as weeding, to be automated without damaging crops. PMID:24949638

Temperature dependence of Brillouin light scattering spectra of acoustic phonons in silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olsson, Kevin S.; Klimovich, Nikita; An, Kyongmo

2015-02-02

Electrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. The need for a better understanding of such non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report the measured BLS spectra of silicon at different temperatures. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in ordermore » to evaluate their potential use as temperature sensors for acoustic phonons.« less

Surface plasmon resonance sensor using vari-focal liquid lens under angular interrogation

NASA Astrophysics Data System (ADS)

Lee, Muyoung; Bang, Yousung; Lee, Jooho; Jang, Wonjae; Won, Yong Hyub

2017-02-01

In this paper, a surface plasmon resonance sensor for the detection of refractive index variation is presented. A novel waveguide type surface plasmon resonance sensing configuration with focal length variable liquid lens is introduced. The method of surface plasmon resonance sensor is based on the waveguide type with incident angle variation. The incident angle is varied by using an electrowetting liquid lens which is possible to actively change focal length as applying voltage. The optical system, which is adapted to electrowetting lens can continuously change the incident angle of light from 73 to 78 degrees with compact size. The surface plasmon waves are excited between metal and dielectric interface. The sensing surfaces are prepared by a coating of gold metal above high refractive index glass substrate. The incident light which is 532nm monochromatic light source passes through a noble metal coated substrate to detect intensity with incident angle variation. An analysis to distinguish the contribution of light with various incident angle is focused on the angular characteristics of the surface plasmon sensor under wavelength interrogation. The resonance angle is determined corresponding to sensing material refractive index with high sensitivity. The result suggests that the performance of surface plasmon resonance sensor can be improved by real time varying incident angle. From this presented study, it provides a different approach for angular interrogation surface plasmon resonance sensor and can be miniaturized for a portable device.

Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology.

PubMed

Strle, Drago; Nahtigal, Uroš; Batistell, Graciele; Zhang, Vincent Chi; Ofner, Erwin; Fant, Andrea; Sturm, Johannes

2015-07-22

This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode's current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm(2) of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA.

Illumination-based synchronization of high-speed vision sensors.

PubMed

Hou, Lei; Kagami, Shingo; Hashimoto, Koichi

2010-01-01

To acquire images of dynamic scenes from multiple points of view simultaneously, the acquisition time of vision sensors should be synchronized. This paper describes an illumination-based synchronization method derived from the phase-locked loop (PLL) algorithm. Incident light to a vision sensor from an intensity-modulated illumination source serves as the reference signal for synchronization. Analog and digital computation within the vision sensor forms a PLL to regulate the output signal, which corresponds to the vision frame timing, to be synchronized with the reference. Simulated and experimental results show that a 1,000 Hz frame rate vision sensor was successfully synchronized with 32 μs jitters.

Signal intensity enhancement of laser ablated volume holograms

NASA Astrophysics Data System (ADS)

Versnel, J. M.; Williams, C.; Davidson, C. A. B.; Wilkinson, T. D.; Lowe, C. R.

2017-11-01

Conventional volume holographic gratings (VHGs) fabricated in photosensitive emulsions such as gelatin containing silver salts enable the facile visualization of the holographic image in ambient lighting. However, for the fabrication of holographic sensors, which require more defined and chemically-functionalised polymer matrices, laser ablation has been introduced to create the VHGs and thereby broaden their applications, although the replay signal can be challenging to detect in ambient lighting. When traditional photochemical bleaching solutions used to reduce light scattering and modulate refractive index within the VHG are applied to laser ablated volume holographic gratings, these procedures decrease the holographic peak intensity. This is postulated to occur because both light and dark fringes contain a proportion of metal particles, which upon solubilisation are converted immediately to silver iodide, yielding no net refractive index modulation. This research advances a hypothesis that the reduced intensity of holographic replay signals is linked to a gradient of different sized metal particles within the emulsion, which reduces the holographic signal and may explain why traditional bleaching processes result in a reduction in intensity. In this report, a novel experimental protocol is provided, along with simulations based on an effective medium periodic 1D stack, that offers a solution to increase peak signal intensity of holographic sensors by greater than 200%. Nitric acid is used to etch the silver nanoparticles within the polymer matrix and is thought to remove the smaller particles to generate more defined metal fringes containing a soluble metal salt. Once the grating efficiency has been increased, this salt can be converted to a silver halide, to modulate the refractive index and increase the intensity of the holographic signal. This new protocol has been tested in a range of polymer chemistries; those containing functional groups that help to stabilize the metal nanoparticles within the matrix yield more intense holographic signals as the integrity of the fringe is more protected with increasing metal solubility.

Multiple approaches for enhancing all-organic electronics photoluminescent sensors: simultaneous oxygen and pH monitoring.

PubMed

Liu, Rui; Xiao, Teng; Cui, Weipan; Shinar, Joseph; Shinar, Ruth

2013-05-17

Key issues in using organic light emitting diodes (OLEDs) as excitation sources in structurally integrated photoluminescence (PL)-based sensors are the low forward light outcoupling, the OLEDs' broad electroluminescence (EL) bands, and the long-lived remnant EL that follows an EL pulse. The outcoupling issue limits the detection sensitivity (S) as only ~20% of the light generated within standard OLEDs can be forward outcoupled and used for sensor probe excitation. The EL broad band interferes with the analyte-sensitive PL, leading to a background that reduces S and dynamic range. In particular, these issues hinder designing compact sensors, potentially miniaturizable, that are devoid of optical filters and couplers. We address these shortcomings by introducing easy-to-employ multiple approaches for outcoupling improvement, PL enhancement, and background EL reduction leading to novel, compact all-organic device architectures demonstrated for simultaneous monitoring of oxygen and pH. The sensor comprises simply-fabricated, directionally-emitting, narrower-band, multicolor microcavity OLED excitation and small molecule- and polymer-based organic photodetectors (OPDs) with a more selective spectral response. Additionally, S and PL intensity for oxygen are enhanced by using polystyrene (PS):polyethylene glycol (PEG) blends as the sensing film matrix. By utilizing higher molecular weight PS, the ratio τ0/τ100 (PL decay time τ at 0% O2/τ at 100% O2) that is often used to express S increases ×1.9 to 20.7 relative to the lower molecular weight PS, where this ratio is 11.0. This increase reduces to ×1.7 when the PEG is added (τ0/τ100=18.2), but the latter results in an increase ×2.7 in the PL intensity. The sensor's response time is <10s in all cases. The microporous structure of these blended films, with PEG decorating PS pores, serves a dual purpose. It results in light scattering that reduces the EL that is waveguided in the substrate of the OLEDs and consequently enhances light outcoupling from the OLEDs by ~60%, and it increases the PL directed toward the OPD. The multiple functional structures of multicolor microcavity OLED pixels/microporous scattering films/OPDs enable generation of enhanced individually addressable sensor arrays, devoid of interfering issues, for O2 and pH as well as for other analytes and biochemical parameters. Copyright © 2013 Elsevier B.V. All rights reserved.

Effective application of optical sensing technology for sustainable liquid level sensing and rainfall measurement

NASA Astrophysics Data System (ADS)

Afzal, Muhammad Hassan Bin

2015-05-01

Rainfall measurement is performed on regular basis to facilitate effectively the weather stations and local inhabitants. Different types of rain gauges are available with different measuring principle for rainfall measurement. In this research work, a novel optical rain sensor is designed, which precisely calculate the rainfall level according to rainfall intensity. This proposed optical rain sensor model introduced in this paper, which is basically designed for remote sensing of rainfall and it designated as R-ORMS (Remote Optical Rainfall Measurement sensor). This sensor is combination of some improved method of tipping bucket rain gauge and most of the optical hydreon rain sensor's principle. This optical sensor can detect the starting time and ending time of rain, rain intensity and rainfall level. An infrared beam from Light Emitting Diode (LED) through powerful convex lens can accurately determines the diameter of each rain drops by total internal reflection principle. Calculations of these accumulative results determine the rain intensity and rainfall level. Accurate rainfall level is determined by internal optical LED based sensor which is embedded in bucket wall. This internal sensor is also following the total internal reflection (TIR) principle and the Fresnel's law. This is an entirely novel design of optical sensing principle based rain sensor and also suitable for remote sensing rainfall level. The performance of this proposed sensor has been comprehensively compared with other sensors with similar attributes and it showed better and sustainable result. Future related works have been proposed at the end of this paper, to provide improved and enhanced performance of proposed novel rain sensor.

Design of fiber optic based respiratory sensor for newborn incubator application

NASA Astrophysics Data System (ADS)

Dhia, Arika; Devara, Kresna; Abuzairi, Tomy; Poespawati, N. R.; Purnamaningsih, Retno W.

2018-02-01

This paper reports the design of respiratory sensor using fiber optic for newborn incubator application. The sensor works based on light intensity losses difference obtained due to thorax movement during respiration. The output of the sensor launched to support electronic circuits to be processed in Arduino Uno microcontroler such that the real-time respiratory rate (breath per minute) can be presented on LCD. Experiment results using thorax expansion of newborn simulator show that the system is able to measure respiratory rate from 10 up to 130 breaths per minute with 0.595% error and 0.2% hysteresis error.

Optical and Electric Multifunctional CMOS Image Sensors for On-Chip Biosensing Applications

PubMed Central

Tokuda, Takashi; Noda, Toshihiko; Sasagawa, Kiyotaka; Ohta, Jun

2010-01-01

In this review, the concept, design, performance, and a functional demonstration of multifunctional complementary metal-oxide-semiconductor (CMOS) image sensors dedicated to on-chip biosensing applications are described. We developed a sensor architecture that allows flexible configuration of a sensing pixel array consisting of optical and electric sensing pixels, and designed multifunctional CMOS image sensors that can sense light intensity and electric potential or apply a voltage to an on-chip measurement target. We describe the sensors’ architecture on the basis of the type of electric measurement or imaging functionalities. PMID:28879978

An Automated Flying-Insect-Detection System

NASA Technical Reports Server (NTRS)

Vann, Timi; Andrews, Jane C.; Howell, Dane; Ryan, Robert

2005-01-01

An automated flying-insect-detection system (AFIDS) was developed as a proof-of-concept instrument for real-time detection and identification of flying insects. This type of system has use in public health and homeland security decision support, agriculture and military pest management, and/or entomological research. Insects are first lured into the AFIDS integrated sphere by insect attractants. Once inside the sphere, the insect's wing beats cause alterations in light intensity that is detected by a photoelectric sensor. Following detection, the insects are encouraged (with the use of a small fan) to move out of the sphere and into a designated insect trap where they are held for taxonomic identification or serological testing. The acquired electronic wing beat signatures are preprocessed (Fourier transformed) in real-time to display a periodic signal. These signals are sent to the end user where they are graphically displayed. All AFIDS data are pre-processed in the field with the use of a laptop computer equipped with LABVIEW. The AFIDS software can be programmed to run continuously or at specific time intervals when insects are prevalent. A special DC-restored transimpedance amplifier reduces the contributions of low-frequency background light signals, and affords approximately two orders of magnitude greater AC gain than conventional amplifiers. This greatly increases the signal-to-noise ratio and enables the detection of small changes in light intensity. The AFIDS light source consists of high-intensity Al GaInP light-emitting diodes (LEDs). The AFIDS circuitry minimizes brightness fluctuations in the LEDs and when integrated with an integrating sphere, creates a diffuse uniform light field. The insect wing beats isotropically scatter the diffuse light in the sphere and create wing beat signatures that are detected by the sensor. This configuration minimizes variations in signal associated with insect flight orientation.

Fiber optic and laser sensors IX; Proceedings of the Meeting, Boston, MA, Sept. 3-5, 1991

NASA Technical Reports Server (NTRS)

Depaula, Ramon P. (Editor); Udd, Eric (Editor)

1991-01-01

The present volume on fiber-optic and laser sensors discusses industrial applications of fiber-optic sensors, fiber-optic temperature sensors, fiber-optic current sensors, fiber-optic pressure/displacement/vibration sensors, and generic fiber-optic systems. Attention is given to a fiber-sensor design for turbine engines, fiber-optic remote Fourier transform IR spectroscopy, near-IR fiber-optic temperature sensors, and an intensity-type fiber-optic electric current sensor. Topics addressed include fiber-optic magnetic field sensors based on the Faraday effect in new materials, diaphragm size and sensitivity for fiber-optic pressure sensors, a microbend pressure sensor for high-temperature environments, and linear position sensing by light exchange between two lossy waveguides. Also discussed are two-mode elliptical-core fiber sensors for measurement of strain and temperature, a fiber-optic interferometric X-ray dosimeter, fiber-optic interferometric sensors using multimode fibers, and optical fiber sensing of corona discharges.

Monitoring of Solar Radiation Intensity using Wireless Sensor Network for Plant Growing

NASA Astrophysics Data System (ADS)

Siregar, B.; Fadli, F.; Andayani, U.; Harahap, LA; Fahmi, F.

2017-01-01

Abstract— Plant growth is highly depending on the sunlight, if the consumption of sunlight is enough, it will grow well. The plant will be green because of its chlorophyll and it can perform photosynthesis at maximum; but if the plants get less sunlight, it will make the plants be yellowing. Radiation is electromagnetic waves that are good for plants, so-called visible light. In the electromagnetic wave spectrum the best wavelength range from 400-700 nm for the plant. A monitoring of sun intensity is needed in order to obtain sufficient solar radiation consumption and provide notification if there is a high radiation. In this study, several sensors and devices were combined such as photosynthetic solar radiation sensors, GSM / GPRS and waspmote as a main board or a microcontroller. The test was carried out on at least three occasions; the system has a stable radiation in the morning with an average of 505.51 micrometers. IN this study, we have successfully developed a monitoring tools for solar radiation intensity applied on plant growth by using wireless sensor network.

A portable smart phone-based plasmonic nanosensor readout platform that measures transmitted light intensities of nanosubstrates using an ambient light sensor.

PubMed

Fu, Qiangqiang; Wu, Ze; Xu, Fangxiang; Li, Xiuqing; Yao, Cuize; Xu, Meng; Sheng, Liangrong; Yu, Shiting; Tang, Yong

2016-05-21

Plasmonic nanosensors may be used as tools for diagnostic testing in the field of medicine. However, quantification of plasmonic nanosensors often requires complex and bulky readout instruments. Here, we report the development of a portable smart phone-based plasmonic nanosensor readout platform (PNRP) for accurate quantification of plasmonic nanosensors. This device operates by transmitting excitation light from a LED through a nanosubstrate and measuring the intensity of the transmitted light using the ambient light sensor of a smart phone. The device is a cylinder with a diameter of 14 mm, a length of 38 mm, and a gross weight of 3.5 g. We demonstrated the utility of this smart phone-based PNRP by measuring two well-established plasmonic nanosensors with this system. In the first experiment, the device measured the morphology changes of triangular silver nanoprisms (AgNPRs) in an immunoassay for the detection of carcinoembryonic antigen (CEA). In the second experiment, the device measured the aggregation of gold nanoparticles (AuNPs) in an aptamer-based assay for the detection of adenosine triphosphate (ATP). The results from the smart phone-based PNRP were consistent with those from commercial spectrophotometers, demonstrating that the smart phone-based PNRP enables accurate quantification of plasmonic nanosensors.

Using a plenoptic sensor to reconstruct vortex phase structures.

PubMed

Wu, Chensheng; Ko, Jonathan; Davis, Christopher C

2016-07-15

A branch point problem and its solution commonly involve recognizing and reconstructing a vortex phase structure around a singular point. In laser beam propagation through random media, the destructive phase contributions from various parts of a vortex phase structure will cause a dark area in the center of the beam's intensity profile. This null of intensity can, in turn, prevent the vortex phase structure from being recognized. In this Letter, we show how to use a plenoptic sensor to transform the light field of a vortex beam so that a simple and direct reconstruction algorithm can be applied to reveal the vortex phase structure. As a result, we show that the plenoptic sensor is effective in detecting branch points and can be used to reconstruct phase distortion in a beam in a wide sense.

Image sensor system with bio-inspired efficient coding and adaptation.

PubMed

Okuno, Hirotsugu; Yagi, Tetsuya

2012-08-01

We designed and implemented an image sensor system equipped with three bio-inspired coding and adaptation strategies: logarithmic transform, local average subtraction, and feedback gain control. The system comprises a field-programmable gate array (FPGA), a resistive network, and active pixel sensors (APS), whose light intensity-voltage characteristics are controllable. The system employs multiple time-varying reset voltage signals for APS in order to realize multiple logarithmic intensity-voltage characteristics, which are controlled so that the entropy of the output image is maximized. The system also employs local average subtraction and gain control in order to obtain images with an appropriate contrast. The local average is calculated by the resistive network instantaneously. The designed system was successfully used to obtain appropriate images of objects that were subjected to large changes in illumination.

Distributed Fiber-Optic Sensors for Vibration Detection

PubMed Central

Liu, Xin; Jin, Baoquan; Bai, Qing; Wang, Yu; Wang, Dong; Wang, Yuncai

2016-01-01

Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach–Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications. PMID:27472334

Note: An absolute X-Y-Θ position sensor using a two-dimensional phase-encoded binary scale

NASA Astrophysics Data System (ADS)

Kim, Jong-Ahn; Kim, Jae Wan; Kang, Chu-Shik; Jin, Jonghan

2018-04-01

This Note presents a new absolute X-Y-Θ position sensor for measuring planar motion of a precision multi-axis stage system. By analyzing the rotated image of a two-dimensional phase-encoded binary scale (2D), the absolute 2D position values at two separated points were obtained and the absolute X-Y-Θ position could be calculated combining these values. The sensor head was constructed using a board-level camera, a light-emitting diode light source, an imaging lens, and a cube beam-splitter. To obtain the uniform intensity profiles from the vignette scale image, we selected the averaging directions deliberately, and higher resolution in the angle measurement could be achieved by increasing the allowable offset size. The performance of a prototype sensor was evaluated in respect of resolution, nonlinearity, and repeatability. The sensor could resolve 25 nm linear and 0.001° angular displacements clearly, and the standard deviations were less than 18 nm when 2D grid positions were measured repeatedly.

Distributed fluorescent optical fiber proximity sensor: Towards a proof of concept.

PubMed

Gălătuș, Ramona; Faragó, Paul; Miluski, Piotr; Valles, Juan-Antonio

2018-06-05

Fluorescent fibers are optical fibers which emit light as a response to an incident phenomenon, usually an incident light. Operation depends on the doping dyes, which determine specific fluorescence and optical characteristics useful in the development of optical sensors. In this work we propose a low-cost distributed proximity sensor implemented using a red fluorescent fiber, to provide a security option for a surface plasmon resonance system. Operation of the proposed sensor relies on having the incident illumination intensity varied by the presence or absence of an obstacle in the vicinity of the sensing element. This will influence the radiated fluorescence accordingly. The proposed setup for the implementation of the optical proximity sensor assumes having a high brightness LED deployed for axial fiber illumination and a blue LED for side illumination. Electronic processing then accounts for gain and digitization. Measurement results of the prototype validate the proposed concept. Copyright © 2018 Elsevier B.V. All rights reserved.

Distributed Fiber-Optic Sensors for Vibration Detection.

PubMed

Liu, Xin; Jin, Baoquan; Bai, Qing; Wang, Yu; Wang, Dong; Wang, Yuncai

2016-07-26

Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach-Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications.

Optical fiber strain sensor with improved linearity range

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

1995-01-01

A strain sensor is constructed from a two mode optical fiber. When the optical fiber is surface mounted in a straight line and the object to which the optical fiber is mounted is subjected to strain within a predetermined range, the light intensity of any point at the output of the optical fiber will have a linear relationship to strain, provided the intermodal phase difference is less than 0.17 radians.

Biological Applications of Extraordinary Electroconductance and Photovoltaic Effects in Inverse Extraordinary Optoconductance

NASA Astrophysics Data System (ADS)

Tran, Lauren Christine

The Extraordinary Electroconductance (EEC) sensor has been previously demonstrated to have an electric field sensitivity of 3.05V/cm in a mesoscopic-scale structure fabricated at the center of a parallel plate capacitor. In this thesis, we demonstrate the first successful application of EEC sensors as electrochemical detectors of protein binding and biological molecule concentration. Using the avidin derivative, captavidin, in complex with the vitamin biotin, the change in four-point measured resistance with fluid protein concentration of bare EEC sensors was shown to increase by a factor of four in the presence of biomolecular binding as compared to baseline. Calculations for approximate field strengths introduced by a bound captavidin molecule are also presented. The development of Inverse-Extraordinary Optoconductance (I-EOC), an effect which occurs in nanoscale sensors, is also discussed. In the I-EOC effect, electron transport transitions from ballistic to diffusive with increasing light intensity. In these novel, room temperature optical detectors, the resistance is low at low light intensity and resistance increases by 9462% in a 250nm device mesa upon full illumination with a 5 mW HeNe laser. This is the inverse of bulk and mesoscopic device behavior, in which resistance decreases with increasing photon density.

An acousto-optic sensor based on resonance grating waveguide structure

PubMed Central

Xie, Antonio Jou; Song, Fuchuan; Seo, Sang-Woo

2014-01-01

This paper presents an acousto-optic (AO) sensor based on resonance grating waveguide structure. The sensor is fabricated using elastic polymer materials to achieve a good sensitivity to ultrasound pressure waves. Ultrasound pressure waves modify the structural parameters of the sensor and result in the optical resonance shift of the sensor. This converts into a light intensity modulation. A commercial ultrasound transducer at 20 MHz is used to characterize a fabricated sensor and detection sensitivity at different optical source wavelength within a resonance spectrum is investigated. Practical use of the sensor at a fixed optical source wavelength is presented. Ultimately, the geometry of the planar sensor structure is suitable for two-dimensional, optical pressure imaging applications such as pressure wave detection and mapping, and ultrasound imaging. PMID:25045203

A real-time detector system for precise timing of audiovisual stimuli.

PubMed

Henelius, Andreas; Jagadeesan, Sharman; Huotilainen, Minna

2012-01-01

The successful recording of neurophysiologic signals, such as event-related potentials (ERPs) or event-related magnetic fields (ERFs), relies on precise information of stimulus presentation times. We have developed an accurate and flexible audiovisual sensor solution operating in real-time for on-line use in both auditory and visual ERP and ERF paradigms. The sensor functions independently of the used audio or video stimulus presentation tools or signal acquisition system. The sensor solution consists of two independent sensors; one for sound and one for light. The microcontroller-based audio sensor incorporates a novel approach to the detection of natural sounds such as multipart audio stimuli, using an adjustable dead time. This aids in producing exact markers for complex auditory stimuli and reduces the number of false detections. The analog photosensor circuit detects changes in light intensity on the screen and produces a marker for changes exceeding a threshold. The microcontroller software for the audio sensor is free and open source, allowing other researchers to customise the sensor for use in specific auditory ERP/ERF paradigms. The hardware schematics and software for the audiovisual sensor are freely available from the webpage of the authors' lab.

All-fiber gas sensor with intracavity photothermal spectroscopy.

PubMed

Zhao, Yan; Jin, Wei; Lin, Yuechuan; Yang, Fan; Ho, Hoi Lut

2018-04-01

We present an all-fiber intracavity photothermal (IC-PT) spectroscopic gas sensor with a hollow-core photonic bandgap fiber (HC-PBF) gas cell. The gas cell is placed inside a fiber-ring laser cavity to achieve higher laser light intensity in the hollow core and hence higher PT modulation signal. An experiment with a 0.62-m-long HC-PBF gas cell demonstrated a noise equivalent concentration of 176 ppb acetylene. Theoretical modeling shows that the IC-PT sensor has the potential of achieving sub-ppb (parts-per-billion) acetylene detection sensitivity.

A fiber optic temperature sensor based on the combination of epoxy and glass particles with different thermo-optic coefficients

NASA Astrophysics Data System (ADS)

Wildner, Wolfgang; Drummer, Dietmar

2016-12-01

This paper describes the development and function of an optical fiber temperature sensor made out of a compound of epoxy and optical glass particles. Because of the different thermo-optic coefficients of these materials, this compound exhibits a strong wavelength and temperature dependent optical transmission, and it therefore can be employed for fiber optic temperature measurements. The temperature at the sensor, which is integrated into a polymer optical fiber (POF), is evaluated by the ratio of the transmitted intensity of two different light-emitting diodes (LED) with a wavelength of 460 nm and 650 nm. The material characterization and influences of different sensor lengths and two particle sizes on the measurement result are discussed. The temperature dependency of the transmission increases with smaller particles and with increasing sensor length. With glass particles with a diameter of 43 μm and a sensor length of 9.8 mm, the intensity ratio of the two LEDs decreases by 60% within a temperature change from 10°C to 40°C.

Low-cost vibration sensor based on dual fiber Bragg gratings and light intensity measurement.

PubMed

Gao, Xueqing; Wang, Yongjiao; Yuan, Bo; Yuan, Yinquan; Dai, Yawen; Xu, Gang

2013-09-20

A vibration monitoring system based on light intensity measurement has been constructed, and the designed accelerometer is based on steel cantilever frame and dual fiber Bragg gratings (FBGs). By using numerical simulations for the dual FBGs, the dependence relationship of the area of main lobes on the difference of initial central wavelengths is obtained and the most optimal choice for the initial value and the vibration amplitude of the difference of central wavelengths of two FBGs is suggested. The vibration monitoring experiments are finished, and the measured data are identical to the simulated results.

Fiber optic controls for aircraft engines - Issues and implications

NASA Technical Reports Server (NTRS)

Dasgupta, Samhita; Poppel, Gary L.; Anderson, William P.

1991-01-01

Some of the issues involved with the application of fiber-optic controls for aircraft engines in the harsh operating environment are addressed, with emphasis on fiber-optic temperature, pressure, position, and speed sensors. Criteria are established to evaluate the optical modulation technique, the sensor/control unit interconnection, and the electrooptic architecture. Single mode and polarization dependent sensor types, sensors which depend on the reflection and/or transmission of light through the engine environment, and intensity-based analog sensors are eliminated as a possible candidate for engine implementation. Fiber-optic harnesses tested for their optical integrity, temperature stability, and mechanical strength, exhibit a capacity to meet mechanical strength requirements and still gain a significant reduction in cable weight.

Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology

PubMed Central

Strle, Drago; Nahtigal, Uroš; Batistell, Graciele; Zhang, Vincent Chi; Ofner, Erwin; Fant, Andrea; Sturm, Johannes

2015-01-01

This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode’s current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm2 of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA. PMID:26205275

Built-in hyperspectral camera for smartphone in visible, near-infrared and middle-infrared lights region (second report): sensitivity improvement of Fourier-spectroscopic imaging to detect diffuse reflection lights from internal human tissues for healthcare sensors

NASA Astrophysics Data System (ADS)

Kawashima, Natsumi; Hosono, Satsuki; Ishimaru, Ichiro

2016-05-01

We proposed the snapshot-type Fourier spectroscopic imaging for smartphone that was mentioned in 1st. report in this conference. For spectroscopic components analysis, such as non-invasive blood glucose sensors, the diffuse reflection lights from internal human skins are very weak for conventional hyperspectral cameras, such as AOTF (Acousto-Optic Tunable Filter) type. Furthermore, it is well known that the spectral absorption of mid-infrared lights or Raman spectroscopy especially in long wavelength region is effective to distinguish specific biomedical components quantitatively, such as glucose concentration. But the main issue was that photon energies of middle infrared lights and light intensities of Raman scattering are extremely weak. For improving sensitivity of our spectroscopic imager, the wide-field-stop & beam-expansion method was proposed. Our line spectroscopic imager introduced a single slit for field stop on the conjugate objective plane. Obviously to increase detected light intensities, the wider slit width of the field stop makes light intensities higher, regardless of deterioration of spatial resolutions. Because our method is based on wavefront-division interferometry, it becomes problems that the wider width of single slit makes the diffraction angle narrower. This means that the narrower diameter of collimated objective beams deteriorates visibilities of interferograms. By installing the relative inclined phaseshifter onto optical Fourier transform plane of infinity corrected optical systems, the collimated half flux of objective beams derived from single-bright points on objective surface penetrate through the wedge prism and the cuboid glass respectively. These two beams interfere each other and form the infererogram as spatial fringe patterns. Thus, we installed concave-cylindrical lens between the wider slit and objective lens as a beam expander. We successfully obtained the spectroscopic characters of hemoglobin from reflected lights from human fingers.

Evaluation of light detector surface area for functional Near Infrared Spectroscopy.

PubMed

Wang, Lei; Ayaz, Hasan; Izzetoglu, Meltem; Onaral, Banu

2017-10-01

Functional Near Infrared Spectroscopy (fNIRS) is an emerging neuroimaging technique that utilizes near infrared light to detect cortical concentration changes of oxy-hemoglobin and deoxy-hemoglobin non-invasively. Using light sources and detectors over the scalp, multi-wavelength light intensities are recorded as time series and converted to concentration changes of hemoglobin via modified Beer-Lambert law. Here, we describe a potential source for systematic error in the calculation of hemoglobin changes and light intensity measurements. Previous system characterization and analysis studies looked into various fNIRS parameters such as type of light source, number and selection of wavelengths, distance between light source and detector. In this study, we have analyzed the contribution of light detector surface area to the overall outcome. Results from Monte Carlo based digital phantoms indicated that selection of detector area is a critical system parameter in minimizing the error in concentration calculations. The findings here can guide the design of future fNIRS sensors. Copyright © 2017 Elsevier Ltd. All rights reserved.

UV sensing using film bulk acoustic resonators based on Au/n-ZnO/piezoelectric-ZnO/Al structure.

PubMed

Bian, Xiaolei; Jin, Hao; Wang, Xiaozhi; Dong, Shurong; Chen, Guohao; Luo, J K; Deen, M Jamal; Qi, Bensheng

2015-03-16

A new type of ultraviolet (UV) light sensor based on film bulk acoustic wave resonator (FBAR) is proposed. The new sensor uses gold and a thin n-type ZnO layer deposited on the top of piezoelectric layer of FBAR to form a Schottky barrier. The Schottky barrier's capacitance can be changed with UV light, resulting in an enhanced shift in the entire FBAR's resonant frequency. The fabricated UV sensor has a 50 nm thick n-ZnO semiconductor layer with a carrier concentration of ~ 10(17) cm(-3). A large frequency downshift is observed when UV light irradiates the FBAR. With 365 nm UV light of intensity 1.7 mW/cm(2), the FBAR with n-ZnO/Au Schottky diode has 250 kHz frequency downshift, much larger than the 60 kHz frequency downshift in a conventional FBAR without the n-ZnO layer. The shift in the new FBAR's resonant frequency is due to the junction formed between Au and n-ZnO semiconductor and its properties changes with UV light. The experimental results are in agreement with the theoretical analysis using an equivalent circuit model of the new FBAR structure.

Improvements to the modal holographic wavefront sensor.

PubMed

Kong, Fanpeng; Lambert, Andrew

2016-05-01

The Zernike coefficients of a light wavefront can be calculated directly by intensity ratios of pairs of spots in the reconstructed image plane of a holographic wavefront sensor (HWFS). However, the response curve of the HWFS heavily depends on the position and size of the detector for each spot and the distortions introduced by other aberrations. In this paper, we propose a method to measure the intensity of each spot by setting a threshold to select effective pixels and using the weighted average intensity within a selected window. Compared with using the integral intensity over a small window for each spot, we show through a numerical simulation that the proposed method reduces the dependency of the HWFS's response curve on the selection of the detector window. We also recorded a HWFS on a holographic plate using a blue laser and demonstrated its capability to detect the strength of encoded Zernike terms in an aberrated beam.

Theoretical investigation for excitation light and fluorescence signal of fiber optical sensor using tapered fiber tip.

PubMed

Yuan, Yinquan; Ding, Liyun

2011-10-24

For fiber optical sensor made of tapered fiber tip, the effects of the geometrical parameters of tapered tip on two important factors have been investigated. One factor is the intensity of the evanescent wave into fluorescent layer through core-medium interface; the other is the intensity of fluorescence signal transmitted from fluorescent layer to measurement end. A dependence relation of the intensity of fluorescence signal transmitted from fluorescent layer to measurement end upon the geometrical parameters of tapered tip has been obtained. Theoretical results show that the intensity of the evanescent wave into fluorescent layer rises with the decrease of the end diameter of tapered tip, and the increase of the tip length; and the transmitted power of fluorescence signal increases linearly with the increase of the tip length due to the contribution of the side area of tapered tip. © 2011 Optical Society of America

Characterization and optimization of an inkjet-printed smart textile UV-sensor cured with UV-LED light

NASA Astrophysics Data System (ADS)

Seipel, S.; Yu, J.; Periyasamy, A. P.; Viková, M.; Vik, M.; Nierstrasz, V. A.

2017-10-01

For the development of niche products like smart textiles and other functional high-end products, resource-saving production processes are needed. Niche products only require small batches, which makes their production with traditional textile production techniques time-consuming and costly. To achieve a profitable production, as well as to further foster innovation, flexible and integrated production techniques are a requirement. Both digital inkjet printing and UV-light curing contribute to a flexible, resource-efficient, energy-saving and therewith economic production of smart textiles. In this article, a smart textile UV-sensor is printed using a piezoelectric drop-on-demand printhead and cured with a UV-LED lamp. The UVcurable ink system is based on free radical polymerization and the integrated UVsensing material is a photochromic dye, Reversacol Ruby Red. The combination of two photoactive compounds, for which UV-light is both the curer and the activator, challenges two processes: polymer crosslinking of the resin and color performance of the photochromic dye. Differential scanning calorimetry (DSC) is used to characterize the curing efficiency of the prints. Color measurements are made to determine the influence of degree of polymer crosslinking on the developed color intensities, as well as coloration and decoloration rates of the photochromic prints. Optimized functionality of the textile UV-sensor is found using different belt speeds and lamp intensities during the curing process.

Light scattering in optical CT scanning of Presage dosimeters

NASA Astrophysics Data System (ADS)

Xu, Y.; Adamovics, J.; Cheeseborough, J. C.; Chao, K. S.; Wuu, C. S.

2010-11-01

The intensity of the scattered light from the Presage dosimeters was measured using a Thorlabs PM100D optical power meter (Thorlabs Inc, Newton, NJ) with an optical sensor of 1 mm diameter sensitive area. Five Presage dosimeters were made as cylinders of 15.2 cm, 10 cm, 4 cm diameters and irradiated with 6 MV photons using a Varian Clinac 2100EX. Each dosimeter was put into the scanning tank of an OCTOPUS" optical CT scanner (MGS Research Inc, Madison, CT) filled with a refractive index matching liquid. A laser diode was positioned at one side of the water tank to generate a stationary laser beam of 0.8 mm width. On the other side of the tank, an in-house manufactured positioning system was used to move the optical sensor in the direction perpendicular to the outgoing laser beam from the dosimeters at an increment of 1 mm. The amount of scattered photons was found to be more than 1% of the primary light signal within 2 mm from the laser beam but decreases sharply with increasing off-axis distance. The intensity of the scattered light increases with increasing light attenuations and/or absorptions in the dosimeters. The scattered light at the same off-axis distance was weaker for dosimeters of larger diameters and for larger detector-to-dosimeter distances. Methods for minimizing the effect of the light scattering in different types of optical CT scanners are discussed.

High-resolution parallel-detection sensor array using piezo-phototronics effect

DOEpatents

Wang, Zhong L.; Pan, Caofeng

2015-07-28

A pressure sensor element includes a substrate, a first type of semiconductor material layer and an array of elongated light-emitting piezoelectric nanostructures extending upwardly from the first type of semiconductor material layer. A p-n junction is formed between each nanostructure and the first type semiconductor layer. An insulative resilient medium layer is infused around each of the elongated light-emitting piezoelectric nanostructures. A transparent planar electrode, disposed on the resilient medium layer, is electrically coupled to the top of each nanostructure. A voltage source is coupled to the first type of semiconductor material layer and the transparent planar electrode and applies a biasing voltage across each of the nanostructures. Each nanostructure emits light in an intensity that is proportional to an amount of compressive strain applied thereto.

Design of an Optical System for Phase Retrieval based on a Spatial Light Modulator

NASA Astrophysics Data System (ADS)

Falldorf, Claas; Agour, Mostafa; von Kopylow, Christoph; Bergmann, Ralf B.

2010-04-01

We present an optical configuration for phase retrieval from a sequence of intensity measurements. The setup is based on a 4f-configuration with a phase modulating spatial light modulator (SLM) located in the Fourier domain. The SLM is used to modulate the incoming light with the transfer function of propagation, thus a sequence of propagated representations of the subjected wave field can be captured across a common sensor plane. The main advantage of this technique is the greatly reduced measurement time, since no mechanical adjustment of the camera sensor is required throughout the measurement process. The treatise is focused on the analysis of the wave field in the sensor domain. From the discussion a set of parameters is derived in order to minimize disturbing effects arising from the discrete nature of the SLM. Finally, the big potential of this approach is demonstrated by means of experimental investigations with regard to wave field sensing.

Suppression of mutants aberrant in light intensity responses of complementary chromatic adaptation.

PubMed Central

Casey, E S; Kehoe, D M; Grossman, A R

1997-01-01

Complementary chromatic adaptation is a process in which cyanobacteria alter the pigment protein (phycocyanin and phycoerythrin) composition of their light-harvesting complexes, the phycobilisomes, to help optimize the absorbance of prevalent wavelengths of light in the environment. Several classes of mutants that display aberrant complementary chromatic adaptation have been isolated. One of the mutant classes, designated "blue" or FdB, accumulates high levels of the blue chromoprotein phycocyanin in low-intensity green light, a condition that normally suppresses phycocyanin synthesis. We demonstrate here that the synthesis of the phycocyanin protein and mRNA in the FdB mutants can be suppressed by increasing the intensity of green light. Hence, these mutants have a decreased sensitivity to green light with respect to suppression of phycocyanin synthesis. Although we were unable to complement the blue mutants, we did isolate genes that could suppress the mutant phenotype. These genes, which have been identified previously, encode a histidine kinase sensor and response regulator protein that play key roles in controlling complementary chromatic adaptation. These findings are discussed with respect to the mechanism by which light quality and quantity control the biosynthesis of the phycobilisome. PMID:9226271

Intensity-modulated refractive index sensor with anti-light source fluctuation based on no-core fiber filter

NASA Astrophysics Data System (ADS)

Zhang, Cheng; Xu, Shan; Zhao, Junfa; Li, Hongqiang; Bai, Hua; Miao, Changyun

2017-12-01

A differential intensity-modulated refractive index (RI) sensor consisting of a no-core fiber (NCF) filter, a circulator and two fiber Bragg gratings (FBGs) is proposed and demonstrated. A section of the NCF is sandwiched between two parts of single mode fibers (SMFs) to form a band-pass filter. The Bragg wavelengths of the FBGs are chosen at the two edges of the filter, respectively. The peak wavelength of the NCF filter has a red-shift with the increase of the surrounding refractive index (SRI) while the Bragg wavelengths have no change, which results in the variation of the difference of the two FBGs reflective intensities, thus the differential intensity modulation to the SRI can be accomplished. Compared with directly connecting the NCF filter and the FBGs, this sensing structure can increase the output power so as to improve the measuring resolution. The experimental results show that the RI sensitivities are -99.191 dB/RIU and -139.958 dB/RIU at the range of 1.3329-1.3781 and 1.3781-1.401, respectively. In addition, the disturbance from the light source fluctuation and temperature cross sensitivity can be minimized effectively, which has great potential in actual applications.

Temperature-Sensitive Coating Sensor Based on Hematite

NASA Technical Reports Server (NTRS)

Bencic, Timothy J.

2011-01-01

A temperature-sensitive coating, based on hematite (iron III oxide), has been developed to measure surface temperature using spectral techniques. The hematite powder is added to a binder that allows the mixture to be painted on the surface of a test specimen. The coating dynamically changes its relative spectral makeup or color with changes in temperature. The color changes from a reddish-brown appearance at room temperature (25 C) to a black-gray appearance at temperatures around 600 C. The color change is reversible and repeatable with temperature cycling from low to high and back to low temperatures. Detection of the spectral changes can be recorded by different sensors, including spectrometers, photodiodes, and cameras. Using a-priori information obtained through calibration experiments in known thermal environments, the color change can then be calibrated to yield accurate quantitative temperature information. Temperature information can be obtained at a point, or over an entire surface, depending on the type of equipment used for data acquisition. Because this innovation uses spectrophotometry principles of operation, rather than the current methods, which use photoluminescence principles, white light can be used for illumination rather than high-intensity short wavelength excitation. The generation of high-intensity white (or potentially filtered long wavelength light) is much easier, and is used more prevalently for photography and video technologies. In outdoor tests, the Sun can be used for short durations as an illumination source as long as the amplitude remains relatively constant. The reflected light is also much higher in intensity than the emitted light from the inefficient current methods. Having a much brighter surface allows a wider array of detection schemes and devices. Because color change is the principle of operation, the development of high-quality, lower-cost digital cameras can be used for detection, as opposed to the high-cost imagers needed for intensity measurements with the current methods. Alternative methods of detection are possible to increase the measurement sensitivity. For example, a monochrome camera can be used with an appropriate filter and a radiometric measurement of normalized intensity change that is proportional to the change coating temperature. Using different spectral regions yields different sensitivities and calibration curves for converting intensity change to temperature units. Alternatively, using a color camera, a ratio of the standard red, green, and blue outputs can be used as a self-referenced change. The blue region (less than 500 nm) does not change nearly as much as the red region (greater than 575 nm), so a ratio of color intensities will yield a calibrated temperature image. The new temperature sensor coating is easy to apply, is inexpensive, can contour complex shape surfaces, and can be a global surface measurement system based on spectrophotometry. The color change, or relative intensity change, at different colors makes the optical detection under white light illumination, and associated interpretation, much easier to measure and interpret than in the detection systems of the current methods.

Fundamental concepts of integrated and fiber optic sensors

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.

1995-01-01

This chapter discusses fiber optic and integrated optic sensor concepts. Unfortunately, there is no standard method to categorize these sensor concepts. Here, fiber optic and integrated optic sensor concepts will be categorized by the primary modulation technique. These modulation techniques have been classified as: intensity, phase, wavelength, polarization, and time/frequency modulation. All modulate the output light with respect to changes in the physical or chemical property to be measured. Each primary modulation technique is then divided into fiber optic and integrated optic sections which are treated independently. For each sensor concept, possible sensor applications are discussed. The sensors and references discussed are not exhaustive, but sufficient to give the reader an overview of sensor concepts developed to date. Sensor multiplexing techniques such as wavelength division, time division, and frequency division will not be discussed as they are beyond the scope of this report.

All-fiber intensity bend sensor based on photonic crystal fiber with asymmetric air-hole structure

NASA Astrophysics Data System (ADS)

Budnicki, Dawid; Szostkiewicz, Lukasz; Szymanski, Michal O.; Ostrowski, Lukasz; Holdynski, Zbigniew; Lipinski, Stanislaw; Murawski, Michal; Wojcik, Grzegorz; Makara, Mariusz; Poturaj, Krzysztof; Mergo, Pawel; Napierala, Marek; Nasilowski, Tomasz

2017-10-01

Monitoring the geometry of an moving element is a crucial task for example in robotics. The robots equipped with fiber bend sensor integrated in their arms can be a promising solution for medicine, physiotherapy and also for application in computer games. We report an all-fiber intensity bend sensor, which is based on microstructured multicore optical fiber. It allows to perform a measurement of the bending radius as well as the bending orientation. The reported solution has a special airhole structure which makes the sensor only bend-sensitive. Our solution is an intensity based sensor, which measures power transmitted along the fiber, influenced by bend. The sensor is based on a multicore fiber with the special air-hole structure that allows detection of bending orientation in range of 360°. Each core in the multicore fiber is sensitive to bend in specified direction. The principle behind sensor operation is to differentiate the confinement loss of fundamental mode propagating in each core. Thanks to received power differences one can distinguish not only bend direction but also its amplitude. Multicore fiber is designed to utilize most common light sources that operate at 1.55 μm thus ensuring high stability of operation. The sensitivity of the proposed solution is equal 29,4 dB/cm and the accuracy of bend direction for the fiber end point is up to 5 degrees for 15 cm fiber length. Such sensitivity allows to perform end point detection with millimeter precision.

Portable device for the detection of nitro-explosives based on optical properties of sensor's material

NASA Astrophysics Data System (ADS)

Baranova, A. A.; Khokhlov, K. O.

2014-11-01

The aim of this study was to design a device for explosives detection. The study design is based on excited steady-state luminescence quenching registration. Sensor's material luminescence intensity reduction occurs due to an interaction of explosives vapours contained in the air. The decrease rate of the luminescence intensity indicates the concentration of vapours. To study the luminescent properties of the sensor element, its luminescence spectra excited by photons with energies in the range 280 - 425 nm were measured. The excitation photoluminescence spectra for luminescence bands of the sensor element were also measured. Excitation source was light emitting diode (375 nm) and luminescent signal receiver was a photodiode (430 - 650 nm) in device designed. The device is operated under control of a program. The algorithm provides multiple operating modes (configuration, calibration, measurement etc.). Thus this device is referred to the class of devices with increased sensitivity to the explosives vapors. The advantages of device are autonomic power, small weight and sizes, simplicity of device operation for measurements.

Polarization interferometry for real-time spectroscopic plasmonic sensing.

PubMed

Otto, Lauren M; Mohr, Daniel A; Johnson, Timothy W; Oh, Sang-Hyun; Lindquist, Nathan C

2015-03-07

We present quantitative, spectroscopic polarization interferometry phase measurements on plasmonic surfaces for sensing applications. By adding a liquid crystal variable wave plate in our beam path, we are able to measure phase shifts due to small refractive index changes on the sensor surface. By scanning in a quick sequence, our technique is extended to demonstrate real-time measurements. While this optical technique is applicable to different sensor geometries-e.g., nanoparticles, nanogratings, or nanoapertures-the plasmonic sensors we use here consist of an ultrasmooth gold layer with buried linear gratings. Using these devices and our phase measurement technique, we calculate a figure of merit that shows improvement over measuring only surface plasmon resonance shifts from a reflected intensity spectrum. To demonstrate the general-purpose versatility of our phase-resolved measurements, we also show numerical simulations with another common device architecture: periodic plasmonic slits. Since our technique inherently measures both the intensity and phase of the reflected or transmitted light simultaneously, quantitative sensor device characterization is possible.

A Near-Infrared Spectrometer Based on Novel Grating Light Modulators

PubMed Central

Wei, Wei; Huang, Shanglian; Wang, Ning; Jin, Zhu; Zhang, Jie; Chen, Weimin

2009-01-01

A near-infrared spectrometer based on novel MOEMS grating light modulators is proposed. The spectrum detection method that combines a grating light modulator array with a single near-infrared detector has been applied. Firstly, optics theory has been used to analyze the essential principles of the proposed spectroscopic sensor. Secondly, the grating light modulators have been designed and fabricated by micro-machining technology. Finally, the principles of this spectroscopic sensor have been validated and its key parameters have been tested by experiments. The result shows that the spectral resolution is better than 10 nm, the wavelength deviation is less than 1 nm, the deviation of the intensity of peak wavelength is no more than 0.5%, the driving voltage of grating light modulators array device is below 25 V and the response frequency of it is about 5 kHz. With low cost, satisfactory precision, portability and other advantages, the spectrometer should find potential applications in food safety and quality monitoring, pharmaceutical identification and agriculture product quality classification. PMID:22574065

A near-infrared spectrometer based on novel grating light modulators.

PubMed

Wei, Wei; Huang, Shanglian; Wang, Ning; Jin, Zhu; Zhang, Jie; Chen, Weimin

2009-01-01

A near-infrared spectrometer based on novel MOEMS grating light modulators is proposed. The spectrum detection method that combines a grating light modulator array with a single near-infrared detector has been applied. Firstly, optics theory has been used to analyze the essential principles of the proposed spectroscopic sensor. Secondly, the grating light modulators have been designed and fabricated by micro-machining technology. Finally, the principles of this spectroscopic sensor have been validated and its key parameters have been tested by experiments. The result shows that the spectral resolution is better than 10 nm, the wavelength deviation is less than 1 nm, the deviation of the intensity of peak wavelength is no more than 0.5%, the driving voltage of grating light modulators array device is below 25 V and the response frequency of it is about 5 kHz. With low cost, satisfactory precision, portability and other advantages, the spectrometer should find potential applications in food safety and quality monitoring, pharmaceutical identification and agriculture product quality classification.

Optical ammonia gas sensor based on a porous silicon rugate filter coated with polymer-supported dye.

PubMed

Shang, Yunling; Wang, Xiaobo; Xu, Erchao; Tong, Changlun; Wu, Jianmin

2011-01-24

An ammonia gas sensor chip was prepared by coating an electrochemically-etched porous Si rugate filter with a chitosan film that is crosslinked by glycidoxypropyltrimethoxysilane (GPTMS). The bromothylmol blue (BTB), a pH indicator, was loaded in the film as ammonia-sensing molecules. White light reflected from the porous Si has a narrow bandwidth spectrum with a peak at 610 nm. Monitoring reflective optical intensity at the peak position allows for direct, real-time observation of changes in the concentration of ammonia gas in air samples. The reflective optical intensity decreased linearly with increasing concentrations of ammonia gas over the range of 0-100 ppm. The lowest detection limit was 0.5 ppm for ammonia gas. At optimum conditions, the full response time of the ammonia gas sensor was less than 15s. The sensor chip also exhibited a good long-term stability over 1 year. Therefore, the simple sensor design has potential application in miniaturized optical measurement for online ammonia gas detection. Copyright © 2010 Elsevier B.V. All rights reserved.

UV dose measurements of photosensitive dermatosis patients by polycrystalline GaN-based portable self-data-acquisition UV monitors.

PubMed

Yagi, Shigeru; Iwanaga, Takeshi; Kojima, Hiroshi; Shoji, Yoshio; Suzuki, Seiji; Seno, Kunihiro; Mori, Hisayoshi; Tokura, Yoshiki; Takigawa, Masahiro; Moriwaki, Shin-Ichi

2002-12-01

We have developed a UV monitor with polycrystalline (poly-) gallium nitride (GaN) UV sensors and evaluated its performance from the viewpoint of its effectiveness for use with photosensitive dermatosis patients. The poly-GaN UV sensor is sensitive to UV light from 280 to 410 nm even without optical filters. The UV monitor is a portable self-data-acquisition instrument with a minimum detection level (defined as average UV intensity over 290 to 400 nm) of 2 microW/cm2 and can store UV dose data for 128 days. It allows easy measurement of four orders of magnitude of ambient UV intensity and dose from indoor light to direct solar radiation in summer. Trial use of the UV monitor by five xeroderma pigmentosum patients started in June 2000 and was carried out for 1 year. It was demonstrated that the UV monitor was useful in improving their quality of life.

Functional Diversity of Photosynthetic Light Use of 16 Vascular Epiphyte Species Under Fluctuating Irradiance in the Canopy of a Giant Virola michelii (Myristicaceae) Tree in the Tropical Lowland Forest of French Guyana

PubMed Central

Rascher, Uwe; Freiberg, Martin; Lüttge, Ulrich

2011-01-01

Here we present the first study, in which a large number of different vascular epiphyte species were measured for their photosynthetic performance in the natural environment of their phorophyte in the lowland rainforest of French Guyana. More than 70 epiphyte species covered the host tree in a dense cover. Of these, the photosynthesis of 16 abundant species was analyzed intensely over several months. Moreover, the light environment was characterized with newly developed light sensors that recorded continuously and with high temporal resolution light intensity next to the epiphytes. Light intensity was highly fluctuating and showed great site specific spatio-temporal variations of photosynthetic photon flux. Using a novel computer routine we quantified the integrated light intensity the epiphytes were exposed to in a 3 h window and we related this light intensity to measurements of the actual photosynthetic status. It could be shown that the photosynthetic apparatus of the epiphytes was well adapted to the quickly changing light conditions. Some of the epiphytes were chronically photoinhibited at predawn and significant acute photoinhibition, expressed by a reduction of potential quantum efficiency (Fv/Fm)30′, was observed during the day. By correlating (Fv/Fm)30′ to the integrated and weighted light intensity perceived during the previous 3 h, it became clear that acute photoinhibition was related to light environment prior to the measurements. Additionally photosynthetic performance was not determined by rain events, with the exception of an Aechmea species. This holds true for all the other 15 species of this study and we thus conclude that actual photosynthesis of these tropical epiphytes was determined by the specific and fluctuating light conditions of their microhabitat and cannot be simply attributed to light-adapted ancestors. PMID:22629271

Distributed optical fiber dynamic magnetic field sensor based on magnetostriction.

PubMed

Masoudi, Ali; Newson, Trevor P

2014-05-01

A distributed optical fiber sensor is introduced which is capable of quantifying multiple magnetic fields along a 1 km sensing fiber with a spatial resolution of 1 m. The operation of the proposed sensor is based on measuring the magnetorestrictive induced strain of a nickel wire attached to an optical fiber. The strain coupled to the optical fiber was detected by measuring the strain-induced phase variation between the backscattered Rayleigh light from two segments of the sensing fiber. A magnetic field intensity resolution of 0.3 G over a bandwidth of 50-5000 Hz was demonstrated.

Sensors with centroid-based common sensing scheme and their multiplexing

NASA Astrophysics Data System (ADS)

Berkcan, Ertugrul; Tiemann, Jerome J.; Brooksby, Glen W.

1993-03-01

The ability to multiplex sensors with different measurands but with a common sensing scheme is of importance in aircraft and aircraft engine applications; this unification of the sensors into a common interface has major implications for weight, cost, and reliability. A new class of sensors based on a common sensing scheme and their E/O Interface has been developed. The approach detects the location of the centroid of a beam of light; the set of fiber optic sensors with this sensing scheme include linear and rotary position, temperature, pressure, as well as duct Mach number. The sensing scheme provides immunity to intensity variations of the source or due to environmental effects on the fiber. A detector spatially multiplexed common electro-optic interface for the sensors has been demonstrated with a position and a temperature sensor.

Design of Oil Viscosity Sensor Based on Plastic Optical Fiber

NASA Astrophysics Data System (ADS)

Yunus, Muhammad; Arifin, A.

2018-03-01

A research of plastic optical fiber based sensors have been studied for measurement of oil viscosity. This sensor was made with straight configuration, U configuration, and gamma configuration have two types, there are optical fiber sensor with cladding and without cladding. Viscosity sensor was made, dipped into an oil sample with a concentration of viscosity percentage about 270 mPa.s - 350 mPa.s. The light from the LED propagated into the optical fiber, then it was received by the photodetector converted to output power. When plastic optical fiber dipped into an oil sample, viscosity of oil affect increase of refractive index on optical fiber resulting in a bigger loss of power so the light intensity will be smaller, consequences the measured output power will be smaller. Sensitivity and resolution viscosity sensor without cladding peel showed the best result rather than viscosity sensor with cladding peel. The best result in the measurement showed in gamma configuration with 3 cm length of cladding peel and the diameter of bending 0,25 cm is the range 103,090 nWatt, sensitivity 1,289 nWatt/mPa.s, and resolution 0,776 mPa.s. This method is effectively and efficiently used as an oil viscosity sensor with high sensitivity and resolution.

Characterization of sensitivity and response time of plastic optical fibre sensor to cadmium ion

NASA Astrophysics Data System (ADS)

Yulianti, I.; Putra, N. M. D.; Masturi; Albadiah, I. V.; Pratiwi, D. A.; Akmalia, N.

2018-03-01

The paper presents an investigation of sensitivity and response time of a chitosan coated-plastic optical fibre (POF) sensor to cadmium ion concentration. The sensor working principles is based on the change of light intensity transmitted by the chitosan coated POF due to the change of cadmium ion concentration. Three sensor probes were fabricated with various coating thickness which are 100.24μm (sensor A), 131.97 μm(sensor B) and 376.24μm (sensor C). The characterization was done by exposing the sensor to cadmium ion solution for various concentrations. The results showed that sample C provides the lowest sensitivity while sample B showed the highest sensitivity which are 15.04mA/ppm and 65.64mA/ppm, respectively. In terms of response time, it was showed that sample A has the highest average response time which is 20.5seconds.

Planar location of the simulative acoustic source based on fiber optic sensor array

NASA Astrophysics Data System (ADS)

Liang, Yi-Jun; Liu, Jun-feng; Zhang, Qiao-ping; Mu, Lin-lin

2010-06-01

A fiber optic sensor array which is structured by four Sagnac fiber optic sensors is proposed to detect and locate a simulative source of acoustic emission (AE). The sensing loops of Sagnac interferometer (SI) are regarded as point sensors as their small size. Based on the derived output light intensity expression of SI, the optimum work condition of the Sagnac fiber optic sensor is discussed through the simulation of MATLAB. Four sensors are respectively placed on a steel plate to structure the sensor array and the location algorithms are expatiated. When an impact is generated by an artificial AE source at any position of the plate, the AE signal will be detected by four sensors at different times. With the help of a single chip microcomputer (SCM) which can calculate the position of the AE source and display it on LED, we have implemented an intelligent detection and location.

Paper-based α-amylase detector for point-of-care diagnostics.

PubMed

Dutta, Satarupa; Mandal, Nilanjan; Bandyopadhyay, Dipankar

2016-04-15

We report the fabrication of a paper-sensor for quantitative detection of α-amylase activity in human blood serum. Pieces of filter papers were coated with starch-iodine solution leading to an intense blue coloration on the surface. Dispensing α-amylase solution on the starch-iodine coated paper reduced the intensity of the color because of starch-hydrolysis catalyzed by amylase. The variation in the intensity of the color with the concentration of amylase was estimated in three stages: (i) initially, the paper-surface was illuminated with a light emitting diode, (ii) then, the transmitted (reflected) rays emitted through (from) the paper were collected on a photoresistor, and (iii) the variations in the electrical resistance of the photoresistor were correlated with the amylase concentration in analyte. The resistance of photoresistor decreased monotonically with an increase in amylase concentration because the intensity of the reflected (transmitted) rays collected from (through) the paper increased with reduction in the color intensity on the paper surface. Since a specific bio-reaction was employed to detect the activity of amylase, the sensor was found to be equally efficient in detecting unknown quantities of amylase in human blood serum. The reported sensor has shown the potential to graduate into a point-of-care detection tool for α-amylase. Copyright © 2015 Elsevier B.V. All rights reserved.

Optimizing the loss of one-dimensional photonic crystal towards high-sensitivity Bloch-surface-wave sensors under intensity interrogation scheme

NASA Astrophysics Data System (ADS)

Kong, Weijing; Wan, Yuhang; Du, Kun; Zhao, Wenhui; Wang, Shuang; Zheng, Zheng

2016-11-01

The reflected intensity change of the Bloch-surface-wave (BSW) resonance influenced by the loss of a truncated onedimensional photonic crystal structure is numerically analyzed and studied in order to enhance the sensitivity of the Bloch-surface-wave-based sensors. The finite truncated one-dimensional photonic crystal structure is designed to be able to excite BSW mode for water (n=1.33) as the external medium and for p-polarized plane wave incident light. The intensity interrogation scheme which can be operated on a typical Kretschmann prism-coupling configuration by measuring the reflected intensity change of the resonance dip is investigated to optimize the sensitivity. A figure of merit (FOM) is introduced to measure the performance of the one-dimensional photonic crystal multilayer structure under the scheme. The detection sensitivities are calculated under different device parameters with a refractive index change corresponding to different solutions of glycerol in de-ionized (DI)-water. The results show that the intensity sensitivity curve varies similarly with the FOM curve and the sensitivity of the Bloch-surface-wave sensor is greatly affected by the device loss, where an optimized loss value can be got. For the low-loss BSW devices, the intensity interrogation sensing sensitivity may drop sharply from the optimal value. On the other hand, the performance of the detection scheme is less affected by the higher device loss. This observation is in accordance with BSW experimental sensing demonstrations as well. The results obtained could be useful for improving the performance of the Bloch-surface-wave sensors for the investigated sensing scheme.

A CMOS active pixel sensor for retinal stimulation

NASA Astrophysics Data System (ADS)

Prydderch, Mark L.; French, Marcus J.; Mathieson, Keith; Adams, Christopher; Gunning, Deborah; Laudanski, Jonathan; Morrison, James D.; Moodie, Alan R.; Sinclair, James

2006-02-01

Degenerative photoreceptor diseases, such as age-related macular degeneration and retinitis pigmentosa, are the most common causes of blindness in the western world. A potential cure is to use a microelectronic retinal prosthesis to provide electrical stimulation to the remaining healthy retinal cells. We describe a prototype CMOS Active Pixel Sensor capable of detecting a visual scene and translating it into a train of electrical pulses for stimulation of the retina. The sensor consists of a 10 x 10 array of 100 micron square pixels fabricated on a 0.35 micron CMOS process. Light incident upon each pixel is converted into output current pulse trains with a frequency related to the light intensity. These outputs are connected to a biocompatible microelectrode array for contact to the retinal cells. The flexible design allows experimentation with signal amplitudes and frequencies in order to determine the most appropriate stimulus for the retina. Neural processing in the retina can be studied by using the sensor in conjunction with a Field Programmable Gate Array (FPGA) programmed to behave as a neural network. The sensor has been integrated into a test system designed for studying retinal response. We present the most recent results obtained from this sensor.

Non-destructive plant health sensing using absorption spectroscopy

NASA Technical Reports Server (NTRS)

Bledsoe, Jim; Manukian, Ara; Pearce, Michael; Weiss, Lee

1988-01-01

The sensor group of the 1988 EGM 4001 class, working on NASA's Controlled Ecological Life Support Systems (CELSS) project, investigated many different plant health indicators and the technologies used to test them. The project selected by the group was to measure chlorophyll levels using absorption spectroscopy. The spectrometer measures the amount of chlorophyll in a leaf by measuring the intensity of light of a specific wavelength that is passed through a leaf. The three wavelengths of light being used corresponded to the near-IR absorption peaks of chlorophyll a, chlorophyll b, and chlorophyll-free structures. Experimentation showed that the sensor is indeed measuring levels of chlorophyll a and b and their changes before the human eye can see any changes. The detector clamp causes little damage to the leaf and will give fairly accurate readings on similar locations on a leaf, freeing the clamp from having to remain on the same spot of a leaf for all measurements. External light affects the readings only slightly so that measurements may be taken in light or dark environments. Future designs and experimentation will concentrate on reducing the size of the sensor and adapting it to a wider range of plants.

ChR2 mutants at L132 and T159 with improved operational light sensitivity for vision restoration.

PubMed

Pan, Zhuo-Hua; Ganjawala, Tushar H; Lu, Qi; Ivanova, Elena; Zhang, Zhifei

2014-01-01

The ectopic expression of microbial opsin-based optogenetic sensors, such as channelrhodopsin-2 (ChR2) in surviving inner retinal neurons, is a promising approach to restoring vision after retinal degeneration. However, a major limitation in using native ChR2 as a light sensor for vision restoration is the low light sensitivity of its expressing cells. Recently, two ChR2 mutations, T159C and L132C, were reported to produce higher photocurrents or have ultra light sensitivity. In this study, we created additional ChR2 mutants at these two sites to search for more light responsive ChR2 forms and evaluate their suitability for vision restoration by examining their light responsive properties in HEK cells and mouse retinal ganglion cells. We found additional ChR2 mutants at these two sites that showed a further increase in current amplitude at low light levels in the cells expressing these mutants, or operational light sensitivity. However, the increase in the operational light sensitivity was correlated with a decrease in temporal kinetics. Therefore, there is a trade-off between operational light sensitivity and temporal resolution for these more light responsive ChR2 mutants. Our results showed that for the two most light responsive mutants, L132C/T159C and L132C/T159S, the required light intensities for generating the threshold spiking activity in retinal ganglion cells were 1.5 and nearly 2 log units lower than wild-type ChR2 (wt-ChR2), respectively. Additionally, their ChR2-mediated spiking activities could follow flicker frequencies up to 20 and 10 Hz, respectively, at light intensities up to 1.5 log units above their threshold levels. Thus, the use of these more light responsive ChR2 mutants could make the optogenetic approach to restoring vision more feasible.

Macrobend optical sensing for pose measurement in soft robot arms

NASA Astrophysics Data System (ADS)

Sareh, Sina; Noh, Yohan; Li, Min; Ranzani, Tommaso; Liu, Hongbin; Althoefer, Kaspar

2015-12-01

This paper introduces a pose-sensing system for soft robot arms integrating a set of macrobend stretch sensors. The macrobend sensory design in this study consists of optical fibres and is based on the notion that bending an optical fibre modulates the intensity of the light transmitted through the fibre. This sensing method is capable of measuring bending, elongation and compression in soft continuum robots and is also applicable to wearable sensing technologies, e.g. pose sensing in the wrist joint of a human hand. In our arrangement, applied to a cylindrical soft robot arm, the optical fibres for macrobend sensing originate from the base, extend to the tip of the arm, and then loop back to the base. The connectors that link the fibres to the necessary opto-electronics are all placed at the base of the arm, resulting in a simplified overall design. The ability of this custom macrobend stretch sensor to flexibly adapt its configuration allows preserving the inherent softness and compliance of the robot which it is installed on. The macrobend sensing system is immune to electrical noise and magnetic fields, is safe (because no electricity is needed at the sensing site), and is suitable for modular implementation in multi-link soft continuum robotic arms. The measurable light outputs of the proposed stretch sensor vary due to bend-induced light attenuation (macrobend loss), which is a function of the fibre bend radius as well as the number of repeated turns. The experimental study conducted as part of this research revealed that the chosen bend radius has a far greater impact on the measured light intensity values than the number of turns (if greater than five). Taking into account that the bend radius is the only significantly influencing design parameter, the macrobend stretch sensors were developed to create a practical solution to the pose sensing in soft continuum robot arms. Henceforward, the proposed sensing design was benchmarked against an electromagnetic tracking system (NDI Aurora) for validation.

UV sensing using film bulk acoustic resonators based on Au/n-ZnO/piezoelectric-ZnO/Al structure

PubMed Central

Bian, Xiaolei; Jin, Hao; Wang, Xiaozhi; Dong, Shurong; Chen, Guohao; Luo, J. K.; Deen, M. Jamal; Qi, Bensheng

2015-01-01

A new type of ultraviolet (UV) light sensor based on film bulk acoustic wave resonator (FBAR) is proposed. The new sensor uses gold and a thin n-type ZnO layer deposited on the top of piezoelectric layer of FBAR to form a Schottky barrier. The Schottky barrier's capacitance can be changed with UV light, resulting in an enhanced shift in the entire FBAR's resonant frequency. The fabricated UV sensor has a 50 nm thick n-ZnO semiconductor layer with a carrier concentration of ~ 1017 cm−3. A large frequency downshift is observed when UV light irradiates the FBAR. With 365 nm UV light of intensity 1.7 mW/cm2, the FBAR with n-ZnO/Au Schottky diode has 250 kHz frequency downshift, much larger than the 60 kHz frequency downshift in a conventional FBAR without the n-ZnO layer. The shift in the new FBAR's resonant frequency is due to the junction formed between Au and n-ZnO semiconductor and its properties changes with UV light. The experimental results are in agreement with the theoretical analysis using an equivalent circuit model of the new FBAR structure. PMID:25773146

Distributed Stress Sensing and Non-Destructive Tests Using Mechanoluminescence Materials

NASA Astrophysics Data System (ADS)

Rahimi, Mohammad Reza

Rapid aging of infrastructure systems is currently pervasive in the US and the anticipated cost until 2020 for rehabilitation of aging lifeline will reach 3.6 trillion US dollars (ASCE 2013). Reliable condition or serviceability assessment is critically important in decision-making for economic and timely maintenance of the infrastructure systems. Advanced sensors and nondestructive test (NDT) methods are the key technologies for structural health monitoring (SHM) applications that can provide information on the current state of structures. There are many traditional sensors and NDT methods, for examples, strain gauges, ultrasound, radiography and other X-ray, etc. to detect any defect on the infrastructure. Considering that civil infrastructure is typically large-scale and exhibits complex behavior, estimation of structural conditions by the local sensing and NDT methods is a challenging task. Non-contact and distributed (or full-field) sensing and NDT method are desirable that can provide rich information on the civil infrastructure's state. Materials with the ability of emitting light, especially in the visible range, are named as luminescent materials. Mechanoluminescence (ML) phenomenon is the light emission from luminescent materials as a response of an induced mechanical stress. ML materials offer new opportunities for SHM that can directly visualize the stress and crack distributions on the surface of structures through ML light emission. Although material research for ML phenomena have been made substantially, applications of the ML sensors to full-field stress and crack visualization are still at infant stage and have yet to be full-fledged. Moreover, practical applications of the ML sensors for SHM of civil infrastructure have difficulties since numerous challenging problems (e.g. environmental effect) arise in actual applications. In order to realize a practical SHM system employing ML sensors, more research needs to be conducted, for examples, fundamental understandings of physics of ML phenomenon, method for quantitative stress measurements, calibration method for ML sensors, improvement of sensitivity, optimal manufacturing and design of ML sensors, environmental effects of ML phenomenon (e.g. temperature), image processing and analysis, etc. In this research, fundamental ML phenomena of two most promising ML sensing materials were experimentally studied and a methodology for full-field quantitative strain measurements, for the first time, was proposed along with a standardized calibration method. Characteristics and behavior of ML composites and thin films coated on the structure have been studied under various material tests including compression, tension, pure shear, bending, etc. In addition, ML emission sensitivity to the manufacturing parameters and experimental conditions was addressed in order to find optimal design the ML sensor. A phenomenological stress-optics transduction model for predicting the ML light intensity from a thin-film ML coating sensor subjected to in-plane stresses was proposed. A new full-field quantitative strain measuring methodology by ML thin film sensor was developed, for the first time, in order to visualize and measure the strain field. The results from the ML sensor were compared and verified by finite element simulation results. For NDT applications of ML sensors, experimental tests were conducted to visualize the cracks on structural surfaces and detect damages on structural components. In summary, this research proposes and realizes a new distributed stress sensor and NDT method using ML sensing materials. The proposed method is experimentally validated to be effective for stress measurement and crack visualizations. Successful completion of this research provides a leap toward a commercial light intensity-based optic sensor to be used as a new full-field stress measurement technology and NDT method.

Ink-jet printed fluorescent materials as light sources for planar optical waveguides on polymer foils

NASA Astrophysics Data System (ADS)

Bollgruen, Patrick; Gleissner, Uwe; Wolfer, Tim; Megnin, Christof; Mager, Dario; Overmeyer, Ludger; Korvink, Jan G.; Hanemann, Thomas

2016-10-01

Polymer-based optical sensor networks on foils (planar optronic systems) are a promising research field, but it can be challenging to supply them with light. We present a solvent-free, ink-jet printable material system with optically active substances to create planar light sources for these networks. The ink is based on a UV-curable monomer, the fluorescent agents are EuDBMPhen or 9,10-diphenylantracene, which fluoresce at 612 or 430 nm, respectively. We demonstrate the application as light source by printing a small area of fluorescent material on an optical waveguide fabricated by flexographic printing on PMMA foil, resulting in a simple polymer-optical device fabricated entirely by additive deposition techniques. When excited by a 405-nm laser of 10 mW, the emitted light couples into the waveguide and appears at the end of the waveguide. In comparison to conventional light sources, the intensity is weak but could be detected with a photodiode power sensor. In return, the concept has the advantage of being completely independent of any electrical elements or external cable connections.

Intelligent rear light for compensation of environmental effects on car visibility

NASA Astrophysics Data System (ADS)

Gruner, Roman; Schubert, Jorg

2004-01-01

LIDAR remote sensing technology has not only applications in geographical, atmospheric or biological sciences but it can also play an important role in the everyday life. Within the last 10 years statistics of European car traffic has shown that about one third of all accidents go back to darkness and poor road conditions. A system collecting information about visibility and distance to following vehicles and setting appropriate rear light intensities could provide a much safer road travel under various environmental conditions. The system that is being developed co-operates with a dirt and brightness sensor to take into account these various external influences on an automobile and applies them to the operation of the rear light. The developed sensors are integrated in an advanced micro-system and capable of providing external environmental data for automatic brightness control within a requested range of light output for constant perceptibility of light signals to the following traffic. This conference gives further information about: (1) construction, optical and laser parameters, (2) application in rear light systems, (3) measurement characteristics, (4) test equipment (LIDAR_Probe), (5) measurement results, test rides, raw data.

User-interactive electronic skin for instantaneous pressure visualization

NASA Astrophysics Data System (ADS)

Wang, Chuan; Hwang, David; Yu, Zhibin; Takei, Kuniharu; Park, Junwoo; Chen, Teresa; Ma, Biwu; Javey, Ali

2013-10-01

Electronic skin (e-skin) presents a network of mechanically flexible sensors that can conformally wrap irregular surfaces and spatially map and quantify various stimuli. Previous works on e-skin have focused on the optimization of pressure sensors interfaced with an electronic readout, whereas user interfaces based on a human-readable output were not explored. Here, we report the first user-interactive e-skin that not only spatially maps the applied pressure but also provides an instantaneous visual response through a built-in active-matrix organic light-emitting diode display with red, green and blue pixels. In this system, organic light-emitting diodes (OLEDs) are turned on locally where the surface is touched, and the intensity of the emitted light quantifies the magnitude of the applied pressure. This work represents a system-on-plastic demonstration where three distinct electronic components—thin-film transistor, pressure sensor and OLED arrays—are monolithically integrated over large areas on a single plastic substrate. The reported e-skin may find a wide range of applications in interactive input/control devices, smart wallpapers, robotics and medical/health monitoring devices.

User-interactive electronic skin for instantaneous pressure visualization.

PubMed

Wang, Chuan; Hwang, David; Yu, Zhibin; Takei, Kuniharu; Park, Junwoo; Chen, Teresa; Ma, Biwu; Javey, Ali

2013-10-01

Electronic skin (e-skin) presents a network of mechanically flexible sensors that can conformally wrap irregular surfaces and spatially map and quantify various stimuli. Previous works on e-skin have focused on the optimization of pressure sensors interfaced with an electronic readout, whereas user interfaces based on a human-readable output were not explored. Here, we report the first user-interactive e-skin that not only spatially maps the applied pressure but also provides an instantaneous visual response through a built-in active-matrix organic light-emitting diode display with red, green and blue pixels. In this system, organic light-emitting diodes (OLEDs) are turned on locally where the surface is touched, and the intensity of the emitted light quantifies the magnitude of the applied pressure. This work represents a system-on-plastic demonstration where three distinct electronic components--thin-film transistor, pressure sensor and OLED arrays--are monolithically integrated over large areas on a single plastic substrate. The reported e-skin may find a wide range of applications in interactive input/control devices, smart wallpapers, robotics and medical/health monitoring devices.

A new fiber optic sensor for inner surface roughness measurement

NASA Astrophysics Data System (ADS)

Xu, Xiaomei; Liu, Shoubin; Hu, Hong

2009-11-01

In order to measure inner surface roughness of small holes nondestructively, a new fiber optic sensor is researched and developed. Firstly, a new model for surface roughness measurement is proposed, which is based on intensity-modulated fiber optic sensors and scattering modeling of rough surfaces. Secondly, a fiber optical measurement system is designed and set up. Under the help of new techniques, the fiber optic sensor can be miniaturized. Furthermore, the use of micro prism makes the light turn 90 degree, so the inner side surface roughness of small holes can be measured. Thirdly, the fiber optic sensor is gauged by standard surface roughness specimens, and a series of measurement experiments have been done. The measurement results are compared with those obtained by TR220 Surface Roughness Instrument and Form Talysurf Laser 635, and validity of the developed fiber optic sensor is verified. Finally, precision and influence factors of the fiber optic sensor are analyzed.

Simultaneous measurement of refractive index and temperature based on intensity demodulation using matching grating method.

PubMed

Qi, Liang; Zhao, Chun-Liu; Kang, Juan; Jin, Yongxing; Wang, Jianfeng; Ye, Manping; Jin, Shangzhong

2013-07-01

A solution refractive index (SRI) and temperature simultaneous measurement sensor with intensity-demodulation system based on matching grating method were demonstrated. Long period grating written in a photonic crystal fiber (LPG-PCF), provides temperature stable and wavelength dependent optical intensity transmission. The reflective peaks of two fiber Bragg gratings (FBGs), one of which is etched then sensitive to both SRI and temperature, another (FBG2) is only sensitive to temperature, were located in the same linear range of the LPG-PCF's transmission spectrum. An identical FBG with FBG2 was chosen as a matching FBG. When environments (SRI and temperature) change, the wavelength shifts of the FBGs are translated effectively to the reflection intensity changes. By monitoring output lights of unmatching and matching paths, the SRI and temperature were deduced by a signal processing unit. Experimental results show that the simultaneous refractive index and temperature measurement system work well. The proposed sensor system is compact and suitable for in situ applications at lower cost.

A comparison of CIE L*a*b* and spectral methods for the analysis of fading in sliced cured ham

NASA Astrophysics Data System (ADS)

Sheridan, C.; O'Farrell, M.; Lewis, E.; Flanagan, C.; Kerry, J.; Jackman, N.

2007-06-01

In the modern retail environment, the appearance of a product is frequently the only quality indicator available to consumers. This is especially true of products such as sliced ham that have been sealed into packages to maintain product freshness. It has been shown that sliced ham products undergo discolouration from their original pink colour to a pale grey colour when exposed to a combination of oxygen and light. This is unappealing to consumers who expect a pink colour for sliced ham. An investigation is made into a sensor that would monitor the initial colour status of cured ham before packaging in order to determine the amount of time left before the ham fades to an unsatisfactory colour. For this sensor to operate, appropriate analysis of the appearance of the meat is required. Two methods for the measurement of the fading were investigated—CIE L*a*b* measurements and analysis of the spectral reflectance of the colour of the ham. Several sliced ham products with differing amounts of fading were examined using both methods. It was observed that the products used covered a wide range of variation in colour. Reproducibility of CIE L*a*b* values proved to be quite difficult and significant overlapping of the L* (lightness) and a* (redness) values measured for pink and grey coloured ham was observed. The variations in these values can be attributed to differences in the intensity of reflected light for different products. L*a*b* measurements are sensitive to light intensity and pigment concentration. Analysis of the spectral reflectance readings did not encounter these problems as the spectral response was normalized (to reduce intensity errors) before data analysis was carried out on the spectral shape or 'pattern' using principal component analysis (PCA) and artificial neural networks (ANN). A classifier based on PCA and ANN was successfully implemented that can discriminate different stages of fading for the ham slices. A case study was carried out on ham slices that had two different initial colours—light and dark. The results of the case study show that the sensor system can better discriminate between a light initial colour and a dark faded colour than the CIE L*a*b* colour measurement system.

Volcanological applications of the Kinect sensor

NASA Astrophysics Data System (ADS)

Tortini, R.; Carn, S. A.

2012-12-01

The Kinect is a motion capture device designed for the Microsoft Xbox system. The device comprises a visible (RGB) camera and an infrared (IR) camera, refractor and light emitter emitting a known structured light pattern at a near-infrared wavelength of 830 nm, plus a three-axis accelerometer and four microphones. Moreover, by combining the signal from the IR camera and the light emitter it is possible to produce a distance image (depth). Thanks to the efforts of the free and open source software community, although originally intended to be used for videogames the Kinect can be exploited as a short range low-cost LiDAR sensor by scientists in various fields. The main limitation of the Kinect is its working distance, which ranges from ~0.5 to 15 m, with a distance sensitivity of ~1 mm at 0.5 m and ~8 cm at 5 m estimated by Mankoff et al. (2011). After their co-registration, we will present the calibration process for the RGB, depth and IR intensity images, and a sensitivity analysis of the IR intensity to the color spectrum will be performed. We expect the intensity to exhibit a non-linear correlation with distance of the target from the sensor, with lower sensitivity and larger errors at greater distances. We envisage several possible applications of the small-scale, precise topographic data acquired by the Kinect in volcanology, and solicit other ideas from the community. Possible applications could include monitoring of light tephra accumulation to characterize mass flux, monitoring of active lava flows or mapping inactive lava tubes, capturing topographic data on the outcrop scale, mapping surface roughness variations on volcanic mass flow deposits, or visualizing analog volcano models in the lab. As a demonstration, we will present an application of the Kinect as a tool for 3D visualization of volcanic rock samples. Data will be collected with free and open source software, demonstrating the cost-effectiveness of the Kinect for volcanological applications, particularly where conditions may be unsuitable for the deployment of more costly instruments. K.D. Mankoff, T.A. Russo, B.K. Norris, S. Hossainzadeh, L. Beem, J.I. Walter, and S.M. Tulaczyk, "Kinects as sensors in earth science: glaciological, geomorphological, and hydrological applications". AGU Fall Meeting 2012, San Francisco (USA), poster.

Fiber optic sensors and systems at the Federal University of Rio de Janeiro

NASA Astrophysics Data System (ADS)

Werneck, Marcelo M.; dos Santos, Paulo A. M.; Ferreira, Aldo P.; Maggi, Luis E.; de Carvalho, Carlos R., Jr.; Ribeiro, R. M.

1998-08-01

As widely known, fiberoptics (FO) are being used in a large variety of sensors and systems particularly for their small dimensions and low cost, large bandwidth and favorable dielectric properties. These properties have allowed us to develop sensors and systems for general applications and, particularly, for biomedical engineering. The intravascular pressure sensor was designed for small dimensions and high bandwidth. The system is based on light-intensity modulation technique and uses a 2 mm-diameter elastomer membrane as the sensor element and a pigtailed laser as a light source. The optical power output curve was linear for pressures within the range of 0 to 300 mmHg. The real time optical biosensor uses the evanescent field technique for monitoring Escherichia coli growth in culture media. The optical biosensor monitors interactions between the analytic (bacteria) and the evanescent field of an optical fiber passing through it. The FO based high voltage and current sensor is a measuring system designed for monitoring voltage and current in high voltage transmission lines. The linearity of the system is better than 2% in both ranges of 0 to 25 kV and 0 to 1000 A. The optical flowmeter uses a cross-correlation technique that analyses two light beams crossing the flow separated by a fixed distance. The x-ray image sensor uses a scintillating FO array, one FO for each image pixel to form an image of the x-ray field. The systems described in these paper use general-purpose components including optical fibers and optoelectronic devices, which are readily available, and of low cost.

Research progress in fiber optic sensors and systems at the Federal University of Rio de Janeiro

NASA Astrophysics Data System (ADS)

Werneck, Marcelo M.; Ferreira, Aldo P.; Maggi, Luis E.; De Carvalho, C. C.; Ribeiro, R. M.

1999-02-01

As widely known, fiberoptics (FO) are being used in a large variety of sensor an systems particularly for their small dimensions and low cost, large bandwidth and favorable dielectric properties. These properties have allowed us to develop sensor and systems for general applications and, particularly, for biomedical engineering. The intravasculator pressure sensor was designed for small dimensions and high bandwidth. The system is based on light- intensity modulation technique and use a 2 mm-diameter elastomer membrane as the sensor element and a pigtailed laser as a light source. The optical power out put curve was linear for pressures within the range of 0 to 300 mmHg. The real time optical biosensor uses the evanescent field technique for monitoring Escherichia coli growth in culture media. The optical biosensor monitors interactions between the analytic and the evanescent field of an optical fiber passing through it. The FO based high voltage and current sensor is a measuring system designed for monitoring voltage and current in high voltage transmission lines. The linearity of the system is better than 2 percent in both ranges of 0 to 25 kV and 0 to 1000 A. The optical flowmeter uses a cross-correlation technique that analyzes two light beams crossing the flow separated by a fixed distance. The x-ray image sensor uses a scintillating FO array, one FO for each image pixel to form an image of the x-ray field. The systems described in this paper use general-purpose components including optical fibers and optoelectronic devices, which are readily available, and of low cost.

Fiber optic backscatter spectroscopic sensor to monitor enamel demineralization and remineralization in vitro

PubMed Central

Kishen, Anil; Shrestha, Annie; Rafique, Adeela

2008-01-01

In this study, a Fiber Optic Backscatter Spectroscopic Sensor (FOBSS) is used to monitor demineralization and remineralization induced changes in the enamel. A bifurcated fiber optic backscatter probe connected to a visible light source and a high resolution spectrophotometer was used to acquire the backscatter light spectrum from the tooth surface. The experiments were conducted in two parts. In Part 1, experiments were carried out using fiber optic backscatter spectroscopy on (1) sound enamel and dentine sections and (2) sound tooth specimens subjected to demineralization and remineralization. In Part 2, polarization microscopy was conducted to examine the depth of demineralization in tooth specimens. The enamel and dentine specimens from the Part-1 experiments showed distinct backscatter spectra. The spectrum obtained from the enamel-dentine combination and the spectrum generated from the average of the enamel and dentine spectral values were closely similar and showed characteristics of dentine. The experiments in Part 2 showed that demineralization and remineralization processes induced a linear decrease and linear increase in the backscatter light intensity respectively. A negative correlation between the decrease in the backscatter light intensity during demineralization and the depth of demineralization determined using the polarization microscopy was calculated to be p = -0.994. This in vitro experiment highlights the potential benefit of using FOBSS to detect demineralization and remineralization of enamel. PMID:20142887

Illuminant-adaptive color reproduction for mobile display

NASA Astrophysics Data System (ADS)

Kim, Jong-Man; Park, Kee-Hyon; Kwon, Oh-Seol; Cho, Yang-Ho; Ha, Yeong-Ho

2006-01-01

This paper proposes an illuminant-adaptive reproduction method using light adaptation and flare conditions for a mobile display. Mobile displays, such as PDAs and cellular phones, are viewed under various lighting conditions. In particular, images displayed in daylight are perceived as quite dark due to the light adaptation of the human visual system, as the luminance of a mobile display is considerably lower than that of an outdoor environment. In addition, flare phenomena decrease the color gamut of a mobile display by increasing the luminance of dark areas and de-saturating the chroma. Therefore, this paper presents an enhancement method composed of lightness enhancement and chroma compensation. First, the ambient light intensity is measured using a lux-sensor, then the flare is calculated based on the reflection ratio of the display device and the ambient light intensity. The relative cone response is nonlinear to the input luminance. This is also changed by the ambient light intensity. Thus, to improve the perceived image, the displayed luminance is enhanced by lightness linearization. In this paper, the image's luminance is transformed by linearization of the response to the input luminance according to the ambient light intensity. Next, the displayed image is compensated according to the physically reduced chroma, resulting from flare phenomena. The reduced chroma value is calculated according to the flare for each intensity. The chroma compensation method to maintain the original image's chroma is applied differently for each hue plane, as the flare affects each hue plane differently. At this time, the enhanced chroma also considers the gamut boundary. Based on experimental observations, the outer luminance-intensity generally ranges from 1,000 lux to 30,000 lux. Thus, in the case of an outdoor environment, i.e. greater than 1,000 lux, this study presents a color reproduction method based on an inverse cone response curve and flare condition. Consequently, the proposed algorithm improves the quality of the perceived image adaptive to an outdoor environment.

Realization of rapid debugging for detection circuit of optical fiber gas sensor: Using an analog signal source

NASA Astrophysics Data System (ADS)

Tian, Changbin; Chang, Jun; Wang, Qiang; Wei, Wei; Zhu, Cunguang

2015-03-01

An optical fiber gas sensor mainly consists of two parts: optical part and detection circuit. In the debugging for the detection circuit, the optical part usually serves as a signal source. However, in the debugging condition, the optical part can be easily influenced by many factors, such as the fluctuation of ambient temperature or driving current resulting in instability of the wavelength and intensity for the laser; for dual-beam sensor, the different bends and stresses of the optical fiber will lead to the fluctuation of the intensity and phase; the intensity noise from the collimator, coupler, and other optical devices in the system will also result in the impurity of the optical part based signal source. In order to dramatically improve the debugging efficiency of the detection circuit and shorten the period of research and development, this paper describes an analog signal source, consisting of a single chip microcomputer (SCM), an amplifier circuit, and a voltage-to-current conversion circuit. It can be used to realize the rapid debugging detection circuit of the optical fiber gas sensor instead of optical part based signal source. This analog signal source performs well with many other advantages, such as the simple operation, small size, and light weight.

Extrinsic fiber optic displacement sensors and displacement sensing systems

DOEpatents

Murphy, K.A.; Gunther, M.F.; Vengsarkar, A.M.; Claus, R.O.

1994-04-05

An extrinsic Fizeau fiber optic sensor comprises a single-mode fiber, used as an input/output fiber, and a multimode fiber, used purely as a reflector, to form an air gap within a silica tube that acts as a Fizeau cavity. The Fresnel reflection from the glass/air interface at the front of the air gap (reference reflection) and the reflection from the air/glass interface at the far end of the air gap (sensing reflection) interfere in the input/output fiber. The two fibers are allowed to move in the silica tube, and changes in the air gap length cause changes in the phase difference between the reference reflection and the sensing reflection. This phase difference is observed as changes in intensity of the light monitored at the output arm of a fused biconical tapered coupler. The extrinsic Fizeau fiber optic sensor behaves identically whether it is surface mounted or embedded, which is unique to the extrinsic sensor in contrast to intrinsic Fabry-Perot sensors. The sensor may be modified to provide a quadrature phase shift extrinsic Fizeau fiber optic sensor for the detection of both the amplitude and the relative polarity of dynamically varying strain. The quadrature light signals may be generated by either mechanical or optical means. A plurality of the extrinsic sensors may connected in cascade and multiplexed to allow monitoring by a single analyzer. 14 figures.

Extrinsic fiber optic displacement sensors and displacement sensing systems

DOEpatents

Murphy, Kent A.; Gunther, Michael F.; Vengsarkar, Ashish M.; Claus, Richard O.

1994-01-01

An extrinsic Fizeau fiber optic sensor comprises a single-mode fiber, used as an input/output fiber, and a multimode fiber, used purely as a reflector, to form an air gap within a silica tube that acts as a Fizeau cavity. The Fresnel reflection from the glass/air interface at the front of the air gap (reference reflection) and the reflection from the air/glass interface at the far end of the air gap (sensing reflection) interfere in the input/output fiber. The two fibers are allowed to move in the silica tube, and changes in the air gap length cause changes in the phase difference between the reference reflection and the sensing reflection. This phase difference is observed as changes in intensity of the light monitored at the output arm of a fused biconical tapered coupler. The extrinsic Fizeau fiber optic sensor behaves identically whether it is surface mounted or embedded, which is unique to the extrinsic sensor in contrast to intrinsic Fabry-Perot sensors. The sensor may be modified to provide a quadrature phase shift extrinsic Fizeau fiber optic sensor for the detection of both the amplitude and the relative polarity of dynamically varying strain. The quadrature light signals may be generated by either mechanical or optical means. A plurality of the extrinsic sensors may connected in cascade and multiplexed to allow monitoring by a single analyzer.

Flight testing of a luminescent surface pressure sensor

NASA Technical Reports Server (NTRS)

Mclachlan, B. G.; Bell, J. H.; Espina, J.; Gallery, J.; Gouterman, M.; Demandante, C. G. N.; Bjarke, L.

1992-01-01

NASA ARC has conducted flight tests of a new type of aerodynamic pressure sensor based on a luminescent surface coating. Flights were conducted at the NASA ARC-Dryden Flight Research Facility. The luminescent pressure sensor is based on a surface coating which, when illuminated with ultraviolet light, emits visible light with an intensity dependent on the local air pressure on the surface. This technique makes it possible to obtain pressure data over the entire surface of an aircraft, as opposed to conventional instrumentation, which can only make measurements at pre-selected points. The objective of the flight tests was to evaluate the effectiveness and practicality of a luminescent pressure sensor in the actual flight environment. A luminescent pressure sensor was installed on a fin, the Flight Test Fixture (FTF), that is attached to the underside of an F-104 aircraft. The response of one particular surface coating was evaluated at low supersonic Mach numbers (M = 1.0-1.6) in order to provide an initial estimate of the sensor's capabilities. This memo describes the test approach, the techniques used, and the pressure sensor's behavior under flight conditions. A direct comparison between data provided by the luminescent pressure sensor and that produced by conventional pressure instrumentation shows that the luminescent sensor can provide quantitative data under flight conditions. However, the test results also show that the sensor has a number of limitations which must be addressed if this technique is to prove useful in the flight environment.

An optical fiber bundle sensor for tip clearance and tip timing measurements in a turbine rig.

PubMed

García, Iker; Beloki, Josu; Zubia, Joseba; Aldabaldetreku, Gotzon; Illarramendi, María Asunción; Jiménez, Felipe

2013-06-05

When it comes to measuring blade-tip clearance or blade-tip timing in turbines, reflective intensity-modulated optical fiber sensors overcome several traditional limitations of capacitive, inductive or discharging probe sensors. This paper presents the signals and results corresponding to the third stage of a multistage turbine rig, obtained from a transonic wind-tunnel test. The probe is based on a trifurcated bundle of optical fibers that is mounted on the turbine casing. To eliminate the influence of light source intensity variations and blade surface reflectivity, the sensing principle is based on the quotient of the voltages obtained from the two receiving bundle legs. A discrepancy lower than 3% with respect to a commercial sensor was observed in tip clearance measurements. Regarding tip timing measurements, the travel wave spectrum was obtained, which provides the average vibration amplitude for all blades at a particular nodal diameter. With this approach, both blade-tip timing and tip clearance measurements can be carried out simultaneously. The results obtained on the test turbine rig demonstrate the suitability and reliability of the type of sensor used, and suggest the possibility of performing these measurements in real turbines under real working conditions.

An Optical Fiber Bundle Sensor for Tip Clearance and Tip Timing Measurements in a Turbine Rig

PubMed Central

García, Iker; Beloki, Josu; Zubia, Joseba; Aldabaldetreku, Gotzon; Illarramendi, María Asunción; Jiménez, Felipe

2013-01-01

When it comes to measuring blade-tip clearance or blade-tip timing in turbines, reflective intensity-modulated optical fiber sensors overcome several traditional limitations of capacitive, inductive or discharging probe sensors. This paper presents the signals and results corresponding to the third stage of a multistage turbine rig, obtained from a transonic wind-tunnel test. The probe is based on a trifurcated bundle of optical fibers that is mounted on the turbine casing. To eliminate the influence of light source intensity variations and blade surface reflectivity, the sensing principle is based on the quotient of the voltages obtained from the two receiving bundle legs. A discrepancy lower than 3% with respect to a commercial sensor was observed in tip clearance measurements. Regarding tip timing measurements, the travel wave spectrum was obtained, which provides the average vibration amplitude for all blades at a particular nodal diameter. With this approach, both blade-tip timing and tip clearance measurements can be carried out simultaneously. The results obtained on the test turbine rig demonstrate the suitability and reliability of the type of sensor used, and suggest the possibility of performing these measurements in real turbines under real working conditions. PMID:23739163

Improving the uniformity of luminous system in radial imaging capsule endoscope system

NASA Astrophysics Data System (ADS)

Ou-Yang, Mang; Jeng, Wei-De

2013-02-01

This study concerns the illumination system in a radial imaging capsule endoscope (RICE). Uniformly illuminating the object is difficult because the intensity of the light from the light emitting diodes (LEDs) varies with angular displacement. When light is emitted from the surface of the LED, it first encounters the cone mirror, from which it is reflected, before directly passing through the lenses and complementary metal oxide semiconductor (CMOS) sensor. The light that is strongly reflected from the transparent view window (TVW) propagates again to the cone mirror, to be reflected and to pass through the lenses and CMOS sensor. The above two phenomena cause overblooming on the image plane. Overblooming causes nonuniform illumination on the image plane and consequently reduced image quality. In this work, optical design software was utilized to construct a photometric model for the optimal design of the LED illumination system. Based on the original RICE model, this paper proposes an optimal design to improve the uniformity of the illumination. The illumination uniformity in the RICE is increased from its original value of 0.128 to 0.69, greatly improving light uniformity.

Fiber-optic thermometry using thermal radiation from Tm end doped SiO{sub 2} fiber sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morita, Kentaro; Katsumata, Toru; Komuro, Shuji

2014-04-15

Fiber-optic thermometry based on temperature dependence of thermal radiation from Tm{sup 3+} ions was studied using Tm end doped SiO{sub 2} fiber sensor. Visible light radiation peaks due to f-f transition of Tm{sup 3+} ion were clearly observed at λ = 690 and 790 nm from Tm end doped SiO{sub 2} fibers sensor at the temperature above 600 °C. Thermal radiation peaks are assigned with f-f transition of Tm{sup 3+} ion, {sup 1}D{sub 2}-{sup 3}H{sub 6}, and {sup 1}G{sub 4}-{sup 3}H{sub 6}. Peak intensity of thermal radiation from Tm{sup 3+} ion increases with temperature. Intensity ratio of thermal radiation peaks atmore » λ = 690 nm against that at λ = 790 nm, I{sub 790/690}, is suitable for the temperature measurement above 750 °C. Two-dimensional temperature distribution in a flame is successfully evaluated by Tm end doped SiO{sub 2} fiber sensor.« less

A Low-Cost and Portable Dual-Channel Fiber Optic Surface Plasmon Resonance System.

PubMed

Liu, Qiang; Liu, Yun; Chen, Shimeng; Wang, Fang; Peng, Wei

2017-12-04

A miniaturization and integration dual-channel fiber optic surface plasmon resonance (SPR) system was proposed and demonstrated in this paper. We used a yellow light-emitting diode (LED, peak wavelength 595 nm) and built-in web camera as a light source and detector, respectively. Except for the detection channel, one of the sensors was used as a reference channel to compensate nonspecific binding and physical absorption. We packaged the LED and surface plasmon resonance (SPR) sensors together, which are flexible enough to be applied to mobile devices as a compact and portable system. Experimental results show that the normalized intensity shift and refractive index (RI) of the sample have a good linear relationship in the RI range from 1.328 to 1.348. We used this sensor to monitor the reversible, specific interaction between lectin concanavalin A (Con A) and glycoprotein ribonuclease B (RNase B), which demonstrate its capabilities of specific identification and biochemical samples concentration detection. This sensor system has potential applications in various fields, such as medical diagnosis, public health, food safety, and environment monitoring.

Nonlinear multilayers as optical limiters

NASA Astrophysics Data System (ADS)

Turner-Valle, Jennifer Anne

1998-10-01

In this work we present a non-iterative technique for computing the steady-state optical properties of nonlinear multilayers and we examine nonlinear multilayer designs for optical limiters. Optical limiters are filters with intensity-dependent transmission designed to curtail the transmission of incident light above a threshold irradiance value in order to protect optical sensors from damage due to intense light. Thin film multilayers composed of nonlinear materials exhibiting an intensity-dependent refractive index are used as the basis for optical limiter designs in order to enhance the nonlinear filter response by magnifying the electric field in the nonlinear materials through interference effects. The nonlinear multilayer designs considered in this work are based on linear optical interference filter designs which are selected for their spectral properties and electric field distributions. Quarter wave stacks and cavity filters are examined for their suitability as sensor protectors and their manufacturability. The underlying non-iterative technique used to calculate the optical response of these filters derives from recognizing that the multi-valued calculation of output irradiance as a function of incident irradiance may be turned into a single-valued calculation of incident irradiance as a function of output irradiance. Finally, the benefits and drawbacks of using nonlinear multilayer for optical limiting are examined and future research directions are proposed.

Typical effects of laser dazzling CCD camera

NASA Astrophysics Data System (ADS)

Zhang, Zhen; Zhang, Jianmin; Shao, Bibo; Cheng, Deyan; Ye, Xisheng; Feng, Guobin

2015-05-01

In this article, an overview of laser dazzling effect to buried channel CCD camera is given. The CCDs are sorted into staring and scanning types. The former includes the frame transfer and interline transfer types. The latter includes linear and time delay integration types. All CCDs must perform four primary tasks in generating an image, which are called charge generation, charge collection, charge transfer and charge measurement. In camera, the lenses are needed to input the optical signal to the CCD sensors, in which the techniques for erasing stray light are used. And the electron circuits are needed to process the output signal of CCD, in which many electronic techniques are used. The dazzling effects are the conjunct result of light distribution distortion and charge distribution distortion, which respectively derive from the lens and the sensor. Strictly speaking, in lens, the light distribution is not distorted. In general, the lens are so well designed and fabricated that its stray light can be neglected. But the laser is of much enough intensity to make its stray light obvious. In CCD image sensors, laser can induce a so large electrons generation. Charges transfer inefficiency and charges blooming will cause the distortion of the charge distribution. Commonly, the largest signal outputted from CCD sensor is restricted by capability of the collection well of CCD, and can't go beyond the dynamic range for the subsequent electron circuits maintaining normal work. So the signal is not distorted in the post-processing circuits. But some techniques in the circuit can make some dazzling effects present different phenomenon in final image.

Measuring Slit Width and Separation in a Diffraction Experiment

ERIC Educational Resources Information Center

Gan, K. K.; Law, A. T.

2009-01-01

We present a procedure for measuring slit width and separation in single- and double-slit diffraction experiments. Intensity spectra of diffracted laser light are measured with an optical sensor (PIN diode). Slit widths and separations are extracted by fitting to the measured spectra. We present a simple fitting procedure to account for the…

Shared Challenges in Object Perception for Robots and Infants

ERIC Educational Resources Information Center

Fitzpatrick, Paul; Needham, Amy; Natale, Lorenzo; Metta, Giorgio

2008-01-01

Robots and humans receive partial, fragmentary hints about the world's state through their respective sensors. These hints--tiny patches of light intensity, frequency components of sound, etc.--are far removed from the world of objects which we feel and perceive so effortlessly around us. The study of infant development and the construction of…

Optical Riblet Sensor: Beam Parameter Requirements for the Probing Laser Source.

PubMed

Tschentscher, Juliane; Hochheim, Sven; Brüning, Hauke; Brune, Kai; Voit, Kay-Michael; Imlau, Mirco

2016-03-30

Beam parameters of a probing laser source in an optical riblet sensor are studied by considering the high demands on a sensors' precision and reliability for the determination of deviations of the geometrical shape of a riblet. Mandatory requirements, such as minimum intensity and light polarization, are obtained by means of detailed inspection of the optical response of the riblet using ray and wave optics; the impact of wavelength is studied. Novel measures for analyzing the riblet shape without the necessity of a measurement with a reference sample are derived; reference values for an ideal riblet structure obtained with the optical riblet sensor are given. The application of a low-cost, frequency-doubled Nd:YVO₄ laser pointer sufficient to serve as a reliable laser source in an appropriate optical riblet sensor is discussed.

Light-controlled biphasic current stimulator IC using CMOS image sensors for high-resolution retinal prosthesis and in vitro experimental results with rd1 mouse.

PubMed

Oh, Sungjin; Ahn, Jae-Hyun; Lee, Sangmin; Ko, Hyoungho; Seo, Jong Mo; Goo, Yong-Sook; Cho, Dong-il Dan

2015-01-01

Retinal prosthetic devices stimulate retinal nerve cells with electrical signals proportional to the incident light intensities. For a high-resolution retinal prosthesis, it is necessary to reduce the size of the stimulator pixels as much as possible, because the retinal nerve cells are concentrated in a small area of approximately 5 mm × 5 mm. In this paper, a miniaturized biphasic current stimulator integrated circuit is developed for subretinal stimulation and tested in vitro. The stimulator pixel is miniaturized by using a complementary metal-oxide-semiconductor (CMOS) image sensor composed of three transistors. Compared to a pixel that uses a four-transistor CMOS image sensor, this new design reduces the pixel size by 8.3%. The pixel size is further reduced by simplifying the stimulation-current generating circuit, which provides a 43.9% size reduction when compared to the design reported to be the most advanced version to date for subretinal stimulation. The proposed design is fabricated using a 0.35 μm bipolar-CMOS-DMOS process. Each pixel is designed to fit in a 50 μ m × 55 μm area, which theoretically allows implementing more than 5000 pixels in the 5 mm × 5 mm area. Experimental results show that a biphasic current in the range of 0 to 300 μA at 12 V can be generated as a function of incident light intensities. Results from in vitro experiments with rd1 mice indicate that the proposed method can be effectively used for retinal prosthesis with a high resolution.

Fixing methods for the use of optical fibers in interferometric arrangements

NASA Astrophysics Data System (ADS)

Cubik, Jakub; Kepak, Stanislav; Fajkus, Marcel; Zboril, Ondrej; Nedoma, Jan; Davidson, Alan; Vasinek, Vladimir

2016-12-01

Today interferometric sensors are among the most accurate available thanks to their inherent high sensitivity. These highly versatile sensors may be used to measure phenomena such as temperature, strain, fluid level, flow, vibration, stress, etc. This article concentrates on the composition of fiber-optic interferometers, in particular the Mach-Zehnder type. The Mach-Zehnder type is composed of two arms, one for measurement and a second serving as a reference. When light enters the interferometer, ideally the phase of the light is shifted only in the measurement arm while the phase in the second arm remains unchanged. Interference occurs when the light recombining at the output and the resulting light intensity is proportional to the measurand. A major issue in the application of fiber based sensors is laying and fixing the fibers effectively in real life environments. Different approaches are necessary for both arms. The reference arm should as far as possible be isolated from the measurand. In this paper, various isolating materials are considered, however there are almost unlimited materials that may be used for isolation purposes. Conventional construction methods and materials were used such as aluminum tubing, flexible PVC tubing, double sided tape, steel clinches, superglue, PVC strips and PVC strips filled by silicon.

Hardware-in-the-loop projector system for light detection and ranging sensor testing

NASA Astrophysics Data System (ADS)

Kim, Hajin J.; Naumann, Charles B.; Cornell, Michael C.

2012-08-01

Efforts in developing a synthetic environment for testing light detection and ranging (LADAR) sensors in a hardware-in-the-loop simulation are continuing at the Aviation and Missile Research, Engineering, and Development Center of the U.S. Army Research, Engineering and Development Command (RDECOM). Current activities have concentrated on evaluating the optical projection techniques for the LADAR synthetic environment. Schemes for generating the optical signals representing the individual pixels of the projection are of particular interest. Several approaches have been investigated and tested with emphasis on operating wavelength, intensity dynamic range and uniformity, and flexibility in pixel waveform generation. This paper will discuss some of the results from these current efforts at RDECOM's System Simulation and Development Directorate's Electro Optical Technology Development Laboratory.

Measurements of spectral responses for developing fiber-optic pH sensor

NASA Astrophysics Data System (ADS)

Yoo, Wook Jae; Heo, Ji Yeon; Jang, Kyoung Won; Seo, Jeong Ki; Moon, Jin Soo; Park, Jang-Yeon; Park, Byung Gi; Cho, Seunghyun; Lee, Bongsoo

2011-01-01

In this study, we have fabricated a fiber-optic pH sensor, which is composed of a light source, a pH-sensing probe, plastic optical fibers and a spectrometer, for determining the degree of infection by Helicobacter pylori in the stomach. As pH indicators, phenol red and m-cresol purple are used, and pH liquid solutions are prepared by mixing phenol red or m-cresol purple solutions and various kinds of pH buffer solutions. The light emitted by a light source is guided by plastic optical fibers to the pH liquid solution, and the optical characteristic of a reflected light is changed according to the color variations of the pH indicator in the pH-sensing probe. Therefore, we have measured the intensities and wavelength shifts of the reflected lights, which change according to the color variations of indicators at different pH values, by using a spectrometer for spectral analysis. Also, the relationships between the pH values of liquid solutions and the optical properties of the modulated lights are obtained on the basis of the changes of the colors of indicators.

Can SOHO SWAN detect CMEs?

NASA Technical Reports Server (NTRS)

St.Cyr, O. C.; Malayeri, M. L.; Yashiro, S.; Quernerais, E.; Bertaux, Jean-Loup; Howard, Russ

2003-01-01

We have investigated the possibility that the Solar Wind Anisotropies (SWAN) remote sensing instrument on SOHO may be able to detect coronal mass ejections (CMEs) in neutral Hydrogen Lyman-? emission. We have identified CMEs near the Sun in observations by the SOHO LASCO white-light coronagraphs and in extreme ultraviolet emissions using SOHO E n . There are very few methods of tracking CMEs after they leave the coronagraph's field-of-view, so this is an important topic to study. The primary science goal of the SWAN investigation is the measurement of large-scale structures in the solar wind, and these are obtained by detecting intensity fluctuations in Lyman-?. SWAN consists of a pair of Sensors on opposite panels of SOHO. The instantaneous field-of-view of each sensor unit is a So x So square, divided into lo pixels. A gimbaled periscope system allows each sensor to map the intensity distribution of Lyman-?, and the entire sky can be scanned in less than one day. This is the typical mode of operation for this instrument.

Local Intensity Enhancements in Spherical Microcavities: Implications for Photonic Chemical and Biological Sensors

NASA Technical Reports Server (NTRS)

Fuller, Kirk A.

2005-01-01

In this report, we summarize recent findings regarding the use spherical microcavities in the amplification of light that is inelastically scattered by either fluorescent or Raman-active molecules. This discussion will focus on Raman scattering, with the understanding that analogous processes apply to fluorescence. Raman spectra can be generated through the use of a very strong light source that stimulates inelastic light scattering by molecules, with the scattering occurring at wavelengths shifted from that of the source and being most prominent at shifts associated with the molecules natural vibrational frequencies. The Raman signal can be greatly enhanced by exposing a molecule to the intense electric fields that arise near surfaces (typically of gold or silver) exhibiting nanoscale roughness. This is known as surface-enhanced Raman scattering (SERS). SERS typically produces gain factors of 103 - 106, but under special conditions, factors of 1010 - 1014 have been achieved.

Separating light absorption layer from channel in ZnO vertical nanorod arrays based photodetectors for high-performance image sensors

NASA Astrophysics Data System (ADS)

Ma, Yang; Wu, Congjun; Xu, Zhihao; Wang, Fei; Wang, Min

2018-05-01

Photoconductor arrays with both high responsivity and large ON/OFF ratios are of great importance for the application of image sensors. Herein, a ZnO vertical nanorod array based photoconductor with a light absorption layer separated from the device channel has been designed, in which the photo-generated carriers along the axial ZnO nanorods drive to the external electrodes through nanorod-nanorod junctions in the dense layer at the bottom. This design allows us to enhance the photocurrent with unchanged dark current by increasing the ratio between the ZnO nanorod length and the thickness of the dense layer to achieve both high responsivity and large ON/OFF ratios. As a result, the as-fabricated devices possess a high responsivity of 1.3 × 105 A/W, a high ON/OFF ratio of 790, a high detectivity of 1.3 × 1013 Jones, and a low detectable light intensity of 1 μW/cm2. More importantly, the developed approach enables the integration of ZnO vertical nanorod array based photodetectors as image sensors with uniform device-to-device performance.

A Neural Network Approach for Building An Obstacle Detection Model by Fusion of Proximity Sensors Data

PubMed Central

Peralta, Emmanuel; Vargas, Héctor; Hermosilla, Gabriel

2018-01-01

Proximity sensors are broadly used in mobile robots for obstacle detection. The traditional calibration process of this kind of sensor could be a time-consuming task because it is usually done by identification in a manual and repetitive way. The resulting obstacles detection models are usually nonlinear functions that can be different for each proximity sensor attached to the robot. In addition, the model is highly dependent on the type of sensor (e.g., ultrasonic or infrared), on changes in light intensity, and on the properties of the obstacle such as shape, colour, and surface texture, among others. That is why in some situations it could be useful to gather all the measurements provided by different kinds of sensor in order to build a unique model that estimates the distances to the obstacles around the robot. This paper presents a novel approach to get an obstacles detection model based on the fusion of sensors data and automatic calibration by using artificial neural networks. PMID:29495338

Phase and amplitude wave front sensing and reconstruction with a modified plenoptic camera

NASA Astrophysics Data System (ADS)

Wu, Chensheng; Ko, Jonathan; Nelson, William; Davis, Christopher C.

2014-10-01

A plenoptic camera is a camera that can retrieve the direction and intensity distribution of light rays collected by the camera and allows for multiple reconstruction functions such as: refocusing at a different depth, and for 3D microscopy. Its principle is to add a micro-lens array to a traditional high-resolution camera to form a semi-camera array that preserves redundant intensity distributions of the light field and facilitates back-tracing of rays through geometric knowledge of its optical components. Though designed to process incoherent images, we found that the plenoptic camera shows high potential in solving coherent illumination cases such as sensing both the amplitude and phase information of a distorted laser beam. Based on our earlier introduction of a prototype modified plenoptic camera, we have developed the complete algorithm to reconstruct the wavefront of the incident light field. In this paper the algorithm and experimental results will be demonstrated, and an improved version of this modified plenoptic camera will be discussed. As a result, our modified plenoptic camera can serve as an advanced wavefront sensor compared with traditional Shack- Hartmann sensors in handling complicated cases such as coherent illumination in strong turbulence where interference and discontinuity of wavefronts is common. Especially in wave propagation through atmospheric turbulence, this camera should provide a much more precise description of the light field, which would guide systems in adaptive optics to make intelligent analysis and corrections.

A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection

PubMed Central

Hung, San-Shan; Chang, Hsing-Cheng; Chang, I-Nan

2016-01-01

A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2′-bipyridyl) dichlororuthenium(II) hexahydrate and Tris(bipyridine)ruthenium(II) chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%. PMID:27941636

A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection.

PubMed

Hung, San-Shan; Chang, Hsing-Cheng; Chang, I-Nan

2016-12-08

A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate and Tris(bipyridine)ruthenium(II) chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%.

Broadband thermal optical limiter for the protection of eyes and sensors

NASA Astrophysics Data System (ADS)

Justus, Brian L.; Huston, Alan L.; Campillo, Anthony J.

1994-05-01

A broadband thermal optical limiter for protecting a light sensitive object from intense laser beams at all near ultraviolet, visible and near infrared wavelengths is disclosed. The broadband thermal optical limiter comprises: a sample cell containing a solution of broadband absorber material dissolved in a thermal solvent; and a first optical device for converging an incident laser beam into the sample cell. The sample cell is responsive to a converged incident laser beam below a predetermined intensity level for passing therethrough the converged incident laser beam below the predetermined intensity level. The sample cell is also responsive to a converged incident laser beam at or above a predetermined intensity level for thermally defocusing substantially all of the converged incident laser beam in different directions and passing therethrough only a remaining small portion of the converged incident laser beam at or above the predetermined intensity level. The broadband thermal optical limiter further includes a second optical device for focusing substantially all of the laser beam passing through the sample cell into the light sensitive object to be protected.

Low cost fiber optic sensing of sugar solution

NASA Astrophysics Data System (ADS)

Muthuraju, M. E.; Patlolla, Anurag Reddy; Vadakkapattu Canthadai, Badrinath; Pachava, Vengalrao

2015-03-01

The demand for highly sensitive and reliable sensors to assess the refractive index of liquid get many applications in chemical and biomedical areas. Indeed, the physical parameters such as concentration, pressure and density, etc., can be found using the refractive index of liquid. In contrast to the conventional refractometer for measurement, optical fiber sensor has several advantages like remote sensing, small in size, low cost, immune to EMI etc., In this paper we have discussed determination of refractive index of sugar solution using optical fiber. An intensity modulated low cost plastic fiber optic refractive index sensor has been designed for the study. The sensor is based on principle of change in angle of reflected light caused by refractive index change of the medium surrounding the fiber. The experimental results obtained for the sugar solution of different refractive indices prove that the fiber optic sensor is cable of measuring the refractive indices as well as the concentrations.

Experimental and theoretical study of the in- fiber twist sensor based on quasi-fan Solc structure filter.

PubMed

Sun, Chunran; Wang, Muguang; Jian, Shuisheng

2017-08-21

In this paper, a novel quasi-fan Solc structure filter based on elliptical-core spun fiber for twist sensing has been experimentally investigated and theoretically analyzed. The discrete model of spun fiber has been built to analyze the transmission characteristics of proposed sensor. Both experimental and simulated results indicate that the extinction ratio of the comb spectrum based on quasi-fan Solc birefringent fiber filter varies with twist angle and agrees well with each other. Based on the intensity modulation, the proposed twist sensor exhibits a high sensitivity of 0.02219 dB/(°/m). Moreover, thanks to the invariability of the fiber birefringence and the state of polarization of the input light, the proposed twist sensor has a very low temperature and strain sensitivity, which can avoid the cross-sensitivity problem existing in most twist sensors.

Plasmonic trace sensing below the photon shot noise limit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pooser, Raphael C.; Lawrie, Benjamin J.

Plasmonic sensors are important detectors of biochemical trace compounds, but those that utilize optical readout are approaching their absolute limits of detection as defined by the Heisenberg uncertainty principle in both differential intensity and phase readout. However, the use of more general minimum uncertainty states in the form of squeezed light can push the noise floor in these sensors below the shot noise limit (SNL) in one analysis variable at the expense of another. Here, we demonstrate a quantum plasmonic sensor whose noise floor is reduced below the SNL in order to perform index of refraction measurements with sensitivities unobtainablemore » with classical plasmonic sensors. The increased signal-to-noise ratio can result in faster detection of analyte concentrations that were previously lost in the noise. As a result, these benefits are the hallmarks of a sensor exploiting quantum readout fields in order to manipulate the limits of the Heisenberg uncertainty principle.« less

Plasmonic trace sensing below the photon shot noise limit

DOE PAGES

Pooser, Raphael C.; Lawrie, Benjamin J.

2015-12-09

Plasmonic sensors are important detectors of biochemical trace compounds, but those that utilize optical readout are approaching their absolute limits of detection as defined by the Heisenberg uncertainty principle in both differential intensity and phase readout. However, the use of more general minimum uncertainty states in the form of squeezed light can push the noise floor in these sensors below the shot noise limit (SNL) in one analysis variable at the expense of another. Here, we demonstrate a quantum plasmonic sensor whose noise floor is reduced below the SNL in order to perform index of refraction measurements with sensitivities unobtainablemore » with classical plasmonic sensors. The increased signal-to-noise ratio can result in faster detection of analyte concentrations that were previously lost in the noise. As a result, these benefits are the hallmarks of a sensor exploiting quantum readout fields in order to manipulate the limits of the Heisenberg uncertainty principle.« less

Superior Self-Powered Room-Temperature Chemical Sensing with Light-Activated Inorganic Halides Perovskites.

PubMed

Chen, Hongjun; Zhang, Meng; Bo, Renheng; Barugkin, Chog; Zheng, Jianghui; Ma, Qingshan; Huang, Shujuan; Ho-Baillie, Anita W Y; Catchpole, Kylie R; Tricoli, Antonio

2018-02-01

Hybrid halide perovskite is one of the promising light absorber and is intensively investigated for many optoelectronic applications. Here, the first prototype of a self-powered inorganic halides perovskite for chemical gas sensing at room temperature under visible-light irradiation is presented. These devices consist of porous network of CsPbBr 3 (CPB) and can generate an open-circuit voltage of 0.87 V under visible-light irradiation, which can be used to detect various concentrations of O 2 and parts per million concentrations of medically relevant volatile organic compounds such as acetone and ethanol with very quick response and recovery time. It is observed that O 2 gas can passivate the surface trap sites in CPB and the ambipolar charge transport in the perovskite layer results in a distinct sensing mechanism compared with established semiconductors with symmetric electrical response to both oxidizing and reducing gases. The platform of CPB-based gas sensor provides new insights for the emerging area of wearable sensors for personalized and preventive medicine. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-sensing of temperature rises on light emitting diode based optrodes

NASA Astrophysics Data System (ADS)

Dehkhoda, Fahimeh; Soltan, Ahmed; Ponon, Nikhil; Jackson, Andrew; O'Neill, Anthony; Degenaar, Patrick

2018-04-01

Objective. This work presents a method to determine the surface temperature of microphotonic medical implants like LEDs. Our inventive step is to use the photonic emitter (LED) employed in an implantable device as its own sensor and develop readout circuitry to accurately determine the surface temperature of the device. Approach. There are two primary classes of applications where microphotonics could be used in implantable devices; opto-electrophysiology and fluorescence sensing. In such scenarios, intense light needs to be delivered to the target. As blue wavelengths are scattered strongly in tissue, such delivery needs to be either via optic fibres, two-photon approaches or through local emitters. In the latter case, as light emitters generate heat, there is a potential for probe surfaces to exceed the 2 °C regulatory. However, currently, there are no convenient mechanisms to monitor this in situ. Main results. We present the electronic control circuit and calibration method to monitor the surface temperature change of implantable optrode. The efficacy is demonstrated in air, saline, and brain. Significance. This paper, therefore, presents a method to utilize the light emitting diode as its own temperature sensor.

Advances in Bio-Tactile Sensors for Minimally Invasive Surgery Using the Fibre Bragg Grating Force Sensor Technique:A Survey

PubMed Central

Abushagur, Abdulfatah A.G.; Arsad, Norhana; Ibne Reaz, Mamun; Ashrif, A.; Bakar, A.

2014-01-01

The large interest in utilising fibre Bragg grating (FBG) strain sensors for minimally invasive surgery (MIS) applications to replace conventional electrical tactile sensors has grown in the past few years. FBG strain sensors offer the advantages of optical fibre sensors, such as high sensitivity, immunity to electromagnetic noise, electrical passivity and chemical inertness, but are not limited by phase discontinuity or intensity fluctuations. FBG sensors feature a wavelength-encoding sensing signal that enables distributed sensing that utilises fewer connections. In addition, their flexibility and lightness allow easy insertion into needles and catheters, thus enabling localised measurements inside tissues and blood. Two types of FBG tactile sensors have been emphasised in the literature: single-point and array FBG tactile sensors. This paper describes the current design, development and research of the optical fibre tactile techniques that are based on FBGs to enhance the performance of MIS procedures in general. Providing MIS or microsurgery surgeons with accurate and precise measurements and control of the contact forces during tissues manipulation will benefit both surgeons and patients. PMID:24721774

Development of integrated semiconductor optical sensors for functional brain imaging

NASA Astrophysics Data System (ADS)

Lee, Thomas T.

Optical imaging of neural activity is a widely accepted technique for imaging brain function in the field of neuroscience research, and has been used to study the cerebral cortex in vivo for over two decades. Maps of brain activity are obtained by monitoring intensity changes in back-scattered light, called Intrinsic Optical Signals (IOS), that correspond to fluctuations in blood oxygenation and volume associated with neural activity. Current imaging systems typically employ bench-top equipment including lamps and CCD cameras to study animals using visible light. Such systems require the use of anesthetized or immobilized subjects with craniotomies, which imposes limitations on the behavioral range and duration of studies. The ultimate goal of this work is to overcome these limitations by developing a single-chip semiconductor sensor using arrays of sources and detectors operating at near-infrared (NIR) wavelengths. A single-chip implementation, combined with wireless telemetry, will eliminate the need for immobilization or anesthesia of subjects and allow in vivo studies of free behavior. NIR light offers additional advantages because it experiences less absorption in animal tissue than visible light, which allows for imaging through superficial tissues. This, in turn, reduces or eliminates the need for traumatic surgery and enables long-term brain-mapping studies in freely-behaving animals. This dissertation concentrates on key engineering challenges of implementing the sensor. This work shows the feasibility of using a GaAs-based array of vertical-cavity surface emitting lasers (VCSELs) and PIN photodiodes for IOS imaging. I begin with in-vivo studies of IOS imaging through the skull in mice, and use these results along with computer simulations to establish minimum performance requirements for light sources and detectors. I also evaluate the performance of a current commercial VCSEL for IOS imaging, and conclude with a proposed prototype sensor.

An integrated optical sensor for measuring glucose concentration

NASA Astrophysics Data System (ADS)

Liu, Y.; Hering, P.; Scully, M. O.

1992-01-01

We used an optical sensor combined with a Mach-Zehnder interferometric waveguide and optical fibers to measure slight changes of aqueous sugar concentrations. The merits of this sensor are simplicity, reliability, high sensitivity and continuous monitoring. The technique is based on the fact that the refractive index of sugar solution changes with the concentration of sugar. In the experiment, one arm of the interferometer is clad with glue and is thus isolated from the sugar solution. The other one is exposed to the sugar solution. A single mode fiber is directly glued onto the interferometric waveguide, to guide the light into the interferometer. If the concentration of sugar covering the waveguide changes, the phase of propagating light in the exposed arm will be changed, while the phase in the other arm is fixed. Hence the output intensity from the interferometer is directly related to the concentration of the sugar solution. The result of this experiment yields the relation between the sugar concentration and output signal. From 0% to 1% concentration of sugar solution, there is only a 1.4×10-3 refractive index difference. Two sets of experimental data have been obtained, showing a linear relation between the sugar concentration and the output signal from our sensor. This sensor could be used for continuous monitoring of blood sugar in the human body.

A cost-effective quasi-distributed liquid leakage sensor based on the polymer optical fiber and flexible lamp belt with LEDs.

PubMed

Zhang, Yingzi; Hou, Yulong; Zhang, Yanjun; Hu, Yanjun; Zhang, Liang; Gao, Xiaolong; Zhang, Huixin; Liu, Wenyi

2018-04-16

A quasi-distributed liquid leakage (QDLL) sensor in local area is proposed and experimentally demonstrated, providing a real-time yet low-cost method than the existing local QDLL sensor. The sensor mainly consists of a flexible lamp belt (FLB) with light-emitting diodes (LEDs) and a polymer optical fiber (POF) processed with side-coupling structures. The side-coupling structures are illuminated by the LEDs one by one, forming a series of sensing probes. The lights are side-coupled into the POF through the side-coupling structure and pulse sequences are obtained from the power meters connected to the both ends of the POF. Each pulse represents a sensing probe, and the intensity of them increase when the coupling medium changes from air to liquid. The location of the leakage incident can be got by the position of each pulse in its output sequence. The influence of different side-coupling structures on side-coupling ratio are investigated. The experiment results validate the detection and localization abilities of the QDLL sensor along a 1 m-long POF with a spatial resolution of 0.1 m, which can be improved by adjusting the side-coupling structure. Furthermore, the temperature dependence is studied and can be compensated.

Atmospheric simulation using a liquid crystal wavefront-controlling device

NASA Astrophysics Data System (ADS)

Brooks, Matthew R.; Goda, Matthew E.

2004-10-01

Test and evaluation of laser warning devices is important due to the increased use of laser devices in aerial applications. This research consists of an atmospheric aberrating system to enable in-lab testing of various detectors and sensors. This system employs laser light at 632.8nm from a Helium-Neon source and a spatial light modulator (SLM) to cause phase changes using a birefringent liquid crystal material. Measuring outgoing radiation from the SLM using a CCD targetboard and Shack-Hartmann wavefront sensor reveals an acceptable resemblance of system output to expected atmospheric theory. Over three turbulence scenarios, an error analysis reveals that turbulence data matches theory. A wave optics computer simulation is created analogous to the lab-bench design. Phase data, intensity data, and a computer simulation affirm lab-bench results so that the aberrating SLM system can be operated confidently.

Control of crankshaft finish by scattering technique

NASA Astrophysics Data System (ADS)

Fontani, Daniela; Francini, Franco; Longobardi, Giuseppe; Sansoni, Paola

2001-06-01

The paper describes a new sensor dedicated to measure and check the surface quality of mechanical products. The results were obtained comparing the light scattered from two different ranges of angles by means of 16 photodiodes. The device is designed for obtaining valid data from curved surfaces as that of a crankshaft. Experimental measurements show that the ratio between scattered and reflected light intensity increases with the surface roughness. This device was developed for the off-tolerance detection of mechanical pieces in industrial production. Results of surface quality on crankshaft supplied by Renault were carried out.

Optical processing furnace with quartz muffle and diffuser plate

DOEpatents

Sopori, Bhushan L.

1995-01-01

An optical furnace for annealing a process wafer comprising a source of optical energy, a quartz muffle having a door to hold the wafer for processing, and a quartz diffuser plate to diffuse the light impinging on the quartz muffle; a feedback system with a light sensor located in the door or wall of the muffle is also provided for controlling the source of optical energy. The quartz for the diffuser plate is surface etched (to give the quartz diffusive qualities) in the furnace during a high intensity burn-in process.

Refractive index sensor based on combination of tilted fiber Bragg grating and waist-enlarged fusion bitaper

NASA Astrophysics Data System (ADS)

Liu, Xiaohang; Zheng, Jie; Yang, Jingyi; Li, Yi; Dong, Xinyong

2015-12-01

Refractive index measurement by using the combination of a tilted fiber Bragg grating (TFBG) and a waist-enlarged fusion bitaper (WEFBT) is proposed and demonstrated. The both devices can couple light between core and cladding modes with coupling coefficients depending on ambient refractive index. It is found that the proposed refractive index sensor offers two measurement ranges respectively from 1.333 to 1.428 and from 1.383 to 1.453 when different sensing segment is used, in addition to advantages of reflection operation mode and intensity-modulated measurement.

Simple refractometer based on in-line fiber interferometers

NASA Astrophysics Data System (ADS)

Esteban, Ó.; Martínez Manuel, R.; Shlyagin, M. G.

2015-09-01

A very simple but accurate optical fiber refractometer based on the Fresnel reflection in the fiber tip and two in-line low-reflective mirrors for light intensity referencing is reported. Each mirror was generated by connecting together 2 fiber sections with FC/PC and FC/APC connectors using the standard FC/PC mating sleeve. For the sensor interrogation, a standard DFB diode laser pumped with a sawtooth-wave current was used. A resolution of 6 x 10-4 was experimentally demonstrated using different liquids. A simple sensor construction and the use of low cost components make the reported system interesting for many applications.

BRDF-dependent accuracy of array-projection-based 3D sensors.

PubMed

Heist, Stefan; Kühmstedt, Peter; Tünnermann, Andreas; Notni, Gunther

2017-03-10

In order to perform high-speed three-dimensional (3D) shape measurements with structured light systems, high-speed projectors are required. One possibility is an array projector, which allows pattern projection at several tens of kilohertz by switching on and off the LEDs of various slide projectors. The different projection centers require a separate analysis, as the intensity received by the cameras depends on the projection direction and the object's bidirectional reflectance distribution function (BRDF). In this contribution, we investigate the BRDF-dependent errors of array-projection-based 3D sensors and propose an error compensation process.

Optical Riblet Sensor: Beam Parameter Requirements for the Probing Laser Source

PubMed Central

Tschentscher, Juliane; Hochheim, Sven; Brüning, Hauke; Brune, Kai; Voit, Kay-Michael; Imlau, Mirco

2016-01-01

Beam parameters of a probing laser source in an optical riblet sensor are studied by considering the high demands on a sensors’ precision and reliability for the determination of deviations of the geometrical shape of a riblet. Mandatory requirements, such as minimum intensity and light polarization, are obtained by means of detailed inspection of the optical response of the riblet using ray and wave optics; the impact of wavelength is studied. Novel measures for analyzing the riblet shape without the necessity of a measurement with a reference sample are derived; reference values for an ideal riblet structure obtained with the optical riblet sensor are given. The application of a low-cost, frequency-doubled Nd:YVO4 laser pointer sufficient to serve as a reliable laser source in an appropriate optical riblet sensor is discussed. PMID:27043567

Corrosion monitoring along infrastructures using distributed fiber optic sensing

NASA Astrophysics Data System (ADS)

Alhandawi, Khalil B.; Vahdati, Nader; Shiryayev, Oleg; Lawand, Lydia

2016-04-01

Pipeline Inspection Gauges (PIGs) are used for internal corrosion inspection of oil pipelines every 3-5 years. However, between inspection intervals, rapid corrosion may occur, potentially resulting in major accidents. The motivation behind this research project was to develop a safe distributed corrosion sensor placed inside oil pipelines continuously monitoring corrosion. The intrinsically safe nature of light provided motivation for researching fiber optic sensors as a solution. The sensing fiber's cladding features polymer plastic that is chemically sensitive to hydrocarbons within crude oil mixtures. A layer of metal, used in the oil pipeline's construction, is deposited on the polymer cladding, which upon corrosion, exposes the cladding to surrounding hydrocarbons. The hydrocarbon's interaction with the cladding locally increases the cladding's refractive index in the radial direction. Light intensity of a traveling pulse is reduced due to local reduction in the modal capacity which is interrogated by Optical Time Domain Reflectometery. Backscattered light is captured in real-time while using time delay to resolve location, allowing real-time spatial monitoring of environmental internal corrosion within pipelines spanning large distances. Step index theoretical solutions were used to calculate the power loss due changes in the intensity profile. The power loss is translated into an attenuation coefficient characterizing the expected OTDR trace which was verified against similar experimental results from the literature. A laboratory scale experiment is being developed to assess the validity of the model and the practicality of the solution.

Optical Sensors for Use in Propulsion Control Systems

NASA Technical Reports Server (NTRS)

Fritsch, Klaus

1997-01-01

This final technical report describes the results of a cooperative effort which was originally established between John Carroll University and the Instrumentation and Control Technology Division at NASA Lewis Research Center on November, 1982, and then continued with the Engine Sensor Technology Branch at NASA Lewis until March, 1995. All work at John Carroll University was directed by the principal investigator of this grant, Klaus Fritsch, Ph.D. For the first two years of this grant this effort was supervised at NASA by Mr. Robert J. Baumbick and for the remainder of the grant by Dr. Glenn M. Beheim. All research was carried out in close cooperation with Dr. Beheim. Electrically passive optical sensors for measurands such as pressure, temperature, position, and rotational speed are required for aircraft engine control in fly-by-light digital aircraft control systems. Fiberoptic data links and optical multiplexing techniques should be used for combining and processing the outputs from several sensors, sharing as many optical end electronic parts as possible. The overall objective of this grant was to explore techniques for designing and constructing such electrically passive optical sensors for measuring physical parameters in jet aircraft engines and for use in aircraft control systems. We have concentrated our efforts on pressure, temperature, and position sensors employing techniques which are relatively immune to transmissivity variations of the fiber links and to variations in intensity of the light source. Infrared light-emitting diodes are employed because of their longevity and immunity to vibration. We have also studied a number of multiplexing techniques. On the following pages I will give thumbnail sketches of the projects carried out under this grant and provide references to publications and John Carroll M.S. theses which resulted directly from this work and which describe these projects in greater detail.

A design of LED adaptive dimming lighting system based on incremental PID controller

NASA Astrophysics Data System (ADS)

He, Xiangyan; Xiao, Zexin; He, Shaojia

2010-11-01

As a new generation energy-saving lighting source, LED is applied widely in various technology and industry fields. The requirement of its adaptive lighting technology is more and more rigorous, especially in the automatic on-line detecting system. In this paper, a closed loop feedback LED adaptive dimming lighting system based on incremental PID controller is designed, which consists of MEGA16 chip as a Micro-controller Unit (MCU), the ambient light sensor BH1750 chip with Inter-Integrated Circuit (I2C), and constant-current driving circuit. A given value of light intensity required for the on-line detecting environment need to be saved to the register of MCU. The optical intensity, detected by BH1750 chip in real time, is converted to digital signal by AD converter of the BH1750 chip, and then transmitted to MEGA16 chip through I2C serial bus. Since the variation law of light intensity in the on-line detecting environment is usually not easy to be established, incremental Proportional-Integral-Differential (PID) algorithm is applied in this system. Control variable obtained by the incremental PID determines duty cycle of Pulse-Width Modulation (PWM). Consequently, LED's forward current is adjusted by PWM, and the luminous intensity of the detection environment is stabilized by self-adaptation. The coefficients of incremental PID are obtained respectively after experiments. Compared with the traditional LED dimming system, it has advantages of anti-interference, simple construction, fast response, and high stability by the use of incremental PID algorithm and BH1750 chip with I2C serial bus. Therefore, it is suitable for the adaptive on-line detecting applications.

Method and apparatus for detecting flaws and defects in heat seals

NASA Technical Reports Server (NTRS)

Rai, Kula R. (Inventor); Lew, Thomas M. (Inventor); Sinclair, Robert B. (Inventor)

1993-01-01

Flaws and defects in heat seals formed between sheets of translucent film are identified by optically examining consecutive lateral sections of the seal along the seal length. Each lateral seal section is illuminated and an optical sensor array detects the intensity of light transmitted through the seal section for the purpose of detecting and locating edges in the heat seal. A line profile for each consecutive seal section is derived having an amplitude proportional to the change in light intensity across the seal section. Instances in the derived line profile where the amplitude is greater than a threshold level indicate the detection of a seal edge. The detected edges in each derived line profile are then compared to a preset profile edge standard to identify the existence of a flaw or defect.

Highly sensitive refractive index sensor based on a TiO₂ nanowire array.

PubMed

Li, Qiu-Shun; Xiang, Dong; Chang, Zhi-Min; Shi, Jian-Guo; Ma, Yao-Hong; Cai, Lei; Feng, Dong; Dong, Wen-Fei

2017-03-01

We propose a novel, highly sensitive refractive index (RI) sensor by means of combining the Kretschmann prism with a TiO₂ nanowire array and do not use a metallic layer in the Kretschmann configuration. Its RI sensing performance was investigated through measuring different concentrations of sodium chloride solution. Experimental results showed that, with increasing RI of liquid, the resonant wavelength in the reflectance spectrum redshifted gradually in the visible light range. There was a very good linear relationship between resonant wavelength and RI in the range of 1.3330 to 1.3546. More importantly, in contrast to the surface plasmon resonance (SPR) sensor, the interferometric sensors showed higher sensitivity to the external RI. In the case of the transverse magnetic mode, the RI sensitivity is up to 320,700.93 a.u./RIU (refractive index unit) by expression of light intensity, which is 9.55 times that of the SPR sensor. As for the transverse electric mode, it achieves 4371.76 nm/RIU by expression of the resonant wavelength, which is increased by a factor of 1.4 in comparison with the SPR sensor. Moreover, the experimental results have favorable repeatability. A TiO₂ nanowire array sensor has also other advantages, such as easy manufacturing, low cost, and in situ determination, etc. To our knowledge, this fact is reported for the first time. It has great potential applications in the field of biological and chemical sensing.

Laser interferometry force-feedback sensor for an interfacial force microscope

DOEpatents

Houston, Jack E.; Smith, William L.

2004-04-13

A scanning force microscope is provided with a force-feedback sensor to increase sensitivity and stability in determining interfacial forces between a probe and a sample. The sensor utilizes an interferometry technique that uses a collimated light beam directed onto a deflecting member, comprising a common plate suspended above capacitor electrodes situated on a substrate forming an interference cavity with a probe on the side of the common plate opposite the side suspended above capacitor electrodes. The probe interacts with the surface of the sample and the intensity of the reflected beam is measured and used to determine the change in displacement of the probe to the sample and to control the probe distance relative to the surface of the sample.

Mid-infrared gas absorption sensor based on a broadband external cavity quantum cascade laser

NASA Astrophysics Data System (ADS)

Sun, Juan; Deng, Hao; Liu, Ningwu; Wang, Hongliang; Yu, Benli; Li, Jingsong

2016-12-01

We developed a laser absorption sensor based on a pulsed, broadband tunable external cavity quantum cascade laser (ECQCL) centered at 1285 cm-1. Unlike traditional infrared spectroscopy system, a quartz crystal tuning fork (QCTF) as a light detector was used for laser signal detection. Fast Fourier transform was applied to extract vibration intensity information of QCTF. The sensor system is successfully tested on nitrous oxide (N2O) spectroscopy measurements and compared with a standard infrared detector. The wide wavelength tunability of ECQCL will allow us to access the fundamental vibrational bands of many chemical agents, which are well-suited for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis.

Mid-infrared gas absorption sensor based on a broadband external cavity quantum cascade laser.

PubMed

Sun, Juan; Deng, Hao; Liu, Ningwu; Wang, Hongliang; Yu, Benli; Li, Jingsong

2016-12-01

We developed a laser absorption sensor based on a pulsed, broadband tunable external cavity quantum cascade laser (ECQCL) centered at 1285 cm -1 . Unlike traditional infrared spectroscopy system, a quartz crystal tuning fork (QCTF) as a light detector was used for laser signal detection. Fast Fourier transform was applied to extract vibration intensity information of QCTF. The sensor system is successfully tested on nitrous oxide (N 2 O) spectroscopy measurements and compared with a standard infrared detector. The wide wavelength tunability of ECQCL will allow us to access the fundamental vibrational bands of many chemical agents, which are well-suited for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis.

Intelligent Photovoltaic Systems by Combining the Improved Perturbation Method of Observation and Sun Location Tracking.

PubMed

Wang, Yajie; Shi, Yunbo; Yu, Xiaoyu; Liu, Yongjie

2016-01-01

Currently, tracking in photovoltaic (PV) systems suffers from some problems such as high energy consumption, poor anti-interference performance, and large tracking errors. This paper presents a solar PV tracking system on the basis of an improved perturbation and observation method, which maximizes photoelectric conversion efficiency. According to the projection principle, we design a sensor module with a light-intensity-detection module for environmental light-intensity measurement. The effect of environmental factors on the system operation is reduced, and intelligent identification of the weather is realized. This system adopts the discrete-type tracking method to reduce power consumption. A mechanical structure with a level-pitch double-degree-of-freedom is designed, and attitude correction is performed by closed-loop control. A worm-and-gear mechanism is added, and the reliability, stability, and precision of the system are improved. Finally, the perturbation and observation method designed and improved by this study was tested by simulated experiments. The experiments verified that the photoelectric sensor resolution can reach 0.344°, the tracking error is less than 2.5°, the largest improvement in the charge efficiency can reach 44.5%, and the system steadily and reliably works.

Intelligent Photovoltaic Systems by Combining the Improved Perturbation Method of Observation and Sun Location Tracking

PubMed Central

Wang, Yajie; Shi, Yunbo; Yu, Xiaoyu; Liu, Yongjie

2016-01-01

Currently, tracking in photovoltaic (PV) systems suffers from some problems such as high energy consumption, poor anti-interference performance, and large tracking errors. This paper presents a solar PV tracking system on the basis of an improved perturbation and observation method, which maximizes photoelectric conversion efficiency. According to the projection principle, we design a sensor module with a light-intensity-detection module for environmental light-intensity measurement. The effect of environmental factors on the system operation is reduced, and intelligent identification of the weather is realized. This system adopts the discrete-type tracking method to reduce power consumption. A mechanical structure with a level-pitch double-degree-of-freedom is designed, and attitude correction is performed by closed-loop control. A worm-and-gear mechanism is added, and the reliability, stability, and precision of the system are improved. Finally, the perturbation and observation method designed and improved by this study was tested by simulated experiments. The experiments verified that the photoelectric sensor resolution can reach 0.344°, the tracking error is less than 2.5°, the largest improvement in the charge efficiency can reach 44.5%, and the system steadily and reliably works. PMID:27327657

Fracto-mechanoluminescent light emission of EuD4TEA-PDMS composites subjected to high strain-rate compressive loading

NASA Astrophysics Data System (ADS)

Ryu, Donghyeon; Castaño, Nicolas; Bhakta, Raj; Kimberley, Jamie

2017-08-01

The objective of this study is to understand light emission characteristics of fracto-mechanoluminescent (FML) europium tetrakis(dibenzoylmethide)-triethylammonium (EuD4TEA) crystals under high strain-rate compressive loading. As a sensing material that can play a pivotal role for the self-powered impact sensor technology, it is important to understand transformative light emission characteristics of the FML EuD4TEA crystals under high strain-rate compressive loading. First, EuD4TEA crystals were synthesized and embedded into polydimethylsiloxane (PDMS) elastomer to fabricate EuD4TEA-PDMS composite test specimens. Second, the prepared EuD4TEA-PDMS composites were tested using the modified Kolsky bar setup equipped with a high-speed camera. Third, FML light emission was captured to yield 12 bit grayscale video footage, which was processed to quantify the FML light emission. Finally, quantitative parameters were generated by taking into account pixel values and population of pixels of the 12 bit grayscale images to represent FML light intensity. The FML light intensity was correlated with high strain-rate compressive strain and strain rate to understand the FML light emission characteristics under high strain-rate compressive loading that can result from impact occurrences.

An etched fiber optic vibration sensor to monitor the simply supported beam

NASA Astrophysics Data System (ADS)

Putha, Kishore; Dinakar, Dantala; Rao, Pachava V.; Sengupta, Dipankar; Srimannarayana, K.; Sai Shankar, M.

2012-04-01

A single mode fiber optic vibration senor is designed and demonstrated to monitor the vibration of a simply supported beam. A rectangular beam (length 30.8 cm, width 2.5cm and thickness 0.5mm) made of spring-steel is arranged as simply supported beam and is made to vibrate periodically. To sense the vibrations a telecommunication fiber is chemically etched such that its diameter reaches 50μm and is glued using an epoxy at the centre of the beam. A broadband light (1550nm) is launched into Fiber Bragg Grating (FBG) through a circulator. The light reflected by the FBG (1540.32nm) is coupled into the centre etched fibre through the circulator and is detected by photodiode connected to a transimpedance amplifier. The electrical signal is logged into the computer through NI-6016 DAQ. The sensor works on transmission power loss due to the mode volume mismatch and flexural strain (field strength) of the fiber due to the bending in the fiber with respect to the bending of the spring-steel beam. The beam is made to vibrate and the corresponding intensity of light is recorded. Fast Fourier transform (FFT) technique is used to measure the frequencies of vibration. The results show that this sensor can sense vibration of low frequency accurately and repeatability is high. The sensor has high linear response to axial displacement of about 0.8 mm with sensitivity of 32mV/10μm strain. This lowcost sensor may find a place in industry to monitor the vibrations of the beam structures and bridges.

Determining the phase and amplitude distortion of a wavefront using a plenoptic sensor.

PubMed

Wu, Chensheng; Ko, Jonathan; Davis, Christopher C

2015-05-01

We have designed a plenoptic sensor to retrieve phase and amplitude changes resulting from a laser beam's propagation through atmospheric turbulence. Compared with the commonly restricted domain of (-π,π) in phase reconstruction by interferometers, the reconstructed phase obtained by the plenoptic sensors can be continuous up to a multiple of 2π. When compared with conventional Shack-Hartmann sensors, ambiguities caused by interference or low intensity, such as branch points and branch cuts, are less likely to happen and can be adaptively avoided by our reconstruction algorithm. In the design of our plenoptic sensor, we modified the fundamental structure of a light field camera into a mini Keplerian telescope array by accurately cascading the back focal plane of its object lens with a microlens array's front focal plane and matching the numerical aperture of both components. Unlike light field cameras designed for incoherent imaging purposes, our plenoptic sensor operates on the complex amplitude of the incident beam and distributes it into a matrix of images that are simpler and less subject to interference than a global image of the beam. Then, with the proposed reconstruction algorithms, the plenoptic sensor is able to reconstruct the wavefront and a phase screen at an appropriate depth in the field that causes the equivalent distortion on the beam. The reconstructed results can be used to guide adaptive optics systems in directing beam propagation through atmospheric turbulence. In this paper, we will show the theoretical analysis and experimental results obtained with the plenoptic sensor and its reconstruction algorithms.

Determining the phase and amplitude distortion of a wavefront using a plenoptic sensor

NASA Astrophysics Data System (ADS)

Wu, Chensheng; Ko, Jonathan; Davis, Christopher C.

2015-05-01

We have designed a plenoptic sensor to retrieve phase and amplitude changes resulting from a laser beam's propagation through atmospheric turbulence. Compared with the commonly restricted domain of (-pi, pi) in phase reconstruction by interferometers, the reconstructed phase obtained by the plenoptic sensors can be continuous up to a multiple of 2pi. When compared with conventional Shack-Hartmann sensors, ambiguities caused by interference or low intensity, such as branch points and branch cuts, are less likely to happen and can be adaptively avoided by our reconstruction algorithm. In the design of our plenoptic sensor, we modified the fundamental structure of a light field camera into a mini Keplerian telescope array by accurately cascading the back focal plane of its object lens with a microlens array's front focal plane and matching the numerical aperture of both components. Unlike light field cameras designed for incoherent imaging purposes, our plenoptic sensor operates on the complex amplitude of the incident beam and distributes it into a matrix of images that are simpler and less subject to interference than a global image of the beam. Then, with the proposed reconstruction algorithms, the plenoptic sensor is able to reconstruct the wavefront and a phase screen at an appropriate depth in the field that causes the equivalent distortion on the beam. The reconstructed results can be used to guide adaptive optics systems in directing beam propagation through atmospheric turbulence. In this paper we will show the theoretical analysis and experimental results obtained with the plenoptic sensor and its reconstruction algorithms.

Low-Light Dependence of the Magnetic Field Effect on Cryptochromes: Possible Relevance to Plant Ecology

PubMed Central

Vanderstraeten, Jacques; Gailly, Philippe; Malkemper, E. Pascal

2018-01-01

Various responses to static magnetic fields (MF) have been reported in plants, and it has been suggested that the geomagnetic field influences plant physiology. Accordingly, diverse mechanisms have been proposed to mediate MF effects in plants. The currently most probable sensor candidates are cryptochromes (Cry) which are sensitive to submillitesla MF. Here, we propose a quantitative approach of the MF effect on Cry depending on light intensity, and try to link it to a possible functional role for magnetic sensitivity in plants. Based on a theoretical evaluation and on a review of relevant data on Arabidopsis thaliana Cry 1, we point out that the MF effect on the signaling state of Cry, as well as the possible consequences of that effect on certain phenotypes (growth in particular) show parallel dependences on light intensity, being most prominent at low light levels. Based on these findings, we propose that Cry magnetosensitivity in plants could represent an ecological adaptation which regulates the amount of Cry signaling state under low light conditions. That hypothesis would preferentially be tested by studying sensitive and specific endpoints, such as the expression of clock proteins that are downregulated by Cry, but under light intensities lower than those used so far. Finally, we highlight that the low-light dependence of the MF effect described here could also apply to light-dependent functions of animal Cry, in particular magnetoreception which, from the present evaluation, would be based on the magnetic sensitivity of the photoreduction reaction, like in plants. PMID:29491873

Improving Inertial Pedestrian Dead-Reckoning by Detecting Unmodified Switched-on Lamps in Buildings

PubMed Central

Jiménez, Antonio R.; Zampella, Francisco; Seco, Fernando

2014-01-01

This paper explores how inertial Pedestrian Dead-Reckoning (PDR) location systems can be improved with the use of a light sensor to measure the illumination gradients created when a person walks under ceiling-mounted unmodified indoor lights. The process of updating the inertial PDR estimates with the information provided by light detections is a new concept that we have named Light-matching (LM). The displacement and orientation change of a person obtained by inertial PDR is used by the LM method to accurately propagate the location hypothesis, and vice versa; the LM approach benefits the PDR approach by obtaining an absolute localization and reducing the PDR-alone drift. Even from an initially unknown location and orientation, whenever the person passes below a switched-on light spot, the location likelihood is iteratively updated until it potentially converges to a unimodal probability density function. The time to converge to a unimodal position hypothesis depends on the number of lights detected and the asymmetries/irregularities of the spatial distribution of lights. The proposed LM method does not require any intensity illumination calibration, just the pre-storage of the position and size of all lights in a building, irrespective of their current on/off state. This paper presents a detailed description of the light-matching concept, the implementation details of the LM-assisted PDR fusion scheme using a particle filter, and several simulated and experimental tests, using a light sensor-equipped Galaxy S3 smartphone and an external foot-mounted inertial sensor. The evaluation includes the LM-assisted PDR approach as well as the fusion with other signals of opportunity (WiFi, RFID, Magnetometers or Map-matching) in order to compare their contribution in obtaining high accuracy indoor localization. The integrated solution achieves a localization error lower than 1 m in most of the cases. PMID:24394599

Biosensing of BCR/ABL fusion gene using an intensity-interrogation surface plasmon resonance imaging system

NASA Astrophysics Data System (ADS)

Wu, Jiangling; Huang, Yu; Bian, Xintong; Li, DanDan; Cheng, Quan; Ding, Shijia

2016-10-01

In this work, a custom-made intensity-interrogation surface plasmon resonance imaging (SPRi) system has been developed to directly detect a specific sequence of BCR/ABL fusion gene in chronic myelogenous leukemia (CML). The variation in the reflected light intensity detected from the sensor chip composed of gold islands array is proportional to the change of refractive index due to the selective hybridization of surface-bound DNA probes with target ssDNA. SPRi measurements were performed with different concentrations of synthetic target DNA sequence. The calibration curve of synthetic target sequence shows a good relationship between the concentration of synthetic target and the change of reflected light intensity. The detection limit of this SPRi measurement could approach 10.29 nM. By comparing SPRi images, the target ssDNA and non-complementary DNA sequence are able to be distinguished. This SPRi system has been applied for assay of BCR/ABL fusion gene extracted from real samples. This nucleic acid-based SPRi biosensor therefore offers an alternative high-effective, high-throughput label-free tool for DNA detection in biomedical research and molecular diagnosis.

Testing of a Fiber Optic Wear, Erosion and Regression Sensor

NASA Technical Reports Server (NTRS)

Korman, Valentin; Polzin, Kurt A.

2011-01-01

The nature of the physical processes and harsh environments associated with erosion and wear in propulsion environments makes their measurement and real-time rate quantification difficult. A fiber optic sensor capable of determining the wear (regression, erosion, ablation) associated with these environments has been developed and tested in a number of different applications to validate the technique. The sensor consists of two fiber optics that have differing attenuation coefficients and transmit light to detectors. The ratio of the two measured intensities can be correlated to the lengths of the fiber optic lines, and if the fibers and the host parent material in which they are embedded wear at the same rate the remaining length of fiber provides a real-time measure of the wear process. Testing in several disparate situations has been performed, with the data exhibiting excellent qualitative agreement with the theoretical description of the process and when a separate calibrated regression measurement is available good quantitative agreement is obtained as well. The light collected by the fibers can also be used to optically obtain the spectra and measure the internal temperature of the wear layer.

Surface plasmon resonance optical cavity enhanced refractive index sensing.

PubMed

Giorgini, A; Avino, S; Malara, P; Gagliardi, G; Casalino, M; Coppola, G; Iodice, M; Adam, P; Chadt, K; Homola, J; De Natale, P

2013-06-01

We report on a method for surface plasmon resonance (SPR) refractive index sensing based on direct time-domain measurements. An optical resonator is built around an SPR sensor, and its photon lifetime is measured as a function of loss induced by refractive index variations. The method does not rely on any spectroscopic analysis or direct intensity measurement. Time-domain measurements are practically immune to light intensity fluctuations and thus lead to high resolution. A proof of concept experiment is carried out in which a sensor response to liquid samples of different refractive indices is measured. A refractive index resolution of the current system, extrapolated from the reproducibility of cavity-decay time determinations over 133 s, is found to be about 10(-5) RIU. The possibility of long-term averaging suggests that measurements with a resolution better than 10(-7) RIU/√Hz are within reach.

Apparatus and method for a light direction sensor

NASA Technical Reports Server (NTRS)

Leviton, Douglas B. (Inventor)

2011-01-01

The present invention provides a light direction sensor for determining the direction of a light source. The system includes an image sensor; a spacer attached to the image sensor, and a pattern mask attached to said spacer. The pattern mask has a slit pattern that as light passes through the slit pattern it casts a diffraction pattern onto the image sensor. The method operates by receiving a beam of light onto a patterned mask, wherein the patterned mask as a plurality of a slit segments. Then, diffusing the beam of light onto an image sensor and determining the direction of the light source.

Low-Cost, Robust, and Field Portable Smartphone Platform Photometric Sensor for Fluoride Level Detection in Drinking Water.

PubMed

Hussain, Iftak; Ahamad, Kamal Uddin; Nath, Pabitra

2017-01-03

Groundwater is the major source of drinking water for people living in rural areas of India. Pollutants such as fluoride in groundwater may be present in much higher concentration than the permissible limit. Fluoride does not give any visible coloration to water, and hence, no effort is made to remove or reduce the concentration of this chemical present in drinking water. This may lead to a serious health hazard for those people taking groundwater as their primary source of drinking water. Sophisticated laboratory grade tools such as ion selective electrodes (ISE) and portable spectrophotometers are commercially available for in-field detection of fluoride level in drinking water. However, such tools are generally expensive and require expertise to handle. In this paper, we demonstrate the working of a low cost, robust, and field portable smartphone platform fluoride sensor that can detect and analyze fluoride concentration level in drinking water. For development of the proposed sensor, we utilize the ambient light sensor (ALS) of the smartphone as light intensity detector and its LED flash light as an optical source. An android application "FSense" has been developed which can detect and analyze the fluoride concentration level in water samples. The custom developed application can be used for sharing of in-field sensing data from any remote location to the central water quality monitoring station. We envision that the proposed sensing technique could be useful for initiating a fluoride removal program undertaken by governmental and nongovernmental organizations here in India.

Development of a wireless crop growth monitor based on optical principle

NASA Astrophysics Data System (ADS)

Li, Xihua; Li, Minzan; Cui, Di

2008-12-01

In order to detect the plant's nitrogen content in real-time, a wireless crop growth monitor is developed. It is made up of a sensor and a controller. The sensor consists of an optical part and a circuit part. The optical part is made up of 4 optical channels and 4 photo-detectors. 2 channels receive the sunlight and the other 2 receive the reflected light from the crop canopy. The intensity of sunlight and the reflected light is measured at the wavebands of 610 nm and 1220 nm respectively. The circuit part is made up of power supply unit, 4 amplifiers and a wireless module. The controller has functions such as keyboard input, LCD display, data storage, data upload and so on. Both hardware and software are introduced in this report. Calibration tests show that the optical part has a high accuracy and the wireless transmission also has a good performance.

Quantum dots in imaging, drug delivery and sensor applications

PubMed Central

Matea, Cristian T; Mocan, Teodora; Tabaran, Flaviu; Pop, Teodora; Mosteanu, Ofelia; Puia, Cosmin; Iancu, Cornel; Mocan, Lucian

2017-01-01

Quantum dots (QDs), also known as nanoscale semiconductor crystals, are nanoparticles with unique optical and electronic properties such as bright and intensive fluorescence. Since most conventional organic label dyes do not offer the near-infrared (>650 nm) emission possibility, QDs, with their tunable optical properties, have gained a lot of interest. They possess characteristics such as good chemical and photo-stability, high quantum yield and size-tunable light emission. Different types of QDs can be excited with the same light wavelength, and their narrow emission bands can be detected simultaneously for multiple assays. There is an increasing interest in the development of nano-theranostics platforms for simultaneous sensing, imaging and therapy. QDs have great potential for such applications, with notable results already published in the fields of sensors, drug delivery and biomedical imaging. This review summarizes the latest developments available in literature regarding the use of QDs for medical applications. PMID:28814860

Quantum dots in imaging, drug delivery and sensor applications.

PubMed

Matea, Cristian T; Mocan, Teodora; Tabaran, Flaviu; Pop, Teodora; Mosteanu, Ofelia; Puia, Cosmin; Iancu, Cornel; Mocan, Lucian

2017-01-01

Quantum dots (QDs), also known as nanoscale semiconductor crystals, are nanoparticles with unique optical and electronic properties such as bright and intensive fluorescence. Since most conventional organic label dyes do not offer the near-infrared (>650 nm) emission possibility, QDs, with their tunable optical properties, have gained a lot of interest. They possess characteristics such as good chemical and photo-stability, high quantum yield and size-tunable light emission. Different types of QDs can be excited with the same light wavelength, and their narrow emission bands can be detected simultaneously for multiple assays. There is an increasing interest in the development of nano-theranostics platforms for simultaneous sensing, imaging and therapy. QDs have great potential for such applications, with notable results already published in the fields of sensors, drug delivery and biomedical imaging. This review summarizes the latest developments available in literature regarding the use of QDs for medical applications.

Fiber optic Raman sensor to monitor the concentration ratio of nitrogen and oxygen in a cryogenic mixture

NASA Astrophysics Data System (ADS)

Tiwari, Vidhu S.; Kalluru, Rajamohan R.; Yueh, Fang Y.; Singh, Jagdish P.; St. Cyr, William; Khijwania, Sunil K.

2007-06-01

A spontaneous Raman scattering optical fiber sensor was developed for a specific need of the National Aeronautics and Space Administration (NASA) for long-term detection and monitoring of the purity of liquid oxygen (LO2) in the oxidizer feed line during ground testing of rocket engines. The Raman peak intensity ratios for liquid nitrogen (LN2) and LO2 with varied weight ratios (LN2/LO2) were analyzed for their applicability to impurity sensing. The study of the sensor performance with different excitation light sources has helped to design a miniaturized, cost-effective system for this application. The optimal system response time of this miniaturized sensor for LN2/LO2 measurement was found to be in the range of a few seconds. It will need to be further reduced to the millisecond range for real-time, quantitative monitoring of the quality of cryogenic fluids in a harsh envioronment.

Tuning operating point of extrinsic Fabry-Perot interferometric fiber-optic sensors using microstructured fiber and gas pressure.

PubMed

Tian, Jiajun; Zhang, Qi; Fink, Thomas; Li, Hong; Peng, Wei; Han, Ming

2012-11-15

Intensity-based demodulation of extrinsic Fabry-Perot interferometric (EFPI) fiber-optic sensors requires the light wavelength to be on the quadrature point of the interferometric fringes for maximum sensitivity. In this Letter, we propose a novel and remote operating-point tuning method for EFPI fiber-optic sensors using microstructured fibers (MFs) and gas pressure. We demonstrated the method using a diaphragm-based EFPI sensor with a microstructured lead-in fiber. The holes in the MF were used as gas channels to remotely control the gas pressure inside the Fabry-Perot cavity. Because of the deformation of the diaphragm with gas pressure, the cavity length and consequently the operating point can be remotely tuned for maximum sensitivity. The proposed operating-point tuning method has the advantage of reduced complexity and cost compared to previously reported methods.

Etalon-induced Baseline Drift And Correction In Atom Flux Sensors Based On Atomic Absorption Spectroscopy

DOE PAGES

Du, Yingge; Chambers, Scott A.

2014-10-20

Atom flux sensors based on atomic absorption (AA) spectroscopy are of significant interest in thin film growth as they can provide unobtrusive, element specific, real-time flux sensing and control. The ultimate sensitivity and performance of the sensors are strongly affected by the long-term and short term baseline drift. Here we demonstrate that an etalon effect resulting from temperature changes in optical viewport housings is a major source of signal instability which has not been previously considered or corrected by existing methods. We show that small temperature variations in the fused silica viewports can introduce intensity modulations of up to 1.5%,more » which in turn significantly deteriorate AA sensor performance. This undesirable effect can be at least partially eliminated by reducing the size of the beam and tilting the incident light beam off the viewport normal.« less

Humidity sensor and ultraviolet photodetector based on carrier trapping effect and negative photoconductivity in graphene quantum dots

NASA Astrophysics Data System (ADS)

Zhuang, ShenDong; Chen, Yan; Zhang, WeiChao; Chen, Zhuo; Wang, ZhenLin

2018-01-01

We report on the experimental realization of a graphene quantum dots (GQD)-based humidity sensor and ultraviolet (UV) photodetector. We demonstrate that the conductance of the GQD increases linearly with increasing relative humidity (RH) of the surrounding environment due to the carrier trapping effect, which forms the basis of a humidity sensor. When the sensor is operated in the dark state, the sensitivity can reach as high as 0.48 nS RH -1. The GQD are also found to exhibit light intensity dependent negative photoconductivity under the UV irradiation, which can be exploited for UV detection. As a result of these carrier trapping and de-trapping processes, the performance of the photodetector can be significantly improved with the increasing RH, and the photoresponsivity can reach a high value of -418.1 μA W-1 in the high humid state of RH=90%.

Smart street lighting solution for remote rural areas of India

NASA Astrophysics Data System (ADS)

Hajra, Debdyut

2017-09-01

Though many smart street lighting solutions is available for urban areas, comparatively fewer solutions exist for rural areas. In the recent times, village streets have been illuminated with artificial lights as a part of rural development drive undertaken by the governments of respective countries. But, vehicle and pedestrian traffic is quite low through village roads. Hence, if light remains on all night long on such roads, then there is a huge wastage of energy. This calls for solutions to reduce this energy loss in an efficient manner. There are a lot of factors which must be kept in mind while designing solutions. Many villages lack the proper infrastructure to support new technologies. Communication facilities are limited, lack of local technically skilled labor, lack of security, etc. After evaluating these opportunities and challenges, an attempt has been made to devise a smart street lighting solution tailored for remote rural areas in India. One part of the solution discusses how intensity of the LED street lights can be varied according to the ambient lighting conditions using sensors and LED switching in LED matrix. An artificial intelligence (AI) has also been modelled to identify traffic conditions using PIR sensors and object identification through image processing and independently control the lights. It also tracks the performance and status of each light. It would send this data and necessary notifications to a distant control center for human evaluation. This solution is also applicable for other rural areas throughout the world.

Low Cost Plastic Optical Fiber Pressure Sensor Embedded in Mattress for Vital Signal Monitoring.

PubMed

Sartiano, Demetrio; Sales, Salvador

2017-12-13

The aim of this paper is to report the design of a low-cost plastic optical fiber (POF) pressure sensor, embedded in a mattress. We report the design of a multipoint sensor, a cheap alternative to the most common fiber sensors. The sensor is implemented using Arduino board, standard LEDs for optical communication in POF (λ = 645 nm) and a silicon light sensor. The Super ESKA ® plastic fibers were used to implement the fiber intensity sensor, arranged in a 4 × 4 matrix. During the breathing cycles, the force transmitted from the lungs to the thorax is in the order of tens of Newtons, and the respiration rate is of one breath every 2-5 s (0.2-0.5 Hz). The sensor has a resolution of force applied on a single point of 2.2-4.5%/N on the normalized voltage output, and a bandwidth of 10 Hz, it is then suitable to monitor the respiration movements. Another issue to be addressed is the presence of hysteresis over load cycles. The sensor was loaded cyclically to estimate the drift of the system, and the hysteresis was found to be negligible.

Use of ambient light in remote photoplethysmographic systems: comparison between a high-performance camera and a low-cost webcam.

PubMed

Sun, Yu; Papin, Charlotte; Azorin-Peris, Vicente; Kalawsky, Roy; Greenwald, Stephen; Hu, Sijung

2012-03-01

Imaging photoplethysmography (PPG) is able to capture useful physiological data remotely from a wide range of anatomical locations. Recent imaging PPG studies have concentrated on two broad research directions involving either high-performance cameras and or webcam-based systems. However, little has been reported about the difference between these two techniques, particularly in terms of their performance under illumination with ambient light. We explore these two imaging PPG approaches through the simultaneous measurement of the cardiac pulse acquired from the face of 10 male subjects and the spectral characteristics of ambient light. Measurements are made before and after a period of cycling exercise. The physiological pulse waves extracted from both imaging PPG systems using the smoothed pseudo-Wigner-Ville distribution yield functional characteristics comparable to those acquired using gold standard contact PPG sensors. The influence of ambient light intensity on the physiological information is considered, where results reveal an independent relationship between the ambient light intensity and the normalized plethysmographic signals. This provides further support for imaging PPG as a means for practical noncontact physiological assessment with clear applications in several domains, including telemedicine and homecare. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

Use of ambient light in remote photoplethysmographic systems: comparison between a high-performance camera and a low-cost webcam

NASA Astrophysics Data System (ADS)

Sun, Yu; Papin, Charlotte; Azorin-Peris, Vicente; Kalawsky, Roy; Greenwald, Stephen; Hu, Sijung

2012-03-01

Imaging photoplethysmography (PPG) is able to capture useful physiological data remotely from a wide range of anatomical locations. Recent imaging PPG studies have concentrated on two broad research directions involving either high-performance cameras and or webcam-based systems. However, little has been reported about the difference between these two techniques, particularly in terms of their performance under illumination with ambient light. We explore these two imaging PPG approaches through the simultaneous measurement of the cardiac pulse acquired from the face of 10 male subjects and the spectral characteristics of ambient light. Measurements are made before and after a period of cycling exercise. The physiological pulse waves extracted from both imaging PPG systems using the smoothed pseudo-Wigner-Ville distribution yield functional characteristics comparable to those acquired using gold standard contact PPG sensors. The influence of ambient light intensity on the physiological information is considered, where results reveal an independent relationship between the ambient light intensity and the normalized plethysmographic signals. This provides further support for imaging PPG as a means for practical noncontact physiological assessment with clear applications in several domains, including telemedicine and homecare.

Microelectromechanical Systems (MEMS) Broadband Light Source Developed

NASA Technical Reports Server (NTRS)

Tuma, Margaret L.

2003-01-01

A miniature, low-power broadband light source has been developed for aerospace applications, including calibrating spectrometers and powering miniature optical sensors. The initial motivation for this research was based on flight tests of a Fabry-Perot fiberoptic temperature sensor system used to detect aircraft engine exhaust gas temperature. Although the feasibility of the sensor system was proven, the commercial light source optically powering the device was identified as a critical component requiring improvement. Problems with the light source included a long stabilization time (approximately 1 hr), a large amount of heat generation, and a large input electrical power (6.5 W). Thus, we developed a new light source to enable the use of broadband optical sensors in aerospace applications. Semiconductor chip-based light sources, such as lasers and light-emitting diodes, have a relatively narrow range of emission wavelengths in comparison to incandescent sources. Incandescent light sources emit broadband radiation from visible to infrared wavelengths; the intensity at each wavelength is determined by the filament temperature and the materials chosen for the filament and the lamp window. However, present commercial incandescent light sources are large in size and inefficient, requiring several watts of electrical power to obtain the desired optical power, and they emit a large percentage of the input power as heat that must be dissipated. The miniature light source, developed jointly by the NASA Glenn Research Center, the Jet Propulsion Laboratory, and the Lighting Innovations Institute, requires one-fifth the electrical input power of some commercial light sources, while providing similar output light power that is easily coupled to an optical fiber. Furthermore, it is small, rugged, and lightweight. Microfabrication technology was used to reduce the size, weight, power consumption, and potential cost-parameters critical to future aerospace applications. This chip-based light source has the potential for monolithic fabrication with on-chip drive electronics. Other uses for these light sources are in systems for vehicle navigation, remote sensing applications such as monitoring bridges for stress, calibration sources for spectrometers, light sources for space sensors, display lighting, addressable arrays, and industrial plant monitoring. Two methods for filament fabrication are being developed: wet-chemical etching and laser ablation. Both yield a 25-mm-thick tungsten spiral filament. The proof-of-concept filament shown was fabricated with the wet etch method. Then it was tested by heating it in a vacuum chamber using about 1.25 W of electrical power; it generated bright, blackbody radiation at approximately 2650 K. The filament was packaged in Glenn's clean-room facilities. This design uses three chips vacuum-sealed with glass tape. The bottom chip consists of a reflective film deposited on silicon, the middle chip contains a tungsten filament bonded to silicon, and the top layer is a transparent window. Lifetime testing on the package will begin shortly. The emitted optical power is expected to be approximately 1.0 W with the spectral peak at 1.1 mm.

A field demonstration of energy conservation using occupancy sensor lighting control in equipment rooms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dagle, J.E.

1992-09-01

The Pacific Northwest Laboratory identified energy savings potential of automatic equipment-room lighting controls, which was demonstrated by the field experiment described in this report. Occupancy sensor applications have gained popularity in recent years due to improved technology that enhances reliability and reduces cost. Automatic lighting control using occupancy sensors has been accepted as an energy-conservation measure because it reduces wasted lighting. This study focused on lighting control for equipment rooms, which have inherent conditions ideal for automatic lighting control, i.e., an area which is seldom occupied, multiple users of the area who would not know if others are in themore » room when they leave, and high lighting energy intensity in the area. Two rooms were selected for this study: a small equipment room in the basement of the 337 Building, and a large equipment area in the upper level of the 329 Building. The rooms were selected to demonstrate the various degrees of complexity which may be encountered in equipment rooms throughout the Hanford Site. The 337 Building equipment-room test case demonstrated a 97% reduction in lighting energy consumption, with an annual energy savings of $184. Including lamp-replacement savings, a total savings of $306 per year is offset by an initial installation cost of $1,100. The installation demonstrates a positive net present value of $2,858 when the lamp-replacement costs are included in a life-cycle analysis. This also corresponds to a 4.0-year payback period. The 329 Building equipment-room installation resulted in a 92% reduction in lighting energy consumption. This corresponds to annual energy savings of $1,372, and a total annual savings of $2,104 per year including lamp-replacement savings. The life-cycle cost analysis shows a net present value of $15,855, with a 5.8-year payback period.« less

Effects of thinning intensities on transpiration and productivity of 50-year-old Pinus koraeinsis stands

NASA Astrophysics Data System (ADS)

Park, J.; Kim, T.; Cho, S.; Ryu, D.; Moon, M.; Kim, H. S.

2015-12-01

This study investigated the effects of thinning intensities on stand transpiration and productivity of 50-year-old Korean pine forests for three years. Forest thinning, which remove some fraction of trees from stand, alters the microclimatic conditions such as radiation distribution within canopy, vapor pressure deficit, and amount of available soil water. These changes influence on the tree water use, and related tree growth. Thinning was conducted on March, 2012 with two intensities (Control, Light-thinning, and Heavy-thinning). Transpiration was estimated from sap flux density, which was measured with Granier-type thermal dissipation sensors. Tree diameter growth was measured with dendrometer, and converted to tree productivity using allometric equations developed specifically in our study sites.The climatic conditions showed remarkable differences among three years. In 2012, total precipitation was highest but spring was dry. 2013 was normal year with frequent rain events. In contrast, 2014 was hot and extremely dry. Stand transpiration was initially decreased ca. 20% and 42% on light-thinning and heavy-thinning stand, respectively. In second year, it gradually recovered in both thinning intensities, and was 19% and 37% lower on light-thinning and heavy-thinning stand, respectively. However, the recovery trends were different between two thinning intensities. Transpiration of heavy-thinning stand was recovered slowly than that of light thinning stand. In 2014, heavy-thinning stand transpired ca. 5% more than control plot in early growing season, but severe drought had negative effects that caused reduction of stand transpiration in thinned stand on late growing season. The tree-level productivity was increased initially ca. 24% and 28% on light-thinning and heavy-thinning stand, respectively. During the following growing seasons, this thinning-induced enhancement of productivity was diminished in light-thinning stand (21% in 2013 and 20% in 2014), but was increased in heavy-thinning stand (49% in 2013 and 56% in 2014). In addition, the relationship between tree diameter and relative growth rate showed opposite trends between heavy thinning and light thinning stands. These results indicate that there are differences in biological reactions with thinning intensities.

Oxygen Sensing Based on the Yellowing of Newspaper.

PubMed

Yu, Jingjing; Qin, Xingcai; Xian, Xiaojun; Tao, Nongjian

2018-01-26

Newspaper is known to turn yellow over time. We show here that this yellowing process is sensitive to oxygen when exposed to UV light, leading to oxygen sensing. Oxygen sensing is critical to many applications, including industrial process control and breath analysis, but the existing oxygen sensors have limitations, especially for breath analysis that operates at 100% humidity. The UV irradiation also triggers fluorescence emission from newspaper, and the fluorescence intensity depends on oxygen concentration, providing an additional oxygen sensing method. Newspaper is stable in ambient air, and reactive to oxygen only with UV activation, which overcomes the instability issue of a typical colorimetric sensor in ambient air. The newspaper oxygen sensor works in 100% relative humidity air, containing various interferents. These unique properties of newspaper promise low cost and reliable oxygen sensing applications.

Development of a Prototype Optical Hydrogen Gas Sensor Using a Getter-Doped Polymer Transducer for Monitoring Cumulative Exposure: Preliminary Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Small IV, W; Maitland, D J; Wilson, T S

2008-06-05

A novel prototype optical sensor for monitoring cumulative hydrogen gas exposure was fabricated and evaluated. Chemical-to-optical transduction was accomplished by detecting the intensity of 670 nm laser light transmitted through a hydrogen getter-doped polymer film mounted at the end of an optical fiber; the transmittance of the composite film increased with uptake of hydrogen by the embedded getter. The composite film consisted of the hydrogen getter 1,4-bis(phenylethynyl)benzene, also known as DEB, with carbon-supported palladium catalyst embedded in silicone elastomer. Because the change in transmittance was irreversible and occurred continuously as the getter captured hydrogen, the sensor behaved like a dosimeter,more » providing a unique indication of the cumulative gas exposure.« less

New light-shielding technique for shortening the baffle length of a star sensor

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Sato, Yukio; Mitani, Kenji; Kanai, Hiroshi; Hama, Kazumori

2002-10-01

We have developed a star sensor with a short baffle of 140 mm. Our baffle provides a Sun rejection angle of 35 degrees with stray light attenuation less than the intensity level of a visual magnitude of Mv = +5 for a wide field of view lens of 13x13 degrees. The application of a new light shielding technique taking advantage of total internal reflection phenomena enables us to reduce the baffle length to about three fourths that of the conventional two-stage baffle. We have introduced two ideas to make the baffle length shorter. The one is the application of a nearly half sphere convex lens as the first focusing lens. The bottom surface reflects the scattering rays with high incident angles of over 50 degrees by using the total internal reflection phenomena. The other is the painting of the surface of the baffle with not frosted but gloss black paint. The gloss black paint enables most of the specular reflection rays to go back to outer space without scattering. We confirm the baffle performance mentioned above by scattering ray tracing simulation and a light attenuation experiment in a darkroom on the ground.

A low-cost, computer-interfaced drawing pad for FMRI studies of dysgraphia and dyslexia.

PubMed

Reitz, Frederick; Richards, Todd; Wu, Kelvin; Boord, Peter; Askren, Mary; Lewis, Thomas; Berninger, Virginia

2013-04-17

We have developed a pen and writing tablet for use by subjects during fMRI scanning. The pen consists of two jacketed, multi-mode optical fibers routed to the tip of a hollowed-out ball-point pen. The pen has been further modified by addition of a plastic plate to maintain a perpendicular pen-tablet orientation. The tablet is simply a non-metallic frame holding a paper print of continuously varying color gradients. The optical fibers are routed out of the MRI bore to a light-tight box in an adjacent control room. Within the box, light from a high intensity LED is coupled into one of the fibers, while the other fiber abuts a color sensor. Light from the LED exits the pen tip, illuminating a small spot on the tablet, and the resulting reflected light is routed to the color sensor. Given a lookup table of position for each color on the tablet, the coordinates of the pen on the tablet may be displayed and digitized in real-time. While simple and inexpensive, the system achieves sufficient resolution to grade writing tasks testing dysgraphic and dyslexic phenomena.

Realization of fiber optic displacement sensors

NASA Astrophysics Data System (ADS)

Guzowski, Bartlomiej; Lakomski, Mateusz

2018-03-01

Fiber optic sensors are very promising because of their inherent advantages such as very small size, hard environment tolerance and impact of electromagnetic fields. In this paper three different types of Intensity Fiber Optic Displacement Sensors (I-FODS) are presented. Three configurations of I-FODS were realized in two varieties. In the first one, the cleaved multimode optical fibers (MMF) were used to collect reflected light, while in the second variety the MMF ended with ball lenses were chosen. To ensure an accurate alignment of optical fibers in the sensor head the MTP C9730 optical fiber ferrules were used. In this paper the influence of distribution of transmitting and detecting optical fibers on sensitivity and linear range of operation of developed I-FODS were investigated. We have shown, that I-FODS with ball lenses receive average 10.5% more reflected power in comparison to the cleaved optical fibers and they increase linearity range of I-FODS by 33%. In this paper, an analysis of each type of the realized sensor and detailed discussion are given.

Polarization Analysis of Light Scattered by Pollen Grains of Cryptomeria japonica

NASA Astrophysics Data System (ADS)

Iwai, Toshiaki

2013-06-01

Pollinosis to airborne pollen grains is a severe problem that concerns the whole world. Almost spring allergies in Japan are caused by pollen grains of Japan cedar (Cryptomeria japonica) during the period of pollination from February to May. One of the key technologies in a pollen monitoring and forecast system is a pollen sensor. The pollen grain of Japan cedar is identified by introducing the degree of polarization to the optical sensor based on the scattered intensity. The detectability and discriminability in identifying the pollen grains of Japan cedar from the polystyrene spherical particles and the Kanto loam grains are achieved up to 95 and 86%, respectively.

Micro-LiDAR velocity, temperature, density, concentration sensor

NASA Technical Reports Server (NTRS)

Dorrington, Adrian A. (Inventor); Danehy, Paul M. (Inventor)

2010-01-01

A light scatter sensor includes a sensor body in which are positioned a plurality of optical fibers. The sensor body includes a surface, in one end of each of the optical fibers terminates at the surface of the sensor body. One of the optical fibers is an illumination fiber for emitting light. A plurality of second optical fibers are collection fibers for collecting scattered light signals. A light sensor processor is connected to the collection fibers to detect the scattered light signals.

Contribution to the theory of photopic vision: Retinal phenomena

NASA Technical Reports Server (NTRS)

Calvet, H.

1979-01-01

Principles of thermodynamics are applied to the study of the ultramicroscopic anatomy of the inner eye. Concepts introduced and discussed include: the retina as a three-dimensional sensor, light signals as coherent beams in relation to the dimensions of retinal pigments, pigment effects topographed by the conjugated antennas effect, visualizing lights, the autotropic function of hemoglobin and some cytochromes, and reversible structural arrangements during photopic adaptation. A paleoecological diagram is presented which traces the evolution of scotopic vision (primitive system) to photopic vision (secondary system) through the emergence of structures sensitive to the intensity, temperature, and wavelengths of the visible range.

A Wide Dynamic Range Tapped Linear Array Image Sensor

NASA Astrophysics Data System (ADS)

Washkurak, William D.; Chamberlain, Savvas G.; Prince, N. Daryl

1988-08-01

Detectors for acousto-optic signal processing applications require fast transient response as well as wide dynamic range. There are two major choices of detectors: conductive or integration mode. Conductive mode detectors have an initial transient period before they reach then' i equilibrium state. The duration of 1 his period is dependent on light level as well as detector capacitance. At low light levels a conductive mode detector is very slow; response time is typically on the order of milliseconds. Generally. to obtain fast transient response an integrating mode detector is preferred. With integrating mode detectors. the dynamic range is determined by the charge storage capability of the tran-sport shift registers and the noise level of the image sensor. The conventional net hod used to improve dynamic range is to increase the shift register charge storage capability. To achieve a dynamic range of fifty thousand assuming two hundred noise equivalent electrons, a charge storage capability of ten million electrons would be required. In order to accommodate this amount of charge. unrealistic shift registers widths would be required. Therefore, with an integrating mode detector it is difficult to achieve a dynamic range of over four orders of magnitude of input light intensity. Another alternative is to solve the problem at the photodetector aml not the shift, register. DALSA's wide dynamic range detector utilizes an optimized, ion implant doped, profiled MOSFET photodetector specifically designed for wide dynamic range. When this new detector operates at high speed and at low light levels the photons are collected and stored in an integrating fashion. However. at bright light levels where transient periods are short, the detector switches into a conductive mode. The light intensity is logarithmically compressed into small charge packets, easily carried by the CCD shift register. As a result of the logarithmic conversion, dynamic ranges of over six orders of magnitide are obtained. To achieve the short integration times necessary in acousto-optic applications. t he wide dynamic range detector has been implemented into a tapped array architecture with eight outputs and 256 photoelements. Operation of each 01)1,1)111 at 16 MHz yields detector integration times of 2 micro-seconds. Buried channel two phase CCD shift register technology is utilized to minimize image sensor noise improve video output rates and increase ease of operation.

Video and thermal imaging system for monitoring interiors of high temperature reaction vessels

DOEpatents

Saveliev, Alexei V [Chicago, IL; Zelepouga, Serguei A [Hoffman Estates, IL; Rue, David M [Chicago, IL

2012-01-10

A system and method for real-time monitoring of the interior of a combustor or gasifier wherein light emitted by the interior surface of a refractory wall of the combustor or gasifier is collected using an imaging fiber optic bundle having a light receiving end and a light output end. Color information in the light is captured with primary color (RGB) filters or complimentary color (GMCY) filters placed over individual pixels of color sensors disposed within a digital color camera in a BAYER mosaic layout, producing RGB signal outputs or GMCY signal outputs. The signal outputs are processed using intensity ratios of the primary color filters or the complimentary color filters, producing video images and/or thermal images of the interior of the combustor or gasifier.

1 kHz 2D Visual Motion Sensor Using 20 × 20 Silicon Retina Optical Sensor and DSP Microcontroller.

PubMed

Liu, Shih-Chii; Yang, MinHao; Steiner, Andreas; Moeckel, Rico; Delbruck, Tobi

2015-04-01

Optical flow sensors have been a long running theme in neuromorphic vision sensors which include circuits that implement the local background intensity adaptation mechanism seen in biological retinas. This paper reports a bio-inspired optical motion sensor aimed towards miniature robotic and aerial platforms. It combines a 20 × 20 continuous-time CMOS silicon retina vision sensor with a DSP microcontroller. The retina sensor has pixels that have local gain control and adapt to background lighting. The system allows the user to validate various motion algorithms without building dedicated custom solutions. Measurements are presented to show that the system can compute global 2D translational motion from complex natural scenes using one particular algorithm: the image interpolation algorithm (I2A). With this algorithm, the system can compute global translational motion vectors at a sample rate of 1 kHz, for speeds up to ±1000 pixels/s, using less than 5 k instruction cycles (12 instructions per pixel) per frame. At 1 kHz sample rate the DSP is 12% occupied with motion computation. The sensor is implemented as a 6 g PCB consuming 170 mW of power.

Dielectric analysis of depth dependent curing behavior of dental resin composites.

PubMed

Steinhaus, Johannes; Moeginger, Bernhard; Grossgarten, Mandy; Rosentritt, Martin; Hausnerova, Berenika

2014-06-01

The aim of this study is to investigate depth dependent changes of polymerization process and kinetics of visible light-curing (VLC) dental composites in real-time. The measured quantity - "ion viscosity" determined by dielectric analysis (DEA) - provides the depth dependent reaction rate which is correlated to the light intensity available in the corresponding depths derived from light transmission measurements. The ion viscosity curves of two composites (VOCO Arabesk Top and Grandio) were determined during irradiation of 40s with a light-curing unit (LCU) in specimen depths of 0.5/0.75/1.0/1.25/1.5/1.75 and 2.0mm using a dielectric cure analyzer (NETZSCH DEA 231 with Mini IDEX sensors). The thickness dependent light transmission was measured by irradiation composite specimens of various thicknesses on top of a radiometer setup. The shape of the ion viscosity curves depends strongly on the specimen thickness above the sensor. All curves exhibit a range of linear time dependency of the ion viscosity after a certain initiation time. The determined initiation times, the slopes of the linear part of the curves, and the ion viscosities at the end of the irradiation differ significantly with depth within the specimen. The slopes of the ion viscosity curves as well as the light intensity values decrease with depth and fit to the Lambert-Beer law. The corresponding attenuation coefficients are determined for Arabesk Top OA2 to 1.39mm(-1) and 1.48mm(-1), respectively, and for Grandio OA2 with 1.17 and 1.39mm(-1), respectively. For thicknesses exceeding 1.5mm a change in polymerization behavior is observed as the ion viscosity increases subsequent to the linear range indicating some kind of reaction acceleration. The two VLC composites and different specimen thicknesses discriminate significantly in their ion viscosity evolution allowing for a precise characterization of the curing process even with respect to the polymerization mechanism. Copyright © 2014. Published by Elsevier Ltd.

Durability tests of a fiber optic corrosion sensor.

PubMed

Wan, Kai Tai; Leung, Christopher K Y

2012-01-01

Steel corrosion is a major cause of degradation in reinforced concrete structures, and there is a need to develop cost-effective methods to detect the initiation of corrosion in such structures. This paper presents a low cost, easy to use fiber optic corrosion sensor for practical application. Thin iron film is deposited on the end surface of a cleaved optical fiber by sputtering. When light is sent into the fiber, most of it is reflected by the coating. If the surrounding environment is corrosive, the film is corroded and the intensity of the reflected signal drops significantly. In previous work, the sensing principle was verified by various experiments in laboratory and a packaging method was introduced. In this paper, the method of multiplexing several sensors by optical time domain reflectometer (OTDR) and optical splitter is introduced, together with the interpretation of OTDR results. The practical applicability of the proposed sensors is demonstrated in a three-year field trial with the sensors installed in an aggressive marine environment. The durability of the sensor against chemical degradation and physical degradation is also verified by accelerated life test and freeze-thaw cycling test, respectively.

A novel optical fiber displacement sensor of wider measurement range based on neural network

NASA Astrophysics Data System (ADS)

Guo, Yuan; Dai, Xue Feng; Wang, Yu Tian

2006-02-01

By studying on the output characteristics of random type optical fiber sensor and semicircular type optical fiber sensor, the ratio of the two output signals was used as the output signal of the whole system. Then the measurement range was enlarged, the linearity was improved, and the errors of reflective and absorbent changing of target surface are automatically compensated. Meantime, an optical fiber sensor model of correcting static error based on BP artificial neural network(ANN) is set up. So the intrinsic errors such as effects of fluctuations in the light, circuit excursion, the intensity losses in the fiber lines and the additional losses in the receiving fiber caused by bends are eliminated. By discussing in theory and experiment, the error of nonlinear is 2.9%, the measuring range reaches to 5-6mm and the relative accuracy is 2%.And this sensor has such characteristics as no electromagnetic interference, simple construction, high sensitivity, good accuracy and stability. Also the multi-point sensor system can be used to on-line and non-touch monitor in working locales.

Studies of third-order optical nonlinearities and optical limiting properties of azo dyes.

PubMed

Gayathri, C; Ramalingam, A

2008-03-01

In order to protect optical sensors and human eyes from debilitating laser effects, the intensity of the incoming laser light has to be opportunely reduced. Here, we report our results on the third-order optical nonlinearity and optical limiting properties of three azo dyes exposed to a 532nm continuous wave laser. We have observed low power optical limiting based on nonlinear refraction in our samples.

A video-angiometer for simultaneous and continuous measurement of inner and outer vessel diameters. Technical report.

PubMed

Assmann, R; Henrich, H

1978-09-29

A system is described for continuously measuring vessel diameters. It bases on the evaluation of video signal differences of a video camera which are induced by light intensity differences (grey levels) caused by the vascular wall structures. The system is electronically linear, automatically measuring and in addition eyeball controlled by the human sensor: the inaccuracy does not exceed the 5% level.

Light sensors for objective light measurement in ambulatory polysomnography.

PubMed

Schembri, Rachel; Spong, Jo; Peters, Allison; Rochford, Peter; Wilksch, Philip; O'Donoghue, Fergal J; Greenwood, Kenneth M; Barnes, Maree; Kennedy, Gerard A; Berlowitz, David J

2017-01-01

Ambulatory polysomnography (PSG) does not commonly include an objective measure of light to determine the time of lights off (Loff), and thus cannot be used to calculate important indices such as sleep onset latency and sleep efficiency. This study examined the technical specifications and appropriateness of a prototype light sensor (LS) for use in ambulatory Compumedics Somte PSG.Two studies were conducted. The first examined the light measurement characteristics of the LS when used with a portable PSG device, specifically recording trace range, linearity, sensitivity, and stability. This involved the LS being exposed to varying incandescent and fluorescent light levels in a light controlled room. Secondly, the LS was trialled in 24 home and 12 hospital ambulatory PSGs to investigate whether light levels in home and hospital settings were within the recording range of the LS, and to quantify the typical light intensity reduction at the time of Loff. A preliminary exploration of clinical utility was also conducted. Linearity between LS voltage and lux was demonstrated, and the LS trace was stable over 14 hours of recording. The observed maximum voltage output of the LS/PSG device was 250 mV, corresponding to a maximum recording range of 350 lux and 523 lux for incandescent and fluorescent light respectively. At the time of Loff, light levels were within the recording range of the LS, and on average dropped by 72 lux (9-245) in the home and 76 lux (4-348) in the hospital setting. Results suggest that clinical utility was greatest in hospital settings where patients are less mobile. The LS was a simple and effective objective marker of light level in portable PSG, which can be used to identify Loff in ambulatory PSG. This allows measurement of additional sleep indices and support with clinical decisions.

A fiber optic sensor with a metal organic framework as a sensing material for trace levels of water in industrial gases.

PubMed

Ohira, Shin-Ichi; Miki, Yusuke; Matsuzaki, Toru; Nakamura, Nao; Sato, Yu-ki; Hirose, Yasuo; Toda, Kei

2015-07-30

Industrial gases such as nitrogen, oxygen, argon, and helium are easily contaminated with water during production, transfer and use, because there is a high volume fraction of water in the atmosphere (approximately 1.2% estimated with the average annual atmospheric temperature and relative humidity). Even trace water (<1 parts per million by volume (ppmv) of H2O, dew point < -76 °C) in the industrial gases can cause quality problems in the process such as production of semiconductors. Therefore, it is important to monitor and to control trace water levels in industrial gases at each supplying step, and especially during their use. In the present study, a fiber optic gas sensor was investigated for monitoring trace water levels in industrial gases. The sensor consists of a film containing a metal organic framework (MOF). MOFs are made of metals coordinated to organic ligands, and have mesoscale pores that adsorb gas molecules. When the MOF, copper benzene-1,3,5-tricarboxylate (Cu-BTC), was used as a sensing material, we investigated the color of Cu-BTC with water adsorption changed both in depth and tone. Cu-BTC crystals appeared deep blue in dry gases, and then changed to light blue in wet gases. An optical gas sensor with the Cu-BTC film was developed using a light emitting diode as the light source and a photodiode as the light intensity detector. The sensor showed a reversible response to trace water, did not require heating to remove the adsorbed water molecules. The sample gas flow rate did not affect the sensitivity. The obtained limit of detection was 40 parts per billion by volume (ppbv). The response time for sample gas containing 2.5 ppmvH2O was 23 s. The standard deviation obtained for daily analysis of 1.0 ppmvH2O standard gas over 20 days was 9%. Furthermore, the type of industrial gas did not affect the sensitivity. These properties mean the sensor will be applicable to trace water detection in various industrial gases. Copyright © 2015 Elsevier B.V. All rights reserved.

Ocular aberrations with ray tracing and Shack-Hartmann wave-front sensors: Does polarization play a role?

NASA Astrophysics Data System (ADS)

Marcos, Susana; Diaz-Santana, Luis; Llorente, Lourdes; Dainty, Chris

2002-06-01

Ocular aberrations were measured in 71 eyes by using two reflectometric aberrometers, employing laser ray tracing (LRT) (60 eyes) and a Shack-Hartmann wave-front sensor (S-H) (11 eyes). In both techniques a point source is imaged on the retina (through different pupil positions in the LRT or a single position in the S-H). The aberrations are estimated by measuring the deviations of the retinal spot from the reference as the pupil is sampled (in LRT) or the deviations of a wave front as it emerges from the eye by means of a lenslet array (in the S-H). In this paper we studied the effect of different polarization configurations in the aberration measurements, including linearly polarized light and circularly polarized light in the illuminating channel and sampling light in the crossed or parallel orientations. In addition, completely depolarized light in the imaging channel was obtained from retinal lipofuscin autofluorescence. The intensity distribution of the retinal spots as a function of entry (for LRT) or exit pupil (for S-H) depends on the polarization configuration. These intensity patterns show bright corners and a dark area at the pupil center for crossed polarization, an approximately Gaussian distribution for parallel polarization and a homogeneous distribution for the autofluorescence case. However, the measured aberrations are independent of the polarization states. These results indicate that the differences in retardation across the pupil imposed by corneal birefringence do not produce significant phase delays compared with those produced by aberrations, at least within the accuracy of these techniques. In addition, differences in the recorded aerial images due to changes in polarization do not affect the aberration measurements in these reflectometric aberrometers.

Glucose Sensing with Phenylboronic Acid Functionalized Hydrogel-Based Optical Diffusers

PubMed Central

2018-01-01

Phenylboronic acids have emerged as synthetic receptors that can reversibly bind to cis-diols of glucose molecules. The incorporation of phenylboronic acids in hydrogels offers exclusive attributes; for example, the binding process with glucose induces Donnan osmotic pressure resulting in volumetric changes in the matrix. However, their practical applications are hindered because of complex readout approaches and their time-consuming fabrication processes. Here, we demonstrate a microimprinting method to fabricate densely packed concavities in phenylboronic acid functionalized hydrogel films. A microengineered optical diffuser structure was imprinted on a phenylboronic acid based cis-diol recognizing motif prepositioned in a hydrogel film. The diffuser structure engineered on the hydrogel was based on laser-inscribed arrays of imperfect microlenses that focused the incoming light at different focal lengths and direction resulting in a diffused profile of light in transmission and reflection readout modes. The signature of the dimensional modulation was detected in terms of changing focal lengths of the microlenses due to the volumetric expansion of the hydrogel that altered the diffusion spectra and transmitted beam profile. The transmitted optical light spread and intensity through the sensor was measured to determine variation in glucose concentrations at physiological conditions. The sensor was integrated in a contact lens and placed over an artificial eye. Artificial stimulation of variation in glucose concentration allowed quantitative measurements using a smartphone’s photodiode. A smartphone app was utilized to convert the received light intensity to quantitative glucose concentration values. The developed sensing platform offers low cost, rapid fabrication, and easy detection scheme as compared to other optical sensing counterparts. The presented detection scheme may have applications in wearable real-time biomarker monitoring devices at point-of-care settings. PMID:29529366

Study on real-time images compounded using spatial light modulator

NASA Astrophysics Data System (ADS)

Xu, Jin; Chen, Zhebo; Ni, Xuxiang; Lu, Zukang

2007-01-01

Image compounded technology is often used on film and its facture. In common, image compounded use image processing arithmetic, get useful object, details, background or some other things from the images firstly, then compounding all these information into one image. When using this method, the film system needs a powerful processor, for the process function is very complex, we get the compounded image for a few time delay. In this paper, we introduce a new method of image real-time compounded, use this method, we can do image composite at the same time with movie shot. The whole system is made up of two camera-lens, spatial light modulator array and image sensor. In system, the spatial light modulator could be liquid crystal display (LCD), liquid crystal on silicon (LCoS), thin film transistor liquid crystal display (TFTLCD), Deformable Micro-mirror Device (DMD), and so on. Firstly, one camera-lens images the object on the spatial light modulator's panel, we call this camera-lens as first image lens. Secondly, we output an image to the panel of spatial light modulator. Then, the image of the object and image that output by spatial light modulator will be spatial compounded on the panel of spatial light modulator. Thirdly, the other camera-lens images the compounded image to the image sensor, and we call this camera-lens as second image lens. After these three steps, we will gain the compound images by image sensor. For the spatial light modulator could output the image continuously, then the image will be compounding continuously too, and the compounding procedure is completed in real-time. When using this method to compounding image, if we will put real object into invented background, we can output the invented background scene on the spatial light modulator, and the real object will be imaged by first image lens. Then, we get the compounded images by image sensor in real time. The same way, if we will put real background to an invented object, we can output the invented object on the spatial light modulator and the real background will be imaged by first image lens. Then, we can also get the compounded images by image sensor real time. Commonly, most spatial light modulator only can do modulate light intensity, so we can only do compounding BW images if use only one panel which without color filter. If we will get colorful compounded image, we need use the system like three spatial light modulator panel projection. In the paper, the system's optical system framework we will give out. In all experiment, the spatial light modulator used liquid crystal on silicon (LCoS). At the end of the paper, some original pictures and compounded pictures will be given on it. Although the system has a few shortcomings, we can conclude that, using this system to compounding images has no delay to do mathematic compounding process, it is a really real time images compounding system.

Fiber-optic voltage measuring system

NASA Astrophysics Data System (ADS)

Ye, Miaoyuan; Nie, De-Xin; Li, Yan; Peng, Yu; Lin, Qi-Qing; Wang, Jing-Gang

1993-09-01

A new fibre optic voltage measuring system has been developed based on the electrooptic effect of bismuth germanium oxide (Bi4Ge3O12)crystal. It uses the LED as the light source. The light beam emitted from the light source is transmitted to the sensor through the optic fibre and the intensity of the output beam is changed by the applied voltage. This optic signal is transmitted to the PIN detector and converted to an electric signal which is processed by the electronic circuit and 8098 single chip microcomputer the output voltage signal obtained is directly proportional to the applied voltage. This paper describes the principle the configuration and the performance parameters of the system. Test results are evaluated and discussed.

Light-Addressable Potentiometric Sensors using ZnO Nanorods as the Sensor Substrate for Bioanalytical Applications.

PubMed

Tu, Ying; Ahmad, Norlaily; Briscoe, Joe; Zhang, De-Wen; Krause, Steffi

2018-06-22

Light-addressable potentiometric sensors (LAPS) are of great interest in bioimaging applications such as the monitoring of concentrations in microfluidic channels or the investigation of metabolic and signaling events in living cells. By measuring the photocurrents at electrolyte-insulator-semiconductor (EIS) and electrolyte-semiconductor structures, LAPS can produce spatiotemporal images of chemical or biological analytes, electrical potentials and impedance. However, its commercial applications are often restricted by their limited AC photocurrents and resolution of LAPS images. Herein, for the first time, the use of 1D semiconducting oxides in the form of ZnO nanorods for LAPS imaging is explored to solve this issue. A significantly increased AC photocurrent with enhanced image resolution has been achieved based on ZnO nanorods, with a photocurrent of 45.7 ± 0.1 nA at a light intensity of 0.05 mW, a lateral resolution as low as 3.0 μm as demonstrated by images of a PMMA dot on ZnO nanorods and a pH sensitivity of 53 mV/pH. The suitability of the device for bioanalysis and bioimaging was demonstrated by monitoring the degradation of a thin poly(ester amide) film with the enzyme α-chymotrypsin using LAPS. This simple and robust route to fabricate LAPS substrates with excellent performance would provide tremendous opportunities for bioimaging.

[Development of a monitor for quantifying personal eye exposure to visible and ultraviolet radiation and its application in epidemiology].

PubMed

Eto, Norihito; Tsubota, Kazuo; Tanaka, Taichiro; Nishiwaki, Yuji

2013-01-01

Eye diseases including cataract, keratitis and pterygium have been reported to be sun-exposure-related. The association between macular degeneration and blue light has also been discussed. Moreover, it is hypothesized that retinal exposure to blue light may influence the human circadian rhythm. However, no monitoring devices exist that can measure eye exposure to visible and ultraviolet (UV) radiation over time. To measure the exact dose at specific times, we have developed a novel sensing system (ray-sensing glass system: RaySeG). RaySeG can continuously measure and record the composition and intensity of light with a time-stamped system. Subjects wearing RaySeG were instructed to walk under various light conditions such as indoor and outdoor. RaySeG consists of two sensors embedded in the eyeglasses. These sensors are for UV (260-400 nm), visible lights (red, 615 nm; green, 540 nm; and blue, 465 nm: peak wavelength for each). The total weight of the system is about 100 g, and the size is comparable to that of a digital audio player. The system continuously recorded changes in visible and UV light exposure under various conditions. After accuracy validation, further experiments with a larger number of subjects are required. Our final goal is to apply the system to evaluating personal eye exposure to UV and visible light in epidemiological studies of eye diseases and circadian rhythm abnormality.

Laser-induced photo emission detection: data acquisition based on light intensity counting

NASA Astrophysics Data System (ADS)

Yulianto, N.; Yudasari, N.; Putri, K. Y.

2017-04-01

Laser Induced Breakdown Detection (LIBD) is one of the quantification techniques for colloids. There are two ways of detection in LIBD: optical detection and acoustic detection. LIBD is based on the detection of plasma emission due to the interaction between particle and laser beam. In this research, the changing of light intensity during plasma formations was detected by a photodiode sensor. A photo emission data acquisition system was built to collect and transform them into digital counts. The real-time system used data acquisition device National Instrument DAQ 6009 and LABVIEW software. The system has been tested on distilled water and tap water samples. The result showed 99.8% accuracy by using counting technique in comparison to the acoustic detection with sample rate of 10 Hz, thus the acquisition system can be applied as an alternative method to the existing LIBD acquisition system.

Plasmonic nanoshell functionalized etched fiber Bragg gratings for highly sensitive refractive index measurements.

PubMed

Burgmeier, Jörg; Feizpour, Amin; Schade, Wolfgang; Reinhard, Björn M

2015-02-15

A novel fiber optical refractive index sensor based on gold nanoshells immobilized on the surface of an etched single-mode fiber including a Bragg grating is demonstrated. The nanoparticle coating induces refractive index dependent waveguide losses, because of the variation of the evanescently guided part of the light. Hence the amplitude of the Bragg reflection is highly sensitive to refractive index changes of the surrounding medium. The nanoshell functionalized fiber optical refractive index sensor works in reflectance mode, is suitable for chemical and biochemical sensing, and shows an intensity dependency of 4400% per refractive index unit in the refractive index range between 1.333 and 1.346. Furthermore, the physical length of the sensor is smaller than 3 mm with a diameter of 6 μm, and therefore offers the possibility of a localized refractive index measurement.

Improving NIR snow pit stratigraphy observations by introducing a controlled NIR light source

NASA Astrophysics Data System (ADS)

Dean, J.; Marshall, H.; Rutter, N.; Karlson, A.

2013-12-01

Near-infrared (NIR) photography in a prepared snow pit measures mm-/grain-scale variations in snow structure, as reflectivity is strongly dependent on microstructure and grain size at the NIR wavelengths. We explore using a controlled NIR light source to maximize signal to noise ratio and provide uniform incident, diffuse light on the snow pit wall. NIR light fired from the flash is diffused across and reflected by an umbrella onto the snow pit; the lens filter transmits NIR light onto the spectrum-modified sensor of the DSLR camera. Lenses are designed to refract visible light properly, not NIR light, so there must be a correction applied for the subsequent NIR bright spot. To avoid interpolation and debayering algorithms automatically performed by programs like Adobe's Photoshop on the images, the raw data are analyzed directly in MATLAB. NIR image data show a doubling of the amount of light collected in the same time for flash over ambient lighting. Transitions across layer boundaries in the flash-lit image are detailed by higher camera intensity values than ambient-lit images. Curves plotted using median intensity at each depth, normalized to the average profile intensity, show a separation between flash- and ambient-lit images in the upper 10-15 cm; the ambient-lit image curve asymptotically approaches the level of the flash-lit image curve below 15cm. We hypothesize that the difference is caused by additional ambient light penetrating the upper 10-15 cm of the snowpack from above and transmitting through the wall of the snow pit. This indicates that combining NIR ambient and flash photography could be a powerful technique for studying penetration depth of radiation as a function of microstructure and grain size. The NIR flash images do not increase the relative contrast at layer boundaries; however, the flash more than doubles the amount of recorded light and controls layer noise as well as layer boundary transition noise.

Development of optical FBG force measurement system for the medical application

NASA Astrophysics Data System (ADS)

Song, Hoseok; Kim, Kiyoung; Suh, Jungwook; Lee, Jungju

2010-03-01

Haptic feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, very long and stiff bar of instruments take haptic feeling away from the surgeon. In minimally invasive robotic surgery (MIRS), moreover, haptic feelings are totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peakforce magnitude by at least a factor of two. Therefore, it is very important to provide haptic information in MIRS. Recently, many sensors are being developed for MIS or MIRS, but they have some obstacles in their application to real situations of medical surgery. The most critical problems are size limit and sterilizability. Optical fiber sensors are one of the most suitable sensors for this environment. Especially, optical fiber Bragg grating (FBG) sensor has one additional advantage than the other optical fiber sensors. FBG sensor is not influenced by intensity of light source. In this paper, we would like to present the initial results of study on the application of the FBG sensor to measure reflected forces in MIRS environments and then suggest the possibility of successful application to the MIRS systems.

Development of optical FBG force measurement system for the medical application

NASA Astrophysics Data System (ADS)

Song, Hoseok; Kim, Kiyoung; Suh, Jungwook; Lee, Jungju

2009-12-01

Haptic feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, very long and stiff bar of instruments take haptic feeling away from the surgeon. In minimally invasive robotic surgery (MIRS), moreover, haptic feelings are totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peakforce magnitude by at least a factor of two. Therefore, it is very important to provide haptic information in MIRS. Recently, many sensors are being developed for MIS or MIRS, but they have some obstacles in their application to real situations of medical surgery. The most critical problems are size limit and sterilizability. Optical fiber sensors are one of the most suitable sensors for this environment. Especially, optical fiber Bragg grating (FBG) sensor has one additional advantage than the other optical fiber sensors. FBG sensor is not influenced by intensity of light source. In this paper, we would like to present the initial results of study on the application of the FBG sensor to measure reflected forces in MIRS environments and then suggest the possibility of successful application to the MIRS systems.

Intense transient electric field sensor based on the electro-optic effect of LiNbO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Qing, E-mail: yangqing@cqu.edu.cn; Sun, Shangpeng; Han, Rui

2015-10-15

Intense transient electric field measurements are widely applied in various research areas. An optical intense E-field sensor for time-domain measurements, based on the electro-optic effect of lithium niobate, has been studied in detail. Principles and key issues in the design of the sensor are presented. The sensor is insulated, small in size (65 mm × 15 mm × 15 mm), and suitable for high-intensity (<801 kV/m) electric field measurements over a wide frequency band (10 Hz–10 MHz). The input/output characteristics of the sensor were obtained and the sensor calibrated. Finally, an application using this sensor in testing laboratory lightning impulsesmore » and in measuring transient electric fields during switch-on of a disconnector confirmed that the sensor is expected to find widespread use in transient intense electric field measurement applications.« less

Intense transient electric field sensor based on the electro-optic effect of LiNbO3

NASA Astrophysics Data System (ADS)

Yang, Qing; Sun, Shangpeng; Han, Rui; Sima, Wenxia; Liu, Tong

2015-10-01

Intense transient electric field measurements are widely applied in various research areas. An optical intense E-field sensor for time-domain measurements, based on the electro-optic effect of lithium niobate, has been studied in detail. Principles and key issues in the design of the sensor are presented. The sensor is insulated, small in size (65 mm × 15 mm × 15 mm), and suitable for high-intensity (<801 kV/m) electric field measurements over a wide frequency band (10 Hz-10 MHz). The input/output characteristics of the sensor were obtained and the sensor calibrated. Finally, an application using this sensor in testing laboratory lightning impulses and in measuring transient electric fields during switch-on of a disconnector confirmed that the sensor is expected to find widespread use in transient intense electric field measurement applications.

Scattering-Type Surface-Plasmon-Resonance Biosensors

NASA Technical Reports Server (NTRS)

Wang, Yu; Pain, Bedabrata; Cunningham, Thomas; Seshadri, Suresh

2005-01-01

Biosensors of a proposed type would exploit scattering of light by surface plasmon resonance (SPR). Related prior biosensors exploit absorption of light by SPR. Relative to the prior SPR biosensors, the proposed SPR biosensors would offer greater sensitivity in some cases, enough sensitivity to detect bioparticles having dimensions as small as nanometers. A surface plasmon wave can be described as a light-induced collective oscillation in electron density at the interface between a metal and a dielectric. At SPR, most incident photons are either absorbed or scattered at the metal/dielectric interface and, consequently, reflected light is greatly attenuated. The resonance wavelength and angle of incidence depend upon the permittivities of the metal and dielectric. An SPR sensor of the type most widely used heretofore includes a gold film coated with a ligand a substance that binds analyte molecules. The gold film is thin enough to support evanescent-wave coupling through its thickness. The change in the effective index of refraction at the surface, and thus the change in the SPR response, increases with the number of bound analyte molecules. The device is illuminated at a fixed wavelength, and the intensity of light reflected from the gold surface opposite the ligand-coated surface is measured as a function of the angle of incidence. From these measurements, the angle of minimum reflection intensity is determined

A fiber optic sensor for on-line non-touch monitoring of roll shape

NASA Astrophysics Data System (ADS)

Guo, Yuan; Qu, Weijian; Yuan, Qi

2009-07-01

Basing on the principle of reflective displacement fibre-optic sensor, a high accuracy non-touch on-line optical fibre sensor for detecting roll shape is presented. The principle and composition of the detection system and the operation process are expatiated also. By using a novel probe of three optical fibres in equal transverse space, the effects of fluctuations in the light source, reflective changing of target surface and the intensity losses in the fibre lines are automatically compensated. Meantime, an optical fibre sensor model of correcting static error based on BP artificial neural network (ANN) is set up. Also by using interpolation method and value filtering to process the signals, effectively reduce the influence of random noise and the vibration of the roll bearing. So the accuracy and resolution were enhanced remarkably. Experiment proves that the resolution is 1μm and the precision can reach to 0.1%. So the system reaches to the demand of practical production process.

Using a Fuzzy Light Sensor to Improve the Efficiency of Solar Panels

NASA Astrophysics Data System (ADS)

Suryono; Suseno, Jatmiko Endro; Sulistiati, Ainie Khuriati Riza; Prahara, Tahan

2018-02-01

Solar panel efficiency can be increased by improving the quality of photovoltaic material, the effectiveness of electronic circuit, and the light source tracking model. This research is aimed at improving the quality of solar panels by tracking light source using a fuzzy logic sensor. A fuzzy light sensor property is obtained from two LDR (light dependent resistor) light sensors installed in parallel to each other and is given a light separator in between them. Both sensors are mounted on a solar panel. Sensor output is acquired using a 12 bit ADC from an ATSAM3XE microcontroller and is then sent to a computer using WIFI radio. A PID (Proportional-Integral-Derivative) control algorithm is used to manage the position of the solar panel in line with the input given by the fuzzy light sensor. This control mechanism works based on the margin of fuzzy membership from both sensors that is used to move a motor DC that in turn moves the solar panel. Experimental results show a characteristically symmetrical fuzzy membership of both sensors with a reflected correlation of R=0.9981 after gains from both sensors are arranged with a program. Upon being tested in the field, this system was capable of improving the performance of solar panels in gaining power compared to their original fixed position. The discrepancy was evident when the angle of incoming sunlight approached both 0° and 180°. Further calculations of data acquired by the fuzzy light sensor show increased solar panel power efficiency by up to 5.6%.

A novel and sensitive fluorescence sensor for glutathione detection by controlling the surface passivation degree of carbon quantum dots.

PubMed

Pan, Jiahong; Zheng, Zengyao; Yang, Jianying; Wu, Yaoyu; Lu, Fushen; Chen, Yaowen; Gao, Wenhua

2017-05-01

A novel fluorescence sensor based on controlling the surface passivation degree of carbon quantum dots (CQDs) was developed for glutathione (GSH) detection. First, we found that the fluorescence intensity of the CQDs which was obtained by directly pyrolyzing citric acid would increased largely after the surface passivation treatment by 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). In the light of this phenomenon, we designed a simple, rapid and selective fluorescence sensor based on the surface passivated CQDs. A certain and excess amount of EDC were mixed with GSH, part of EDC would form a stable complex with GSH owing to the exposed sulfhydryl group of GSH. As the synthesized CQDs were added into the above mixture solution, the fluorescence intensity of the (EDC/GSH)/CQDs mixture solution could be directly related to the amount of GSH. Compared to other fluorescence analytical methods, the fluorescence sensor we design is neither the traditional fluorescent "turn on" probes nor "turn off" probes. It is a new fluorescence analytical method that target object indirectly control the surface passivation degree of CQDs so that it can realize the detection of the target object. Moreover, the proposed method manifested great advantages including short analysis time, low cost and ease of operation. Copyright © 2017 Elsevier B.V. All rights reserved.

Contribution of PsbS Function and Stomatal Conductance to Foliar Temperature in Higher Plants

PubMed Central

Kulasek, Milena; Bernacki, Maciej Jerzy; Ciszak, Kamil; Witoń, Damian; Karpiński, Stanisław

2016-01-01

Natural capacity has evolved in higher plants to absorb and harness excessive light energy. In basic models, the majority of absorbed photon energy is radiated back as fluorescence and heat. For years the proton sensor protein PsbS was considered to play a critical role in non-photochemical quenching (NPQ) of light absorbed by PSII antennae and in its dissipation as heat. However, the significance of PsbS in regulating heat emission from a whole leaf has never been verified before by direct measurement of foliar temperature under changing light intensity. To test its validity, we here investigated the foliar temperature changes on increasing and decreasing light intensity conditions (foliar temperature dynamics) using a high resolution thermal camera and a powerful adjustable light-emitting diode (LED) light source. First, we showed that light-dependent foliar temperature dynamics is correlated with Chl content in leaves of various plant species. Secondly, we compared the foliar temperature dynamics in Arabidopsis thaliana wild type, the PsbS null mutant npq4-1 and a PsbS-overexpressing transgenic line under different transpiration conditions with or without a photosynthesis inhibitor. We found no direct correlations between the NPQ level and the foliar temperature dynamics. Rather, differences in foliar temperature dynamics are primarily affected by stomatal aperture, and rapid foliar temperature increase during irradiation depends on the water status of the leaf. We conclude that PsbS is not directly involved in regulation of foliar temperature dynamics during excessive light energy episodes. PMID:27273581

Textile Pressure Sensor Made of Flexible Plastic Optical Fibers

PubMed Central

Rothmaier, Markus; Luong, Minh Phi; Clemens, Frank

2008-01-01

In this paper we report the successful development of pressure sensitive textile prototypes based on flexible optical fibers technology. Our approach is based on thermoplastic silicone fibers, which can be integrated into woven textiles. As soon as pressure at a certain area of the textile is applied to these fibers they change their cross section reversibly, due to their elastomeric character, and a simultaneous change in transmitted light intensity can be detected. We have successfully manufactured two different woven samples with fibers of 0.51 and 0.98 mm diameter in warp and weft direction, forming a pressure sensitive matrix. Determining their physical behavior when a force is applied shows that pressure measurements are feasible. Their usable working range is between 0 and 30 N. Small drifts in the range of 0.2 to 4.6%, over 25 load cycles, could be measured. Finally, a sensor array of 2 × 2 optical fibers was tested for sensitivity, spatial resolution and light coupling between fibers at intersections. PMID:27879938

Design of Weft Detection System in The Stenter Machine

NASA Astrophysics Data System (ADS)

Gu, Minming; Xu, Xianju; Dai, Wenzhan

2017-12-01

In order to build an effective automatic weft-straightening system, it is important for the sensing device to detect most the possible fabric styles, designs, colours and structures, an optical sensing system that detects the angular orientation of weft threads in a moving web of a textile has been built. It contains an adjustable light source, two lens systems and photodiode sensor array. The sensor array includes 13 radial pattern of photosensitive areas that each generate an electrical signal proportional to the total intensity of the light incident on the area. The moving shadow of a weft thread passing over the area will modulate the output signal. A signal processed circuit was built to do the I/V conversion, amplifying, hardware filtering. An embed micro control system then deals with the information of these signals, calculates the angle of the weft drew. Finally, the experiments were done, the results showed that the weft detection system can deal with the fabric weft skew up to 30° and has achieved good results in the application.

Brillouin light scattering as a probe for low frequency quasiparticles in solids

NASA Astrophysics Data System (ADS)

Klimovich, Nikita; Olson, Kevin; An, Kyongmo; Sullivan, Sean; Weathers, Annie; Shi, Li; Li, Xiaoqin

2015-03-01

In increasingly small electronic and spintronic devices, electrons, optical phonons, acoustic phonons, and magnons are often driven out of local thermal equilibrium. Thermal transport based on equilibrium dynamics does not adequately describe these systems necessitating a better understanding of non-equilibrium transport processes. Measuring the specific temperatures of the different energy carriers is therefore crucial in understanding the thermal transport. Brillouin light scattering (BLS) has recently been explored as a temperature sensor for low frequency acoustic phonons in glass, and also magnons in metallic and insulating ferromagnetic materials. We report the measured BLS spectra of acoustic phonons in Silicon at different temperatures. The temperature dependence of the BLS peak frequency, linewidth, and integrated intensity are examined to evaluate their potential uses as temperature sensors of acoustic phonons. We also observe a large nonequilibrium in phonon-magnon temperature in YIG under the effects of laser heating and thereby extract a value for the phonon-magnon coupling coefficient. This work is funded by the National Science Foundation and the Army Research Office.

Event-based Sensing for Space Situational Awareness

NASA Astrophysics Data System (ADS)

Cohen, G.; Afshar, S.; van Schaik, A.; Wabnitz, A.; Bessell, T.; Rutten, M.; Morreale, B.

A revolutionary type of imaging device, known as a silicon retina or event-based sensor, has recently been developed and is gaining in popularity in the field of artificial vision systems. These devices are inspired by a biological retina and operate in a significantly different way to traditional CCD-based imaging sensors. While a CCD produces frames of pixel intensities, an event-based sensor produces a continuous stream of events, each of which is generated when a pixel detects a change in log light intensity. These pixels operate asynchronously and independently, producing an event-based output with high temporal resolution. There are also no fixed exposure times, allowing these devices to offer a very high dynamic range independently for each pixel. Additionally, these devices offer high-speed, low power operation and a sparse spatiotemporal output. As a consequence, the data from these sensors must be interpreted in a significantly different way to traditional imaging sensors and this paper explores the advantages this technology provides for space imaging. The applicability and capabilities of event-based sensors for SSA applications are demonstrated through telescope field trials. Trial results have confirmed that the devices are capable of observing resident space objects from LEO through to GEO orbital regimes. Significantly, observations of RSOs were made during both day-time and nighttime (terminator) conditions without modification to the camera or optics. The event based sensor’s ability to image stars and satellites during day-time hours offers a dramatic capability increase for terrestrial optical sensors. This paper shows the field testing and validation of two different architectures of event-based imaging sensors. An eventbased sensor’s asynchronous output has an intrinsically low data-rate. In addition to low-bandwidth communications requirements, the low weight, low-power and high-speed make them ideally suitable to meeting the demanding challenges required by space-based SSA systems. Results from these experiments and the systems developed highlight the applicability of event-based sensors to ground and space-based SSA tasks.

A ruthenium(II) complex as turn-on Cu(II) luminescent sensor based on oxidative cyclization mechanism and its application in vivo

NASA Astrophysics Data System (ADS)

Zhang, Yunfei; Liu, Zonglun; Yang, Kui; Zhang, Yi; Xu, Yongqian; Li, Hongjuan; Wang, Chaoxia; Lu, Aiping; Sun, Shiguo

2015-02-01

Copper ions play a vital role in a variety of fundamental physiological processes not only in human beings and plants, but also for extensive insects and microorganisms. In this paper, a novel water-soluble ruthenium(II) complex as a turn-on copper(II) ions luminescent sensor based on o-(phenylazo)aniline was designed and synthesized. The azo group would undergo a specific oxidative cyclization reaction with copper(II) ions and turn into high luminescent benzotriazole, triggering significant luminescent increasements which were linear to the concentrations of copper(II) ions. The sensor distinguished by its high sensitivity (over 80-fold luminescent switch-on response), good selectivity (the changes of the emission intensity in the presence of other metal ions or amino acids were negligible) and low detection limit (4.42 nM) in water. Moreover, the copper(II) luminescent sensor exhibited good photostability under light irradiation. Furthermore, the applicability of the proposed sensor in biological samples assay was also studied and imaged copper(II) ions in living pea aphids successfully.

Affordable and personalized lighting using inverse modeling and virtual sensors

NASA Astrophysics Data System (ADS)

Basu, Chandrayee; Chen, Benjamin; Richards, Jacob; Dhinakaran, Aparna; Agogino, Alice; Martin, Rodney

2014-03-01

Wireless sensor networks (WSN) have great potential to enable personalized intelligent lighting systems while reducing building energy use by 50%-70%. As a result WSN systems are being increasingly integrated in state-ofart intelligent lighting systems. In the future these systems will enable participation of lighting loads as ancillary services. However, such systems can be expensive to install and lack the plug-and-play quality necessary for user-friendly commissioning. In this paper we present an integrated system of wireless sensor platforms and modeling software to enable affordable and user-friendly intelligent lighting. It requires ⇠ 60% fewer sensor deployments compared to current commercial systems. Reduction in sensor deployments has been achieved by optimally replacing the actual photo-sensors with real-time discrete predictive inverse models. Spatially sparse and clustered sub-hourly photo-sensor data captured by the WSN platforms are used to develop and validate a piece-wise linear regression of indoor light distribution. This deterministic data-driven model accounts for sky conditions and solar position. The optimal placement of photo-sensors is performed iteratively to achieve the best predictability of the light field desired for indoor lighting control. Using two weeks of daylight and artificial light training data acquired at the Sustainability Base at NASA Ames, the model was able to predict the light level at seven monitored workstations with 80%-95% accuracy. We estimate that 10% adoption of this intelligent wireless sensor system in commercial buildings could save 0.2-0.25 quads BTU of energy nationwide.

An Automated Flying-Insect Detection System

NASA Technical Reports Server (NTRS)

Vann, Timi; Andrews, Jane C.; Howell, Dane; Ryan, Robert

2007-01-01

An automated flying-insect detection system (AFIDS) was developed as a proof-of-concept instrument for real-time detection and identification of flying insects. This type of system has use in public health and homeland-security decision support, agriculture and military pest management, and/or entomological research. Insects are first lured into the AFIDS integrated sphere by insect attractants. Once inside the sphere, the insect s wing beats cause alterations in light intensity that is detected by a photoelectric sensor. Following detection, the insects are encouraged (with the use of a small fan) to move out of the sphere and into a designated insect trap where they are held for taxonomic identification or serological testing. The acquired electronic wing-beat signatures are preprocessed (Fourier transformed) in real time to display a periodic signal. These signals are sent to the end user where they are graphically. All AFIDS data are preprocessed in the field with the use of a laptop computer equipped with LabVIEW. The AFIDS software can be programmed to run continuously or at specific time intervals when insects are prevalent. A special DC-restored transimpedance amplifier reduces the contributions of low-frequency background light signals, and affords approximately two orders of magnitude greater AC gain than conventional amplifiers. This greatly increases the signal-to-noise ratio and enables the detection of small changes in light intensity. The AFIDS light source consists of high-intensity Al-GaInP light-emitting diodes (LEDs). The AFIDS circuitry minimizes brightness fluctuations in the LEDs and when integrated with an integrating sphere, creates a diffuse uniform light field. The insect wing beats isotropically scatter the diffuse light in the sphere and create wing-beat signatures that are detected by the sensor. This configuration minimizes variations in signal associated with insect flight orientation. Preliminary data indicate that AFIDS has sufficient sensitivity and frequency measuring capability to differentiate between male and female mosquitoes (Figure 1, bottom panel) and fruit flies (data not shown). Similar studies show that AFIDS can be utilized to detect discrete differences between two mosquito species, Aedes aegypti and Aedes albopictus. When fully deployable, a wireless network of AFIDS monitors could be used in combination with other remotely sensed data and visually displayed in a geographic information system (GIS) to provide real-time surveillance (see Figure 2). More accurate and sensitive insect population forecasts and effective rapid response and mitigation of insect issues would then be possible.

Optical fiber network sensor system for monitoring methane concentration

NASA Astrophysics Data System (ADS)

Zhang, Zhi-wei; Zhang, Ji-long

2011-08-01

With regard to the high accuracy optic-fiber sensor for monitoring methane concentration, the choice of light source depends on methane peak values. Besides, the environment of mine should be considered, that is to say other gas should be considered, such as vapor, CO and CO2 etc, without absorbent spectrum in the decided wavelength. It has been reported that vapor, CO and CO2 have no obvious absorption in 0.85μm, 1.3μm and 1.66μm area, CH4 has no obvious absorption in 0.85μm area. So diode laser with 1.3μm or 1.66μm peak wavelength is chosen as the optic-fiber sensor's light source for detecting methane concentration. On the basis of the principle of optic absorption varied with methane concentration at its characteristic absorbent wavelength, the advantage of optic-fiber sensor technology and the circumstance characteristic of the coal mine. An optic-fiber sensor system is presented for monitoring methane concentration. Space Division Multiple Access Technology (SDMAT) and long optical path absorbent pool technology are combined in the study. Considering the circumstance characteristic of the coal mine, the optic-fiber network sensors for detecting methane concentration from mix gas of vapor, CO, CH4 and CO2 are used. It introduces the principle of an optic-fiber sensor system for monitoring methane concentration in coal mine. It contains the structure block diagram of monitoring system, the system is mainly made up of diode laser for monitoring methane concentration, Y-shaped photo-coupler with coupled rate 50:50, optical switch 1×2, gas absorbent cell, the computer data process and control system and photoelectric transformer. In this study, in order to decrease to the influence of the dark-current of photodiode, intensity in light sources and temperature drifts of processing circuit on the system accuracy in measurement, a beam of light is broken down into two beams in the coupler of Y-shaped coupler, the one acts as the reference optical path, the other is known as the sensing optical path. The experimental result shows that diode laser with 1654.141nm in wavelength is taken as the optic source for detecting methane concentration, the detective limit of the sensor is below 4.274mg/m3 when the optical path of absorbent pool is 20 centimeters, and the prevision and stability could satisfy practical application. The whole instrument can also reach on-line measurement with multiple points on different spot.

From dark to bright: novel daylighting applications in solid state lighting

NASA Astrophysics Data System (ADS)

Adler, Helmar G.

2011-10-01

The term "daylighting" is used in various ways, on one hand in a more architectural sense, i.e. using existing daylight to illuminate spaces, and on the other, more recently, for using light sources to replicate daylight. The emergence of solid state lighting (SSL) opens up a large number of new avenues for daylighting. SSL allows innovative controllability of intensity and color for artificial light sources that can be advantageously applied to daylighting. With the assistance of these new technologies the combination of natural and artificial lighting could lead to improvements in energy savings and comfort of living beings. Thus it is imperative to revisit or even improve daylighting research so that building networks of the future with their sensor, energy (e.g. HVAC) and lighting requirements can benefit from the emerging capabilities. This paper will briefly review existing daylighting concepts and technology and discuss new ideas. An example of a tunable multi-color SSL system will be shown.

4D light-field sensing system for people counting

NASA Astrophysics Data System (ADS)

Hou, Guangqi; Zhang, Chi; Wang, Yunlong; Sun, Zhenan

2016-03-01

Counting the number of people is still an important task in social security applications, and a few methods based on video surveillance have been proposed in recent years. In this paper, we design a novel optical sensing system to directly acquire the depth map of the scene from one light-field camera. The light-field sensing system can count the number of people crossing the passageway, and record the direction and intensity of rays at a snapshot without any assistant light devices. Depth maps are extracted from the raw light-ray sensing data. Our smart sensing system is equipped with a passive imaging sensor, which is able to naturally discern the depth difference between the head and shoulders for each person. Then a human model is built. Through detecting the human model from light-field images, the number of people passing the scene can be counted rapidly. We verify the feasibility of the sensing system as well as the accuracy by capturing real-world scenes passing single and multiple people under natural illumination.

A survey of camera error sources in machine vision systems

NASA Astrophysics Data System (ADS)

Jatko, W. B.

In machine vision applications, such as an automated inspection line, television cameras are commonly used to record scene intensity in a computer memory or frame buffer. Scene data from the image sensor can then be analyzed with a wide variety of feature-detection techniques. Many algorithms found in textbooks on image processing make the implicit simplifying assumption of an ideal input image with clearly defined edges and uniform illumination. The ideal image model is helpful to aid the student in understanding the principles of operation, but when these algorithms are blindly applied to real-world images the results can be unsatisfactory. This paper examines some common measurement errors found in camera sensors and their underlying causes, and possible methods of error compensation. The role of the camera in a typical image-processing system is discussed, with emphasis on the origination of signal distortions. The effects of such things as lighting, optics, and sensor characteristics are considered.

Realization of 2:1 MUX using Mach Zhender Interferometer structure and its application in selection of output signal of MOEMS pressure and temperature sensor

NASA Astrophysics Data System (ADS)

Jindal, Sumit Kumar; Raghuwanshi, Sanjeev Kumar

2016-03-01

In this paper we have initially designed a circular diaphragm based MOEMS pressure sensor and a thermistor based temperature sensor. This has been done by the help of externally modulated LiNbO3 Mach Zhender Interferometer (MZI) which senses the input voltage signal and modulates it to give an output in the form of intensity of light. This output is then calibrated to understand the proper relation between the input applied and output measured. The next aspect has been the use of MZI to work as a 2:1 MUX where two input lines are -pressure signal and temperature signal. The arrangement of MZI is then modulated in such a way that based on the requirement it chooses the proper input signal and sends it to the output port for the measurement. The design has been simulated in Opti-BPM software.

Efficacy and mode of action of a noise-sensor light alarm to decrease noise in the pediatric intensive care unit: a prospective, randomized study.

PubMed

Jousselme, Chloé; Vialet, Renaud; Jouve, Elisabeth; Lagier, Pierre; Martin, Claude; Michel, Fabrice

2011-03-01

To determine whether a sound-activated light-alarm device could reduce the noise in the central area of our pediatric intensive care unit and to determine whether this reduction was significant enough to decrease the noise that could be perceived by a patient located in a nearby room. The secondary objective was to determine the mode of action of the device. In a 16-bed pediatric and neonatal intensive care unit, a large and clearly noticeable sound-activated light device was set in the noisiest part of the central area of our unit, and noise measurements were made in the central area and in a nearby room. In a prospective, quasi-experimental design, sound levels were compared across three different situations--no device present, device present and turned on, and device present but turned off--and noise level measurements were made over a total of 18 days. None. Setting a sound-activated light device on or off. When the device was present, the noise was about 2 dB lower in the central area and in a nearby room, but there was no difference in noise level with the device turned on vs. turned off. The noise decrease in the central area was of limited importance but was translated in a nearby room. The sound-activated light device did not directly decrease noise when turned on, but repetition of the visual signal throughout the day raised staff awareness of noise levels over time.

Fiber Sensor Systems Based on Fiber Laser and Microwave Photonic Technologies

PubMed Central

Fu, Hongyan; Chen, Daru; Cai, Zhiping

2012-01-01

Fiber-optic sensors, especially fiber Bragg grating (FBG) sensors are very attractive due to their numerous advantages over traditional sensors, such as light weight, high sensitivity, cost-effectiveness, immunity to electromagnetic interference, ease of multiplexing and so on. Therefore, fiber-optic sensors have been intensively studied during the last several decades. Nowadays, with the development of novel fiber technology, more and more newly invented fiber technologies bring better and superior performance to fiber-optic sensing networks. In this paper, the applications of some advanced photonic technologies including fiber lasers and microwave photonic technologies for fiber sensing applications are reviewed. FBG interrogations based on several kinds of fiber lasers, especially the novel Fourier domain mode locking fiber laser, have been introduced; for the application of microwave photonic technology, examples of microwave photonic filtering utilized as a FBG sensing interrogator and microwave signal generation acting as a transversal loading sensor have been given. Both theoretical analysis and experimental demonstrations have been carried out. The comparison of these advanced photonic technologies for the applications of fiber sensing is carried out and important issues related to the applications have been addressed and the suitable and potential application examples have also been discussed in this paper. PMID:22778591

High-sensitivity refractive index sensor based on large-angle tilted fiber grating with carbon nanotube deposition

NASA Astrophysics Data System (ADS)

Badmos, Abdulyezir A.; Sun, Qizhen; Yan, Zhijun; Arif, Raz N.; Zhang, Junxi; Rozhin, Alex; Zhang, Lin

2016-04-01

This paper presents a highly sensitive ambient refractive index (RI) sensor based on 81° tilted fiber grating (81°-TFG) structure UV-inscribed in standard telecom fiber (62.5μm cladding radius) with carbon nanotube (CNT) overlay deposition. The sensing mechanism is based on the ability of CNT to induce change in transmitted optical power and the high sensitivity of 81°-TFG to ambient refractive index. The thin CNT film with high refractive index enhances the cladding modes of the TFG, resulting in the significant interaction between the propagating light and the surrounding medium. Consequently, the surrounding RI change will induce not only the resonant wavelength shift but also the power intensity change of the attenuation band in the transmission spectrum. Result shows that the change in transmitted optical power produces a corresponding linear reduction in intensity with increment in RI values. The sample shows high sensitivities of 207.38nm/RIU, 241.79nm/RIU at RI range 1.344-1.374 and 113.09nm/RIU, 144.40nm/RIU at RI range 1.374-1.392 (for X-pol and Y-pol respectively). It also shows power intensity sensitivity of 65.728dBm/RIU and 45.898 (for X-pol and Y-pol respectively). The low thermal sensitivity property of the 81°-TFG offers reduction in thermal cross-sensitivity and enhances specificity of the sensor.

Plasmonic improvement of microcavity biomedical sensor spectroscopic characteristics

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas; Ghadiri, Reza

2014-03-01

New opportunity to improve a sensetivity of a label-free biomolecule detection in sensing systems based on microcavity evanescent wave optical sensors has been recently found and is being under intensive development. Novel technique based on combination of optical resonance on microring structures with plasmon resonance. Recently developed tools based on neural network data processing can realize real-time identification of biological agents. So combining advantages of plasmon enhancing optical microcavity resonance with identification tools can give a new platform for ulta sensitive label-free biomedical sensor. Our developed technique used standard glass and polymer microspheres as sensetive elements. They are fixed in the solution flow by adhesive layer on the surface being in the field of evanescence wave. Sensitive layer have been treated by gold nanoparticel (GN) solution. Another technique used thin film gold layers deposited on the substrate below adhesive. The light from a tuneable diode laser is coupled into the microsphere through a prism and was sharply focussed on the single microsphere. Images were recorded by CMOS camera. Normalized by free spectral range resonance shift of whispering gallery mode (WGM) and a relative efficiency of their excitation were used as input data for biomolecule classification. Both biomolecules and NP injection was obtained caused WGM spectra modification. But after NP treatment spectral shift and intensity of WGM resonances in biomolecule solutions increased. WGM resonances in microspheres fixed on substrate with gold layer with optimized layer thickness in biomolecule solutions also had higher intensity and spectra modification then without gold layer.

Fast fingerprint database maintenance for indoor positioning based on UGV SLAM.

PubMed

Tang, Jian; Chen, Yuwei; Chen, Liang; Liu, Jingbin; Hyyppä, Juha; Kukko, Antero; Kaartinen, Harri; Hyyppä, Hannu; Chen, Ruizhi

2015-03-04

Indoor positioning technology has become more and more important in the last two decades. Utilizing Received Signal Strength Indicator (RSSI) fingerprints of Signals of OPportunity (SOP) is a promising alternative navigation solution. However, as the RSSIs vary during operation due to their physical nature and are easily affected by the environmental change, one challenge of the indoor fingerprinting method is maintaining the RSSI fingerprint database in a timely and effective manner. In this paper, a solution for rapidly updating the fingerprint database is presented, based on a self-developed Unmanned Ground Vehicles (UGV) platform NAVIS. Several SOP sensors were installed on NAVIS for collecting indoor fingerprint information, including a digital compass collecting magnetic field intensity, a light sensor collecting light intensity, and a smartphone which collects the access point number and RSSIs of the pre-installed WiFi network. The NAVIS platform generates a map of the indoor environment and collects the SOPs during processing of the mapping, and then the SOP fingerprint database is interpolated and updated in real time. Field tests were carried out to evaluate the effectiveness and efficiency of the proposed method. The results showed that the fingerprint databases can be quickly created and updated with a higher sampling frequency (5Hz) and denser reference points compared with traditional methods, and the indoor map can be generated without prior information. Moreover, environmental changes could also be detected quickly for fingerprint indoor positioning.

EUV focus sensor: design and modeling

NASA Astrophysics Data System (ADS)

Goldberg, Kenneth A.; Teyssier, Maureen E.; Liddle, J. Alexander

2005-05-01

We describe performance modeling and design optimization of a prototype EUV focus sensor (FS) designed for use with existing 0.3-NA EUV projection-lithography tools. At 0.3-NA and 13.5-nm wavelength, the depth of focus shrinks to 150 nm increasing the importance of high-sensitivity focal-plane detection tools. The FS is a free-standing Ni grating structure that works in concert with a simple mask pattern of regular lines and spaces at constant pitch. The FS pitch matches that of the image-plane aerial-image intensity: it transmits the light with high efficiency when the grating is aligned with the aerial image laterally and longitudinally. Using a single-element photodetector, to detect the transmitted flux, the FS is scanned laterally and longitudinally so the plane of peak aerial-image contrast can be found. The design under consideration has a fixed image-plane pitch of 80-nm, with aperture widths of 12-40-nm (1-3 wave-lengths), and aspect ratios of 2-8. TEMPEST-3D is used to model the light transmission. Careful attention is paid to the annular, partially coherent, unpolarized illumination and to the annular pupil of the Micro-Exposure Tool (MET) optics for which the FS is designed. The system design balances the opposing needs of high sensitivity and high throughput opti-mizing the signal-to-noise ratio in the measured intensity contrast.

EUV Focus Sensor: Design and Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldberg, Kenneth A.; Teyssier, Maureen E.; Liddle, J. Alexander

We describe performance modeling and design optimization of a prototype EUV focus sensor (FS) designed for use with existing 0.3-NA EUV projection-lithography tools. At 0.3-NA and 13.5-nm wavelength, the depth of focus shrinks to 150 nm increasing the importance of high-sensitivity focal-plane detection tools. The FS is a free-standing Ni grating structure that works in concert with a simple mask pattern of regular lines and spaces at constant pitch. The FS pitch matches that of the image-plane aerial-image intensity: it transmits the light with high efficiency when the grating is aligned with the aerial image laterally and longitudinally. Using amore » single-element photodetector, to detect the transmitted flux, the FS is scanned laterally and longitudinally so the plane of peak aerial-image contrast can be found. The design under consideration has a fixed image-plane pitch of 80-nm, with aperture widths of 12-40-nm (1-3 wavelengths), and aspect ratios of 2-8. TEMPEST-3D is used to model the light transmission. Careful attention is paid to the annular, partially coherent, unpolarized illumination and to the annular pupil of the Micro-Exposure Tool (MET) optics for which the FS is designed. The system design balances the opposing needs of high sensitivity and high throughput optimizing the signal-to-noise ratio in the measured intensity contrast.« less

Method and Apparatus for Characterizing Pressure Sensors using Modulated Light Beam Pressure

NASA Technical Reports Server (NTRS)

Youngquist, Robert C. (Inventor)

2003-01-01

Embodiments of apparatuses and methods are provided that use light sources instead of sound sources for characterizing and calibrating sensors for measuring small pressures to mitigate many of the problems with using sound sources. In one embodiment an apparatus has a light source for directing a beam of light on a sensing surface of a pressure sensor for exerting a force on the sensing surface. The pressure sensor generates an electrical signal indicative of the force exerted on the sensing surface. A modulator modulates the beam of light. A signal processor is electrically coupled to the pressure sensor for receiving the electrical signal.

Sensitivity of a fibre scattered-light interferometer to external phase perturbations in an optical fibre

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alekseev, A E; Potapov, V T; Gorshkov, B G

2015-10-31

Sensitivity of a fibre scattered-light interferometer to external phase perturbations is studied for the first time. An expression is derived for an average power of a useful signal at the interferometer output under external harmonic perturbations in a signal fibre of the interferometer. It is shown that the maximum sensitivity of the scattered-light interferometer depends on the dispersion of the interferogram intensity. An average signal-to-noise ratio is determined theoretically and experimentally at the output of the interferometer at different amplitudes of external perturbations. Using the measured dependences of the signal-to-noise ratio, the threshold sensitivity of the fibre scattered-light interferometer tomore » external phase perturbations is found. The results obtained can be used to optimise characteristics of optical time-domain reflectometers and to design individual phase-sensitive fibre-optic sensors. (laser applications and other topics in quantum electronics)« less

Turbine-blade tip clearance and tip timing measurements using an optical fiber bundle sensor

NASA Astrophysics Data System (ADS)

Garcia, Iker; Beloki, Josu; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon

2013-04-01

Traditional limitations of capacitive, inductive or discharging probe sensor for tip timing and tip clearance measurements are overcome by reflective intensity modulated optical fiber sensors. This paper presents the signals and results corresponding to a one stage turbine rig which rotor has 146 blades, obtained from a transonic wind-tunnel test. The probe is based on a trifurcated bundle of optical fibers that is mounted on turbine casing. It is composed of a central illuminating fiber that guides the light from a laser to the turbine blade, and two concentric rings of receiving fibers that collect the reflected light. Two photodetectors turn this reflected light signal from the receiving rings into voltage. The electrical signals are acquired and saved by a high-sample-rate oscilloscope. In tip clearance calculations the ratio of the signals provided by each ring of receiving fibers is evaluated and translated into distance. In the case of tip timing measurements, only one of the signals is considered to get the arrival time of the blade. The differences between the real and theoretical arrival times of the blades are used to obtain the deflections amplitude. The system provides the travelling wave spectrum, which presents the average vibration amplitude of the blades at a certain nodal diameter. The reliability of the results in the turbine rig testing facilities suggests the possibility of performing these measurements in real turbines under real working conditions.

Small Imaging Depth LIDAR and DCNN-Based Localization for Automated Guided Vehicle †

PubMed Central

Ito, Seigo; Hiratsuka, Shigeyoshi; Ohta, Mitsuhiko; Matsubara, Hiroyuki; Ogawa, Masaru

2018-01-01

We present our third prototype sensor and a localization method for Automated Guided Vehicles (AGVs), for which small imaging LIght Detection and Ranging (LIDAR) and fusion-based localization are fundamentally important. Our small imaging LIDAR, named the Single-Photon Avalanche Diode (SPAD) LIDAR, uses a time-of-flight method and SPAD arrays. A SPAD is a highly sensitive photodetector capable of detecting at the single-photon level, and the SPAD LIDAR has two SPAD arrays on the same chip for detection of laser light and environmental light. Therefore, the SPAD LIDAR simultaneously outputs range image data and monocular image data with the same coordinate system and does not require external calibration among outputs. As AGVs travel both indoors and outdoors with vibration, this calibration-less structure is particularly useful for AGV applications. We also introduce a fusion-based localization method, named SPAD DCNN, which uses the SPAD LIDAR and employs a Deep Convolutional Neural Network (DCNN). SPAD DCNN can fuse the outputs of the SPAD LIDAR: range image data, monocular image data and peak intensity image data. The SPAD DCNN has two outputs: the regression result of the position of the SPAD LIDAR and the classification result of the existence of a target to be approached. Our third prototype sensor and the localization method are evaluated in an indoor environment by assuming various AGV trajectories. The results show that the sensor and localization method improve the localization accuracy. PMID:29320434

Small Imaging Depth LIDAR and DCNN-Based Localization for Automated Guided Vehicle.

PubMed

Ito, Seigo; Hiratsuka, Shigeyoshi; Ohta, Mitsuhiko; Matsubara, Hiroyuki; Ogawa, Masaru

2018-01-10

We present our third prototype sensor and a localization method for Automated Guided Vehicles (AGVs), for which small imaging LIght Detection and Ranging (LIDAR) and fusion-based localization are fundamentally important. Our small imaging LIDAR, named the Single-Photon Avalanche Diode (SPAD) LIDAR, uses a time-of-flight method and SPAD arrays. A SPAD is a highly sensitive photodetector capable of detecting at the single-photon level, and the SPAD LIDAR has two SPAD arrays on the same chip for detection of laser light and environmental light. Therefore, the SPAD LIDAR simultaneously outputs range image data and monocular image data with the same coordinate system and does not require external calibration among outputs. As AGVs travel both indoors and outdoors with vibration, this calibration-less structure is particularly useful for AGV applications. We also introduce a fusion-based localization method, named SPAD DCNN, which uses the SPAD LIDAR and employs a Deep Convolutional Neural Network (DCNN). SPAD DCNN can fuse the outputs of the SPAD LIDAR: range image data, monocular image data and peak intensity image data. The SPAD DCNN has two outputs: the regression result of the position of the SPAD LIDAR and the classification result of the existence of a target to be approached. Our third prototype sensor and the localization method are evaluated in an indoor environment by assuming various AGV trajectories. The results show that the sensor and localization method improve the localization accuracy.

Finding the Acceleration and Speed of a Light-Emitting Object on an Inclined Plane with a Smartphone Light Sensor

ERIC Educational Resources Information Center

Kapucu, Serkan

2017-01-01

This study investigates how the acceleration and speed of a light-emitting object on an inclined plane may be determined using a smartphone's light sensor. A light-emitting object was released from the top of an inclined plane and its illuminance values were detected by a smartphone's light sensor during its subsequent motion down the plane. Using…

Quantifying light exposure patterns in young adult students

NASA Astrophysics Data System (ADS)

Alvarez, Amanda A.; Wildsoet, Christine F.

2013-08-01

Exposure to bright light appears to be protective against myopia in both animals (chicks, monkeys) and children, but quantitative data on human light exposure are limited. In this study, we report on a technique for quantifying light exposure using wearable sensors. Twenty-seven young adult subjects wore a light sensor continuously for two weeks during one of three seasons, and also completed questionnaires about their visual activities. Light data were analyzed with respect to refractive error and season, and the objective sensor data were compared with subjects' estimates of time spent indoors and outdoors. Subjects' estimates of time spent indoors and outdoors were in poor agreement with durations reported by the sensor data. The results of questionnaire-based studies of light exposure should thus be interpreted with caution. The role of light in refractive error development should be investigated using multiple methods such as sensors to complement questionnaires.

Quantifying light exposure patterns in young adult students

PubMed Central

Alvarez, Amanda A.; Wildsoet, Christine F.

2014-01-01

Exposure to bright light appears to be protective against myopia in both animals (chicks, monkeys) and children, but quantitative data on human light exposure are limited. In this study, we report on a technique for quantifying light exposure using wearable sensors. Twenty-seven young adult subjects wore a light sensor continuously for two weeks during one of three seasons, and also completed questionnaires about their visual activities. Light data were analyzed with respect to refractive error and season, and the objective sensor data were compared with subjects’ estimates of time spent indoors and outdoors. Subjects’ estimates of time spent indoors and outdoors were in poor agreement with durations reported by the sensor data. The results of questionnaire-based studies of light exposure should thus be interpreted with caution. The role of light in refractive error development should be investigated using multiple methods such as sensors to complement questionnaires. PMID:25342873

The Design of Optical Sensor for the Pinhole/Occulter Facility

NASA Technical Reports Server (NTRS)

Greene, Michael E.

1990-01-01

Three optical sight sensor systems were designed, built and tested. Two optical lines of sight sensor system are capable of measuring the absolute pointing angle to the sun. The system is for use with the Pinhole/Occulter Facility (P/OF), a solar hard x ray experiment to be flown from Space Shuttle or Space Station. The sensor consists of a pinhole camera with two pairs of perpendicularly mounted linear photodiode arrays to detect the intensity distribution of the solar image produced by the pinhole, track and hold circuitry for data reduction, an analog to digital converter, and a microcomputer. The deflection of the image center is calculated from these data using an approximation for the solar image. A second system consists of a pinhole camera with a pair of perpendicularly mounted linear photodiode arrays, amplification circuitry, threshold detection circuitry, and a microcomputer board. The deflection of the image is calculated by knowing the position of each pixel of the photodiode array and merely counting the pixel numbers until threshold is surpassed. A third optical sensor system is capable of measuring the internal vibration of the P/OF between the mask and base. The system consists of a white light source, a mirror and a pair of perpendicularly mounted linear photodiode arrays to detect the intensity distribution of the solar image produced by the mirror, amplification circuitry, threshold detection circuitry, and a microcomputer board. The deflection of the image and hence the vibration of the structure is calculated by knowing the position of each pixel of the photodiode array and merely counting the pixel numbers until threshold is surpassed.

Radiotherapy-induced Cherenkov luminescence imaging in a human body phantom.

PubMed

Ahmed, Syed Rakin; Jia, Jeremy Mengyu; Bruza, Petr; Vinogradov, Sergei; Jiang, Shudong; Gladstone, David J; Jarvis, Lesley A; Pogue, Brian W

2018-03-01

Radiation therapy produces Cherenkov optical emission in tissue, and this light can be utilized to activate molecular probes. The feasibility of sensing luminescence from a tissue molecular oxygen sensor from within a human body phantom was examined using the geometry of the axillary lymph node region. Detection of regions down to 30-mm deep was feasible with submillimeter spatial resolution with the total quantity of the phosphorescent sensor PtG4 near 1 nanomole. Radiation sheet scanning in an epi-illumination geometry provided optimal coverage, and maximum intensity projection images provided illustration of the concept. This work provides the preliminary information needed to attempt this type of imaging in vivo. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

An automatic analyzer of solid state nuclear track detectors using an optic RAM as image sensor

NASA Astrophysics Data System (ADS)

Staderini, Enrico Maria; Castellano, Alfredo

1986-02-01

An optic RAM is a conventional digital random access read/write dynamic memory device featuring a quartz windowed package and memory cells regularly ordered on the chip. Such a device is used as an image sensor because each cell retains data stored in it for a time depending on the intensity of the light incident on the cell itself. The authors have developed a system which uses an optic RAM to acquire and digitize images from electrochemically etched CR39 solid state nuclear track detectors (SSNTD) in the track count rate up to 5000 cm -2. On the digital image so obtained, a microprocessor, with appropriate software, performs image analysis, filtering, tracks counting and evaluation.

All-optical phase modulation for integrated interferometric biosensors.

PubMed

Dante, Stefania; Duval, Daphné; Sepúlveda, Borja; González-Guerrero, Ana Belen; Sendra, José Ramón; Lechuga, Laura M

2012-03-26

We present the theoretical and the experimental implementation of an all-optical phase modulation system in integrated Mach-Zehnder Interferometers to solve the drawbacks related to the periodic nature of the interferometric signal. Sensor phase is tuned by modulating the emission wavelength of low-cost commercial laser diodes by changing their output power. FFT deconvolution of the signal allows for direct phase readout, immune to sensitivity variations and to light intensity fluctuations. This simple phase modulation scheme increases the signal-to-noise ratio of the measurements in one order of magnitude, rendering in a sensor with a detection limit of 1.9·10⁻⁷ RIU. The viability of the all-optical modulation approach is demonstrated with an immunoassay detection as a biosensing proof of concept.

Calculating the Areas of Polygons with a Smartphone Light Sensor

ERIC Educational Resources Information Center

Kapucu, Serkan; Simsek, Mertkan; Öçal, Mehmet Fatih

2017-01-01

This study explores finding the areas of polygons with a smartphone light sensor. A square and an irregular pentagon were chosen as our polygons. During the activity, the LED light was placed at the vertices of our polygons, and the illuminance values of this LED light were detected by the smartphone light sensor. The smartphone was placed on a…

Development of optical fiber Bragg grating force-reflection sensor system of medical application for safe minimally invasive robotic surgery

NASA Astrophysics Data System (ADS)

Song, Hoseok; Kim, Kiyoung; Lee, Jungju

2011-07-01

Force feedback plays a very important role in medical surgery. In minimally invasive surgery (MIS), however, the very long and stiff bars of surgical instruments greatly diminish force feedback for the surgeon. In the case of minimally invasive robotic surgery (MIRS), force feedback is totally eliminated. Previous researchers have reported that the absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peak force magnitude by at least a factor of two. Therefore, it is very important to provide force information in MIRS. Recently, many sensors are being developed for MIS and MIRS, but some obstacles to their application in actual medical surgery must be surmounted. The most critical problems are size limit and sterilizability. Optical fiber sensors are among the most suitable sensors for the surgical environment. The optical fiber Bragg grating (FBG) sensor, in particular, offers an important additional advantage over other optical fiber sensors in that it is not influenced by the intensity of the light source. In this paper, we present the initial results of a study on the application of a FBG sensor to measure reflected forces in MIRS environments and suggest the possibility of successful application to MIRS systems.

A new intelligent curtain control system based on 51 single chip microcomputer

NASA Astrophysics Data System (ADS)

Sun, Tuan; Wang, Yanhua; Wu, Mengmeng

2017-04-01

This paper uses 51 (single chip microcomputer) SCM as the operation and data processing center. According to the change of sunshine intensity and ambient temperature, a new type of intelligent curtain control system is designed by adopting photosensitive element and temperature sensor. In addition, the design also has a manual control mode. In the rain, when the light intensity is weak, the open position of the curtain can be set by the user. The system can maximize the user to provide user-friendly operation and comfortable living environment. The system can be applied to home or office environment, with a wide range of applications and simple operation and so on.

Towards field detection of polycyclic aromatic hydrocarbons (PAHs) in environment water using a self-assembled SERS sensor

NASA Astrophysics Data System (ADS)

Yan, Xia; Shi, Xiaofeng; Yang, Jie; Zhang, Xu; Jia, Wenjie; Ma, Jun

2017-10-01

A self-assembled surface enhanced Raman scattering (SERS) sensor is reported in this paper. To achieve high sensitivity, a high sensitive SERS substrate and a high efficient self-constructed light path were made. The SERS substrate was composed by gold nanoparticles (AuNPs, pH=13), glycidyl methacrylate-ethylene dimethacrylate (GMA-EDMA) porous material and syringe filter. The substrate had a good repeatability, and the relative standard deviation (RSD) of the same substrate was less than 5%. The efficiency of the self-constructed light path is about two times better than RPB Y type reflection fiber when the energy density was roughly equal on samples. The size of the SERS sensor is 350×300×180 mm and the weight is 15 kg. Its miniaturization and portable can comply with the requirements of field detection. Besides, it has good sensitivity, stability and selectivity. For lab experiments, strong enhancements of Raman scattering from organic pollutant polycyclic aromatic hydrocarbons (PAHs) molecules were exhibited. The dependences of SERS intensities on concentrations of PAHs were investigated, and the results indicated that they revealed a satisfactory linear relationship in low concentrations. The limits of detection (LODs) of PAHs phenanthrene and fluorene are 8.3×10-10 mol/L and 7.1×10-10 mol/L respectively [signal to noise ratio (S/N) =3]. Based on this SERS sensor, signals of benzo (a) pyrene and pyrene were found in environmental water and the sensor would be an ideal candidate for field detection of PAHs.

Prevention of the adverse photic effects of peripheral light-focusing using UV-blocking contact lenses.

PubMed

Kwok, L Stephen; Kuznetsov, Valerian A; Ho, Arthur; Coroneo, Minas T

2003-04-01

Peripheral light-focusing (PLF) is an occult form of ultraviolet radiation (UVR) hazardous to the human eye. In PLF, obliquely incident light is refracted from the peripheral cornea to concentrated sites inside the anterior segment. In the current study, the directionality of this phenomenon for UVR and whether PLF is established in outdoor settings exposed to sunlight were investigated. The protection provided by a UV-blocking contact lens was also evaluated. UVA and UVB sensors were placed on the nasal limbus of an anatomically based model eye. The temporal limbus was exposed to a UV light source placed at various angles behind the frontal plane. PLF was quantified with the sensor output. The ensemble was mounted in the orbit of a mannequin head and exposed to sunlight in three insolation environments within the region of Sydney, Australia. PLF for UVA and UVB was determined with no eyewear or with sunglasses and commercially available soft contact lenses, with and without UV-blocking capability. The intensity of UVA peaked at approximately 120 degrees incidence, the level at which the UVB response was also at its maximum. The intensification of UVA was up to x18.3. The intensity of PLF for UVA and UVB was reduced by an order of magnitude by a UV-blocking contact lens, whereas a clear contact lenses had a much lesser effect. Only the UV-blocking contact lens achieved a significant effect on UVA and UVB irradiance in the urban, beach, and mountain locales (P < 0.056). The results identify another type of sunlight hazard: the peripheral focusing of obliquely incident light. UVR from albedo (reflected ambient light) is capable of establishing PLF in the anterior segment, but this can be shielded by UV-blocking soft contact lenses. Sunglasses may be unable to shield oblique rays, unless side protection is incorporated. Contact lenses can offer UVR protection against all angles of incidence, including the peak-response angle. They can also protect the eye in settings in which the wearing of sunglasses is not feasible or convenient.

ZnO nanoparticles based fiber optic gas sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narasimman, S.; Sivacoumar, R.; Alex, Z. C.

In this work, ZnO nanoparticles were synthesized by simple aqueous chemical route method. The synthesized ZnO nanoparticles were characterized by X-ray diffraction and scanning electron microscope. The sensitivity of the nanoparticles was studied for different gases like acetone, ammonia and ethanol in terms of variation in spectral light intensity. The XRD and SEM analysis confirms the formation of hexagonal wurtzite structure with the grain size of 11.2 nm. The small cladding region of the optical fiber was replaced with the synthesized nanoparticles. The light spectrum was recorded for different gas concentrations. The synthesized nanoparticles showed high sensitivity towards ammonia in lowmore » ppm level and acetone in high ppm level.« less

Shear-induced surface alignment of polymer dispersed liquid crystal microdroplets on the boundary layer

NASA Technical Reports Server (NTRS)

Parmar, D. S.; Singh, J. J.

1993-01-01

Polymer dispersed liquid crystal thin films have been deposited on a glass substrate, utilizing the processes of polymerization and solvent evaporation induced phase separation. Liquid crystal microdroplets trapped on the upper surface of the thin film respond to the shear stress due to air or gas flow on the surface layer. Response to an applied step shear stress input on the surface layer has been measured by measuring the time response of the transmitted light intensity. Initial results on the measurements of the light transmission as a function of the air flow differential pressure indicate that these systems offer features suitable for boundary layer and gas flow sensors.

Characterization of an Optical Device with an Array of Blue Light Emitting Diodes LEDS for Treatment of Neonatal Jaundice.

NASA Astrophysics Data System (ADS)

Sebbe, Priscilla Fróes; Villaverde, Antonio G. J. Balbin; Nicolau, Renata Amadei; Barbosa, Ana Maria; Veissid, Nelson

2008-04-01

Phototherapy is a treatment that consists in irradiating a patient with light of high intensity, which promotes beneficial photochemical transformations in the irradiated area. The phototherapy for neonates is applied to break down the bilirubin, an organic pigment that is a sub product of the erythrocytes degradation, and to increase its excretion by the organism. Neonates should be irradiated with light of wavelength that the bilirubin can absorb, and with spectral irradiances between 4 and 16 μW/cm2/nm. The efficiency of the treatment depends on the irradiance and the area of the body that is irradiated. A convenient source of light for treatment of neonatal jaundice is the blue Light Emitter Diode (LED), emitting in the range of 400 to 500 nm, with power of the order of 10-150 mW. Some of the advantages for using LEDS are: low cost, operating long lifetime (over 100,000 hours), narrow emission linewith, low voltage power supply requirement and low heating. The aim of this work was to build and characterize a device for phototherapy treatment of neonatal jaundice. This consists of a blanket with 88 blue LEDs (emission peak at 472 nm), arranged in an 8×11 matrix, all connected in parallel and powered by a 5V-2A power supply. The device was characterized by using a spectroradiometer USB2000 (Ocean Optics Inc, USA), with a sensitivity range of 339-1019 nm. For determination of light spatial uniformity was used a calibrated photovoltaic sensor for measuring light intensity and mapping of the light intensity spatial distribution. Results indicate that our device shows a uniform spatial distribution for distances from the blanket larger than 10 cm, with a maximum of irradiance at such a distance. This device presenting a large and uniform area of irradiation, efficient wavelength emission and high irradiance seems to be promising for neonates' phototherapy treatment.

Thumb-actuated two-axis controller

NASA Technical Reports Server (NTRS)

Hollow, R. H. (Inventor)

1986-01-01

A two axis joystick controller is described. It produces at least one output signal in relation to pivotal displacement of a member with respect to an intersection of the two axes. The member is pivotally movable on a support with respect to the two axes. The support has a centrally disposed aperture. A light source is mounted on the pivotally movable member above the aperture to direct light through the aperture. A light sensor is mounted below the aperture in the support at the intersection of the two axes to receive the light from the light source directed through the aperture. The light sensor produces at least one output signal related to a location on the sensor at which the light from the light source strikes the sensor.

LED Context Lighting System in Residential Areas

PubMed Central

Im, Kyoung-Mi

2014-01-01

As issues of environment and energy draw keen interest around the globe due to such problems as global warming and the energy crisis, LED with high optical efficiency is brought to the fore as the next generation lighting. In addition, as the national income level gets higher and life expectancy is extended, interest in the enhancement of life quality is increasing. Accordingly, the trend of lightings is changing from mere adjustment of light intensity to system lighting in order to enhance the quality of one's life as well as reduce energy consumption. Thus, this study aims to design LED context lighting system that automatically recognizes the location and acts of a user in residential areas and creates an appropriate lighting environment. The proposed system designed in this study includes three types of processing: first, the creation of a lighting environment index suitable for the user's surroundings and lighting control scenarios and second, it measures and analyzes the optical characteristics that change depending on the dimming control of lighting and applies them to the index. Lastly, it adopts PIR, piezoelectric, and power sensor to grasp the location and acts of the user and create a lighting environment suitable for the current context. PMID:25101325

Wing Scale Orientation Alters Reflection Directions in the Green Hairstreak Chrysozephyrus smaragdinus (Lycaenidae; Lepidoptera).

PubMed

Imafuku, Michio; Ogihara, Naomichi

2016-12-01

There have been only a few reports on the directional reflection of light by butterfly wings. Here, we systematically investigated this phenomenon in a lycaenid butterfly, Chrysozephyrus smaragdinus,in which males have bright green wings based on structural coloration. We used a device that measures intensities of light in hemispherical space by vertical shifting of a sensor and horizontal rotation of the stage carrying the wing, which is illuminated from the top, to determine the direction of light reflected by the fore- and hindwings. The orientation and curvature of wing scales were also examined microscopically. The forewing of this species reflected light shone from the top largely forward, whereas the hindwing reflected it slightly forward. This difference was attributed to the tilt angles of the wing scales. Light reflection by the forewing was relatively weak, and widely scattered, whereas that by the hindwing was rather concentrated, resulting in higher reflectance. This difference was attributed to difference in the curvature of the wing scales on the two wings.

Parallel detecting, spectroscopic ellipsometers/polarimeters

DOEpatents

Furtak, Thomas E.

2002-01-01

The parallel detecting spectroscopic ellipsometer/polarimeter sensor has no moving parts and operates in real-time for in-situ monitoring of the thin film surface properties of a sample within a processing chamber. It includes a multi-spectral source of radiation for producing a collimated beam of radiation directed towards the surface of the sample through a polarizer. The thus polarized collimated beam of radiation impacts and is reflected from the surface of the sample, thereby changing its polarization state due to the intrinsic material properties of the sample. The light reflected from the sample is separated into four separate polarized filtered beams, each having individual spectral intensities. Data about said four individual spectral intensities is collected within the processing chamber, and is transmitted into one or more spectrometers. The data of all four individual spectral intensities is then analyzed using transformation algorithms, in real-time.

Theoretical analysis of metamaterial-gold auxiliary grating sensing structure for surface plasmon resonance sensing application based on polarization control method

NASA Astrophysics Data System (ADS)

Sun, Yi; Cai, Haoyuan; Wang, Xiaoping

2017-12-01

A metamaterial-gold multilayer sensing structure designed using the particle swarm optimization (PSO) algorithm with an auxiliary grating is proposed for using in a surface plasmon resonance (SPR) sensor system based on the polarization control method. After numerical calculations and simulation analysis, it was found that the metamaterial sensing structure significantly improves the sensitivity of the SPR signal with intensity singularity. The metamaterial sensing structure also increases the penetration depth of evanescent wave, making it possible to detect low-molecular-weight biomolecules and larger cells such as bacteria. The auxiliary grating structure was designed to identify the refractive index of the sensing region on both sides of intensity singularity. The stability of recognition and the electric field intensity of the visible light band were also studied.

Optical penetration sensor for pulsed laser welding

DOEpatents

Essien, Marcelino; Keicher, David M.; Schlienger, M. Eric; Jellison, James L.

2000-01-01

An apparatus and method for determining the penetration of the weld pool created from pulsed laser welding and more particularly to an apparatus and method of utilizing an optical technique to monitor the weld vaporization plume velocity to determine the depth of penetration. A light source directs a beam through a vaporization plume above a weld pool, wherein the plume changes the intensity of the beam, allowing determination of the velocity of the plume. From the velocity of the plume, the depth of the weld is determined.

Design of embedded intelligent monitoring system based on face recognition

NASA Astrophysics Data System (ADS)

Liang, Weidong; Ding, Yan; Zhao, Liangjin; Li, Jia; Hu, Xuemei

2017-01-01

In this paper, a new embedded intelligent monitoring system based on face recognition is proposed. The system uses Pi Raspberry as the central processor. A sensors group has been designed with Zigbee module in order to assist the system to work better and the two alarm modes have been proposed using the Internet and 3G modem. The experimental results show that the system can work under various light intensities to recognize human face and send alarm information in real time.

Jammed-array wideband sawtooth filter.

PubMed

Tan, Zhongwei; Wang, Chao; Goda, Keisuke; Malik, Omer; Jalali, Bahram

2011-11-21

We present an all-optical passive low-cost spectral filter that exhibits a high-resolution periodic sawtooth spectral pattern without the need for active optoelectronic components. The principle of the filter is the partial masking of a phased array of virtual light sources with multiply jammed diffraction orders. We utilize the filter's periodic linear map between frequency and intensity to demonstrate fast sensitive interrogation of fiber Bragg grating sensor arrays and ultrahigh-frequency electrical sawtooth waveform generation. © 2011 Optical Society of America

[Optic method of searching for acupuncture points and channels].

PubMed

Gertsik, G Ia; Zmievskoĭ, G N; Ivantsov, V I; Sang Min Li; Iu Byiung Kim; Gil Von Iun

2001-01-01

A procedure is proposed to search for acupuncture points and channels (APC) by space-sensitive recording of optical radiation diffusely reflected by surface (dermal and hypodermal) tissues of the body. For this purpose, the body surface is probed by low-intensity infrared radiation from a laser or noncoherent (light-emitting diodes) source by using a fiber-optic multichannel sensor. It is shown that it is most advisable to apply sources at wavelengths of 840-850 and 1260-1300 nm.

Using Accelerometers to Measure Physical Activity in Large-Scale Epidemiologic Studies: Issues and Challenges

PubMed Central

Lee, I-Min; Shiroma, Eric J

2013-01-01

Background Current guidelines for aerobic activity require that adults carry out ≥150 minutes/week of moderate-intensity physical activity, with a large body of epidemiologic evidence showing this level of activity to decrease the incidence of many chronic diseases. Less is known about whether light-intensity activities also have such benefits, and whether sedentary behavior is an independent predictor of increased risks of these chronic diseases, as imprecise assessments of these behaviours and cross-sectional study designs have limited knowledge to date. Methods Recent technological advances in assessment methods have made the use of movement sensors, such as the accelerometer, feasible for use in longitudinal, large-scale epidemiologic studies. Several such studies are collecting sensor-assessed, objective measures of physical activity with the aim of relating these to the development of clinical endpoints. This is a relatively new area of research; thus, in this paper, we use the Women’s Health Study (WHS) as a case study to illustrate challenges related to data collection, data processing, and analyses of the vast amount of data collected. Results The WHS plans to collect 7 days of accelerometer-assessed physical activity and sedentary behavior in ~18,000 women aged ≥62 years. Several logistical challenges exist in collecting data; nonetheless as of 31 August 2013, 11,590 women have already provided some data. Additionally, the WHS experience on data reduction and data analyses can help inform other similar large-scale epidemiologic studies. Conclusions Important data on the health effects of light-intensity activity and sedentary behaviour will emerge from large-scale epidemiologic studies collecting objective assessments of these behaviours. PMID:24297837

Multiple resonant absorber with prism-incorporated graphene and one-dimensional photonic crystals in the visible and near-infrared spectral range

NASA Astrophysics Data System (ADS)

Zou, X. J.; Zheng, G. G.; Chen, Y. Y.; Xu, L. H.; Lai, M.

2018-04-01

A multi-band absorber constructed from prism-incorporated one-dimensional photonic crystal (1D-PhC) containing graphene defects is achieved theoretically in the visible and near-infrared (vis-NIR) spectral range. By means of the transfer matrix method (TMM), the effect of structural parameters on the optical response of the structure has been investigated. It is possible to achieve multi-peak and complete optical absorption. The simulations reveal that the light intensity is enhanced at the graphene plane, and the resonant wavelength and the absorption intensity can also be tuned by tilting the incidence angle of the impinging light. In particular, multiple graphene sheets are embedded in the arrays, without any demand of manufacture process to cut them into periodic patterns. The proposed concept can be extended to other two-dimensional (2D) materials and engineered for promising applications, including selective or multiplex filters, multiple channel sensors, and photodetectors.

Finding the Average Speed of a Light-Emitting Toy Car with a Smartphone Light Sensor

ERIC Educational Resources Information Center

Kapucu, Serkan

2017-01-01

This study aims to demonstrate how the average speed of a light-emitting toy car may be determined using a smartphone's light sensor. The freely available Android smartphone application, "AndroSensor," was used for the experiment. The classroom experiment combines complementary physics knowledge of optics and kinematics to find the…

Double NIR laser stimulation and enhancing the thermal sensitivity of Er3+/Tm3+/Nd3+ doped multilayer core-shell nanoparticles.

PubMed

Ba, Zhaojing; Hu, Min; Zhao, Yiming; Wang, Yiqing; Wang, Jing; Zhang, Zhenxi

2018-08-31

Non-contact thermal sensors are important devices to study cellular processes and monitor temperature in vivo. Herein, a novel highly sensitive nanothermometer based on NaYF 4 :Yb,Er@ NaYF 4 @NaYF 4 :Yb,Tm@ NaYF 4 :Nd (denoted as Er@Y@Tm@Nd) was prepared by a facile solvothermal method. When excited by the near-infrared (NIR) light of 808 and 980 nm, the as-prepared Er@Y@Tm@Nd nanoparticles could emit both blue and green light, respectively, since the lanthanide cations responsible for these emissions are gathered inside this nanostructure. The green and blue light intensity ratio exhibits obvious temperature dependence in the range of the physiological temperature. Additionally, the fluorescence intensity of Er 3+ and Tm 3+ are also greatly enhanced due to the multilayer structure that implies avoiding the Er 3+ and Tm 3+ energy cross-relaxation by introduction of a NaYF 4 wall between them. The as-prepared core-shell-shell-shell structure with Er 3+ and Tm 3+ in different layers improves dozens of times of the thermal sensitivity based on the non-thermal coupling levels of the probe: the maximum values for the sensitivity are 2.95% K -1 (I Er-521 /I Tm-450 ) and 6.30% K -1 (I Tm-474 /I Er-541 ) when excited by 980 and 808 nm laser sources, respectively. These values are well above those previously reported (<0.7% K -1 ), indicating that the prepared nanostructures are temperature sensors with excellent thermal sensitivity and sensitive to NIR wavelength excitation that makes them highly preferred for thermal detection.

An ultrasensitive photoelectrochemical immunosensor for insulin detection based on BiOBr/Ag2S composite by in-situ growth method with high visible-light activity.

PubMed

Fan, Dawei; Wang, Haoyuan; Khan, Malik Saddam; Bao, Chunzhu; Wang, Huan; Wu, Dan; Wei, Qin; Du, Bin

2017-11-15

A novel ultrasensitive label-free immunosensor based on BiOBr/Ag 2 S composite with high visible-light photoelectrochemical activity was prepared for the detection of insulin. After BiOBr was modified by thioglycolic acid, Ag 2 S nanoparticles were grown in-situ on the surface of BiOBr hierarchical microspheres to first form novel BiOBr/Ag 2 S composite. When ascorbic acid (AA) was used as an efficient electron donor for scavenging photo-generated holes, BiOBr/Ag 2 S composite material showed excellent photoelectrochemical activity. In order to immobilize insulin antibody, adhesive polydopamine (PDA) film formed by self-polymerization of dopamine was fabricated onto BiOBr/Ag 2 S modified electrode. Moreover, PDA film could further enhance the visible light absorption of BiOBr/Ag 2 S. When the solutions of 0.08molL -1 AgNO 3 and 0.1molL -1 AA were selected respectively during fabrication and detection process of this sensor, the best photocurrent singles were obtained. Under the optimum experimental condition, the specific binding between insulin and antibody resulted in a decrease in photocurrent intensity and the intensity decreased linearly with the logarithm of insulin concentration in the range of 0.001-20ngmL -1 with a detection limit of 0.2pgmL -1 . The photoelectrochemical sensor ITO/BiOBr/Ag 2 S/PDA/anti-Insulin/BSA/Insulin revealed facile preparation, high sensitivity, and acceptable reproducibility, which may have practical applications in the biosensor, clinical diagnosis of cancers, photocatalysis, and other related fields. Copyright © 2017 Elsevier B.V. All rights reserved.

Estimation of Rain Intensity Spectra over the Continental US Using Ground Radar-Gauge Measurements

NASA Technical Reports Server (NTRS)

Lin, Xin; Hou, Arthur Y.

2013-01-01

A high-resolution surface rainfall product is used to estimate rain characteristics over the continental US as a function of rain intensity. By defining each data at 4-km horizontal resolutions and 1-h temporal resolutions as an individual precipitating/nonprecipitating sample, statistics of rain occurrence and rain volume including their geographical and seasonal variations are documented. Quantitative estimations are also conducted to evaluate the impact of missing light rain events due to satellite sensors' detection capabilities. It is found that statistics of rain characteristics have large seasonal and geographical variations across the continental US. Although heavy rain events (> 10 mm/hr.) only occupy 2.6% of total rain occurrence, they may contribute to 27% of total rain volume. Light rain events (< 1.0 mm/hr.), occurring much more frequently (65%) than heavy rain events, can also make important contributions (15%) to the total rain volume. For minimum detectable rain rates setting at 0.5 and 0.2 mm/hr which are close to sensitivities of the current and future space-borne precipitation radars, there are about 43% and 11% of total rain occurrence below these thresholds, and they respectively represent 7% and 0.8% of total rain volume. For passive microwave sensors with their rain pixel sizes ranging from 14 to 16 km and the minimum detectable rain rates around 1 mm/hr., the missed light rain events may account for 70% of train occurrence and 16% of rain volume. Statistics of rain characteristics are also examined on domains with different temporal and spatial resolutions. Current issues in estimates of rain characteristics from satellite measurements and model outputs are discussed.

A label-free fiber-optic Turbidity Affinity Sensor (TAS) for continuous glucose monitoring.

PubMed

Dutt-Ballerstadt, Ralph; Evans, Colton; Pillai, Arun P; Gowda, Ashok

2014-11-15

In this paper, we describe the concept of a novel implantable fiber-optic Turbidity Affinity Sensor (TAS) and report on the findings of its in-vitro performance for continuous glucose monitoring. The sensing mechanism of the TAS is based on glucose-specific changes in light scattering (turbidity) of a hydrogel suspension consisting of small particles made of crosslinked dextran (Sephadex G100), and a glucose- and mannose-specific binding protein - Concanavalin A (ConA). The binding of ConA to Sephadex particles results in a significant turbidity increase that is much greater than the turbidity contribution by the individual components. The turbidity of the TAS was measured by determining the intensity of light passing through the suspension enclosed within a small semi-permeable hollow fiber (OD: 220 μm, membrane thickness: 20 μm, molecular weight cut-off: 10 kDa) using fiber optics. The intensity of measured light of the TAS was proportional to the glucose concentration over the concentration range from 50mg/dL to 400mg/dL in PBS and whole blood at 37°C (R>0.96). The response time was approximately 4 min. The stability of the glucose response of the TAS decreased only slightly (by 20%) over an 8-day study period at 37°C. In conclusion, this study demonstrated proof-of-concept of the TAS for interstitial glucose monitoring. Due to the large signal amplitude of the turbidity change, and the lack of need for wavelength-specific emission and excitation filters, a very small, robust and compact TAS device with an extremely short optical pathlength could be feasibly designed and implemented for in-vivo glucose monitoring in people with diabetes. Copyright © 2014 Elsevier B.V. All rights reserved.

One dimensional wavefront distortion sensor comprising a lens array system

DOEpatents

Neal, Daniel R.; Michie, Robert B.

1996-01-01

A 1-dimensional sensor for measuring wavefront distortion of a light beam as a function of time and spatial position includes a lens system which incorporates a linear array of lenses, and a detector system which incorporates a linear array of light detectors positioned from the lens system so that light passing through any of the lenses is focused on at least one of the light detectors. The 1-dimensional sensor determines the slope of the wavefront by location of the detectors illuminated by the light. The 1 dimensional sensor has much greater bandwidth that 2 dimensional systems.

One dimensional wavefront distortion sensor comprising a lens array system

DOEpatents

Neal, D.R.; Michie, R.B.

1996-02-20

A 1-dimensional sensor for measuring wavefront distortion of a light beam as a function of time and spatial position includes a lens system which incorporates a linear array of lenses, and a detector system which incorporates a linear array of light detectors positioned from the lens system so that light passing through any of the lenses is focused on at least one of the light detectors. The 1-dimensional sensor determines the slope of the wavefront by location of the detectors illuminated by the light. The 1 dimensional sensor has much greater bandwidth that 2 dimensional systems. 8 figs.

CdSe/ZnS quantum dots conjugated with a fluorescein derivative: a FRET-based pH sensor for physiological alkaline conditions.

PubMed

Kurabayashi, Tomokazu; Funaki, Nayuta; Fukuda, Takeshi; Akiyama, Shinnosuke; Suzuki, Miho

2014-01-01

Dual pH-dependent fluorescence peaks from a semiconductor quantum dot (QD) and a pH-dependent fluorescent dye can be measured by irradiating with a single wavelength light, and the pH can be estimated from the ratio of the fluorescent intensity of the two peaks. In this work, ratiometric pH sensing was achieved in an aqueous environment by a fluorescent CdSe/ZnS QD appended with a pH-sensitive organic dye, based on fluorescence resonance energy transfer (FRET). By functionalizing the CdSe/ZnS QD with 5-(and 6)-carboxynaphthofluorescein succinimidyl ester as a pH-dependent fluorescent dye, we succeeded in fabricating sensitive nanocomplexes with a linear response to a broad range of physiological pH levels (7.5-9.5) when excited at 450 nm. We found that a purification process is important for increasing the high-fluorescence intensity ratio of a ratiometric fluorescence pH-sensor, and the fluorescence intensity ratio was improved up to 1.0 at pH 8.0 after the purification process to remove unreacted CdSe/ZnS QDs even though the fluorescence of the dye could not be observed without the purification process. The fluorescence intensity ratio corresponds to the fluorescence intensity of the dye, and this fluorescent dye exhibited pH-dependent fluorescence intensity changes. These facts indicate that the fluorescence intensity ratio linearly increased with increasing pH value of the buffer solution containing the QD and the dye. The FRET efficiencies changed from 0.3 (pH 7.5) to 6.2 (pH 9.5).

Study on micro-bend light transmission performance of novel liquid-core optical fiber

NASA Astrophysics Data System (ADS)

Ma, Junyan; Zhao, Zhimin; Wang, Kaisheng; Guo, Linfeng

2007-01-01

With the increasing development of material technology and electronic integration technology, optical fiber and its using in smart structure have become hot in the field of material research. And liquid-core optical fiber is a special kind of optical fiber, which is made using liquid material as core and polymer material as optical layer and protective covering, and it has the characteristics of large core diameter, high numerical aperture, large-scope and efficient spectrum transmission and long life for using. So the liquid-core optical fiber is very suitable for spectrum cure, ultraviolet solidification, fluorescence detection, criminal investigation and evidence obtainment, etc, and especially as light transfer element in some new structures for the measurement of some signals, such as concentration, voltage, temperature, light intensity and so on. In this paper, the novel liquid-core optical fiber is self-made, and then through the test of its light transmission performance in free state, the relation between axial micro-bend and light-intensity loss are presented. When the liquid-core optical fiber is micro-bent axially, along with the axial displacement's increase, output power of light is reducing increasingly, and approximately has linear relation to micro-displacement in a range. According to the results liquid-core fiber-optic micro-bend sensor can be designed to measure micro-displacement of the tested objects. Experimental data and analysis provide experimental basis for further application of liquid-core optical fiber.

Design rules for a compact and low-cost optical position sensing of MOEMS tilt mirrors based on a Gaussian-shaped light source

NASA Astrophysics Data System (ADS)

Baumgart, Marcus; Tortschanoff, Andreas

2013-05-01

A tilt mirror's deflection angle tracking setup is examined from a theoretical point of view. The proposed setup is based on a simple optical approach and easily scalable. Thus, the principle is especially of interest for small and fast oscillating MEMS/MOEMS based tilt mirrors. An experimentally established optical scheme is used as a starting point for accurate and fast mirror angle-position detection. This approach uses an additional layer, positioned under the MOEMS mirror's backside, consisting of a light source in the center and two photodetectors positioned symmetrical around the center. The mirror's back surface is illuminated by the light source and the intensity change due to mirror tilting is tracked via the photodiodes. The challenge of this method is to get a linear relation between the measured intensity and the current mirror tilt angle even for larger angles. State-of-the-art MOEMS mirrors achieve angles up to ±30°, which exceeds the linear angle approximations. The use of an LED, small laser diode or VCSEL as a lightsource is appropriate due to their small size and inexpensive price. Those light sources typically emit light with a Gaussian intensity distribution. This makes an analytical prediction of the expected detector signal quite complicated. In this publication an analytical simulation model is developed to evaluate the influence of the main parameters for this optical mirror tilt-sensor design. An easy and fast to calculate value directly linked to the mirror's tilt-angle is the "relative differential intensity" (RDI = (I1 - I2) / (I1 + I2)). Evaluation of its slope and nonlinear error highlights dependencies between the identified parameters for best SNR and linearity. Also the energy amount covering the detector area is taken into account. Design optimizing rules are proposed and discussed based on theoretical considerations.

Multi-Fibre Optode Microsensors: affordable designs for monitoring oxygen in soils under varying environmental conditions

NASA Astrophysics Data System (ADS)

Rezanezhad, F.; Milojevic, T.; Parsons, C. T.; Smeaton, C. M.; Van Cappellen, P.

2017-12-01

Molecular oxygen (O2) measurements in field and laboratory soil and sediment systems provide useful insight into the biogeochemical functioning of natural environments. However, monitoring soil and sediment O2 is often challenging due to high costs, analyte consumption, and limited customizability and durability of existing O2 sensors. To meet this challenge, an in-house luminescence-based Multi Fibre Optode (MuFO) microsensor system was developed to monitor O2 levels under changing moisture and temperature regimes. The design is simplified by the use of a basic DSLR camera, LED light and fibre optic cables. The technique is based on O2 quenching the luminescent light intensity emitted from a luminophore (platinum(II) meso-tetra(pentafluorophenyl)porphyrin, PtTFPP) that is dip-coated onto the tips of the fibre optic cables, where increasing O2 corresponds to decreasing light intensity, based on the classic Stern-Volmer relationship. High-resolution digital images of the sensor-emitted light are then converted into % O2 saturation. The method was successfully tested in two artificial soil (20% peat, 80% sand) column experiments designed to simulate freeze-thaw cycles (temperature cycling from -10°C to 25°C) and water table fluctuations under controlled conditions. Depth distributions of O2 levels were monitored without interruption for multiple freeze-thaw and water table cycles. No degradation of optode performance or O2 signals were observed for the duration of the column experiments, which supports the long-term deployment of the microsensors for continuous O2 monitoring in field and laboratory settings. The technical specifications of the system are fair, with a detection limit of 0.2% O2 saturation. The main advantages of the MuFO system over commercial applications are the comparatively low cost ($1,800 USD; about ¼ the cost of commercial versions) and ease of customizability. The system has been further developed for near real-time monitoring in the field, where the imaged data is transmitted remotely using a photo-logging system. The MuFO sensor is currently being tested at a Southern Ontario field site in a year-long experiment. Here we present the field and laboratory results of soil O2 monitoring by this newly developed MuFO microsensor system under varying environmental conditions.

Novel sensor for color control in solid state lighting applications

NASA Astrophysics Data System (ADS)

Gourevitch, Alex; Thurston, Thomas; Singh, Rajiv; Banachowicz, Bartosz; Korobov, Vladimir; Drowley, Cliff

2010-02-01

LED wavelength and luminosity shifts due to temperature, dimming, aging, and binning uncertainty can cause large color errors in open-loop light-mixing illuminators. Multispectral color light sensors combined with feedback circuits can compensate for these LED shifts. Typical color light sensor design variables include the choice of light-sensing material, filter configuration, and read-out circuitry. Cypress Semiconductor has designed and prototyped a color sensor chip that consists of photodiode arrays connected to a I/F (Current to Frequency) converter. This architecture has been chosen to achieve high dynamic range (~100dB) and provide flexibility for tailoring sensor response. Several different optical filter configurations were evaluated in this prototype. The color-sensor chip was incorporated into an RGB light color mixing system with closed-loop optical feedback. Color mixing accuracy was determined by calculating the difference between (u',v') set point values and CIE coordinates measured with a reference colorimeter. A typical color precision ▵u'v' less than 0.0055 has been demonstrated over a wide range of colors, a temperature range of 50C, and light dimming up to 80%.

Characterization of measurement artefacts in fluoroptic temperature sensors: implications for laser thermal therapy at 810 nm.

PubMed

Davidson, Sean R H; Vitkin, I Alex; Sherar, Michael D; Whelan, William M

2005-04-01

Fluoroptic sensors are used to measure interstitial temperatures but their utility for monitoring laser interstitial thermal therapy (LITT) is unclear because these sensors exhibit a measurement artefact when exposed to the near-infrared (NIR) treatment light. This study investigates the cause of the artefact to determine whether fluoroptic sensors can provide reliable temperature measurements during LITT. The temperature rise measured by a fluoroptic sensor irradiated in non-absorbing media (air and water) was considered an artefact. Temperature rise was measured as a function of distance from a laser source. Two different sensor designs and several laser powers were investigated. A relationship between fluence rate and measurement artefact in water was determined and coupled with a numerical simulation of LITT in liver to estimate the error in temperature measurements made by fluoroptic sensors in tissue in proximity to the laser source. The effect of ambient light on the performance of sensors capped with a transparent material ("clear-capped sensors") was also investigated. The temperature rise recorded in air by both clear- and black-capped fluoroptic sensors decreased with distance from a laser source in a manner similar to fluence rate. Sensor cap material, laser power, and the thermal properties of the surrounding medium affected the magnitude of the artefact. Numerical simulations indicated that the accuracy of a clear-capped fluoroptic sensor used to monitor a typical LITT treatment in liver is > 1 degrees C provided the sensor is further than approximately 3 mm from the source. It was also shown that clear-capped fluoroptic sensors are affected by ambient light. The measurement artefact experienced by both black-capped and clear-capped fluoroptic sensors irradiated by NIR light scales with fluence rate and is due to direct absorption of the laser light, which results in sensor self-heating. Clear-capped fluoroptic sensors can be used to accurately monitor LITT in tissue but should be shielded from ambient light. Copyright 2005 Wiley-Liss, Inc.

Multiple channel optical data acquisition system

DOEpatents

Fasching, G.E.; Goff, D.R.

1985-02-22

A multiple channel optical data acquisition system is provided in which a plurality of remote sensors monitoring specific process variable are interrogated by means of a single optical fiber connecting the remote station/sensors to a base station. The remote station/sensors derive all power from light transmitted through the fiber from the base station. Each station/sensor is individually accessed by means of a light modulated address code sent over the fiber. The remote station/sensors use a single light emitting diode to both send and receive light signals to communicate with the base station and provide power for the remote station. The system described can power at least 100 remote station/sensors over an optical fiber one mile in length.

Development of a disposable force-sensing glove for clinicians and demonstration of its force measurements on patients during rehabilitation following anterior cruciate ligament reconstruction surgery

NASA Astrophysics Data System (ADS)

Wang, Wei-Chih; Linders, David R.; Nuckley, David J.

2017-12-01

For many clinicians, their effectiveness is dependent on the magnitude of forces they manually apply to their patients. However, current state-of-the-art care strategies lack quantitative feedback, making it difficult to provide consistent care over time and among multiple clinicians. To provide real-time quantitative feedback to clinicians, we have developed a disposable glove with a force sensor embedded in the fingertips or palm. The sensor is based on the fiber-optic bendloss effect whereby light intensity from an infrared source is attenuated as the fiber is bent between a series of corrugated teeth. The sensor fabricated has a very low profile (10×7×1 mm) and has demonstrated high sensitivity, accuracy, range, and durability. Force feedback up to 90 N with an average force threshold at 0.19 N and average sensor resolution at 0.05 N has been demonstrated. A preliminary clinical study has also been conducted with anterior cruciate ligament reconstruction patients who show significant range of motion improvement when treated with the force-sensing glove.

Fiber optic temperature sensor

NASA Technical Reports Server (NTRS)

Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor)

2000-01-01

A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

Fiber optic temperature sensor

NASA Technical Reports Server (NTRS)

Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor); Mattes, Brenton L. (Inventor); Charnetski, Clark J. (Inventor)

1999-01-01

A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

Micro-optoelectromechanical systems accelerometer based on intensity modulation using a one-dimensional photonic crystal.

PubMed

Sheikhaleh, Arash; Abedi, Kambiz; Jafari, Kian; Gholamzadeh, Reza

2016-11-10

In this paper, we propose what we believe is a novel sensitive micro-optoelectromechanical systems (MOEMS) accelerometer based on intensity modulation by using a one-dimensional photonic crystal. The optical sensing system of the proposed structure includes an air-dielectric multilayer photonic bandgap material, a laser diode (LD) light source, a typical photodiode (1550 nm) and a set of integrated optical waveguides. The proposed sensor provides several advantages, such as a relatively wide measurement range, good linearity in the whole measurement range, integration capability, negligible cross-axis sensitivity, high reliability, and low air-damping coefficient, which results in a wider frequency bandwidth for a fixed resonance frequency. Simulation results show that the functional characteristics of the sensor are as follows: a mechanical sensitivity of 119.21 nm/g, a linear measurement range of ±38g and a resonance frequency of 1444 Hz. Thanks to the above-mentioned characteristics, the proposed MOEMS accelerometer is suitable for a wide spectrum of applications, ranging from consumer electronics to aerospace and inertial navigation.

Light and lunar cycle as cues to diel migration of a sound-scattering layer

NASA Astrophysics Data System (ADS)

Benoit-Bird, Kelly J.; Au, Whitlow W. L.

2001-05-01

The Hawaiian mesopelagic boundary community is an island-associated midwater scattering layer comprised of small fishes, shrimps, and squids that undergoes diel vertical as well as horizontal migrations. It has been hypothesized that light levels are an important cue or trigger for vertical migration and presumably, horizontal migration. The migration pattern of the scattering layer was measured over complete lunar cycles while the incident light levels were recorded. Due to differences in the rise and set times of the moon and cloud cover, light and lunar cycle were not completely coupled, allowing separation of the light effects of moon phase and other cues associated with lunar cycle. Four calibrated echosounder moorings were deployed with approximately even spacing, perpendicular to the leeward coast of Oahu. Moorings were deployed for one complete lunar cycle at each of three locations, recording 10 echoes every 15 min. Light sensors measured the nocturnal light intensity at 30-s intervals. Statistical analysis revealed significant effects of both light and other lunar cycle cues. Overall, the effect size was very low considering the light transmission characteristics of the subtropical Pacific, making measurement from stationary acoustic platforms critical.

Nanostructured biosensor using bioluminescence quenching technique for glucose detection.

PubMed

Chen, Longyan; Chen, Longyi; Dotzert, Michelle; Melling, C W James; Zhang, Jin

2017-08-22

Most methods for monitoring glucose level require an external energy source which may limit their application, particularly in vivo test. Bioluminescence technique offers an alternative way to provide emission light without external energy source by using bioluminescent proteins found from firefly or marine vertebrates and invertebrates. For quick and non-invasive detection of glucose, we herein developed a nanostructured biosensor by applying the bioluminescence technique. Luciferase bioluminescence protein (Rluc) is conjugated with β-cyclodextrin (β-CD). The bioluminescence intensity of Rluc can be quenched by 8 ± 3 nm gold nanoparticles (Au NPs) when Au NPs covalently bind to β-CD. In the presence of glucose, Au NPs are replaced and leave far from Rluc through a competitive reaction, which results in the restored bioluminescence intensity of Rluc. A linear relationship is observed between the restored bioluminescence intensity and the logarithmic glucose concentration in the range of 1-100 µM. In addition, the selectivity of this designed sensor has been evaluated. The performance of the senor for determination of the concentration of glucose in the blood of diabetic rats is studied for comparison with that of the concentration of glucose in aqueous. This study demonstrates the design of a bioluminescence sensor for quickly detecting the concentration of glucose sensitively.

Luminescent sensors for tracking spatial particle distributions in an explosion

NASA Astrophysics Data System (ADS)

Anderson, Benjamin R.; Gunawidjaja, Ray; Diez-y-Riega, Helena; Eilers, Hergen; Svingala, Forrest R.; Daniels, Amber; Lightstone, James M.

2017-01-01

We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 or p-Eu:ZrO2. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 355 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference.

Distributed Peer-to-Peer Target Tracking in Wireless Sensor Networks

PubMed Central

Wang, Xue; Wang, Sheng; Bi, Dao-Wei; Ma, Jun-Jie

2007-01-01

Target tracking is usually a challenging application for wireless sensor networks (WSNs) because it is always computation-intensive and requires real-time processing. This paper proposes a practical target tracking system based on the auto regressive moving average (ARMA) model in a distributed peer-to-peer (P2P) signal processing framework. In the proposed framework, wireless sensor nodes act as peers that perform target detection, feature extraction, classification and tracking, whereas target localization requires the collaboration between wireless sensor nodes for improving the accuracy and robustness. For carrying out target tracking under the constraints imposed by the limited capabilities of the wireless sensor nodes, some practically feasible algorithms, such as the ARMA model and the 2-D integer lifting wavelet transform, are adopted in single wireless sensor nodes due to their outstanding performance and light computational burden. Furthermore, a progressive multi-view localization algorithm is proposed in distributed P2P signal processing framework considering the tradeoff between the accuracy and energy consumption. Finally, a real world target tracking experiment is illustrated. Results from experimental implementations have demonstrated that the proposed target tracking system based on a distributed P2P signal processing framework can make efficient use of scarce energy and communication resources and achieve target tracking successfully.

Loss-compensation technique using a split-spectrum approach for optical fiber air-gap intensity-based sensors

NASA Astrophysics Data System (ADS)

Wang, Anbo; Miller, Mark S.; Gunther, Michael F.; Murphy, Kent A.; Claus, Richard O.

1993-03-01

A self-referencing technique compensating for fiber losses and source fluctuations in air-gap intensity-based optical fiber sensors is described and demonstrated. A resolution of 0.007 micron has been obtained over a measurement range of 0-250 microns for an intensity-based displacement sensor using this referencing technique. The sensor is shown to have minimal sensitivity to fiber bending losses and variations in the LED input power. A theoretical model for evaluation of step-index multimode optical fiber splice is proposed. The performance of the sensor as a displacement sensor agrees well with the theoretical analysis.

Smooth light extraction in lighting optical fibre

NASA Astrophysics Data System (ADS)

Fernandez-Balbuena, A. A.; Vazquez-Molini, D.; Garcia-Botella, A.; Martinez-Anton, J. C.; Bernabeu, E.

2011-10-01

Recent advances in LED technology have relegated the use of optical fibre for general lighting, but there are several applications where it can be used as scanners lighting systems, daylight, cultural heritage lighting, sensors, explosion risky spaces, etc. Nowadays the use of high intensity LED to inject light in optical fibre increases the possibility of conjugate fibre + LED for lighting applications. New optical fibres of plastic materials, high core diameter up to 12.6 mm transmit light with little attenuation in the visible spectrum but there is no an efficient and controlled way to extract the light during the fibre path. Side extracting fibres extracts all the light on 2π angle so is not well suited for controlled lighting. In this paper we present an extraction system for mono-filament optical fibre which provides efficient and controlled light distribution. These lighting parameters can be controlled with an algorithm that set the position, depth and shape of the optical extraction system. The extraction system works by total internal reflection in the core of the fibre with high efficiency and low cost. A 10 m length prototype is made with 45° sectional cuts in the fibre core as extraction system. The system is tested with a 1W white LED illuminator in one side.

A real-time monitoring system for night glare protection

NASA Astrophysics Data System (ADS)

Ma, Jun; Ni, Xuxiang

2010-11-01

When capturing a dark scene with a high bright object, the monitoring camera will be saturated in some regions and the details will be lost in and near these saturated regions because of the glare vision. This work aims at developing a real-time night monitoring system. The system can decrease the influence of the glare vision and gain more details from the ordinary camera when exposing a high-contrast scene like a car with its headlight on during night. The system is made up of spatial light modulator (The liquid crystal on silicon: LCoS), image sensor (CCD), imaging lens and DSP. LCoS, a reflective liquid crystal, can modular the intensity of reflective light at every pixel as a digital device. Through modulation function of LCoS, CCD is exposed with sub-region. With the control of DSP, the light intensity is decreased to minimum in the glare regions, and the light intensity is negative feedback modulated based on PID theory in other regions. So that more details of the object will be imaging on CCD and the glare protection of monitoring system is achieved. In experiments, the feedback is controlled by the embedded system based on TI DM642. Experiments shows: this feedback modulation method not only reduces the glare vision to improve image quality, but also enhances the dynamic range of image. The high-quality and high dynamic range image is real-time captured at 30hz. The modulation depth of LCoS determines how strong the glare can be removed.

[A mobile sensor for remote detection of natural gas leakage].

PubMed

Zhang, Shuai; Liu, Wen-qing; Zhang, Yu-jun; Kan, Rui-feng; Ruan, Jun; Wang, Li-ming; Yu, Dian-qiang; Dong, Jin-ting; Han, Xiao-lei; Cui, Yi-ben; Liu, Jian-guo

2012-02-01

The detection of natural gas pipeline leak becomes a significant issue for body security, environmental protection and security of state property. However, the leak detection is difficult, because of the pipeline's covering many areas, operating conditions and complicated environment. A mobile sensor for remote detection of natural gas leakage based on scanning wavelength differential absorption spectroscopy (SWDAS) is introduced. The improved soft threshold wavelet denoising was proposed by analyzing the characteristics of reflection spectrum. And the results showed that the signal to noise ratio (SNR) was increased three times. When light intensity is 530 nA, the minimum remote sensitivity will be 80 ppm x m. A widely used SWDAS can make quantitative remote sensing of natural gas leak and locate the leak source precisely in a faster, safer and more intelligent way.

Smart-Home Architecture Based on Bluetooth mesh Technology

NASA Astrophysics Data System (ADS)

Wan, Qing; Liu, Jianghua

2018-03-01

This paper describes the smart home network system based on Nordic nrf52832 device. Nrf52832 is new generation RF SOC device focus on sensor monitor and low power Bluetooth connection applications. In this smart home system, we set up a self-organizing network system which consists of one control node and a lot of monitor nodes. The control node manages the whole network works; the monitor nodes collect the sensor information such as light intensity, temperature, humidity, PM2.5, etc. Then update to the control node by Bluetooth mesh network. The design results show that the Bluetooth mesh wireless network system is flexible and construction cost is low, which is suitable for the communication characteristics of a smart home network. We believe it will be wildly used in the future.

UV Light Illumination Can Improve the Sensing Properties of LaFeO₃ to Acetone Vapor.

PubMed

Zhang, Heng; Qin, Hongwei; Gao, Chengyong; Zhou, Guangjun; Chen, Yanping; Hu, Jifan

2018-06-21

The synthesized LaFeO₃ nanocrystalline sensor powders show positive response to sensing acetone vapor at 200 °C. The responses to acetone vapor (at 0.5, 1, 2, 5, 10 ppm) are 1.18, 1.22, 1.89, 3.2 and 7.83. To make the sensor operate at a lower optimum temperature, UV light illumination 365 nm is performed. Response of the sensor has a larger improvement under 365 nm UV light illumination than without it. The responses to acetone vapor (at 0.5, 1, 2, 5, 10 ppm) are 1.37, 1.85, 3.16, 8.32 and 14.1. Furthermore, the optimum operating temperature is reduced to 170 °C. As the relative humidity increases, the resistance and sensitivity of sensor are reduced. The sensor shows good selectivity toward acetone when compared with other gases. Since the detection of ultralow concentrations of acetone vapor is possible, the sensor can be used to preliminarily judge diabetes in the general public, as a high concentration of acetone is exhaled in breath of diabetic patients. The sensor shows a good stability, which is further enhanced under UV light illumination. The sensor shows better stability when under 365 nm UV light illumination. Whether under light illumination or not. The LaFeO₃ material shows good performance as a sensor when exposed to acetone vapor.

Theoretical analyses of localized surface plasmon resonance spectrum with nanoparticles imprinted polymers

NASA Astrophysics Data System (ADS)

Li, Hong; Peng, Wei; Wang, Yanjie; Hu, Lingling; Liang, Yuzhang; Zhang, Xinpu; Yao, Wenjuan; Yu, Qi; Zhou, Xinlei

2011-12-01

Optical sensors based on nanoparticles induced Localized Surface Plasmon Resonance are more sensitive to real-time chemical and biological sensing, which have attracted intensive attentions in many fields. In this paper, we establish a simulation model based on nanoparticles imprinted polymer to increase sensitivity of the LSPR sensor by detecting the changes of Surface Plasmon Resonance signals. Theoretical analysis and numerical simulation of parameters effects to absorption peak and light field distribution are highlighted. Two-dimensional simulated color maps show that LSPR lead to centralization of the light energy around the gold nanoparticles, Transverse Magnetic wave and total reflection become the important factors to enhance the light field in our simulated structure. Fast Fourier Transfer analysis shows that the absorption peak of the surface plasmon resonance signal resulted from gold nanoparticles is sharper while its wavelength is bigger by comparing with silver nanoparticles; a double chain structure make the amplitude of the signals smaller, and make absorption wavelength longer; the absorption peak of enhancement resulted from nanopore arrays has smaller wavelength and weaker amplitude in contrast with nanoparticles. These simulation results of the Localized Surface Plasmon Resonance can be used as an enhanced transduction mechanism for enhancement of sensitivity in recognition and sensing of target analytes in accordance with different requirements.

Rapid Prototyping of a Smart Device-based Wireless Reflectance Photoplethysmograph

PubMed Central

Ghamari, M.; Aguilar, C.; Soltanpur, C.; Nazeran, H.

2017-01-01

This paper presents the design, fabrication, and testing of a wireless heart rate (HR) monitoring device based on photoplethysmography (PPG) and smart devices. PPG sensors use infrared (IR) light to obtain vital information to assess cardiac health and other physiologic conditions. The PPG data that are transferred to a computer undergo further processing to derive the Heart Rate Variability (HRV) signal, which is analyzed to generate quantitative markers of the Autonomic Nervous System (ANS). The HRV signal has numerous monitoring and diagnostic applications. To this end, wireless connectivity plays an important role in such biomedical instruments. The photoplethysmograph consists of an optical sensor to detect the changes in the light intensity reflected from the illuminated tissue, a signal conditioning unit to prepare the reflected light for further signal conditioning through amplification and filtering, a low-power microcontroller to control and digitize the analog PPG signal, and a Bluetooth module to transmit the digital data to a Bluetooth-based smart device such as a tablet. An Android app is then used to enable the smart device to acquire and digitally display the received analog PPG signal in real-time on the smart device. This article is concluded with the prototyping of the wireless PPG followed by the verification procedures of the PPG and HRV signals acquired in a laboratory environment. PMID:28959119

Rapid Prototyping of a Smart Device-based Wireless Reflectance Photoplethysmograph.

PubMed

Ghamari, M; Aguilar, C; Soltanpur, C; Nazeran, H

2016-03-01

This paper presents the design, fabrication, and testing of a wireless heart rate (HR) monitoring device based on photoplethysmography (PPG) and smart devices. PPG sensors use infrared (IR) light to obtain vital information to assess cardiac health and other physiologic conditions. The PPG data that are transferred to a computer undergo further processing to derive the Heart Rate Variability (HRV) signal, which is analyzed to generate quantitative markers of the Autonomic Nervous System (ANS). The HRV signal has numerous monitoring and diagnostic applications. To this end, wireless connectivity plays an important role in such biomedical instruments. The photoplethysmograph consists of an optical sensor to detect the changes in the light intensity reflected from the illuminated tissue, a signal conditioning unit to prepare the reflected light for further signal conditioning through amplification and filtering, a low-power microcontroller to control and digitize the analog PPG signal, and a Bluetooth module to transmit the digital data to a Bluetooth-based smart device such as a tablet. An Android app is then used to enable the smart device to acquire and digitally display the received analog PPG signal in real-time on the smart device. This article is concluded with the prototyping of the wireless PPG followed by the verification procedures of the PPG and HRV signals acquired in a laboratory environment.

Self-Referenced Smartphone-Based Nanoplasmonic Imaging Platform for Colorimetric Biochemical Sensing.

PubMed

Wang, Xinhao; Chang, Te-Wei; Lin, Guohong; Gartia, Manas Ranjan; Liu, Gang Logan

2017-01-03

Colorimetric sensors usually suffer due to errors from variation in light source intensity, the type of light source, the Bayer filter algorithm, and the sensitivity of the camera to incoming light. Here, we demonstrate a self-referenced portable smartphone-based plasmonic sensing platform integrated with an internal reference sample along with an image processing method to perform colorimetric sensing. Two sensing principles based on unique nanoplasmonics enabled phenomena from a nanostructured plasmonic sensor, named as nanoLCA (nano Lycurgus cup array), were demonstrated here for colorimetric biochemical sensing: liquid refractive index sensing and optical absorbance enhancement sensing. Refractive indices of colorless liquids were measured by simple smartphone imaging and color analysis. Optical absorbance enhancement in the colorimetric biochemical assay was achieved by matching the plasmon resonance wavelength with the chromophore's absorbance peak wavelength. Such a sensing mechanism improved the limit of detection (LoD) by 100 times in a microplate reader format. Compared with a traditional colorimetric assay such as urine testing strips, a smartphone plasmon enhanced colorimetric sensing system provided 30 times improvement in the LoD. The platform was applied for simulated urine testing to precisely identify the samples with higher protein concentration, which showed potential point-of-care and early detection of kidney disease with the smartphone plasmonic resonance sensing system.

Optical Sensors Using Stimulated Brillouin Scattering

NASA Technical Reports Server (NTRS)

Christensen, Caleb A (Inventor); Zavriyev, Anton (Inventor)

2017-01-01

A method for enhancing a sensitivity of an optical sensor having an optical cavity counter-propagates beams of pump light within the optical cavity to produce scattered light based on Stimulated Brillouin Scattering (SBS). The properties of the pump light are selected to generate fast-light conditions for the scattered light, such that the scattered light includes counter-propagating beams of fast light. The method prevents the pump light from resonating within the optical cavity, while allowing the scattered light to resonate within the optical cavity. At least portions of the scattered light are interfered outside of the optical cavity to produce a beat note for a measurement of the optical sensor. The disclosed method is particularly applicable to optical gyroscopes.

Multi-Gas Sensor

NASA Technical Reports Server (NTRS)

Sachse, Glenn W. (Inventor); Wang, Liang-Guo (Inventor); LeBel, Peter J. (Inventor); Steele, Tommy C. (Inventor); Rana, Mauro (Inventor)

1999-01-01

A multi-gas sensor is provided which modulates a polarized light beam over a broadband of wavelengths between two alternating orthogonal polarization components. The two orthogonal polarization components of the polarization modulated beam are directed along two distinct optical paths. At least one optical path contains one or more spectral discrimination element, with each spectral discrimination element having spectral absorption features of one or more gases of interest being measured. The two optical paths then intersect, and one orthogonal component of the intersected components is transmitted and the other orthogonal component is reflected. The combined polarization modulated beam is partitioned into one or more smaller spectral regions of interest where one or more gases of interest has an absorption band. The difference in intensity between the two orthogonal polarization components is then determined in each partitioned spectral region of interest as an indication of the spectral emission/absorption of the light beam by the gases of interest in the measurement path. The spectral emission/absorption is indicative of the concentration of the one or more gases of interest in the measurement path. More specifically, one embodiment of the present invention is a gas filter correlation radiometer which comprises a polarizer, a polarization modulator, a polarization beam splitter, a beam combiner, wavelength partitioning element, and detection element. The gases of interest are measured simultaneously and, further, can be measured independently or non-independently. Furthermore, optical or electronic element are provided to balance optical intensities between the two optical paths.

Fast Fingerprint Database Maintenance for Indoor Positioning Based on UGV SLAM

PubMed Central

Tang, Jian; Chen, Yuwei; Chen, Liang; Liu, Jingbin; Hyyppä, Juha; Kukko, Antero; Kaartinen, Harri; Hyyppä, Hannu; Chen, Ruizhi

2015-01-01

Indoor positioning technology has become more and more important in the last two decades. Utilizing Received Signal Strength Indicator (RSSI) fingerprints of Signals of OPportunity (SOP) is a promising alternative navigation solution. However, as the RSSIs vary during operation due to their physical nature and are easily affected by the environmental change, one challenge of the indoor fingerprinting method is maintaining the RSSI fingerprint database in a timely and effective manner. In this paper, a solution for rapidly updating the fingerprint database is presented, based on a self-developed Unmanned Ground Vehicles (UGV) platform NAVIS. Several SOP sensors were installed on NAVIS for collecting indoor fingerprint information, including a digital compass collecting magnetic field intensity, a light sensor collecting light intensity, and a smartphone which collects the access point number and RSSIs of the pre-installed WiFi network. The NAVIS platform generates a map of the indoor environment and collects the SOPs during processing of the mapping, and then the SOP fingerprint database is interpolated and updated in real time. Field tests were carried out to evaluate the effectiveness and efficiency of the proposed method. The results showed that the fingerprint databases can be quickly created and updated with a higher sampling frequency (5Hz) and denser reference points compared with traditional methods, and the indoor map can be generated without prior information. Moreover, environmental changes could also be detected quickly for fingerprint indoor positioning. PMID:25746096

High dynamic spectroscopy using a digital micromirror device and periodic shadowing.

PubMed

Kristensson, Elias; Ehn, Andreas; Berrocal, Edouard

2017-01-09

We present an optical solution called DMD-PS to boost the dynamic range of 2D imaging spectroscopic measurements up to 22 bits by incorporating a digital micromirror device (DMD) prior to detection in combination with the periodic shadowing (PS) approach. In contrast to high dynamic range (HDR), where the dynamic range is increased by recording several images at different exposure times, the current approach has the potential of improving the dynamic range from a single exposure and without saturation of the CCD sensor. In the procedure, the spectrum is imaged onto the DMD that selectively reduces the reflection from the intense spectral lines, allowing the signal from the weaker lines to be increased by a factor of 2⁸ via longer exposure times, higher camera gains or increased laser power. This manipulation of the spectrum can either be based on a priori knowledge of the spectrum or by first performing a calibration measurement to sense the intensity distribution. The resulting benefits in detection sensitivity come, however, at the cost of strong generation of interfering stray light. To solve this issue the Periodic Shadowing technique, which is based on spatial light modulation, is also employed. In this proof-of-concept article we describe the full methodology of DMD-PS and demonstrate - using the calibration-based concept - an improvement in dynamic range by a factor of ~100 over conventional imaging spectroscopy. The dynamic range of the presented approach will directly benefit from future technological development of DMDs and camera sensors.

A Programmable Optical Stimulator for the Drosophila Eye.

PubMed

Chen, Xinping; Leon-Salas, Walter D; Zigon, Taylor; Ready, Donald F; Weake, Vikki M

2017-10-01

A programmable optical stimulator for Drosophila eyes is presented. The target application of the stimulator is to induce retinal degeneration in fly photoreceptor cells by exposing them to light in a controlled manner. The goal of this work is to obtain a reproducible system for studying age-related changes in susceptibility to environmental ocular stress. The stimulator uses light emitting diodes and an embedded computer to control illuminance, color (blue or red) and duration in two independent chambers. Further, the stimulator is equipped with per-chamber light and temperature sensors and a fan to monitor light intensity and to control temperature. An ON/OFF temperature control implemented on the embedded computer keeps the temperature from reaching levels that will induce the heat shock stress response in the flies. A custom enclosure was fabricated to house the electronic components of the stimulator. The enclosure provides a light-impermeable environment that allows air flow and lets users easily load and unload fly vials. Characterization results show that the fabricated stimulator can produce light at illuminances ranging from 0 to 16000 lux and power density levels from 0 to 7.2 mW/cm 2 for blue light. For red light the maximum illuminance is 8000 lux which corresponds to a power density of 3.54 mW/cm 2 . The fans and the ON/OFF temperature control are able to keep the temperature inside the chambers below 28.17°C. Experiments with white-eye male flies were performed to assess the ability of the fabricated simulator to induce blue light-dependent retinal degeneration. Retinal degeneration is observed in flies exposed to 8 hours of blue light at 7949 lux. Flies in a control experiment with no light exposure show no retinal degeneration. Flies exposed to red light for the similar duration and light intensity (8 hours and 7994 lux) do not show retinal degeneration either. Hence, the fabricated stimulator can be used to create environmental ocular stress using blue light.

Dual-Fiberoptic Microcantilever Proximity Sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goedeke, S.M.

2001-08-08

Microcantilevers are key components of many Micro-Electro-Mechanical Systems (MEMS) and Micro-Optical-Electro-Mechanical Systems (MOEMS) because slight changes to them physically or chemically lead to changes in mechanical characteristics. An inexpensive dual-fiberoptic microcantilever proximity sensor and model to predict its performance are reported here. Motion of a magnetic-material-coated cantilever is the basis of a system under development for measuring magnetic fields. The dual fiber proximity sensor will be used to monitor the motion of the cantilever. The specific goal is to sense induction fields produced by a current carrying conductor. The proximity sensor consists of two fibers side by side with claddingsmore » in contact. The fiber core diameter, 50 microns, and cladding thickness, 10 microns, are as small as routinely available commercially with the exception of single mode fiber. Light is launched into one fiber from a light-emitting diode (LED). It emerges from that fiber and reflects from the cantilever into the adjacent receiving fiber connected to a detector. The sensing end is cast molded with a diameter of 3-mm over the last 20-mm, yielding a low profile sensor. This reflective triangulation approach is probably the oldest and simplest fiber proximity sensing approach, yet the novelty here is in demonstrating high sensitivity at low expense from a triangular microstructure with amorphous magnetic coatings of iron, cobalt, permalloy, etc. The signal intensity versus distance curve yields an approximate gaussian shape. For a typical configuration, the signal grows from 10% to 90% of maximum in traversing from 6 to 50 microns from a coated cantilever. With signal levels exceeding a volt, nanometer resolution should be readily achievable for periodic signals.« less

Noncanonical Photodynamics of the Orange/Green Cyanobacteriochrome Power Sensor NpF2164g7 from the PtxD Phototaxis Regulator of Nostoc punctiforme.

PubMed

Kirpich, Julia S; Chang, Che-Wei; Madsen, Dorte; Gottlieb, Sean M; Martin, Shelley S; Rockwell, Nathan C; Lagarias, J Clark; Larsen, Delmar S

2018-05-08

Forward and reverse primary (<10 ns) and secondary (>10 ns) photodynamics of cyanobacteriochrome (CBCR) NpF2164g7 were characterized by global analysis of ultrafast broadband transient absorption measurements. NpF2164g7 is the most C-terminal bilin-binding GAF domain in the Nostoc punctiforme phototaxis sensor PtxD (locus Npun_F2164). Although a member of the canonical red/green CBCR subfamily phylogenetically, NpF2164g7 exhibits an orange-absorbing 15Z P o dark-adapted state instead of the typical red-absorbing 15Z P r dark-adapted state characteristic of this subfamily. The green-absorbing 15E P g photoproduct of NpF2164g7 is unstable, allowing this CBCR domain to function as a power sensor. Photoexcitation of the 15Z P o state triggers inhomogeneous excited-state dynamics with three spectrally and temporally distinguishable pathways to generate the light-adapted 15E P g state in high yield (estimated at 25-30%). Although observed in other CBCR domains, the inhomogeneity in NpF2164g7 extends far into secondary relaxation dynamics (10 ns -1 ms) through to formation of 15E P g . In the reverse direction, the primary dynamics after photoexcitation of 15E P g are qualitatively similar to those of other red/green CBCRs, but secondary dynamics involve a "pre-equilibrium" step before regenerating 15Z P o . The anomalous photodynamics of NpF2164g7 may reflect an evolutionary adaptation of CBCR sensors that function as broadband light intensity sensors.

Low-cost fabrication of optical waveguides, interconnects and sensing structures on all-polymer-based thin foils

NASA Astrophysics Data System (ADS)

Rezem, Maher; Kelb, Christian; Günther, Axel; Rahlves, Maik; Reithmeier, Eduard; Roth, Bernhard

2016-03-01

Micro-optical sensors based on optical waveguides are widely used to measure temperature, force and strain but also to detect biological and chemical substances such as explosives or toxins. While optical micro-sensors based on silicon technology require complex and expensive process technologies, a new generation of sensors based completely on polymers offer advantages especially in terms of low-cost and fast production techniques. We have developed a process to integrate micro-optical components such as embedded waveguides and optical interconnects into polymer foils with a thickness well below one millimeter. To enable high throughput production, we employ hot embossing technology, which is capable of reel-to-reel fabrication with a surface roughness in the optical range. For the waveguide fabrication, we used the thermoplastic polymethylmethacrylate (PMMA) as cladding and several optical adhesives as core materials. The waveguides are characterized with respect to refractive indices and propagation losses. We achieved propagation losses are as low as 0.3 dB/cm. Furthermore, we demonstrate coupling structures and their fabrication especially suited to integrate various light sources such as vertical-cavity surface-emitting lasers (VCSEL) and organic light emitting diodes (OLED) into thin polymer foils. Also, we present a concept of an all-polymer and waveguide based deformation sensor based on intensity modulation, which can be fabricated by utilizing our process. For future application, we aim at a low-cost and high-throughput reel-to-reel production process enabling the fabrication of large sensor arrays or disposable single-use sensing structures, which will open optical sensing to a large variety of application fields ranging from medical diagnosis to automotive sensing.

Fiber Optic Force Sensors for MRI-Guided Interventions and Rehabilitation: A Review

PubMed Central

Iordachita, Iulian I.; Tokuda, Junichi; Hata, Nobuhiko; Liu, Xuan; Seifabadi, Reza; Xu, Sheng; Wood, Bradford; Fischer, Gregory S.

2017-01-01

Magnetic Resonance Imaging (MRI) provides both anatomical imaging with excellent soft tissue contrast and functional MRI imaging (fMRI) of physiological parameters. The last two decades have witnessed the manifestation of increased interest in MRI-guided minimally invasive intervention procedures and fMRI for rehabilitation and neuroscience research. Accompanying the aspiration to utilize MRI to provide imaging feedback during interventions and brain activity for neuroscience study, there is an accumulated effort to utilize force sensors compatible with the MRI environment to meet the growing demand of these procedures, with the goal of enhanced interventional safety and accuracy, improved efficacy and rehabilitation outcome. This paper summarizes the fundamental principles, the state of the art development and challenges of fiber optic force sensors for MRI-guided interventions and rehabilitation. It provides an overview of MRI-compatible fiber optic force sensors based on different sensing principles, including light intensity modulation, wavelength modulation, and phase modulation. Extensive design prototypes are reviewed to illustrate the detailed implementation of these principles. Advantages and disadvantages of the sensor designs are compared and analyzed. A perspective on the future development of fiber optic sensors is also presented which may have additional broad clinical applications. Future surgical interventions or rehabilitation will rely on intelligent force sensors to provide situational awareness to augment or complement human perception in these procedures. PMID:28652857

Piezoelectroluminescent Optical Fiber Sensor for Diagnostics of the Stress State and Defectoscopy of Composites

NASA Astrophysics Data System (ADS)

Pan'kov, A. A.

2017-05-01

A mathematical model is developed for a piezoelectroluminescent optical fiber pressure sensor is developed in which the mechanoluminescence effect results from the interaction of electroluminescent and piezoelectric coverings put on an optical fiber. The additional control electrodes expand the possibilities of analyzing the distribution of pressure along the fiber. The probability density function of pressure distribution along the sensor is found from results of the measured intensity of light coming from the optical fiber. The problem is reduced to the solution of the Fredholm integral equation of the first kind with a difference kernel depending on the effective parameters of the sensor and properties of an electroluminophor. An algorithm of step-by-step scanning of the nonuniform pressure along the sensor by using the running wave of control voltage is developed. On each step, the amplitude of the wave is increased by a small value, which leads to the appearance of additional luminescence sections of the electroluminophor and the corresponding "glow pulses" at the output of the optical fiber sensor. The sought-for nodal values of pressure and their locations are calculated according to the form of the glow pulses with account of amplitude of the wave at each scanning step. Results of numerical modeling of the process of location of pressure nonuniformities along the sensor by the running wave are found for different scanning steps.

Respiration rate detection based on intensity modulation using plastic optical fiber

NASA Astrophysics Data System (ADS)

Anwar, Zawawi Mohd; Ziran Nurul Sufia, Nor; Hadi, Manap

2017-11-01

This paper presents the implementation of respiration rate measurement via a simple intensity-based optical fiber sensor using optical fiber technology. The breathing rate is measured based on the light intensity variation due to the longitudinal gap changes between two separated fibers. In order to monitor the breathing rate continuously, the output from the photodetector conditioning circuit is connected to a low-cost Arduino kit. At the sensing point, two optical fiber cables are positioned in series with a small gap and fitted inside a transparent plastic tube. To ensure smooth movement of the fiber during inhale and exhale processes as well as to maintain the gap of the fiber during idle condition, the fiber is attached firmly to a stretchable bandage. This study shows that this simple fiber arrangement can be applied to detect respiration activity which might be critical for patient monitoring.

End-to-end learning for digital hologram reconstruction

NASA Astrophysics Data System (ADS)

Xu, Zhimin; Zuo, Si; Lam, Edmund Y.

2018-02-01

Digital holography is a well-known method to perform three-dimensional imaging by recording the light wavefront information originating from the object. Not only the intensity, but also the phase distribution of the wavefront can then be computed from the recorded hologram in the numerical reconstruction process. However, the reconstructions via the traditional methods suffer from various artifacts caused by twin-image, zero-order term, and noise from image sensors. Here we demonstrate that an end-to-end deep neural network (DNN) can learn to perform both intensity and phase recovery directly from an intensity-only hologram. We experimentally show that the artifacts can be effectively suppressed. Meanwhile, our network doesn't need any preprocessing for initialization, and is comparably fast to train and test, in comparison with the recently published learning-based method. In addition, we validate that the performance improvement can be achieved by introducing a prior on sparsity.

Wireless Occupancy Sensors for Lighting Controls: An Applications Guide for Federal Facility Managers

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

This guide provides federal facility managers with an overview of the energy savings potential of wireless lighting occupancy sensors for various room types, cost considerations, key steps to successful installation of wireless sensors, pros and cons of various technology options, light source considerations, and codes and standards.

Fiber-optical sensor with intensity compensation model in college teaching of physics experiment

NASA Astrophysics Data System (ADS)

Su, Liping; Zhang, Yang; Li, Kun; Zhang, Yu

2017-08-01

Optical fiber sensor technology is one of the main contents of modern information technology, which has a very important position in modern science and technology. Fiber optic sensor experiment can improve students' enthusiasm and broaden their horizons in college physics experiment. In this paper the main structure and working principle of fiberoptical sensor with intensity compensation model are introduced. And thus fiber-optical sensor with intensity compensation model is applied to measure micro displacement of Young's modulus measurement experiment and metal linear expansion coefficient measurement experiment in the college physics experiment. Results indicate that the measurement accuracy of micro displacement is higher than that of the traditional methods using fiber-optical sensor with intensity compensation model. Meanwhile this measurement method makes the students understand on the optical fiber, sensor and nature of micro displacement measurement method and makes each experiment strengthen relationship and compatibility, which provides a new idea for the reform of experimental teaching.

CMOS Active-Pixel Image Sensor With Intensity-Driven Readout

NASA Technical Reports Server (NTRS)

Langenbacher, Harry T.; Fossum, Eric R.; Kemeny, Sabrina

1996-01-01

Proposed complementary metal oxide/semiconductor (CMOS) integrated-circuit image sensor automatically provides readouts from pixels in order of decreasing illumination intensity. Sensor operated in integration mode. Particularly useful in number of image-sensing tasks, including diffractive laser range-finding, three-dimensional imaging, event-driven readout of sparse sensor arrays, and star tracking.

Reducing the impact of intensive care unit mattress compressibility during CPR: a simulation-based study.

PubMed

Lin, Yiqun; Wan, Brandi; Belanger, Claudia; Hecker, Kent; Gilfoyle, Elaine; Davidson, Jennifer; Cheng, Adam

2017-01-01

The depth of chest compression (CC) during cardiac arrest is associated with patient survival and good neurological outcomes. Previous studies showed that mattress compression can alter the amount of CCs given with adequate depth. We aim to quantify the amount of mattress compressibility on two types of ICU mattresses and explore the effect of memory foam mattress use and a backboard on mattress compression depth and effect of feedback source on effective compression depth. The study utilizes a cross-sectional self-control study design. Participants working in the pediatric intensive care unit (PICU) performed 1 min of CC on a manikin in each of the following four conditions: (i) typical ICU mattress; (ii) typical ICU mattress with a CPR backboard; (iii) memory foam ICU mattress; and (iv) memory foam ICU mattress with a CPR backboard, using two different sources of real-time feedback: (a) external accelerometer sensor device measuring total compression depth and (b) internal light sensor measuring effective compression depth only. CPR quality was concurrently measured by these two devices. The differences of the two measures (mattress compression depth) were summarized and compared using multilevel linear regression models. Effective compression depths with different sources of feedback were compared with a multilevel linear regression model. The mean mattress compression depth varied from 24.6 to 47.7 mm, with percentage of depletion from 31.2 to 47.5%. Both use of memory foam mattress (mean difference, MD 11.7 mm, 95%CI 4.8-18.5 mm) and use of backboard (MD 11.6 mm, 95% CI 9.0-14.3 mm) significantly minimized the mattress compressibility. Use of internal light sensor as source of feedback improved effective CC depth by 7-14 mm, compared with external accelerometer sensor. Use of a memory foam mattress and CPR backboard minimizes mattress compressibility, but depletion of compression depth is still substantial. A feedback device measuring sternum-to-spine displacement can significantly improve effective compression depth on a mattress. Not applicable. This is a mannequin-based simulation research.

Light sensing in a photoresponsive, organic-based complementary inverter.

PubMed

Kim, Sungyoung; Lim, Taehoon; Sim, Kyoseung; Kim, Hyojoong; Choi, Youngill; Park, Keechan; Pyo, Seungmoon

2011-05-01

A photoresponsive organic complementary inverter was fabricated and its light sensing characteristics was studied. An organic circuit was fabricated by integrating p-channel pentacene and n-channel copper hexadecafluorophthalocyanine (F16CuPc) organic thin-film transistors (OTFTs) with a polymeric gate dielectric. The F16CuPc OTFT showed typical n-type characteristics and a strong photoresponse under illumination. Whereas under illumination, the pentacene OTFT showed a relatively weak photoresponse with typical p-type characteristics. The characteristics of the organic electro-optical circuit could be controlled by the incident light intensity, a gate bias, or both. The logic threshold (V(M), when V(IN) = V(OUT)) was reduced from 28.6 V without illumination to 19.9 V at 6.94 mW/cm². By using solely optical or a combination of optical and electrical pulse signals, light sensing was demonstrated in this type of organic circuit, suggesting that the circuit can be potentially used in various optoelectronic applications, including optical sensors, photodetectors and electro-optical transceivers.

Measuring high spatiotemporal variability in saltation intensity using a low-cost Saltation Detection System: Wind tunnel and field experiments

NASA Astrophysics Data System (ADS)

de Winter, W.; van Dam, D. B.; Delbecque, N.; Verdoodt, A.; Ruessink, B. G.; Sterk, G.

2018-04-01

The commonly observed over prediction of aeolian saltation transport on sandy beaches is, at least in part, caused by saltation intermittency. To study small-scale saltation processes, high frequency saltation sensors are required on a high spatial resolution. Therefore, we developed a low-cost Saltation Detection System (SalDecS) with the aim to measure saltation intensity at a frequency of 10 Hz and with a spatial resolution of 0.10 m in wind-normal direction. Linearity and equal sensitivity of the saltation sensors were investigated during wind tunnel and field experiments. Wind tunnel experiments with a set of 7 SalDec sensors revealed that the variability of sensor sensitivity is at maximum 9% during relatively low saltation intensities. During more intense saltation the variability of sensor sensitivity decreases. A sigmoidal fit describes the relation between mass flux and sensor output measured during 5 different wind conditions. This indicates an increasing importance of sensor saturation with increasing mass flux. We developed a theoretical model to simulate and describe the effect of grain size, grain velocity and saltation intensity on sensor saturation. Time-averaged field measurements revealed sensitivity equality for 85 out of a set of 89 horizontally deployed SalDec sensors. On these larger timescales (hours) saltation variability imposed by morphological features, such as sand strips, can be recognized. We conclude that the SalDecS can be used to measure small-scale spatiotemporal variabilities of saltation intensity to investigate saltation characteristics related to wind turbulence.

A Microfluidic Long-Period Fiber Grating Sensor Platform for Chloride Ion Concentration Measurement

PubMed Central

Wang, Jian-Neng

2011-01-01

Optical fiber sensors based on waveguide technology are promising and attractive in chemical, biotechnological, agronomy, and civil engineering applications. A microfluidic system equipped with a long-period fiber grating (LPFG) capable of measuring chloride ion concentrations of several sample materials is presented. The LPFG-based microfluidic platform was shown to be effective in sensing very small quantities of samples and its transmitted light signal could easily be used as a measurand. The investigated sample materials included reverse osmosis (RO) water, tap water, dilute aqueous sample of sea sand soaked in RO water, aqueous sample of sea sand soaked in RO water, dilute seawater, and seawater. By employing additionally a chloride ion-selective electrode sensor for the calibration of chloride-ion concentration, a useful correlation (R2 = 0.975) was found between the separately-measured chloride concentration and the light intensity transmitted through the LPFG at a wavelength of 1,550 nm. Experimental results show that the sensitivity of the LPFG sensor by light intensity interrogation was determined to be 5.0 × 10−6 mW/mg/L for chloride ion concentrations below 2,400 mg/L. The results obtained from the analysis of data variations in time-series measurements for all sample materials show that standard deviations of output power were relatively small and found in the range of 7.413 × 10−5−2.769 × 10−3 mW. In addition, a fairly small coefficients of variations were also obtained, which were in the range of 0.03%–1.29% and decreased with the decrease of chloride ion concentrations of sample materials. Moreover, the analysis of stability performance of the LPFG sensor indicated that the random walk coefficient decreased with the increase of the chloride ion concentration, illustrating that measurement stability using the microfluidic platform was capable of measuring transmitted optical power with accuracy in the range of −0.8569 mW/ h to −0.5169 mW/ h. Furthermore, the bias stability was determined to be in the range of less than 6.134 × 10−8 mW/h with 600 s time cluster to less than 1.412 × 10−6 mW/h with 600 s time cluster. Thus, the proposed LPFG-based microfluidic platform has the potential for civil, chemical, biological, and biochemical sensing with aqueous solutions. The compact (3.5 × 4.2 cm), low-cost, real-time, small-volume (∼70 μL), low-noise, and high-sensitive chloride ion sensing system reported here could hopefully benefit the development and applications in the field of chemical, biotechnical, soil and geotechnical, and civil engineering. PMID:22164091

Tunable-optical-filter-based white-light interferometry for sensing.

PubMed

Yu, Bing; Wang, Anbo; Pickrell, Gary; Xu, Juncheng

2005-06-15

We describe tunable-optical-filter-based white-light interferometry for sensor interrogation. By introducing a tunable optical filter into a white-light interferometry system, one can interrogate an interferometer with either quadrature demodulation or spectral-domain detection at low cost. To demonstrate the feasibility of effectively demodulating various types of interferometric sensor, experiments have been performed using an extrinsic Fabry-Perot tunable filter to interrogate two extrinsic Fabry-Perot interferometric temperature sensors and a diaphragm-based pressure sensor.

Intelligent Luminance Control of Lighting Systems Based on Imaging Sensor Feedback

PubMed Central

Liu, Haoting; Zhou, Qianxiang; Yang, Jin; Jiang, Ting; Liu, Zhizhen; Li, Jie

2017-01-01

An imaging sensor-based intelligent Light Emitting Diode (LED) lighting system for desk use is proposed. In contrast to the traditional intelligent lighting system, such as the photosensitive resistance sensor-based or the infrared sensor-based system, the imaging sensor can realize a finer perception of the environmental light; thus it can guide a more precise lighting control. Before this system works, first lots of typical imaging lighting data of the desk application are accumulated. Second, a series of subjective and objective Lighting Effect Evaluation Metrics (LEEMs) are defined and assessed for these datasets above. Then the cluster benchmarks of these objective LEEMs can be obtained. Third, both a single LEEM-based control and a multiple LEEMs-based control are developed to realize a kind of optimal luminance tuning. When this system works, first it captures the lighting image using a wearable camera. Then it computes the objective LEEMs of the captured image and compares them with the cluster benchmarks of the objective LEEMs. Finally, the single LEEM-based or the multiple LEEMs-based control can be implemented to get a kind of optimal lighting effect. Many experiment results have shown the proposed system can tune the LED lamp automatically according to environment luminance changes. PMID:28208781

Intelligent Luminance Control of Lighting Systems Based on Imaging Sensor Feedback.

PubMed

Liu, Haoting; Zhou, Qianxiang; Yang, Jin; Jiang, Ting; Liu, Zhizhen; Li, Jie

2017-02-09

An imaging sensor-based intelligent Light Emitting Diode (LED) lighting system for desk use is proposed. In contrast to the traditional intelligent lighting system, such as the photosensitive resistance sensor-based or the infrared sensor-based system, the imaging sensor can realize a finer perception of the environmental light; thus it can guide a more precise lighting control. Before this system works, first lots of typical imaging lighting data of the desk application are accumulated. Second, a series of subjective and objective Lighting Effect Evaluation Metrics (LEEMs) are defined and assessed for these datasets above. Then the cluster benchmarks of these objective LEEMs can be obtained. Third, both a single LEEM-based control and a multiple LEEMs-based control are developed to realize a kind of optimal luminance tuning. When this system works, first it captures the lighting image using a wearable camera. Then it computes the objective LEEMs of the captured image and compares them with the cluster benchmarks of the objective LEEMs. Finally, the single LEEM-based or the multiple LEEMs-based control can be implemented to get a kind of optimal lighting effect. Many experiment results have shown the proposed system can tune the LED lamp automatically according to environment luminance changes.

Detection of land mines by amplified fluorescence quenching of polymer films: a man-portable chemical sniffer for detection of ultratrace concentrations of explosives emanating from land mines

NASA Astrophysics Data System (ADS)

la Grone, Marcus J.; Cumming, Colin J.; Fisher, Mark E.; Fox, Michael J.; Jacob, Sheena; Reust, Dennis; Rockley, Mark G.; Towers, Eric

2000-08-01

The explosive charge within a landmine is the source for a mixture of chemical vapors that form a distinctive 'chemical signature' indicative of a landmine. The concentration of these compounds in the air over landmines is extremely low, well below the minimum detection limits of most field- portable chemical sensors. Described in this paper is a man- portable landmine detection system that has for the first time demonstrated the ability to detect landmines by direct sensing of the vapors of signature compounds in the air over landmines. The system utilizes fluorescent polymers developed by collaborators at the MIT. The sensor can detect ultra-trace concentrations of TNT vapor and other nitroaromatic compounds found in many landmine explosives. Thin films of the polymers exhibit intense fluorescence, but when exposed to vapors of nitroaromatic explosives the intensity of the light emitted from the films decreases. A single molecule of TNT binding to a receptor site quenches the fluorescence from many polymer repeat units, increasing the sensitivity by orders of magnitude. A sensor prototype has been develop that response in near real-time to low femtogram quantities of nitroaromatic explosives. The prototype is portable, lightweight, has low power consumption, is simple to operate, and is relatively inexpensive. Simultaneous field testing of the sensor and experienced canine landmine detection teams was recently completed. Although the testing was limited in scope, the performance of the senor met or exceeded that of the canines against buried landmines.

Role of CBFs as Integrators of Chloroplast Redox, Phytochrome and Plant Hormone Signaling during Cold Acclimation

PubMed Central

Kurepin, Leonid V.; Dahal, Keshav P.; Savitch, Leonid V.; Singh, Jas; Bode, Rainer; Ivanov, Alexander G.; Hurry, Vaughan; Hüner, Norman P. A.

2013-01-01

Cold acclimation of winter cereals and other winter hardy species is a prerequisite to increase subsequent freezing tolerance. Low temperatures upregulate the expression of C-repeat/dehydration-responsive element binding transcription factors (CBF/DREB1) which in turn induce the expression of COLD-REGULATED (COR) genes. We summarize evidence which indicates that the integration of these interactions is responsible for the dwarf phenotype and enhanced photosynthetic performance associated with cold-acclimated and CBF-overexpressing plants. Plants overexpressing CBFs but grown at warm temperatures mimic the cold-tolerant, dwarf, compact phenotype; increased photosynthetic performance; and biomass accumulation typically associated with cold-acclimated plants. In this review, we propose a model whereby the cold acclimation signal is perceived by plants through an integration of low temperature and changes in light intensity, as well as changes in light quality. Such integration leads to the activation of the CBF-regulon and subsequent upregulation of COR gene and GA 2-oxidase (GA2ox) expression which results in a dwarf phenotype coupled with increased freezing tolerance and enhanced photosynthetic performance. We conclude that, due to their photoautotrophic nature, plants do not rely on a single low temperature sensor, but integrate changes in light intensity, light quality, and membrane viscosity in order to establish the cold-acclimated state. CBFs appear to act as master regulators of these interconnecting sensing/signaling pathways. PMID:23778089

Automated Sensing of Douglas Fir Bud-Burst

NASA Astrophysics Data System (ADS)

Lintz, H. E.; Kruger, A.; Wagner, D. A.; Tenney, I. J.

2011-12-01

The timing of plant biological events such as budburst in the spring can have major impacts on plant productivity and ecosystem carbon balance. While research efforts that address the timing of events is gaining considerable momentum, the technology available for sensing and recording the timing of events is limited, especially for trees. Thus, researchers often perform manual measurements, which can be time-consuming and labor-intensive. This has resulted in efforts such as Project BudBurst, a network of professional and volunteer observers across the United States that monitor plants as seasons change. Access to forest trees can be difficult during periods of greatest interest, such as when buds open in the spring. For example, high elevation, snow, and melting snow during the spring hamper access to trees in alpine regions. Researchers at Oregon State University and The University of Iowa are developing instrumentation for automating sensing of budburst in Douglas firs. While the instrumentation targets Douglas firs, it can find application in studying budburst in other species. We present an initial bud-burst sensor that uses optical techniques to sense bud opening. An optical fiber illuminates a target bud with modulated light, a second fiber detects, and guides reflect light to a photodetector and signal processing electronics. Changes in the reflected light indicate the budburst. The instrumentation exploits advances in microelectronics, particularly miniaturization and low power consumption, and uses advanced signal processing techniques such as lock-in detection. The instrumentation records the reflected light every 15 minutes on high-capacity, non-volatile Flash media. Power consumption is very low and sensors have an extrapolated, continuous operating time more than 9 months, suggesting their deployment in the fall, and retrieval in the following spring. We believe the sensor will enable a caliber of research not yet achievable owing to the difficulty of phenological data collection. We aim to make the sensor cost-effective and ultimately deployable in a wireless network. We envision its application in various disciplines and sectors including forestry, agriculture, climate change research, and genomics.

Evaluation of Peripheral Blood Circulation Disorder in Scleroderma Patients Using an Optical Sensor with a Pressurization Mechanism

PubMed Central

Yamakoshi, Yoshiki

2016-01-01

Blood circulation function of peripheral blood vessels in skin dermis was evaluated employing an optical sensor with a pressurization mechanism using the blood outflow and reflow characteristics. The device contains a light source and an optical sensor. When applied to the skin surface, it first exerts the primary pressure (higher than the systolic blood pressure), causing an outflow of blood from the dermal peripheral blood vessels. After two heartbeats, the pressure is lowered (secondary pressure) and blood reflows into the peripheral blood vessels. Hemoglobin concentration, which changes during blood outflow and reflow, is derived from the received light intensity using the Beer–Lambert law. This method was evaluated in 26 healthy female volunteers and 26 female scleroderma patients. In order to evaluate the blood circulation function of the peripheral blood vessels of scleroderma patients, pressurization sequence which consists of primary pressure followed by secondary pressure was adopted. Blood reflow during the first heartbeat period after applying the secondary pressure of 40mmHg was (mean±SD) 0.059±0.05%mm for scleroderma patients and 0.173±0.104%mm for healthy volunteers. Blood reflow was significantly lower in scleroderma patients than in healthy volunteers (p<0.05). This result indicates that the information necessary for assessing blood circulation disorder of peripheral blood vessels in scleroderma patients is objectively obtained by the proposed method. PMID:27479094

Evaluation of Peripheral Blood Circulation Disorder in Scleroderma Patients Using an Optical Sensor with a Pressurization Mechanism.

PubMed

Yamakoshi, Yoshiki; Motegi, Sei-Ichiro; Ishikawa, Osamu

2016-01-01

Blood circulation function of peripheral blood vessels in skin dermis was evaluated employing an optical sensor with a pressurization mechanism using the blood outflow and reflow characteristics. The device contains a light source and an optical sensor. When applied to the skin surface, it first exerts the primary pressure (higher than the systolic blood pressure), causing an outflow of blood from the dermal peripheral blood vessels. After two heartbeats, the pressure is lowered (secondary pressure) and blood reflows into the peripheral blood vessels. Hemoglobin concentration, which changes during blood outflow and reflow, is derived from the received light intensity using the Beer-Lambert law. This method was evaluated in 26 healthy female volunteers and 26 female scleroderma patients. In order to evaluate the blood circulation function of the peripheral blood vessels of scleroderma patients, pressurization sequence which consists of primary pressure followed by secondary pressure was adopted. Blood reflow during the first heartbeat period after applying the secondary pressure of 40mmHg was (mean±SD) 0.059±0.05%mm for scleroderma patients and 0.173±0.104%mm for healthy volunteers. Blood reflow was significantly lower in scleroderma patients than in healthy volunteers (p<0.05). This result indicates that the information necessary for assessing blood circulation disorder of peripheral blood vessels in scleroderma patients is objectively obtained by the proposed method.

Integrative Multi-Spectral Sensor Device for Far-Infrared and Visible Light Fusion

NASA Astrophysics Data System (ADS)

Qiao, Tiezhu; Chen, Lulu; Pang, Yusong; Yan, Gaowei

2018-06-01

Infrared and visible light image fusion technology is a hot spot in the research of multi-sensor fusion technology in recent years. Existing infrared and visible light fusion technologies need to register before fusion because of using two cameras. However, the application effect of the registration technology has yet to be improved. Hence, a novel integrative multi-spectral sensor device is proposed for infrared and visible light fusion, and by using the beam splitter prism, the coaxial light incident from the same lens is projected to the infrared charge coupled device (CCD) and visible light CCD, respectively. In this paper, the imaging mechanism of the proposed sensor device is studied with the process of the signals acquisition and fusion. The simulation experiment, which involves the entire process of the optic system, signal acquisition, and signal fusion, is constructed based on imaging effect model. Additionally, the quality evaluation index is adopted to analyze the simulation result. The experimental results demonstrate that the proposed sensor device is effective and feasible.

Expression and testing in plants of ArcLight, a genetically-encoded voltage indicator used in neuroscience research.

PubMed

Matzke, Antonius J M; Matzke, Marjori

2015-10-12

It is increasingly appreciated that electrical controls acting at the cellular and supra-cellular levels influence development and initiate rapid responses to environmental cues. An emerging method for non-invasive optical imaging of electrical activity at cell membranes uses genetically-encoded voltage indicators (GEVIs). Developed by neuroscientists to chart neuronal circuits in animals, GEVIs comprise a fluorescent protein that is fused to a voltage-sensing domain. One well-known GEVI, ArcLight, undergoes strong shifts in fluorescence intensity in response to voltage changes in mammalian cells. ArcLight consists of super-ecliptic (SE) pHluorin (pH-sensitive fluorescent protein) with an A227D substitution, which confers voltage sensitivity in neurons, fused to the voltage-sensing domain of the voltage-sensing phosphatase of C iona i ntestinalis (Ci-VSD). In an ongoing effort to adapt tools of optical electrophysiology for plants, we describe here the expression and testing of ArcLight and various derivatives in different membranes of root cells in Arabidopsis thaliana. Transgenic constructs were designed to express ArcLight and various derivatives targeted to the plasma membrane and nuclear membranes of Arabidopsis root cells. In transgenic seedlings, changes in fluorescence intensity of these reporter proteins following extracellular ATP (eATP) application were monitored using a fluorescence microscope equipped with a high speed camera. Coordinate reductions in fluorescence intensity of ArcLight and Ci-VSD-containing derivatives were observed at both the plasma membrane and nuclear membranes following eATP treatments. However, similar responses were observed for derivatives lacking the Ci-VSD. The dispensability of the Ci-VSD suggests that in plants, where H(+) ions contribute substantially to electrical activities, the voltage-sensing ability of ArcLight is subordinate to the pH sensitivity of its SEpHluorin base. The transient reduction of ArcLight fluorescence triggered by eATP most likely reflects changes in pH and not membrane voltage. The pH sensitivity of ArcLight precludes its use as a direct sensor of membrane voltage in plants. Nevertheless, ArcLight and derivatives situated in the plasma membrane and nuclear membranes may offer robust, fluorescence intensity-based pH indicators for monitoring concurrent changes in pH at these discrete membrane systems. Such tools will assist analyses of pH as a signal and/or messenger at the cell surface and the nuclear periphery in living plants.

A Wide Area Bipolar Cascade Resonant Cavity Light Emitting Diode for a Hybrid Range-Intensity Sensor

DTIC Science & Technology

2008-06-19

forward bias voltage and a small amount of current flow- ing due to a forward biased tunnel current. (d) shows a drop in the forward bias current due...flowing due to a forward biased tunnel current. (d) shows a drop in the forward bias current due to the widening of the forbidden band, and fewer...3-14 xii Figure Page 3.10. Energy bands of a tunnel junction at various bias levels. (a) shows the junction under reverse bias with holes in

Building Twilight "Light Sensors" to Study the Effects of Light Pollution on Fireflies

ERIC Educational Resources Information Center

Thancharoen, Anchana; Branham, Marc A.; Lloyd, James E.

2008-01-01

Light pollution negatively affects many nocturnal organisms. We outline two experiments that can be conducted by students to examine the effects of light pollution on firefly behavior. Inexpensive electronic light sensors, which are easy to construct and calibrate, are used to sample light levels along transects in spaces where fireflies are…

Remote environmental sensor array system

NASA Astrophysics Data System (ADS)

Hall, Geoffrey G.

This thesis examines the creation of an environmental monitoring system for inhospitable environments. It has been named The Remote Environmental Sensor Array System or RESA System for short. This thesis covers the development of RESA from its inception, to the design and modeling of the hardware and software required to make it functional. Finally, the actual manufacture, and laboratory testing of the finished RESA product is discussed and documented. The RESA System is designed as a cost-effective way to bring sensors and video systems to the underwater environment. It contains as water quality probe with sensors such as dissolved oxygen, pH, temperature, specific conductivity, oxidation-reduction potential and chlorophyll a. In addition, an omni-directional hydrophone is included to detect underwater acoustic signals. It has a colour, high-definition and a low-light, black and white camera system, which it turn are coupled to a laser scaling system. Both high-intensity discharge and halogen lighting system are included to illuminate the video images. The video and laser scaling systems are manoeuvred using pan and tilt units controlled from an underwater computer box. Finally, a sediment profile imager is included to enable profile images of sediment layers to be acquired. A control and manipulation system to control the instruments and move the data across networks is integrated into the underwater system while a power distribution node provides the correct voltages to power the instruments. Laboratory testing was completed to ensure that the different instruments associated with the RESA performed as designed. This included physical testing of the motorized instruments, calibration of the instruments, benchmark performance testing and system failure exercises.

Robust sensor for turbidity measurement from light scattering and absorbing liquids.

PubMed

Kontturi, Ville; Turunen, Petri; Uozumi, Jun; Peiponen, Kai-Erik

2009-12-01

Internationally standardized turbidity measurements for probing solid particles in liquid are problematic in the case of simultaneous light scattering and absorption. A method and a sensor to determine the turbidity in the presence of light absorption are presented. The developed sensor makes use of the total internal reflection of a laser beam at the liquid-prism interface, and the turbidity is assessed using the concept of laser speckle pattern. Using average filtering in speckle data analyzing the observed dynamic speckle pattern, which is due to light scattering from particles and the static speckle due to stray light of the sensor, can be separated from each other. Good correlation between the standard deviation of dynamic speckle and turbidity value for nonabsorbing and for absorbing liquids was observed. The sensor is suggested, for instance, for the measurement of ill-behaved as well as small-volume turbid liquids in both medicine and process industry.

Focal plane wavefront sensor achromatization: The multireference self-coherent camera

NASA Astrophysics Data System (ADS)

Delorme, J. R.; Galicher, R.; Baudoz, P.; Rousset, G.; Mazoyer, J.; Dupuis, O.

2016-04-01

Context. High contrast imaging and spectroscopy provide unique constraints for exoplanet formation models as well as for planetary atmosphere models. But this can be challenging because of the planet-to-star small angular separation (<1 arcsec) and high flux ratio (>105). Recently, optimized instruments like VLT/SPHERE and Gemini/GPI were installed on 8m-class telescopes. These will probe young gazeous exoplanets at large separations (≳1 au) but, because of uncalibrated phase and amplitude aberrations that induce speckles in the coronagraphic images, they are not able to detect older and fainter planets. Aims: There are always aberrations that are slowly evolving in time. They create quasi-static speckles that cannot be calibrated a posteriori with sufficient accuracy. An active correction of these speckles is thus needed to reach very high contrast levels (>106-107). This requires a focal plane wavefront sensor. Our team proposed a self coherent camera, the performance of which was demonstrated in the laboratory. As for all focal plane wavefront sensors, these are sensitive to chromatism and we propose an upgrade that mitigates the chromatism effects. Methods: First, we recall the principle of the self-coherent camera and we explain its limitations in polychromatic light. Then, we present and numerically study two upgrades to mitigate chromatism effects: the optical path difference method and the multireference self-coherent camera. Finally, we present laboratory tests of the latter solution. Results: We demonstrate in the laboratory that the multireference self-coherent camera can be used as a focal plane wavefront sensor in polychromatic light using an 80 nm bandwidth at 640 nm (bandwidth of 12.5%). We reach a performance that is close to the chromatic limitations of our bench: 1σ contrast of 4.5 × 10-8 between 5 and 17 λ0/D. Conclusions: The performance of the MRSCC is promising for future high-contrast imaging instruments that aim to actively minimize the speckle intensity so as to detect and spectrally characterize faint old or light gaseous planets.

Fiber-optic proximity sensor

NASA Technical Reports Server (NTRS)

Bejczy, A. K.; Hermann, W. A.; Primus, H. C.

1980-01-01

Proximity sensor for mechanical hand of remote manipulator incorporates fiber optics to conduct signals between light source and light detector. Fiber optics are not prone to noise from electromagnetic interference and radio-frequency interference as are sensors using long electrical cables.

Light backscatter fiber optic sensor: a new tool for predicting the stability of pork emulsions containing antioxidative potato protein hydrolysate.

PubMed

Nieto, Gema; Xiong, Youling L; Payne, Fred; Castillo, Manuel

2015-02-01

The objective of this study was to determine whether light backscatter response from fresh pork meat emulsions is correlated to final product stability indices. A specially designed fiber optic measurement system was used in combination with a miniature fiber optic spectrometer to determine the intensity of light backscatter within the wavelength range 300-1100 nm (UV/VIS/NIR) at different radial distances (2, 2.5 and 3mm) with respect to the light source in pork meat emulsions with two fat levels (15%, 30%) and two levels (0, 2.5%) of the natural antioxidant hydrolyzed potato protein (HPP). Textural parameters (hardness, deformability, cohesiveness and breaking force), cooking loss, TBARS (1, 2, 3, and 7 days of storage at 4 °C) and CIELAB color coordinates of cooked emulsions were measured. The light backscatter was directly correlated with cooking losses, color, breaking force and TBARS. The optical configuration proposed would compensate for the emulsion heterogeneity, maximizing the existing correlation between the optical signal and the emulsion quality metrics.

CdSe/ZnS quantum dot fluorescence spectra shape-based thermometry via neural network reconstruction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munro, Troy; Laboratory of Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Heverlee; Liu, Liwang

As a system of interest gets small, due to the influence of the sensor mass and heat leaks through the sensor contacts, thermal characterization by means of contact temperature measurements becomes cumbersome. Non-contact temperature measurement offers a suitable alternative, provided a reliable relationship between the temperature and the detected signal is available. In this work, exploiting the temperature dependence of their fluorescence spectrum, the use of quantum dots as thermomarkers on the surface of a fiber of interest is demonstrated. The performance is assessed of a series of neural networks that use different spectral shape characteristics as inputs (peak-based—peak intensity,more » peak wavelength; shape-based—integrated intensity, their ratio, full-width half maximum, peak normalized intensity at certain wavelengths, and summation of intensity over several spectral bands) and that yield at their output the fiber temperature in the optically probed area on a spider silk fiber. Starting from neural networks trained on fluorescence spectra acquired in steady state temperature conditions, numerical simulations are performed to assess the quality of the reconstruction of dynamical temperature changes that are photothermally induced by illuminating the fiber with periodically intensity-modulated light. Comparison of the five neural networks investigated to multiple types of curve fits showed that using neural networks trained on a combination of the spectral characteristics improves the accuracy over use of a single independent input, with the greatest accuracy observed for inputs that included both intensity-based measurements (peak intensity) and shape-based measurements (normalized intensity at multiple wavelengths), with an ultimate accuracy of 0.29 K via numerical simulation based on experimental observations. The implications are that quantum dots can be used as a more stable and accurate fluorescence thermometer for solid materials and that use of neural networks for temperature reconstruction improves the accuracy of the measurement.« less

User-Wearable Devices that Monitor Exposure to Blue Light and Recommend Adjustments Thereto

NASA Technical Reports Server (NTRS)

Lee, Yong Jin (Inventor)

2017-01-01

Described herein are user-wearable devices that include an optical sensor, and methods for use therewith. In certain embodiments, an optical sensor of a user-wearable device (e.g., a wrist-worn device) is used to detect blue light that is incident on the optical sensor and to produce a blue light detection signal indicative thereof, and thus, indicative of the response of the user's intrinsically photosensitive Retinal Ganglion Cells (ipRGCs). In dependence on the blue light detection signal, there is a determination of a metric indicative of an amount of blue light detected by the optical sensor. The metric is compared to a corresponding threshold, and a user notification is triggered in dependence on results of the comparing, wherein the user notification informs a person wearing the user-wearable device to adjust their exposure to light.

Slow-light enhanced subwavelength plasmonic waveguide refractive index sensors.

PubMed

Huang, Yin; Min, Changjun; Dastmalchi, Pouya; Veronis, Georgios

2015-06-01

We introduce slow-light enhanced subwavelength scale refractive index sensors which consist of a plasmonic metal-dielectric-metal (MDM) waveguide based slow-light system sandwiched between two conventional MDM waveguides. We first consider a MDM waveguide with small width structrue for comparison, and then consider two MDM waveguide based slow light systems: a MDM waveguide side-coupled to arrays of stub resonators system and a MDM waveguide side-coupled to arrays of double-stub resonators system. We find that, as the group velocity decreases, the sensitivity of the effective index of the waveguide mode to variations of the refractive index of the fluid filling the sensors as well as the sensitivities of the reflection and transmission coefficients of the waveguide mode increase. The sensing characteristics of the slow-light waveguide based sensor structures are systematically analyzed. We show that the slow-light enhanced sensors lead to not only 3.9 and 3.5 times enhancements in the refractive index sensitivity, and therefore in the minimum detectable refractive index change, but also to 2 and 3 times reductions in the required sensing length, respectively, compared to a sensor using a MDM waveguide with small width structure.

Optical fibre sensors for the monitoring of a microwave plasma UV lamp and ozone generation system

NASA Astrophysics Data System (ADS)

O'Keeffe, S.; Ortoneda, M.; Cullen, J. D.; Shaw, A.; Fitzpatrick, C.; Lewis, E.; Phipps, D. A.; Al-Shamma'a, A. I.

2008-09-01

The food industry is keen to have new techniques that improve the safety and shelf life of food products without the use of preservatives. The use of UV light and ozone (O3) gas are becoming increasingly popular as methods to decontaminate food and thus extending its shelf life. A microwave radiation device that is a novel source of both germicidal UV and O3 suitable for the food industry has been developed, which offers speed, cost and energy benefits over existing sources. With this system comes the need to monitor a number of conditions, primarily UV intensity and ozone gas concentrations. An optical fibre sensor system is being developed to analyse these properties, in order to control and optimise the outputs of the microwave plasma UV lamp.

Reducing a congestion with introduce the greedy algorithm on traffic light control

NASA Astrophysics Data System (ADS)

Catur Siswipraptini, Puji; Hendro Martono, Wisnu; Hartanti, Dian

2018-03-01

The density of vehicles causes congestion seen at every junction in the city of jakarta due to the static or manual traffic timing lamp system consequently the length of the queue at the junction is uncertain. The research has been aimed at designing a sensor based traffic system based on the queue length detection of the vehicle to optimize the duration of the green light. In detecting the length of the queue of vehicles using infrared sensor assistance placed in each intersection path, then apply Greedy algorithm to help accelerate the movement of green light duration for the path that requires, while to apply the traffic lights regulation program based on greedy algorithm which is then stored on microcontroller with Arduino Mega 2560 type. Where a developed system implements the greedy algorithm with the help of the infrared sensor it will extend the duration of the green light on the long vehicle queue and accelerate the duration of the green light at the intersection that has the queue not too dense. Furthermore, the design is made to form an artificial form of the actual situation of the scale model or simple simulator (next we just called as scale model of simulator) of the intersection then tested. Sensors used are infrared sensors, where the placement of sensors in each intersection on the scale model is placed within 10 cm of each sensor and serves as a queue detector. From the results of the test process on the scale model with a longer queue obtained longer green light time so it will fix the problem of long queue of vehicles. Using greedy algorithms can add long green lights for 2 seconds on tracks that have long queues at least three sensor levels and accelerate time at other intersections that have longer queue sensor levels less than level three.

Swept optical SSB-SC modulation technique for high-resolution large-dynamic-range static strain measurement using FBG-FP sensors.

PubMed

Huang, Wenzhu; Zhang, Wentao; Li, Fang

2015-04-01

This Letter presents a static strain demodulation technique for FBG-FP sensors using a suppressed carrier LiNbO(3) (LN) optical single sideband (SSB-SC) modulator. A narrow-linewidth tunable laser source is generated by driving the modulator using a linear chirp signal. Then this tunable single-frequency laser is used to interrogate the FBG-FP sensors with the Pound-Drever-Hall (PDH) technique, which is beneficial to eliminate the influence of light intensity fluctuation of the modulator at different tuning frequencies. The static strain is demodulated by calculating the wavelength difference of the PDH signals between the sensing FBG-FP sensor and the reference FBG-FP sensor. As an experimental result using the modulator, the linearity (R²) of the time-frequency response increases from 0.989 to 0.997, and the frequency-swept range (dynamic range) increases from hundreds of MHz to several GHz compared with commercial PZT-tunable lasers. The high-linearity time-wavelength relationship of the modulator is beneficial for improving the strain measurement resolution, as it can solve the problem of the frequency-swept nonlinearity effectively. In the laboratory test, a 0.67 nanostrain static strain resolution, with a 6 GHz dynamic range, is demonstrated.

Zero-power infrared digitizers based on plasmonically enhanced micromechanical photoswitches

NASA Astrophysics Data System (ADS)

Qian, Zhenyun; Kang, Sungho; Rajaram, Vageeswar; Cassella, Cristian; McGruer, Nicol E.; Rinaldi, Matteo

2017-10-01

State-of-the-art sensors use active electronics to detect and discriminate light, sound, vibration and other signals. They consume power constantly, even when there is no relevant data to be detected, which limits their lifetime and results in high costs of deployment and maintenance for unattended sensor networks. Here we propose a device concept that fundamentally breaks this paradigm—the sensors remain dormant with near-zero power consumption until awakened by a specific physical signature associated with an event of interest. In particular, we demonstrate infrared digitizing sensors that consist of plasmonically enhanced micromechanical photoswitches (PMPs) that selectively harvest the impinging electromagnetic energy in design-defined spectral bands of interest, and use it to create mechanically a conducting channel between two electrical contacts, without the need for any additional power source. Our zero-power digitizing sensor prototypes produce a digitized output bit (that is, a large and sharp off-to-on state transition with an on/off conductance ratio >1012 and subthreshold slope >9 dec nW-1) when exposed to infrared radiation in a specific narrow spectral band (∼900 nm bandwidth in the mid-infrared) with the intensity above a power threshold of only ∼500 nW, which is not achievable with any existing photoswitch technologies.

Illumination adaptation with rapid-response color sensors

NASA Astrophysics Data System (ADS)

Zhang, Xinchi; Wang, Quan; Boyer, Kim L.

2014-09-01

Smart lighting solutions based on imaging sensors such as webcams or time-of-flight sensors suffer from rising privacy concerns. In this work, we use low-cost non-imaging color sensors to measure local luminous flux of different colors in an indoor space. These sensors have much higher data acquisition rate and are much cheaper than many o_-the-shelf commercial products. We have developed several applications with these sensors, including illumination feedback control and occupancy-driven lighting.

Effects of thinning intensities on transpiration and productivity of 50-year-old Pinus koraeinsis stands

NASA Astrophysics Data System (ADS)

Park, Juhan; Kim, Taekyu; Moon, Minkyu; Cho, Sungsik; Ryu, Daun; Kim, Hyun Seok

2015-04-01

This study investigated the effects of thinning intensities on stand transpiration and productivity of 50-year-old Korean pine forests for two years. Forest thinning, which removes some fraction of trees from stand, is widely conducted for reducing competition between remaining trees, improving tree productivity, reducing the risk of natural fire, and thus maintaining healthy forest. Forest thinning alters the microclimatic conditions such as radiation distribution within canopy, vapor pressure deficit, and amount of available soil water. These changes influence on the tree water use, and related productivity. Thinning was conducted on March, 2012 with two intensities (Control, Light-thinning (20%), and Heavy-thinning (40% of tree density)). Transpiration was estimated from sap flux density, which was measured with Granier-type thermal dissipation sensors. Tree diameter growth was measured with dendrometer, and converted to tree productivity using allometric equations developed specifically in our study sites. The climatic conditions showed little differences between two years. During the first growing season after thinning, stand transpiration was ca. 20% and 42% lower on light-thinning and heavy-thinning stand, respectively, even though sap flux density were higher in thinned stand. The difference in stand transpiration among treatments showed seasonal trends, so it was larger on summer when soil moisture was abundant due to monsoon, but was diminished on spring and autumn when soil moisture was limited. Tree-level productivity increased ca. 8% and 21% on light-thinning and heavy thinning stand, respectively. However, stand net primary production was ca. 20% lower on light-thinning stand, and ca. 31% on heavy-thinning stand. As a result, water use efficiency increased only in heavy-thinning stand. During the second growing season after thinning, stand transpiration was ca. 19% lower on light-thinning stand, and ca. 37% lower on heavy-thinning stand. The reduction of stand transpiration difference in heavy-thinning stand was caused mainly by increase in sap flux density. Trees in thinned stand showed higher productivity, but the magnitude was ca. 4% on light-thinning stand, and ca. 27% on heavy-thinning stand. Stand net primary production was ca. 23% lower on light-thinning stand, and ca. 28% on heavy-thinning stand. As a result, heavy-thinning stand showed highest water use efficiency. These results indicate that there are differences in biological reactions with thinning intensities.

Luminescent Sensors for Tracking Spatial Particle Distribution in an Explosion

NASA Astrophysics Data System (ADS)

Eilers, Hergen; Gunawidjaja, Ray; Diez-Y-Riega, Helena; Svingala, Forrest; Daniels, Amber; Lightstone, James; Washington State University Collaboration; Nswc Iheodtd Collaboration

2015-06-01

We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 orp-Eu:ZrO2/c-Tb:Y2O3. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 365 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference. Defense Threat Reduction Agency, HDTRA1-10-1-0005.

A Probability-Based Algorithm Using Image Sensors to Track the LED in a Vehicle Visible Light Communication System.

PubMed

Huynh, Phat; Do, Trong-Hop; Yoo, Myungsik

2017-02-10

This paper proposes a probability-based algorithm to track the LED in vehicle visible light communication systems using a camera. In this system, the transmitters are the vehicles' front and rear LED lights. The receivers are high speed cameras that take a series of images of the LEDs. ThedataembeddedinthelightisextractedbyfirstdetectingthepositionoftheLEDsintheseimages. Traditionally, LEDs are detected according to pixel intensity. However, when the vehicle is moving, motion blur occurs in the LED images, making it difficult to detect the LEDs. Particularly at high speeds, some frames are blurred at a high degree, which makes it impossible to detect the LED as well as extract the information embedded in these frames. The proposed algorithm relies not only on the pixel intensity, but also on the optical flow of the LEDs and on statistical information obtained from previous frames. Based on this information, the conditional probability that a pixel belongs to a LED is calculated. Then, the position of LED is determined based on this probability. To verify the suitability of the proposed algorithm, simulations are conducted by considering the incidents that can happen in a real-world situation, including a change in the position of the LEDs at each frame, as well as motion blur due to the vehicle speed.

Micro/Nanofibre Optical Sensors: Challenges and Prospects

PubMed Central

Tong, Limin

2018-01-01

Micro/nanofibres (MNFs) are optical fibres with diameters close to or below the vacuum wavelength of visible or near-infrared light. Due to its wavelength- or sub-wavelength scale diameter and relatively large index contrast between the core and cladding, an MNF can offer engineerable waveguiding properties including optical confinement, fractional evanescent fields and surface intensity, which is very attractive to optical sensing on the micro and nanometer scale. In particular, the waveguided low-loss tightly confined large fractional evanescent fields, enabled by atomic level surface roughness and extraordinary geometric and material uniformity in a glass MNF, is one of its most prominent merits in realizing optical sensing with high sensitivity and great versatility. Meanwhile, the mesoporous matrix and small diameter of a polymer MNF, make it an excellent host fibre for functional materials for fast-response optical sensing. In this tutorial, we first introduce the basics of MNF optics and MNF optical sensors, and review the progress and current status of this field. Then, we discuss challenges and prospects of MNF sensors to some extent, with several clues for future studies. Finally, we conclude with a brief outlook for MNF optical sensors.

A low-cost polarimeter for an undergraduate laboratory to study the polarization pattern of skylight

NASA Astrophysics Data System (ADS)

Abayaratne, Chula P.; Bandara, Vibodha

2017-03-01

A simple, low-cost, fully automated polarimeter, which demonstrates fundamental properties of skylight scattering and polarization for undergraduate physics students, is described. The polarimeter includes a microprocessor-based control unit, a Sun tracker, an elevation-azimuth mount with two degrees of freedom, and a polarization sensor unit equipped with a light-dependent resistor for measuring light intensity. Results obtained in the principal plane of the Sun using the polarimeter on a relatively clear day, together with the theoretically expected results for a molecular atmosphere, are presented. A root-mean-square error comparison indicates fairly good agreement between theory and experiment. Construction and experimentation with the polarimeter will provide students with insight into important physical concepts involved in skylight scattering and polarization as well as improve their instrumentation capabilities.

Fiber optic level sensor for cryogens

NASA Technical Reports Server (NTRS)

Sharma, M.

1981-01-01

Sensor is useful in cryogenic environments where liquids of very low index of refraction are encountered. It is "yes/no" indication of whether liquid is in contact with sensor. Sharp bends in fiber alter distribution of light among propagation modes. This amplifies change in light output observed when sensor contacts liquid, without requiring long fiber that would increse insertion loss.

Sensor/amplifier for weak light sources

NASA Technical Reports Server (NTRS)

Desmet, D. J.; Jason, A. J.; Parr, A. C.

1980-01-01

Light sensor/amplifier circuit detects weak light converts it into strong electrical signal in electrically noisy environment. Circuit is relatively simple and uses inexpensive, readily available components. Device is useful in such applications as fire detection and photographic processing.

Reducing cross-sensitivity of TiO2-(B) nanowires to humidity using ultraviolet illumination for trace explosive detection.

PubMed

Wang, Danling; Chen, Antao; Jen, Alex K-Y

2013-04-14

Environmental humidity is an important factor that can influence the sensing performance of a metal oxide. TiO2-(B) in the form of nanowires has been demonstrated to be a promising material for the detection of explosive gases such as 2,4,6-trinitrotoluene (TNT). However, the elimination of cross-sensitivity of the explosive detectors based on TiO2-(B) toward environmental humidity is still a major challenge. It was found that the cross-sensitivity could be effectively modulated when the thin film of TiO2-(B) nanowires was exposed to ultraviolet (UV) light during the detection of explosives under operating conditions. Such a modulation of sensing responses of TiO2-(B) nanowires to explosives by UV light was attributed to a photocatalytic effect, with which the water adsorbed on the TiO2-(B) nanowire surface was split and therefore the sensor response performance was less affected. It was revealed that the cross-sensitivity could be suppressed up to 51% when exposed to UV light of 365 nm wavelength with an intensity of 40 mW cm(-2). This finding proves that the reduction of cross-sensitivity to humidity through UV irradiation is an effective approach that can improve the performance of a sensor based on TiO2-(B) nanowires for the detection of explosive gas.

Microlens array processor with programmable weight mask and direct optical input

NASA Astrophysics Data System (ADS)

Schmid, Volker R.; Lueder, Ernst H.; Bader, Gerhard; Maier, Gert; Siegordner, Jochen

1999-03-01

We present an optical feature extraction system with a microlens array processor. The system is suitable for online implementation of a variety of transforms such as the Walsh transform and DCT. Operating with incoherent light, our processor accepts direct optical input. Employing a sandwich- like architecture, we obtain a very compact design of the optical system. The key elements of the microlens array processor are a square array of 15 X 15 spherical microlenses on acrylic substrate and a spatial light modulator as transmissive mask. The light distribution behind the mask is imaged onto the pixels of a customized a-Si image sensor with adjustable gain. We obtain one output sample for each microlens image and its corresponding weight mask area as summation of the transmitted intensity within one sensor pixel. The resulting architecture is very compact and robust like a conventional camera lens while incorporating a high degree of parallelism. We successfully demonstrate a Walsh transform into the spatial frequency domain as well as the implementation of a discrete cosine transform with digitized gray values. We provide results showing the transformation performance for both synthetic image patterns and images of natural texture samples. The extracted frequency features are suitable for neural classification of the input image. Other transforms and correlations can be implemented in real-time allowing adaptive optical signal processing.

Sensitivity improvement of one-shot Fourier spectroscopic imager for realization of noninvasive blood glucose sensors in smartphones

NASA Astrophysics Data System (ADS)

Kawashima, Natsumi; Nogo, Kosuke; Hosono, Satsuki; Nishiyama, Akira; Wada, Kenji; Ishimaru, Ichiro

2016-11-01

The use of the wide-field-stop and beam-expansion method for sensitivity enhancement of one-shot Fourier spectroscopy is proposed to realize health care sensors installed in smartphones for daily monitoring. When measuring the spectral components of human bodies noninvasively, diffuse reflected light from biological membranes is too weak for detection using conventional hyperspectral cameras. One-shot Fourier spectroscopy is a spatial phase-shift-type interferometer that can determine the one-dimensional spectral characteristics from a single frame. However, this method has low sensitivity, so that only the spectral characteristics of light sources with direct illumination can be obtained, because a single slit is used as a field stop. The sensitivity of the proposed spectroscopic method is improved by using the wide-field-stop and beam-expansion method. The use of a wider field stop slit width increases the detected light intensity; however, this simultaneously narrows the diffraction angle. The narrower collimated objective beam diameter degrades the visibility of interferograms. Therefore, a plane-concave cylindrical lens between the objective plane and the single slit is introduced to expand the beam diameter. The resulting sensitivity improvement achieved when using the wide-field-stop and beam-expansion method allows the spectral characteristics of hemoglobin to be obtained noninvasively from a human palm using a midget lamp.

A novel automated method for doing registration and 3D reconstruction from multi-modal RGB/IR image sequences

NASA Astrophysics Data System (ADS)

Kirby, Richard; Whitaker, Ross

2016-09-01

In recent years, the use of multi-modal camera rigs consisting of an RGB sensor and an infrared (IR) sensor have become increasingly popular for use in surveillance and robotics applications. The advantages of using multi-modal camera rigs include improved foreground/background segmentation, wider range of lighting conditions under which the system works, and richer information (e.g. visible light and heat signature) for target identification. However, the traditional computer vision method of mapping pairs of images using pixel intensities or image features is often not possible with an RGB/IR image pair. We introduce a novel method to overcome the lack of common features in RGB/IR image pairs by using a variational methods optimization algorithm to map the optical flow fields computed from different wavelength images. This results in the alignment of the flow fields, which in turn produce correspondences similar to those found in a stereo RGB/RGB camera rig using pixel intensities or image features. In addition to aligning the different wavelength images, these correspondences are used to generate dense disparity and depth maps. We obtain accuracies similar to other multi-modal image alignment methodologies as long as the scene contains sufficient depth variations, although a direct comparison is not possible because of the lack of standard image sets from moving multi-modal camera rigs. We test our method on synthetic optical flow fields and on real image sequences that we created with a multi-modal binocular stereo RGB/IR camera rig. We determine our method's accuracy by comparing against a ground truth.

Thermal tuning of infrared resonant absorbers based on hybrid gold-VO{sub 2} nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kocer, Hasan; Department of Electrical Engineering, Turkish Military Academy, 06654 Ankara; Butun, Serkan

2015-04-20

Resonant absorbers based on plasmonic materials, metamaterials, and thin films enable spectrally selective absorption filters, where absorption is maximized at the resonance wavelength. By controlling the geometrical parameters of nano/microstructures and materials' refractive indices, resonant absorbers are designed to operate at wide range of wavelengths for applications including absorption filters, thermal emitters, thermophotovoltaic devices, and sensors. However, once resonant absorbers are fabricated, it is rather challenging to control and tune the spectral absorption response. Here, we propose and demonstrate thermally tunable infrared resonant absorbers using hybrid gold-vanadium dioxide (VO{sub 2}) nanostructure arrays. Absorption intensity is tuned from 90% to 20%more » and 96% to 32% using hybrid gold-VO{sub 2} nanowire and nanodisc arrays, respectively, by heating up the absorbers above the phase transition temperature of VO{sub 2} (68 °C). Phase change materials such as VO{sub 2} deliver useful means of altering optical properties as a function of temperature. Absorbers with tunable spectral response can find applications in sensor and detector applications, in which external stimulus such as heat, electrical signal, or light results in a change in the absorption spectrum and intensity.« less

A fiber optic multi-stress monitoring system for power transformer

NASA Astrophysics Data System (ADS)

Kim, Dae-gil; Sampath, Umesh; Kim, Hyunjin; Song, Minho

2017-04-01

A fiber-optic multi-stress monitoring system which uses 4 FBG sensors and a fiber-optic mandrel acoustic emission sensor is proposed. FBG sensors and a mandrel sensor measure different types of stresses occurring in electrical power transformer, such as temperature and acoustic signals. The sensor system uses single broadband light source to address the outputs of both sensors using single fiber-optic circuitry. An athermal-packaged FBG is used to supply quasi-coherent light for the Sagnac interferometer demodulation which processes the mandrel sensor output. The proposed sensor system could simplify the optical circuit for the multi-stress measurements and enhance the cost-effectiveness of the sensor system.

Thin-film fiber optic hydrogen and temperature sensor system

DOEpatents

Nave, Stanley E.

1998-01-01

The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiberoptic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences.

Thin-film fiber optic hydrogen and temperature sensor system

DOEpatents

Nave, S.E.

1998-07-21

The invention discloses a sensor probe device for monitoring of hydrogen gas concentrations and temperatures by the same sensor probe. The sensor probe is constructed using thin-film deposition methods for the placement of a multitude of layers of materials sensitive to hydrogen concentrations and temperature on the end of a light transparent lens located within the sensor probe. The end of the lens within the sensor probe contains a lens containing a layer of hydrogen permeable material which excludes other reactive gases, a layer of reflective metal material that forms a metal hydride upon absorbing hydrogen, and a layer of semi-conducting solid that is transparent above a temperature dependent minimum wavelength for temperature detection. The three layers of materials are located at the distal end of the lens located within the sensor probe. The lens focuses light generated by broad-band light generator and connected by fiber-optics to the sensor probe, onto a reflective metal material layer, which passes through the semi-conducting solid layer, onto two optical fibers located at the base of the sensor probe. The reflected light is transmitted over fiber optic cables to a spectrometer and system controller. The absence of electrical signals and electrical wires in the sensor probe provides for an elimination of the potential for spark sources when monitoring in hydrogen rich environments, and provides a sensor free from electrical interferences. 3 figs.

Suppression of sun interference in the star sensor baffling stray light by total internal reflection

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Shimoji, Haruhiko; Yoshikawa, Shoji; Miyatake, Katsumasa; Hama, Kazumori; Nakamura, Shuji

2005-09-01

We have developed a star sensor as an experimental device onboard the SERVIS-1 satellite launched in October 2003. The in-orbit data have verified its fundamental performance. One of the advantages of our star sensor is that the baffle has a small length of 120 mm instead of 182 mm in the conventional two-stage baffle design. The key concepts for light shielding are total internal reflection phenomena inside a nearly half sphere (NHS) lens and scattering light control by gloss black paint. However, undesirable background noise by the sun outside of the field of view (FOV) was observed in the corner of the FOV in the orbital experiment. Ray trace simulations revealed that slight scattering light on the specular baffle wall entered the NHS lens and reached the corner of the image sensor through the multi-reflection path inside the lens. It was found that the stray light path can be shielded effectively if the diameter of the aperture under the NHS lens was reduced. We redesigned the baffle and evaluated the light shielding ability with our sun interference test facility on the ground, and confirmed that the stray light was reduced below the acceptable level. As a result, the light shielding technique which we have proposed was proved to be effective for a small-size baffle. The redesigned star sensor is planned to be installed as a main attitude sensor for the SERVIS-2 satellite scheduled to be launched in February 2008.

Light-Regulated Electrochemical Sensor Array for Efficiently Discriminating Hazardous Gases.

PubMed

Liang, Hongqiu; Zhang, Xin; Sun, Huihui; Jin, Han; Zhang, Xiaowei; Jin, Qinghui; Zou, Jie; Haick, Hossam; Jian, Jiawen

2017-10-27

Inadequate detection limit and unsatisfactory discrimination features remain the challenging issues for the widely applied electrochemical gas sensors. Quite recently, we confirmed that light-regulated electrochemical reaction significantly enhanced the electrocatalytic activity, and thereby can potentially extend the detection limit to the parts per billion (ppb) level. Nevertheless, impact of the light-regulated electrochemical reaction on response selectivity has been discussed less. Herein, we systematically report on the effect of illumination on discrimination features via design and fabrication of a light-regulated electrochemical sensor array. Upon illumination (light on), response signal to the examined gases (C 3 H 6 , NO, and CO) is selectively enhanced, resulting in the sensor array demonstrating disparate response patterns when compared with that of the sensor array operated at light off. Through processing all the response patterns derived from both light on and light off with a pattern recognition algorithm, a satisfactory discrimination feature is observed. In contrast, apparent mutual interference between NO and CO is found when the sensor array is solely operated without illumination. The impact mechanism of the illumination is studied and it is deduced that the effect of the illumination on the discriminating features can be mainly attributed to the competition of electrocatalytic activity and gas-phase reactivity. If the enhanced electrocatalytic activity (to specific gas) dominates the whole sensing progress, enhancements in the corresponding response signal would be observed upon illumination. Otherwise, illumination gives a negligible impact. Hence, the response signal to part of the examined gases is selectively enhanced by illumination. Conclusively, light-regulated electrochemical reaction would provide an efficient approach to designing future smart sensing devices.

Measurement and application of bidirectional reflectance distribution function

NASA Astrophysics Data System (ADS)

Liao, Fei; Li, Lin; Lu, Chengwen

2016-10-01

When a beam of light with certain intensity and distribution reaches the surface of a material, the distribution of the diffused light is related to the incident angle, the receiving angle, the wavelength of the light and the types of the material. Bidirectional Reflectance Distribution Function (BRDF) is a method to describe this distribution. For an optical system, the optical and mechanical materials' BRDF are unique, and if we want to calculate stray light of the system we should know the correct BRDF data of the whole materials. There are fundamental significances in the area of space remote sensor where BRDF is needed in the precise radiation calibration. It is also important in the military field where BRDF can be used in the object identification and target tracking, etc. In this paper, 11 kinds of aerospace materials' BRDF are measured and more than 310,000 groups of BRDF data are achieved , and also a BRDF database is established in China for the first time. With the BRDF data of the database, we can create the detector model, build the stray light radiation surface model in the stray light analysis software. In this way, the stray radiation on the detector can be calculated correctly.

Finding the average speed of a light-emitting toy car with a smartphone light sensor

NASA Astrophysics Data System (ADS)

Kapucu, Serkan

2017-07-01

This study aims to demonstrate how the average speed of a light-emitting toy car may be determined using a smartphone’s light sensor. The freely available Android smartphone application, ‘AndroSensor’, was used for the experiment. The classroom experiment combines complementary physics knowledge of optics and kinematics to find the average speed of a moving object. The speed of the toy car is found by determining the distance between the light-emitting toy car and the smartphone, and the time taken to travel these distances. To ensure that the average speed of the toy car calculated with the help of the AndroSensor was correct, the average speed was also calculated by analyzing video-recordings of the toy car. The resulting speeds found with these different methods were in good agreement with each other. Hence, it can be concluded that reliable measurements of the average speed of light-emitting objects can be determined with the help of the light sensor of an Android smartphone.

Pressure sensor using liquid crystals

NASA Technical Reports Server (NTRS)

Parmar, Devendra S. (Inventor); Holmes, Harlan K. (Inventor)

1994-01-01

A pressure sensor includes a liquid crystal positioned between transparent, electrically conductive films (18 and 20), that are biased by a voltage (V) which induces an electric field (E) that causes the liquid crystal to assume a first state of orientation. Application of pressure (P) to a flexible, transparent film (24) causes the conductive film (20) to move closer to or farther from the conductive film (18), thereby causing a change in the electric field (E'(P)) which causes the liquid crystal to assume a second state of orientation. Polarized light (P.sub.1) is directed into the liquid crystal and transmitted or reflected to an analyzer (A or 30). Changes in the state of orientation of the liquid crystal induced by applied pressure (P) result in a different light intensity being detected at the analyzer (A or 30) as a function of the applied pressure (P). In particular embodiments, the liquid crystal is present as droplets (10) in a polymer matrix (12) or in cells (14) in a polymeric or dielectric grid (16) material in the form of a layer (13) between the electrically conductive films (18 and 20). The liquid crystal fills the open wells in the polymer matrix (12) or grid (16) only partially.

Control of arc length during gas metal arc welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madigan, R.B.; Quinn, T.P.

1994-12-31

An arc-length control system has been developed for gas metal arc welding (GMAW) under spray transfer welding conditions. The ability to monitor and control arc length during arc welding allows consistent weld characteristics to be maintained and therefore improves weld quality. Arc length control has only been implemented for gas tungsten arc welding (GTAW), where an automatic voltage control (AVC) unit adjusts torch-to-work distance. The system developed here compliments the voltage- and current-sensing techniques commonly used for control of GMAW. The system consists of an arc light intensity sensor (photodiode), a Hall-effect current sensor, a personal computer and software implementingmore » a data interpretation and control algorithms. Arc length was measured using both arc light and arc current signals. Welding current was adjusted to maintain constant arc length. A proportional-integral-derivative (PID) controller was used. Gains were automatically selected based on the desired welding conditions. In performance evaluation welds, arc length varied from 2.5 to 6.5 mm while welding up a sloped workpiece (ramp in CTWD) without the control. Arc length was maintained within 1 mm of the desired (5 mm ) with the control.« less

Use of Occupancy Sensors in LED Parking Lot and Garage Applications: Early Experiences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kinzey, Bruce R.; Myer, Michael; Royer, Michael P.

2012-11-07

Occupancy sensor systems are gaining traction as an effective technological approach to reducing energy use in exterior commercial lighting applications. Done correctly, occupancy sensors can substantially enhance the savings from an already efficient lighting system. However, this technology is confronted by several potential challenges and pitfalls that can leave a significant amount of the prospective savings on the table. This report describes anecdotal experiences from field installations of occupancy sensor controlled light-emitting diode (LED) lighting at two parking structures and two parking lots. The relative levels of success at these installations reflect a marked range of potential outcomes: from anmore » additional 76% in energy savings to virtually no additional savings. Several issues that influenced savings were encountered in these early stage installations and are detailed in the report. Ultimately, care must be taken in the design, selection, and commissioning of a sensor-controlled lighting installation, else the only guaranteed result may be its cost.« less

Optochemical sensor based on screenprinted fluorescent sensorspots surrounded by organic photodiodes for multianalyte detection

NASA Astrophysics Data System (ADS)

Kraker, E.; Lamprecht, B.; Haase, A.; Jakopic, G.; Abel, T.; Konrad, C.; Köstler, S.; Tscherner, M.; Stadlober, B.; Mayr, T.

2010-08-01

A compact, integrated photoluminescence based oxygen sensor, utilizing an organic light emitting device (OLED) as the light source and an organic photodiode (OPD) as the detection unit, is described. The detection system of the sensor array consists of an array of circular screen-printed fluorescent sensor spots surrounded by organic photodiodes as integrated fluorescence detectors. The OPD originates from the well-known Tang photodiode, consisting of a stacked layer of copper phthalocyanine (CuPc, p-type material) and perylene tetracarboxylic bisbenzimidazole (PTCBi, n-type material). An additional layer of tris-8-hydroxyquinolinatoaluminium (Alq3, n-type material) was inserted between the PTCBi layer and cathode. An ORMOCERR layer was used as encapsulation layer. For excitation an organic light emitting diode is used. The sensor spot and the detector are processed on the same flexible substrate. This approach not only simplifies the detection system by minimizing the numbers of required optical components - no optical filters have to be used for separating the excitation light and the luminescent emission-, but also has a large potential for low-cost sensor applications. The feasibility of the concept is demonstrated by an integrated oxygen sensor, indicating good performance. Sensor schemes for other chemical parameters are proposed.

Fiber Optic Geophysics Sensor Array

NASA Astrophysics Data System (ADS)

Grochowski, Lucjan

1989-01-01

The distributed optical sensor arrays are analysed in view of specific needs of 3-D seismic explorations methods. There are compared advantages and disadventages of arrays supported by the sensors which are modulated in intensity and phase. In these systems all-fiber optic structures and their compabilities with digital geophysic formats are discussed. It was shown that the arrays based on TDM systems with the intensity modulated sensors are economically and technically the best matched for geophysic systems supported by a large number of the sensors.

Integration of OLEDs in biomedical sensor systems: design and feasibility analysis

NASA Astrophysics Data System (ADS)

Rai, Pratyush; Kumar, Prashanth S.; Varadan, Vijay K.

2010-04-01

Organic (electronic) Light Emitting Diodes (OLEDs) have been shown to have applications in the field of lighting and flexible display. These devices can also be incorporated in sensors as light source for imaging/fluorescence sensing for miniaturized systems for biomedical applications and low-cost displays for sensor output. The current device capability aligns well with the aforementioned applications as low power diffuse lighting and momentary/push button dynamic display. A top emission OLED design has been proposed that can be incorporated with the sensor and peripheral electrical circuitry, also based on organic electronics. Feasibility analysis is carried out for an integrated optical imaging/sensor system, based on luminosity and spectrum band width. A similar study is also carried out for sensor output display system that functions as a pseudo active OLED matrix. A power model is presented for device power requirements and constraints. The feasibility analysis is also supplemented with the discussion about implementation of ink-jet printing and stamping techniques for possibility of roll to roll manufacturing.

Theoretical and experimental study of low-finesse extrinsic Fabry-Perot interferometric fiber optic sensors

NASA Astrophysics Data System (ADS)

Han, Ming

In this dissertation, detailed and systematic theoretical and experimental study of low-finesse extrinsic Fabry-Perot interferometric (EFPI) fiber optic sensors together with their signal processing methods for white-light systems are presented. The work aims to provide a better understanding of the operational principle of EFPI fiber optic sensors, and is useful and important in the design, optimization, fabrication and application of single mode fiber(SMF) EFPI (SMF-EFPI) and multimode fiber (MMF) EFPI (MMF-EFPI) sensor systems. The cases for SMF-EFPI and MMF-EFPI sensors are separately considered. In the analysis of SMF-EFPI sensors, the light transmitted in the fiber is approximated by a Gaussian beam and the obtained spectral transfer function of the sensors includes an extra phase shift due to the light coupling in the fiber end-face. This extra phase shift has not been addressed by previous researchers and is of great importance for high accuracy and high resolution signal processing of white-light SMF-EFPI systems. Fringe visibility degradation due to gap-length increase and sensor imperfections is studied. The results indicate that the fringe visibility of a SMF-EFPI sensor is relatively insensitive to the gap-length change and sensor imperfections. Based on the spectral fringe pattern predicated by the theory of SMF-EFPI sensors, a novel curve fitting signal processing method (Type 1 curve-fitting method) is presented for white-light SMF-EFPI sensor systems. Other spectral domain signal processing methods including the wavelength-tracking, the Type 2-3 curve fitting, Fourier transform, and two-point interrogation methods are reviewed and systematically analyzed. Experiments were carried out to compare the performances of these signal processing methods. The results have shown that the Type 1 curve fitting method achieves high accuracy, high resolution, large dynamic range, and the capability of absolute measurement at the same time, while others either have less resolution, or are not capable of absolute measurement. Previous mathematical models for MMF-EFPI sensors are all based on geometric optics; therefore their applications have many limitations. In this dissertation, a modal theory is developed that can be used in any situations and is more accurate. The mathematical description of the spectral fringes of MMF-EFPI sensors is obtained by the modal theory. Effect on the fringe visibility of system parameters, including the sensor head structure, the fiber parameters, and the mode power distribution in the MMF of the MMF-EFPI sensors, is analyzed. Experiments were carried out to validate the theory. Fundamental mechanism that causes the degradation of the fringe visibility in MMF-EFPI sensors are revealed. It is shown that, in some situations at which the fringe visibility is important and difficult to achieve, a simple method of launching the light into the MMF-EFPI sensor system from the output of a SMF could be used to improve the fringe visibility and to ease the fabrication difficulties of MMF-EFPI sensors. Signal processing methods that are well-understood in white-light SMF-EFPI sensor systems may exhibit new aspects when they are applied to white-light MMF-EFPI sensor systems. This dissertation reveals that the variations of mode power distribution (MPD) in the MMF could cause phase variations of the spectral fringes from a MMF-EFPI sensor and introduce measurement errors for a signal processing method in which the phase information is used. This MPD effect on the wavelength-tracking method in white-light MMF-EFPI sensors is theoretically analyzed. The fringe phases changes caused by MPD variations were experimentally observed and thus the MFD effect is validated.

Fiber optic gas sensor

NASA Technical Reports Server (NTRS)

Chen, Peng (Inventor); Buric, Michael P. (Inventor); Swinehart, Philip R. (Inventor); Maklad, Mokhtar S. (Inventor)

2010-01-01

A gas sensor includes an in-fiber resonant wavelength device provided in a fiber core at a first location. The fiber propagates a sensing light and a power light. A layer of a material is attached to the fiber at the first location. The material is able to absorb the gas at a temperature dependent gas absorption rate. The power light is used to heat the material and increases the gas absorption rate, thereby increasing sensor performance, especially at low temperatures. Further, a method is described of flash heating the gas sensor to absorb more of the gas, allowing the sensor to cool, thereby locking in the gas content of the sensor material, and taking the difference between the starting and ending resonant wavelengths as an indication of the concentration of the gas in the ambient atmosphere.

Development of low-cost meteorological observation system based on wireless network for poor-visibility occurred by snowstorm

NASA Astrophysics Data System (ADS)

Kobayashi, Y.; Watanabe, K.; Imai, M.; Watanabe, K.; Naruse, N.; Takahashi, Y.

2016-12-01

Hyper-densely monitoring for poor-visibility occurred by snowstorm is needed to make an alert system, because the snowstorm is difficult to predict from the observation only at a representative point. There are some problems in the previous approaches for the poor-visibility monitoring using video analyses or visibility meters; these require a wired network monitoring (a large amount of data: 10MB/sec at least) and the system cost is high (10,000 at each point). Thus, the risk of poor-visibility has been mainly measured at specific point such as airport and mountain pass, and estimated by simulation two dimensionally. To predict it two dimensionally and accurately, we have developed a low-cost meteorological system to observe the snowstorm hyper-densely. We have developed a low-cost visibility meter which works as the reduced intensity of semiconducting laser light when snow particles block off. Our developed system also has a capability of extending a hyper-densely observation in real-time on wireless network using Zigbee; A/D conversion and wireless data sent from temperature and illuminance sensors. We use a semiconducting laser chip (5) for the light source and a reflection mechanism by the use of three mirrors so as to send the light to a non-sensitive illuminance sensor directly. Thus, our visibility detecting system ($500) becomes much cheaper than previous one. We have checked the correlation between the reduced intensity taken by our system and the visibility recorded by conventional video camera. The value for the correlation coefficient was -0.67, which indicates a strong correlation. It means that our developed system is practical. In conclusion, we have developed low-cost meteorological detecting system to observe poor-visibility occurred by snowstorm, having a potential of hyper-densely monitoring on wireless network, and have made sure the practicability.

Fiber optic geophysical sensors

DOEpatents

Homuth, Emil F.

1991-01-01

A fiber optic geophysical sensor in which laser light is passed through a sensor interferometer in contact with a geophysical event, and a reference interferometer not in contact with the geophysical event but in the same general environment as the sensor interferometer. In one embodiment, a single tunable laser provides the laser light. In another embodiment, separate tunable lasers are used for the sensor and reference interferometers. The invention can find such uses as monitoring for earthquakes, and the weighing of objects.

Design of a Thermoacoustic Sensor for Low Intensity Ultrasound Measurements Based on an Artificial Neural Network.

PubMed

Xing, Jida; Chen, Jie

2015-06-23

In therapeutic ultrasound applications, accurate ultrasound output intensities are crucial because the physiological effects of therapeutic ultrasound are very sensitive to the intensity and duration of these applications. Although radiation force balance is a benchmark technique for measuring ultrasound intensity and power, it is costly, difficult to operate, and compromised by noise vibration. To overcome these limitations, the development of a low-cost, easy to operate, and vibration-resistant alternative device is necessary for rapid ultrasound intensity measurement. Therefore, we proposed and validated a novel two-layer thermoacoustic sensor using an artificial neural network technique to accurately measure low ultrasound intensities between 30 and 120 mW/cm2. The first layer of the sensor design is a cylindrical absorber made of plexiglass, followed by a second layer composed of polyurethane rubber with a high attenuation coefficient to absorb extra ultrasound energy. The sensor determined ultrasound intensities according to a temperature elevation induced by heat converted from incident acoustic energy. Compared with our previous one-layer sensor design, the new two-layer sensor enhanced the ultrasound absorption efficiency to provide more rapid and reliable measurements. Using a three-dimensional model in the K-wave toolbox, our simulation of the ultrasound propagation process demonstrated that the two-layer design is more efficient than the single layer design. We also integrated an artificial neural network algorithm to compensate for the large measurement offset. After obtaining multiple parameters of the sensor characteristics through calibration, the artificial neural network is built to correct temperature drifts and increase the reliability of our thermoacoustic measurements through iterative training about ten seconds. The performance of the artificial neural network method was validated through a series of experiments. Compared to our previous design, the new design reduced sensing time from 20 s to 12 s, and the sensor's average error from 3.97 mW/cm2 to 1.31 mW/cm2 respectively.

Optical Structural Health Monitoring Device

NASA Technical Reports Server (NTRS)

Buckner, Benjamin D.; Markov, Vladimir; Earthman, James C.

2010-01-01

This non-destructive, optical fatigue detection and monitoring system relies on a small and unobtrusive light-scattering sensor that is installed on a component at the beginning of its life in order to periodically scan the component in situ. The method involves using a laser beam to scan the surface of the monitored component. The device scans a laser spot over a metal surface to which it is attached. As the laser beam scans the surface, disruptions in the surface cause increases in scattered light intensity. As the disruptions in the surface grow, they will cause the light to scatter more. Over time, the scattering intensities over the scanned line can be compared to detect changes in the metal surface to find cracks, crack precursors, or corrosion. This periodic monitoring of the surface can be used to indicate the degree of fatigue damage on a component and allow one to predict the remaining life and/or incipient mechanical failure of the monitored component. This wireless, compact device can operate for long periods under its own battery power and could one day use harvested power. The prototype device uses the popular open-source TinyOS operating system on an off-the-shelf Mica2 sensor mote, which allows wireless command and control through dynamically reconfigurable multi-node sensor networks. The small size and long life of this device could make it possible for the nodes to be installed and left in place over the course of years, and with wireless communication, data can be extracted from the nodes by operators without physical access to the devices. While a prototype has been demonstrated at the time of this reporting, further work is required in the system s development to take this technology into the field, especially to improve its power management and ruggedness. It should be possible to reduce the size and sensitivity as well. Establishment of better prognostic methods based on these data is also needed. The increase of surface roughness with fatigue is closely connected to the microstructure of the metal, and ongoing research is seeking to connect this observed evidence of the fatigue state with microstructural theories of fatigue evolution to allow more accurate prognosis of remaining component life. Plans are also being discussed for flight testing, perhaps on NASA s SOFIA platform.

Fiber-Optic Sensor for Aircraft Lightning Current Measurement

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George G.; Mata, Carlos T.; Mata,Angel G.; Snyder, Gary P.

2012-01-01

An electric current sensor based on Faraday rotation effect in optical fiber was developed for measuring aircraft lightning current. Compared to traditional sensors, the design has many advantages including the ability to measure total current and to conform to structure geometries. The sensor is also small, light weight, non-conducting, safe from interference, and free of hysteresis and saturation. Potential applications include characterization of lightning current waveforms, parameters and paths, and providing environmental data for aircraft certifications. In an optical fiber as the sensing medium, light polarization rotates when exposed to a magnetic field in the direction of light propagation. By forming closed fiber loops around a conductor and applying Ampere s law, measuring the total light rotation yields the enclosed current. A reflective polarimetric scheme is used, where polarization change is measured after the polarized light travels round-trip through the sensing fiber. The sensor system was evaluated measuring rocket-triggered lightning over the 2011 summer. Early results compared very well against a reference current shunt resistor, demonstrating the sensor's accuracy and feasibility in a lightning environment. While later comparisons show gradually increasing amplitude deviations for an undetermined cause, the overall waveforms still compared very well.

Simultaneous remote measurement of CO2 concentration, humidity and temperature with a matrix of optical fiber sensors

NASA Astrophysics Data System (ADS)

Wysokiński, Karol; Filipowicz, Marta; Stańczyk, Tomasz; Lipiński, Stanisław; Napierała, Marek; Murawski, Michał; Nasiłowski, Tomasz

2017-10-01

A matrix of optical fiber sensors eligible for remote measurements is reported in this paper. The aim of work was to monitor the air quality with a device, which does not need any electricity on site of the measurement. The matrix consists of several sensors detecting carbon dioxide concentration, relative humidity and temperature. Sensors utilize active optical materials, which change their color when exposed to varied conditions. All the sensors are powered with standard light emitting diodes. Light is transmitted by an optical fiber from the light source and then it reaches the active layer which changes its color, when the conditions change. This results in a change of attenuation of light passing through the active layer. Modified light is then transmitted by another optical fiber to the detector, where simple photoresistor is used. It is powered by a stabilized DC power supply and the current is measured. Since no expensive elements are needed to manufacture such a matrix of sensors, its price may be competitive to the price of the devices already available on the market, while the matrix also exhibits other valuable properties.

Fiber-Optic Sensor for Aircraft Lightning Current Measurement

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George G.; Mata, Carlos T.; Mata, Angel G.; Snyder, Gary P.

2012-01-01

An electric current sensor based on Faraday rotation effect in optical fiber was developed for measuring aircraft lightning current. Compared to traditional sensors, the design has many advantages including the ability to measure total current and to conform to structure geometries. The sensor is also small, light weight, non-conducting, safe from interference, and free of hysteresis and saturation. Potential applications include characterization of lightning current waveforms, parameters and paths, and providing environmental data for aircraft certifications. In an optical fiber as the sensing medium, light polarization rotates when exposed to a magnetic field in the direction of light propagation. By forming closed fiber loops around a conductor and applying Ampere s law, measuring the total light rotation yields the enclosed current. A reflective polarimetric scheme is used, where polarization change is measured after the polarized light travels round-trip through the sensing fiber. The sensor system was evaluated measuring rocket-triggered lightning over the 2011 summer. Early results compared very well against a reference current shunt resistor, demonstrating the sensor s accuracy and feasibility in a lightning environment. While later comparisons show gradually increasing amplitude deviations for an undetermined cause, the overall waveforms still compared very well.

Precise color images a high-speed color video camera system with three intensified sensors

NASA Astrophysics Data System (ADS)

Oki, Sachio; Yamakawa, Masafumi; Gohda, Susumu; Etoh, Takeharu G.

1999-06-01

High speed imaging systems have been used in a large field of science and engineering. Although the high speed camera systems have been improved to high performance, most of their applications are only to get high speed motion pictures. However, in some fields of science and technology, it is useful to get some other information, such as temperature of combustion flame, thermal plasma and molten materials. Recent digital high speed video imaging technology should be able to get such information from those objects. For this purpose, we have already developed a high speed video camera system with three-intensified-sensors and cubic prism image splitter. The maximum frame rate is 40,500 pps (picture per second) at 64 X 64 pixels and 4,500 pps at 256 X 256 pixels with 256 (8 bit) intensity resolution for each pixel. The camera system can store more than 1,000 pictures continuously in solid state memory. In order to get the precise color images from this camera system, we need to develop a digital technique, which consists of a computer program and ancillary instruments, to adjust displacement of images taken from two or three image sensors and to calibrate relationship between incident light intensity and corresponding digital output signals. In this paper, the digital technique for pixel-based displacement adjustment are proposed. Although the displacement of the corresponding circle was more than 8 pixels in original image, the displacement was adjusted within 0.2 pixels at most by this method.

Multiagent robotic systems' ambient light sensor

NASA Astrophysics Data System (ADS)

Iureva, Radda A.; Maslennikov, Oleg S.; Komarov, Igor I.

2017-05-01

Swarm robotics is one of the fastest growing areas of modern technology. Being subclass of multi-agent systems it inherits the main part of scientific-methodological apparatus of construction and functioning of practically useful complexes, which consist of rather autonomous independent agents. Ambient light sensors (ALS) are widely used in robotics. But speaking about swarm robotics, the technology which has great number of specific features and is developing, we can't help mentioning that its important to use sensors on each robot not only in order to help it to get directionally oriented, but also to follow light emitted by robot-chief or to help to find the goal easier. Key words: ambient light sensor, swarm system, multiagent system, robotic system, robotic complexes, simulation modelling

Exciton Emission Intensity Modulation of Monolayer MoS2 via Au Plasmon Coupling

PubMed Central

Mukherjee, B.; Kaushik, N.; Tripathi, Ravi P. N.; Joseph, A. M.; Mohapatra, P. K.; Dhar, S.; Singh, B. P.; Kumar, G. V. Pavan; Simsek, E.; Lodha, S.

2017-01-01

Modulation of photoluminescence of atomically thin transition metal dichalcogenide two-dimensional materials is critical for their integration in optoelectronic and photonic device applications. By coupling with different plasmonic array geometries, we have shown that the photoluminescence intensity can be enhanced and quenched in comparison with pristine monolayer MoS2. The enhanced exciton emission intensity can be further tuned by varying the angle of polarized incident excitation. Through controlled variation of the structural parameters of the plasmonic array in our experiment, we demonstrate modulation of the photoluminescence intensity from nearly fourfold quenching to approximately threefold enhancement. Our data indicates that the plasmonic resonance couples to optical fields at both, excitation and emission bands, and increases the spontaneous emission rate in a double spacing plasmonic array structure as compared with an equal spacing array structure. Furthermore our experimental results are supported by numerical as well as full electromagnetic wave simulations. This study can facilitate the incorporation of plasmon-enhanced transition metal dichalcogenide structures in photodetector, sensor and light emitter applications. PMID:28134260

The design of a small flow optical sensor of particle counter

NASA Astrophysics Data System (ADS)

Zhan, Yongbo; zhang, Jianwei; Zeng, Jianxiong; Li, Bin; Chen, Lu

2018-01-01

Based on the principle of Mie scattering, we design a small flow optical sensor of particle counter. Firstly, laser illumination system was simulated and designed by ZEMAX optical design software, and the uniform light intensity of photosensitive area was obtained. The gas circuit structure was also designed according to the related theory of fluid mechanics. Then, the method of combining with MIST scattering calculation software and geometric modeling was firstly used to design spherical reflection system, on the basis of the formula of object-image distance. Finally, the test was conducted after the optical sensor placed in self-designed pre-amplification and high-speed processing circuit. The test results show that the counting efficiency of 0.3 μm gear is above 70%, 0.5 μm gear and 1.0 μm gear are both reached more than 90%, and the dispersion coefficient of each gear is very nearly the same, compared with the standard machine of Kanomax 3886 under the particle spraying flow of 2.5SCFH, 3.0SCFH, 3.5SCFH.

NFC-enabled, tattoo-like stretchable biosensor manufactured by "cut-and-paste" method.

PubMed

Hyoyoung Jeong; Taewoo Ha; Kuang, Irene; Linxiao Shen; Zhaohe Dai; Nan Sun; Nanshu Lu

2017-07-01

The wearables industry is lacking in devices that have the ability to provide valuable biometrics data in a soft, wireless and disposable system. Such a system should be high performance, multifunctional, but battery-free and low cost. Near field communication (NFC) is a wireless communication protocol built in many smartphones nowadays that can read data from battery-free passive tags. As a result, NFC-enabled wearable biosensors have been reported, but they are either unstretchable or have to be manufactured by labor- and time-intensive photolithography and transfer-printing processes. Using a dry and freeform "cut-and-paste" method, we have built a wireless and low-cost stretchable biosensor that integrates temperature sensor, light source/sensor, NFC chip, and antenna. It is battery-free and can be laminated on any part of human skin like a temporary transfer tattoo. The sensor can fully follow the stretching and compression of skin without mechanical failure or delamination. Thus, it is imperceptible to wear and can perform high-fidelity sensing. Potential applications include, but are not limited to, skin thermography and photometry.

iRadioactivity — Possibilities and Limitations for Using Smartphones and Tablet PCs as Radioactive Counters

NASA Astrophysics Data System (ADS)

Kuhn, Jochen; Molz, Alexander; Gröber, Sebastian; Frübis, Jan

2014-09-01

A study conducted in 2013 showed that about 70-80% of teens and young adults in the United States own a smartphone.1 Furthermore the number of tablet PC users in the United States will increase up to more than 80% by 2015.2 As a result, these devices have increasingly become everyday tools, particularly for the younger generation. In recent years, various articles have been published about the use of smartphones and tablet PCs as experimental tools especially in the physics classroom. This is possible because today's smartphones and tablet PCs are equipped with many sensors, which can be used to perform quantitative measurements of sound, acceleration, magnetic flux density, air pressure, light intensity, humidity, angular velocity, temperature, or position on Earth (GPS). While previous articles mainly present experiments on mechanics or acoustics, in which the acceleration sensor or the microphone is used (for a synopsis of different examples, see Ref. 3; for recent papers, see Refs.), in this article we focus on experiments for studying radioactivity using the camera sensor.

Development of phase detection schemes based on surface plasmon resonance using interferometry.

PubMed

Kashif, Muhammad; Bakar, Ahmad Ashrif A; Arsad, Norhana; Shaari, Sahbudin

2014-08-28

Surface plasmon resonance (SPR) is a novel optical sensing technique with a unique ability to monitor molecular binding in real-time for biological and chemical sensor applications. Interferometry is an excellent tool for accurate measurement of SPR changes, the measurement and comparison is made for the sensitivity, dynamic range and resolution of the different analytes using interferometry techniques. SPR interferometry can also employ phase detection in addition to the amplitude of the reflected light wave, and the phase changes more rapidly compared with other approaches, i.e., intensity, angle and wavelength. Therefore, the SPR phase interferometer offers the advantages of spatial phase resolution and high sensitivity. This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes. The main application areas of SPR sensors are demonstrated, i.e., the Fabry-Perot interferometer, Michelson interferometer and Mach-Zehnder interferometer, with different configurations. The three interferometers are discussed in detail, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors.

Development of Phase Detection Schemes Based on Surface Plasmon Resonance Using Interferometry

PubMed Central

Kashif, Muhammad; Bakar, Ahmad Ashrif A.; Arsad, Norhana; Shaari, Sahbudin

2014-01-01

Surface plasmon resonance (SPR) is a novel optical sensing technique with a unique ability to monitor molecular binding in real-time for biological and chemical sensor applications. Interferometry is an excellent tool for accurate measurement of SPR changes, the measurement and comparison is made for the sensitivity, dynamic range and resolution of the different analytes using interferometry techniques. SPR interferometry can also employ phase detection in addition to the amplitude of the reflected light wave, and the phase changes more rapidly compared with other approaches, i.e., intensity, angle and wavelength. Therefore, the SPR phase interferometer offers the advantages of spatial phase resolution and high sensitivity. This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes. The main application areas of SPR sensors are demonstrated, i.e., the Fabry-Perot interferometer, Michelson interferometer and Mach-Zehnder interferometer, with different configurations. The three interferometers are discussed in detail, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors. PMID:25171117

Flexible cellulose and ZnO hybrid nanocomposite and its UV sensing characteristics

NASA Astrophysics Data System (ADS)

Mun, Seongcheol; Kim, Hyun Chan; Ko, Hyun-U.; Zhai, Lindong; Kim, Jung Woong; Kim, Jaehwan

2017-12-01

This paper reports the synthesis and UV sensing characteristics of a cellulose and ZnO hybrid nanocomposite (CEZOHN) prepared by exploiting the synergetic effects of ZnO functionality and the renewability of cellulose. Vertically aligned ZnO nanorods were grown well on a flexible cellulose film by direct ZnO seeding and hydrothermal growing processes. The ZnO nanorods have the wurtzite structure and an aspect ratio of 9 11. Photoresponse of the prepared CEZOHN was evaluated by measuring photocurrent under UV illumination. CEZOHN shows bi-directional, linear and fast photoresponse as a function of UV intensity. Electrode materials, light sources, repeatability, durability and flexibility of the prepared CEZOHN were tested and the photocurrent generation mechanism is discussed. The silver nanowire coating used for electrodes on CEZOHN is compatible with a transparent UV sensor. The prepared CEZOHN is flexible, transparent and biocompatible, and hence can be used for flexible and wearable UV sensors.

Photochromic cross-link polymer for color changing and sensing surface

NASA Astrophysics Data System (ADS)

Fu, Richard; Shi, Jianmin; Forsythe, Eric; Srour, Merric

2016-12-01

Photochromic cross-link polymers were developed using patented ultraviolet (UV) photoinitiator and commercial photochromic dyes. The photochromic dyes have been characterized by measuring absorbance before and after UV activation using UV-visible (Vis) spectrometry with varying activation intensities and wavelengths. Photochromic cross-link polymers were characterized by a dynamic xenon and UV light activation and fading system. The curing processes on cloth were established and tested to obtain effective photochromic responses. Both PulseForge photonic curing and PulseForge plus heat surface curing processes had much better photochromic responses (18% to 19%, 16% to 25%, respectively) than the xenon lamp treatment (8%). The newly developed photochromic cross-link polymer showed remarkable coloration contrasts and fast and comparable coloration and fading rates. Those intelligent, controlled color changing and sensing capabilities will be used on flexible and "drapeable" surfaces, which will incorporate ultra-low power sensors, sensor indicators, and identifiers.

Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

1989-01-01

Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

1990-01-01

Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

Optical fiber sensor for low dose gamma irradiation monitoring

NASA Astrophysics Data System (ADS)

de Andrés, Ana I.; Esteban, Ã.`scar; Embid, Miguel

2016-05-01

An optical fiber gamma ray detector is presented in this work. It is based on a Terbium doped Gadolinium Oxysulfide (Gd2O2S:Tb) scintillating powder which cover a chemically etched polymer fiber tip. This etching improves the fluorescence gathering by the optical fiber. The final diameter has been selected to fulfill the trade-off between light gathering and mechanical strength. Powder has been encapsulated inside a microtube where the fiber tip is immersed. The sensor has been irradiated with different air Kerma doses up to 2 Gy/h with a 137Cs source, and the spectral distribution of the fluorescence intensity has been recorded in a commercial grade CCD spectrometer. The obtained signal-to-noise ratio is good enough even for low doses, which has allowed to reduce the integration time in the spectrometer. The presented results show the feasibility for using low cost equipment to detect/measure ionizing radiation as gamma rays are.

A novel reaction-based fluorescent probe for the detection of cysteine in milk and water samples.

PubMed

Wang, Jialin; Wang, Hao; Hao, Yanfeng; Yang, Shaoxiang; Tian, Hongyu; Sun, Baoguo; Liu, Yongguo

2018-10-01

A novel fluorescent probe 3'-hydroxy-3-oxo-3H-spiro [isobenzofuran-1,9'-xanthene]-6'-yl-2,4-dinitrobenzenesulfonate (probe 1) was designed and synthesized as a visual sensor for the detection of cysteine levels in milk and water samples. The addition of cysteine to the solution of probe 1 resulted in an increase in fluorescence intensity and color change, from light yellow to yellow-green. The distinct color response indicated that probe 1 could be used as a visual sensor for cysteine. Cysteine can be detected quantitatively at concentrations between 0 and 400 μM and the detection limit of the fluorescence response to the probe was 6.5 μM. This suggests that probe 1 could be used as a signaling tool to determine the cysteine levels in samples, such as milk and water. Copyright © 2018 Elsevier Ltd. All rights reserved.

Automatic detection of small surface targets with electro-optical sensors in a harbor environment

NASA Astrophysics Data System (ADS)

Bouma, Henri; de Lange, Dirk-Jan J.; van den Broek, Sebastiaan P.; Kemp, Rob A. W.; Schwering, Piet B. W.

2008-10-01

In modern warfare scenarios naval ships must operate in coastal environments. These complex environments, in bays and narrow straits, with cluttered littoral backgrounds and many civilian ships may contain asymmetric threats of fast targets, such as rhibs, cabin boats and jet-skis. Optical sensors, in combination with image enhancement and automatic detection, assist an operator to reduce the response time, which is crucial for the protection of the naval and land-based supporting forces. In this paper, we present our work on automatic detection of small surface targets which includes multi-scale horizon detection and robust estimation of the background intensity. To evaluate the performance of our detection technology, data was recorded with both infrared and visual-light cameras in a coastal zone and in a harbor environment. During these trials multiple small targets were used. Results of this evaluation are shown in this paper.

Wavefront correction by target-phase-locking technology in a 500 TW laser facility

NASA Astrophysics Data System (ADS)

Wang, D. E.; Dai, W. J.; Zhou, K. N.; Su, J. Q.; Xue, Q.; Yuan, Q.; Zhang, X.; Deng, X. W.; Yang, Y.; Wang, Y. C.; Xie, N.; Sun, L.; Hu, D. X.; Zhu, Q. H.

2017-03-01

We demonstrate a novel approach termed target-phase-locking that could improve the entire beam wavefront quality of a 500 TW Nd3+:phosphate glass laser facility. The thermal and static wavefront from front-end to target is corrected by using one deformable mirror that receives feedback from both the focal-spot sensor and wavefront sensor, and only the main laser of the laser system is employed in the correction process, with auxiliary calibration light no longer necessary. As a result, a static focal spot with full width at half maximum of 8.87  ×  5.74 µm is achieved, the thermal wavefront induced by flash-lamp-pumped Nd3+:phosphate glass is compensated with PV from 3.54-0.43 µm, and a dynamic focal spot with intensity exceeding 1020 W cm-2 is precisely predicted at the target with such an approach.

Heterogeneously Nd3+ doped single nanoparticles for NIR-induced heat conversion, luminescence, and thermometry.

PubMed

Marciniak, Lukasz; Pilch, Aleksandra; Arabasz, Sebastian; Jin, Dayong; Bednarkiewicz, Artur

2017-06-22

The current frontier in nanomaterials engineering is to intentionally design and fabricate heterogeneous nanoparticles with desirable morphology and composition, and to integrate multiple functionalities through highly controlled epitaxial growth. Here we show that heterogeneous doping of Nd 3+ ions following a core-shell design already allows three optical functions, namely efficient (η > 72%) light-to-heat conversion, bright NIR emission, and sensitive (S R > 0.1% K -1 ) localized temperature quantification, to be built within a single ca. 25 nm nanoparticle. Importantly, all these optical functions operate within the transparent biological window of the NIR spectral region (λ exc ∼ 800 nm, λ emi ∼ 860 nm), in which light scattering and absorption by tissues and water are minimal. We find NaNdF 4 as a core is efficient in absorbing and converting 808 nm light to heat, while NaYF 4 :1%Nd 3+ as a shell is a temperature sensor based on the ratio-metric luminescence reading but an intermediate inert spacer shell, e.g. NaYF 4 , is necessary to insulate the heat convertor and thermometer by preventing the possible Nd-Nd energy relaxation. Moreover, we notice that while temperature sensitivity and luminescence intensity are optically stable, increased excitation intensity to generate heat above room temperature may saturate the sensing capacity of temperature feedback. We therefore propose a dual beam photoexcitation scheme as a solution for possible light-induced hyperthermia treatment.

Optical multi-species gas monitoring sensor and system

NASA Technical Reports Server (NTRS)

Korman, Valentin (Inventor); Polzin, Kurt A. (Inventor)

2012-01-01

The system includes at least one light source generating light energy having a corresponding wavelength. The system's sensor is based on an optical interferometer that receives light energy from each light source. The interferometer includes a free-space optical path disposed in an environment of interest. The system's sensor includes an optical device disposed in the optical path that causes light energy of a first selected wavelength to continue traversing the optical path whereas light energy of at least one second selected wavelength is directed away from the optical path. The interferometer generates an interference between the light energy of the first selected wavelength so-traversing the optical path with the light energy at the corresponding wavelength incident on the optical interferometer. A first optical detector detects the interference. At least one second detector detects the light energy at the at least one second selected wavelength directed away from the optical path.

A flexible and miniaturized hair dye based photodetector via chemiluminescence pathway.

PubMed

Lin, Ching-Chang; Sun, Da-Shiuan; Lin, Ya-Lin; Tsai, Tsung-Tso; Cheng, Chieh; Sun, Wen-Hsien; Ko, Fu-Hsiang

2017-04-15

A flexible and miniaturized metal semiconductor metal (MSM) biomolecular photodetector was developed as the core photocurrent system through chemiluminescence for hydrogen peroxide sensing. The flexible photocurrent sensing system was manufactured on a 30-µm-thick crystalline silicon chip by chemical etching process, which produced a flexible silicon chip. A surface texturization design on the flexible device enhanced the light-trapping effect and minimized reflectivity losses from the incident light. The model protein streptavidin bound to horseradish peroxidase (HRP) was successfully immobilized onto the sensor surface through high-affinity conjugation with biotin. The luminescence reaction occurred with luminol, hydrogen peroxide and HRP enzyme, and the emission of light from the catalytic reaction was detected by underlying flexible photodetector. The chemiluminescence in the miniaturized photocurrent sensing system was successfully used to determine the hydrogen peroxide concentration in real-time analyses. The hydrogen peroxide detection limit of the flexible MSM photodetector was 2.47mM. The performance of the flexible MSM photodetector maintained high stability under bending at various bending radii. Moreover, for concave bending, a significant improvement in detection signal intensity (14.5% enhancement compared with a flat configuration) was observed because of the increased photocurrent, which was attributed to enhancement of light trapping. Additionally, this detector was used to detect hydrogen peroxide concentrations in commercial hair dye products, which is a significant issue in the healthcare field. The development of this novel, flexible and miniaturized MSM biomolecular photodetector with excellent mechanical flexibility and high sensitivity demonstrates the applicability of this approach to future wearable sensor development efforts. Copyright © 2016 Elsevier B.V. All rights reserved.

Force transformation in spider strain sensors: white light interferometry

PubMed Central

Schaber, Clemens F.; Gorb, Stanislav N.; Barth, Friedrich G.

2012-01-01

Scanning white light interferometry and micro-force measurements were applied to analyse stimulus transformation in strain sensors in the spider exoskeleton. Two compound or ‘lyriform’ organs consisting of arrays of closely neighbouring, roughly parallel sensory slits of different lengths were examined. Forces applied to the exoskeleton entail strains in the cuticle, which compress and thereby stimulate the individual slits of the lyriform organs. (i) For the proprioreceptive lyriform organ HS-8 close to the distal joint of the tibia, the compression of the slits at the sensory threshold was as small as 1.4 nm and hardly more than 30 nm, depending on the slit in the array. The corresponding stimulus forces were as small as 0.01 mN. The linearity of the loading curve seems reasonable considering the sensor's relatively narrow biological intensity range of operation. The slits' mechanical sensitivity (slit compression/force) ranged from 106 down to 13 nm mN−1, and gradually decreased with decreasing slit length. (ii) Remarkably, in the vibration-sensitive lyriform organ HS-10 on the metatarsus, the loading curve was exponential. The organ is thus adapted to the detection of a wide range of vibration amplitudes, as they are found under natural conditions. The mechanical sensitivities of the two slits examined in this organ in detail differed roughly threefold (522 and 195 nm mN−1) in the biologically most relevant range, again reflecting stimulus range fractionation among the slits composing the array. PMID:22031733

Opto-mechanical door locking system

NASA Astrophysics Data System (ADS)

Patil, Saurabh S.; Rodrigues, Vanessa M.; Patil, Ajeetkumar; Chidangil, Santhosh

2015-09-01

We present an Opto-mechanical Door Locking System which is an optical system that combines a simple combination of a coherent light source (Laser) and a photodiode based sensor with focus toward security applications. The basic construct of the KEY comprises a Laser source in a cylindrical enclosure that slides perfectly into the LOCK. The Laser is pulsed at a fixed encrypted frequency unique to that locking system. Transistor-transistor logic (TTL) circuitry is used to achieve encryption. The casing of the key is designed in such a way that it will power the pulsing laser only when the key is inserted in the slot provided for it. The Lock includes a photo-sensor that will convert the detected light intensity to a corresponding electrical signal by decrypting the frequency. The lock also consists of a circuit with a feedback system that will carry the digital information regarding the encryption frequency code. The information received from the sensor is matched with the stored code; if found a perfect match, a signal will be sent to the servo to unlock the mechanical lock or to carry out any other operation. This technique can be incorporated in security systems for residences and safe houses, and can easily replace all conventional locks which formerly used fixed patterns to unlock. The major advantage of this proposed optomechanical system over conventional ones is that it no longer relies on a solid/imprinted pattern to perform its task and hence makes it almost impossible to tamper with.

The design of tea garden environmental monitoring system based on WSN

NASA Astrophysics Data System (ADS)

Chen, Huajun; Yuan, Lina

2018-01-01

Through the application of wireless sensor network (WSN) in tea garden, it can realize the change of traditional tea garden to the modern ones, and effectively improves the comprehensive productive capacity of tea garden. According to the requirement of real-time remote in agricultural information collection and monitoring and the power supply affected by environmental limitations, based on WSN, this paper designs a set of tea garden environmental monitoring system, which achieves the monitoring nodes with ad-hoc network as well as automatic acquisition and transmission to the tea plantations of air temperature, light intensity, soil temperature and humidity.

[Gas pipeline leak detection based on tunable diode laser absorption spectroscopy].

PubMed

Zhang, Qi-Xing; Wang, Jin-Jun; Liu, Bing-Hai; Cai, Ting-Li; Qiao, Li-Feng; Zhang, Yong-Ming

2009-08-01

The principle of tunable diode laser absorption spectroscopy and harmonic detection technique was introduced. An experimental device was developed by point sampling through small multi-reflection gas cell. A specific line near 1 653. 7 nm was targeted for methane measurement using a distributed feedback diode laser as tunable light source. The linearity between the intensity of second harmonic signal and the concentration of methane was determined. The background content of methane in air was measured. The results show that gas sensors using tunable diode lasers provide a high sensitivity and high selectivity method for city gas pipeline leak detection.

Infrared light detection using a whispering-gallery-mode optical microcavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Jiangang, E-mail: jzhu@seas.wustl.edu, E-mail: ozdemir@seas.wustl.edu, E-mail: yang@seas.wustl.edu; Ozdemir, Sahin Kaya, E-mail: jzhu@seas.wustl.edu, E-mail: ozdemir@seas.wustl.edu, E-mail: yang@seas.wustl.edu; Yang, Lan, E-mail: jzhu@seas.wustl.edu, E-mail: ozdemir@seas.wustl.edu, E-mail: yang@seas.wustl.edu

2014-04-28

We demonstrate a thermal infrared (IR) detector based on an ultra-high-quality-factor (Q) whispering-gallery-mode (WGM) microtoroidal silica resonator and investigate its performance to detect IR radiation at 10 μm wavelength. The bandwidth and the sensitivity of the detector are dependent on the power of a probe laser and the detuning between the probe laser and the resonance frequency of the resonator. The microtoroid IR sensor achieved a noise-equivalent-power (NEP) of 7.46 nW, corresponding to an IR intensity of 0.095 mW/cm{sup 2}.

Fiber optic coupled optical sensor

DOEpatents

Fleming, Kevin J.

2001-01-01

A displacement sensor includes a first optical fiber for radiating light to a target, and a second optical fiber for receiving light from the target. The end of the first fiber is adjacent and not axially aligned with the second fiber end. A lens focuses light from the first fiber onto the target and light from the target onto the second fiber.

Dual light field and polarization imaging using CMOS diffractive image sensors.

PubMed

Jayasuriya, Suren; Sivaramakrishnan, Sriram; Chuang, Ellen; Guruaribam, Debashree; Wang, Albert; Molnar, Alyosha

2015-05-15

In this Letter we present, to the best of our knowledge, the first integrated CMOS image sensor that can simultaneously perform light field and polarization imaging without the use of external filters or additional optical elements. Previous work has shown how photodetectors with two stacks of integrated metal gratings above them (called angle sensitive pixels) diffract light in a Talbot pattern to capture four-dimensional light fields. We show, in addition to diffractive imaging, that these gratings polarize incoming light and characterize the response of these sensors to polarization and incidence angle. Finally, we show two applications of polarization imaging: imaging stress-induced birefringence and identifying specular reflections in scenes to improve light field algorithms for these scenes.

Prototype fiber Bragg Grattings (FBG) sensor based on intensity modulation of the laser diode low frequency vibrations measurement

NASA Astrophysics Data System (ADS)

Setiono, Andi; Ula, Rini Khamimatul; Hanto, Dwi; Widiyatmoko, Bambang; Purnamaningsih, Retno Wigajatri

2016-02-01

In general, Fiber Bragg Grating (FBG) sensor works based on observation of spectral response characteristic to detect the desired parameter. In this research, we studied intensity response characteristic of FBG to detect the dynamic strain. Experiment result show that the reflected intensity had linier relationships with dynamic strain. Based on these characteristics, we developed the FBG sensor to detect low frequency vibration. This sensor is designed by attaching the FBG on the bronze cantilever with dimensions of 85×3×0.5 mm. Measurement results showed that the sensor was able to detect vibrations in the frequency range of 7-10 Hz at temperature range of 25-45 ˚C. The measured frequency range is still within the frequency range of digging activity, therefore this vibration sensor can be applied for oil pipelines vandalisation detection system.

Sensor lighting considerations for earth observatory satellite missions

NASA Technical Reports Server (NTRS)

Cooley, J. L.

1972-01-01

Facets of sensor lighting conditions for Earth observatory satellite missions are considered. Assuming onboard sensors of a given width viewing perpendicular to the subsatellite ground track along sun-synchronous orbits with various nodes, the ground trace of the ends of the sensor coverage were found, as well as the variation in solar illumination on the ground across the line covered by the sensor during the day for any point along the orbit. The changes with season and variation during the year were also found.