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Sample records for detect dysthyroid optic

  1. Dysthyroid optic neuropathy (DON).

    PubMed

    Ebner, Roberto

    2002-03-01

    Dysthyroid Optic Neuropathy (DON) affects a small percentage of patients with Graves disease, but, when it occurs, it can cause significant and permanent loss of vision. DON is treatable if recognized early. Systemic steroids can be effective, but may cause side affects. Orbital injection of steroids may play a role in selected patients. Orbital radiation has a more permanent effect and has gained wide acceptance as a relatively non-invasive method of reversing DON. Surgery to decompress crowded orbits has been used for years and continues to be a viable approach for those patients with optic neuropathy, especially when there is significant proptosis. Optic nerve decompression can also be achieved through a transethmoidal approach. PMID:15513451

  2. Color Doppler imaging of orbital venous flow in dysthyroid optic neuropathy.

    PubMed

    Nakase, Y; Osanai, T; Yoshikawa, K; Inoue, Y

    1994-01-01

    Color Doppler imaging was performed to evaluate the venous stasis in 39 orbits, including 9 optic neuropathy orbits, of 20 patients with dysthyroid ophthalmopathy and 22 orbits of 11 healthy subjects. The superior ophthalmic vein (SOV) was detected in 26 dysthyroid ophthalmopathy orbits and in 13 control orbits. The blood flow in the SOV was in the anteroposterior direction in 20 dysthyroid ophthalmopathy orbits and in 13 control orbits. Reversed flow, ie, the flow in the posteroanterior direction, was seen in 6 dysthyroid ophthalmopathy orbits and in none of the control orbits. In dysthyroid ophthalmopathy orbits, the blood flow in the SOV was reversed in 5 (36%) of the 14 orbits with apical orbital crowding observed on computed tomography, which means there was compression of the optic nerve by enlarged extraocular muscles, as compared to in 1 (4%) of the 25 orbits without apical orbital crowding (P < 0.05). The percentage of the orbits having reversed flow in SOV was 44% of dysthyroid ophthalmopathy orbits with optic neuropathy as opposed to 7% of those without optic neuropathy (P < 0.05). Reversed blood flow in the SOV strongly supported the existence of severe venous stasis in the orbits, which may be related to the development of dysthyroid optic neuropathy. PMID:7933702

  3. Methylprednisolone pulse therapy in severe dysthyroid optic neuropathy

    SciTech Connect

    Guy, J.R.; Fagien, S.; Donovan, J.P.; Rubin, M.L. )

    1989-07-01

    Five patients with severe dysthyroid optic neuropathy were treated with intravenous methylprednisolone (1 g daily for 3 consecutive days). Before administration, visual acuity of the more severely affected eyes of each patient was counting fingers at 5 feet, 8/200, 20/400, 20/200, and 20/80. Immediately after completion of pulse therapy, visual acuity improved to 20/25 in four patients and 20/30 in one. Remissions were maintained with oral prednisone and external beam irradiation of the orbit. Pulse methylprednisolone therapy appears to be beneficial in the initial management of severe dysthyroid optic neuropathy.

  4. Dysthyroid optic neuropathy. The crowded orbital apex syndrome.

    PubMed

    Neigel, J M; Rootman, J; Belkin, R I; Nugent, R A; Drance, S M; Beattie, C W; Spinelli, J A

    1988-11-01

    The authors have reviewed the clinical presentation, visual fields, color vision testing, visual-evoked potentials, and computed tomographic (CT) findings of 58 patients (95 eyes) with dysthyroid optic neuropathy. The authors compared these findings to a control group of 60 patients (119 eyes) with thyroid eye disease who underwent CT scanning and did not exhibit evidence of optic neuropathy. Clinically, dysthyroid optic neuropathy is an insidious disease; when compared with the usual Graves' orbitopathy patient, the optic neuropathy group presented at a later age and with a later onset of thyroid eye disease. The patients in this group were more likely to be male and/or diabetic, and often presented with desaturation of color vision. Asymmetrical extraocular muscle restriction and vertical tropias were more frequent in the optic neuropathy group. The most sensitive indicators of optic nerve dysfunction appeared to be visual-evoked potentials and color vision. Computed tomographic studies confirmed that apical orbital crowding was a characteristic feature of optic neuropathy. These findings should alert the clinician to a more aggressive approach to these patients. PMID:3211460

  5. A retrospective review of 26 cases of dysthyroid optic neuropathy

    SciTech Connect

    Panzo, G.J.; Tomsak, R.L.

    1983-08-01

    Sixteen patients (14 women and two men) with dysthyroid optic neuropathy (26 involved eyes) were treated with either oral corticosteroids, orbital irradiation, surgical orbital decompression, combined corticosteroids and irradiation, or combined corticosteroids and surgical decompression. Thirteen of 16 eyes responded favorably to corticosteroid therapy but eight of the 13 relapsed upon discontinuation of treatment. Two of four eyes responded to irradiation initially but later relapsed. The response to orbital decompression was almost uniformly beneficial (eight of nine eyes responded) and lasting in all. Combined modes of therapy offered no additional advantage.

  6. Imaging studies for diagnosing Graves' orbitopathy and dysthyroid optic neuropathy

    PubMed Central

    Gonçalves, Allan C. Pieroni; Gebrim, Eloísa M. M. S.; Monteiro, Mário L. R.

    2012-01-01

    Although the diagnosis of Graves' orbitopathy is primarily made clinically based on laboratory tests indicative of thyroid dysfunction and autoimmunity, imaging studies, such as computed tomography, magnetic resonance imaging, ultrasound and color Doppler imaging, play an important role both in the diagnosis and follow-up after clinical or surgical treatment of the disease. Imaging studies can be used to evaluate morphological abnormalities of the orbital structures during the diagnostic workup when a differential diagnosis versus other orbital diseases is needed. Imaging may also be useful to distinguish the inflammatory early stage from the inactive stage of the disease. Finally, imaging studies can be of great help in identifying patients prone to develop dysthyroid optic neuropathy and therefore enabling the timely diagnosis and treatment of the condition, avoiding permanent visual loss. In this paper, we review the imaging modalities that aid in the diagnosis and management of Graves' orbitopathy, with special emphasis on the diagnosis of optic nerve dysfunction in this condition. PMID:23184212

  7. Orbital Volumetry in Graves' Orbitopathy: Muscle and Fat Involvement in relation to Dysthyroid Optic Neuropathy.

    PubMed

    Al-Bakri, Moug; Rasmussen, Ase Krogh; Thomsen, Carsten; Toft, Peter Bjerre

    2014-01-01

    Purpose. We wanted to investigate the relative significance of fat and muscle enlargement in the development of dysthyroid optic neuropathy (DON) in Graves' orbitopathy (GO). Methods. Preoperative coronal CT scans of 13 patients with and without DON who subsequently underwent orbital decompression were retrospectively analyzed. Thirteen patients imaged for unilateral orbital fractures served as controls. Results. The retrobulbar muscle volume was 2.1 ± 0.5 cm(3) (mean ± SD) in controls, 4.3 ± 1.5 cm(3) in GO without DON, and 4.7 ± 1.7 cm(3) in GO with DON. The retrobulbar fat volume was 5.4 ± 1.6 cm(3) in controls, 8.7 ± 8.0 cm(3) in GO without DON, and 9.4 ± 3.1 cm(3) in GO with DON. The muscle and fat volumes were higher in patients with GO than in controls (P < 0.001), but the volumes in orbits with and without DON were not significantly different. The volume of the optic nerve were similar in the 3 groups. The number of apical, coronal 2 mm thick slices with no fat was 2.9 ± 0.9 in normal orbits, it was 4.1 ± 1.0 in GO orbits without DON and 5.3 ± 0.8 in GO orbits with DON (P = 0.007). Conclusion. Apical muscle enlargement may be more important than orbital fat enlargement in the development of DON. However, the fact that apical crowding and muscle enlargement also occur in orbits without DON suggests that other factors also play a role in the development of DON. PMID:25101183

  8. [Dysthyroidism with anti-VEGF treatment, a class effect? about one case report].

    PubMed

    Khouri, Charles; Jean Bart, Elodie; Logerot, Sophie; Decker-Bellaton, Amandine; Bontemps, Hervé; Mallaret, Michel

    2014-01-01

    Tyrosine-kinase inhibitors are recent therapy used in different neoplastic diseases. Dysthyroidism seems to be a class effect of these drugs with a potentially cross cumulative effect. We describe here the case of a man who first developed dysthyroidism with sunitinib, then a deep and permanent hypothyroidism when axitinib was introduced. PMID:25293486

  9. Optical Detection of Formaldehyde

    NASA Technical Reports Server (NTRS)

    Patty, Kira D.; Gregory, Don A.

    2008-01-01

    The potential for buildup .of formaldehyde in closed space environments poses a direct health hazard to personnel. The National Aeronautic Space Agency (NASA) has established a maximum permitted concentration of 0.04 ppm for 7 to 180 days for all space craft. Early detection is critical to ensure that formaldehyde levels do not accumulate. above these limits. New sensor technologies are needed to enable real time,in situ detection in a compact and reusable form factor. Addressing this need,research into the use of reactive fluorescent dyes which reversibly bind to formaldehyde (liquid or gas) has been conducted to support the development of a formaldehyde.sensor. In the presence of formaldehyde the dyes' characteristic fluorescence peaks shift providing the basis for an optical detection. Dye responses to formaldehyde exposure were characterized; demonstrating the optical detection of formaldehyde in under 10 seconds and down to concentrations of 0.5 ppm. To .incorporate the dye .in.an optical sensor device requires. a means of containing and manipulating the dye. Multiple form factors using two dissimilar sbstrates were considered to determine a suitable configuration. A prototype sensor was demonstrated and considerations for a field able sensor were presented. This research provides a necessary first step toward the development of a compact, reusable; real time optical formaldehyde sensor suitable for use in the U.S. space program,

  10. HIV detection by optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Joshi, Narahari V.; Doria, M.; Medina, Honorio

    2001-10-01

    Reliable and economical Human Immnodeficiency Virus (HIV) testing was achieved by optical absorption spectroscopy of the core of the hair in the range of 400 nm to 800 nm. In HIV+ patients, extra optical active material is deposited in the core and optical absorption spectra, recorded in polarized radiation reveal special features, which can be used for guidance, detection, monitoring and control.

  11. Optical Detection of Tunneling Ionization

    SciTech Connect

    Verhoef, Aart J.; Mitrofanov, Alexander V.; Kartashov, Daniil V.; Baltuska, Andrius

    2010-04-23

    We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.

  12. Hanle detection for optical clocks.

    PubMed

    Zhang, Xiaogang; Zhang, Shengnan; Pan, Duo; Chen, Peipei; Xue, Xiaobo; Zhuang, Wei; Chen, Jingbiao

    2015-01-01

    Considering the strong inhomogeneous spatial polarization and intensity distribution of spontaneous decay fluorescence due to the Hanle effect, we propose and demonstrate a universe Hanle detection configuration of electron-shelving method for optical clocks. Experimental results from Ca atomic beam optical frequency standard with electron-shelving method show that a designed Hanle detection geometry with optimized magnetic field direction, detection laser beam propagation and polarization direction, and detector position can improve the fluorescence collection rate by more than one order of magnitude comparing with that of inefficient geometry. With the fixed 423 nm fluorescence, the improved 657 nm optical frequency standard signal intensity is presented. The potential application of the Hanle detection geometry designed for facilitating the fluorescence collection for optical lattice clock with a limited solid angle of the fluorescence collection has been discussed. The Hanle detection geometry is also effective for ion detection in ion optical clock and quantum information experiments. Besides, a cylinder fluorescence collection structure is designed to increase the solid angle of the fluorescence collection in Ca atomic beam optical frequency standard. PMID:25734183

  13. Hanle Detection for Optical Clocks

    PubMed Central

    Zhang, Xiaogang; Zhang, Shengnan; Pan, Duo; Chen, Peipei; Xue, Xiaobo; Zhuang, Wei; Chen, Jingbiao

    2015-01-01

    Considering the strong inhomogeneous spatial polarization and intensity distribution of spontaneous decay fluorescence due to the Hanle effect, we propose and demonstrate a universe Hanle detection configuration of electron-shelving method for optical clocks. Experimental results from Ca atomic beam optical frequency standard with electron-shelving method show that a designed Hanle detection geometry with optimized magnetic field direction, detection laser beam propagation and polarization direction, and detector position can improve the fluorescence collection rate by more than one order of magnitude comparing with that of inefficient geometry. With the fixed 423 nm fluorescence, the improved 657 nm optical frequency standard signal intensity is presented. The potential application of the Hanle detection geometry designed for facilitating the fluorescence collection for optical lattice clock with a limited solid angle of the fluorescence collection has been discussed. The Hanle detection geometry is also effective for ion detection in ion optical clock and quantum information experiments. Besides, a cylinder fluorescence collection structure is designed to increase the solid angle of the fluorescence collection in Ca atomic beam optical frequency standard. PMID:25734183

  14. Schlieren optics for leak detection

    NASA Technical Reports Server (NTRS)

    Peale, Robert E.; Ruffin, Alranzo B.

    1995-01-01

    The purpose of this research was to develop an optical method of leak detection. Various modifications of schlieren optics were explored with initial emphasis on leak detection of the plumbing within the orbital maneuvering system of the space shuttle (OMS pod). The schlieren scheme envisioned for OMS pod leak detection was that of a high contrast pattern on flexible reflecting material imaged onto a negative of the same pattern. We find that the OMS pod geometry constrains the characteristic length scale of the pattern to the order of 0.001 inch. Our experiments suggest that optical modulation transfer efficiency will be very low for such patterns, which will limit the sensitivity of the technique. Optical elements which allow a negative of the scene to be reversibly recorded using light from the scene itself were explored for their potential in adaptive single-ended schlieren systems. Elements studied include photochromic glass, bacteriorhodopsin, and a transmissive liquid crystal display. The dynamics of writing and reading patterns were studied using intensity profiles from recorded images. Schlieren detection of index gradients in air was demonstrated.

  15. Optically detected magnetic resonance imaging

    SciTech Connect

    Blank, Aharon; Shapiro, Guy; Fischer, Ran; London, Paz; Gershoni, David

    2015-01-19

    Optically detected magnetic resonance provides ultrasensitive means to detect and image a small number of electron and nuclear spins, down to the single spin level with nanoscale resolution. Despite the significant recent progress in this field, it has never been combined with the power of pulsed magnetic resonance imaging techniques. Here, we demonstrate how these two methodologies can be integrated using short pulsed magnetic field gradients to spatially encode the sample. This result in what we denote as an 'optically detected magnetic resonance imaging' technique. It offers the advantage that the image is acquired in parallel from all parts of the sample, with well-defined three-dimensional point-spread function, and without any loss of spectroscopic information. In addition, this approach may be used in the future for parallel but yet spatially selective efficient addressing and manipulation of the spins in the sample. Such capabilities are of fundamental importance in the field of quantum spin-based devices and sensors.

  16. Optical Detection of Blade Flutter

    NASA Technical Reports Server (NTRS)

    Nieberding, W. C.; Pollack, J. L.

    1977-01-01

    Dynamic strain gages mounted on rotor blades are used as the primary instrumentation for detecting the onset of flutter and defining the vibratory mode and frequency. Optical devices are evaluated for performing the same measurements as well as providing supplementary information on the vibratory characteristics. Two separate methods are studied: stroboscopic imagery of the blade tip and photoelectric scanning of blade tip motion. Both methods give visual data in real time as well as video tape records. The optical systems are described, and representative results are presented. The potential of this instrumentation in flutter research is discussed.

  17. Fiber optic hydrogen detection system

    NASA Astrophysics Data System (ADS)

    Kazemi, Alex A.; Larson, David B.; Wuestling, Mark D.

    1999-12-01

    Commercial and military launch vehicles are designed to use hydrogen as the main propellant, which is very volatile, extremely flammable, and highly explosive. Current detection systems uses Teflon transfer tubes at a large number of vehicle locations through which gas samples are drawn and the stream analyzed by a mass spectrometer. A concern with this approach is the high cost of the system. Also, the current system does not provide leak location and is not in real-time. This system is very complex and cumbersome for production and ground support measurement personnel. The fiber optic micromirror sensor under development for cryogenic environment relies on a reversible chemical interaction causing a change in reflectivity of a thin film of coated Palladium. The magnitude of the reflectivity change is correlated to hydrogen concentration. The sensor uses only a tiny light beam, with no electricity whatsoever at the sensor, leading to devices that is intrinsically safe from explosive ignition. The sensor, extremely small in size and weight detects, hydrogen concentration using a passive element consisting of chemically reactive microcoatings deposited on the surface of a glass microlens, which is then bonded to an optical fiber. The system uses a multiplexing technique with a fiber optic driver-receiver consisting of a modulated LED source that is launched into the sensor, and a photodiode detector that synchronously measures the reflected signal. The system incorporates a microprocessor (or PC) to perform the data analysis and storage, as well as trending and set alarm function. As it is a low cost system with a fast response, many more detection sensors can be used that will be extremely helpful in determining leak location for safety of crew and vehicles during launch operations.

  18. Capillary Electrophoresis - Optical Detection Systems

    SciTech Connect

    Sepaniak, M. J.

    2001-08-06

    Molecular recognition systems are developed via molecular modeling and synthesis to enhance separation performance in capillary electrophoresis and optical detection methods for capillary electrophoresis. The underpinning theme of our work is the rational design and development of molecular recognition systems in chemical separations and analysis. There have been, however, some subtle and exciting shifts in our research paradigm during this period. Specifically, we have moved from mostly separations research to a good balance between separations and spectroscopic detection for separations. This shift is based on our perception that the pressing research challenges and needs in capillary electrophoresis and electrokinetic chromatography relate to the persistent detection and flow rate reproducibility limitations of these techniques (see page 1 of the accompanying Renewal Application for further discussion). In most of our work molecular recognition reagents are employed to provide selectivity and enhance performance. Also, an emerging trend is the use of these reagents with specially-prepared nano-scale materials. Although not part of our DOE BES-supported work, the modeling and synthesis of new receptors has indirectly supported the development of novel microcantilevers-based MEMS for the sensing of vapor and liquid phase analytes. This fortuitous overlap is briefly covered in this report. Several of the more significant publications that have resulted from our work are appended. To facilitate brevity we refer to these publications liberally in this progress report. Reference is also made to very recent work in the Background and Preliminary Studies Section of the Renewal Application.

  19. Effects of adult dysthyroidism on the morphology of hippocampal granular cells in rats.

    PubMed

    Martí-Carbonell, Maria Assumpció; Garau, Adriana; Sala-Roca, Josefina; Balada, Ferran

    2012-01-01

    Thyroid hormones are essential for normal brain development and very important in the normal functioning of the brain. Thyroid hormones action in the adult brain has not been widely studied. The effects of adult hyperthyroidism are not as well understood as adult hypothyroidism, mainly in hippocampal granular cells. The purpose of the present study is to assess the consequences of adult hormone dysthyroidism (excess/deficiency of TH) on the morphology of dentate granule cells in the hippocampus by performing a quantitative study of dendritic arborizations and dendritic spines using Golgi impregnated material. Hypo-and hyperthyroidism were induced in rats by adding 0.02 percent methimazole and 1 percent L-thyroxine, respectively, to drinking water from 40 days of age. At 89 days, the animals' brains were removed and stained by a modified Golgi method and blood samples were collected in order to measure T4 serum levels. Neurons were selected and drawn using a camera lucida. Our results show that both methimazole and thyroxine treatment affect granule cell morphology. Treatments provoke alterations in the same direction, namely, reduction of certain dendritic-branching parameters that are more evident in the methimazole than in the thyroxine group. We also observe a decrease in spine density in both the methimazole and thyroxine groups. PMID:23093010

  20. Fiber optic sensors for corrosion detection

    NASA Technical Reports Server (NTRS)

    Smith, Alphonso C.

    1993-01-01

    The development of fiber optic sensors for the detection of a variety of material parameters has grown tremendously over the past several years. Additionally, the potential for analytical applications of fiber optic sensors have become more widely used. New pH sensors have also been developed using fiber optic techniques to detect fluorescence characteristics from immobilized fluorogenic reagent chemicals. The primary purpose of this research was to investigate the feasibility of using fiber optic sensors to detect the presence of Al(sup 3+) ions made in the process of environmental corrosion of aluminum materials. The Al(sup 3+) ions plus a variety of other type of metal ions can be detected using analytical techniques along with fiber optic sensors.

  1. Optical detection of pores in adipocyte membrane

    NASA Astrophysics Data System (ADS)

    Yanina, I. Yu.; Doubrovski, V. A.; Tuchin, V. V.

    2013-08-01

    Structures that can be interpreted as cytoplasm droplets leaking through the membrane are experimentally detected on the membranes of adipocytes using optical digital microscopy. The effect of an aqueous alcohol solution of brilliant green on the amount and sizes of structures is studied. It is demonstrated that the optical irradiation of the adipocytes that are sensitized with the aid of the brilliant green leads to an increase in the amount of structures (pores) after the irradiation. The experimental results confirm the existence of an earlier-proposed effect of photochemical action on the sensitized cells of adipose tissue that involves additional formation of pores in the membrane of the sensitized cell under selective optical irradiation. The proposed method for the detection of micropores in the membrane of adipose tissue based on the detection of the cytoplasm droplets leaking from the cell can be considered as a method for the optical detection of nanosized pores.

  2. Optical Detection Of Flameout In A Combustor

    NASA Technical Reports Server (NTRS)

    Borg, Stephen E.; West, James W.; Harper, Samuel E.; Alderfer, David W.; Lawrence, Robert M.

    1994-01-01

    Fuel supply shut down in time to prevent explosion. Optical flameout detector designed to signal control system of facility to cut off supply of fuel into combustion chamber if flame goes out. Combustor which optical flameout detector designed burns methane in air to provide hot gases for 8-ft high-temperature test chamber. Acoustical flameout detector for same combustor described in "Acoustical Detection of Flameout in Combustor" (LAR-14900). Fiber optic probes mounted to fuel-spray bar upstream of flame. No focusing optics used, and probes aimed across flow of gases at spot on combustion chamber wall downstream from spray bar. Arrangement enables flameout detection system to respond quickly to potential loss of flame since it detects movement of flame front away from spray bar face. Overall response time of detection system under 10 milliseconds.

  3. Optical Detection Of Cryogenic Leaks

    NASA Technical Reports Server (NTRS)

    Wyett, Lynn M.

    1988-01-01

    Conceptual system identifies leakage without requiring shutdown for testing. Proposed device detects and indicates leaks of cryogenic liquids automatically. Detector makes it unnecessary to shut equipment down so it can be checked for leakage by soap-bubble or helium-detection methods. Not necessary to mix special gases or other materials with cryogenic liquid flowing through equipment.

  4. Combined hostile fire and optics detection

    NASA Astrophysics Data System (ADS)

    Brännlund, Carl; Tidström, Jonas; Henriksson, Markus; Sjöqvist, Lars

    2013-10-01

    Snipers and other optically guided weapon systems are serious threats in military operations. We have studied a SWIR (Short Wave Infrared) camera-based system with capability to detect and locate snipers both before and after shot over a large field-of-view. The high frame rate SWIR-camera allows resolution of the temporal profile of muzzle flashes which is the infrared signature associated with the ejection of the bullet from the rifle. The capability to detect and discriminate sniper muzzle flashes with this system has been verified by FOI in earlier studies. In this work we have extended the system by adding a laser channel for optics detection. A laser diode with slit-shaped beam profile is scanned over the camera field-of-view to detect retro reflection from optical sights. The optics detection system has been tested at various distances up to 1.15 km showing the feasibility to detect rifle scopes in full daylight. The high speed camera gives the possibility to discriminate false alarms by analyzing the temporal data. The intensity variation, caused by atmospheric turbulence, enables discrimination of small sights from larger reflectors due to aperture averaging, although the targets only cover a single pixel. It is shown that optics detection can be integrated in combination with muzzle flash detection by adding a scanning rectangular laser slit. The overall optics detection capability by continuous surveillance of a relatively large field-of-view looks promising. This type of multifunctional system may become an important tool to detect snipers before and after shot.

  5. Developments in distributed optical fiber detection technology

    NASA Astrophysics Data System (ADS)

    Ye, Wei; Zhu, Qianxia; You, Tianrong

    2014-12-01

    The distributed optical fiber detection technology plays an important role in many fields, such as key regional security monitoring, pipeline maintenance and communication cable protection. It is superior to the traditional detector, and has a good prospect. This paper presents an overview of various distributed optical fiber sensors. At first, some related technologies of the optical fiber detection schemes are introduced in respect of sensing distance, real-time ability, signal strength, and system complexity; and the advantages and limitations of fiber gratings sensors, reflection-based optical fiber sensors, and interference- based optical fiber sensors are discussed. Then some advanced distributed optical fiber detection systems are mentioned. And the double-loop Sagnac distributed system is improved by adding photoelectric modulators and depolarizers. In order to denoise and enhance the original signal, a spectral subtraction-likelihood ratio method is improved. The experiment results show the spatial resolution is +/-15m per kilometer. Finally, based on the development trends of optical fiber detection technology at home and abroad, development tendency and application fields are predicted.

  6. Optical Detection of Lightning from Space

    NASA Technical Reports Server (NTRS)

    Christian, H. J.

    1999-01-01

    Two primary detection techniques (optical and RF) have a proven capability for detecting lightning from low earth orbit. However, the lightning processes that generate the optical and RF signals are vastly different providing significantly different information content from each sensor type. Because of the intervening ionosphere, low frequency RF components do not reach satellite altitudes. As a consequence, many of the processes associated with the major energy release of a lightning event (i.e. return strokes, k-changes, recoil streamers, etc), in all likelihood contribute little to the RF signal arriving at the satellite. The optical output from lighting, on the other hand, has been shown to be highly correlated with the energetic, charge-transferring processes mentioned above. On the down side, the optical energy, while essentially unaffected by the atmosphere once it emerges from the cloud, is heavily scattered within the cloud. While there is little absorption by the cloud, the great optical depth makes the total light energy emerging from the cloud to be dependent on where in the cloud the lightning occurred. Analyses suggest that when lightning is confined to the lowest regions of the cloud, the light is strongly attenuated and detection becomes problematic. Fortunately, the vast majority of lightning flashes are comprised of channels that propagate through the middle of the cloud and higher. These flashes produce bright signals at the top of a cloud and are readily detectable. Presently, we have two optical instruments in orbit. The Optical Transient Detector (OTD) has been orbiting the earth since April, 1995, while the Lightning Imaging Sensor (LIS) was launched on the Tropical Rainfall Measuring Mission (TRMM) in November of 1997. Both instruments are relatively small, solid state optical imagers, designed specifically to detect and locate lightning activity from low earth orbit with high detection efficiency and location accuracy.

  7. Crowd Event Detection on Optical Flow Manifolds.

    PubMed

    Rao, Aravinda S; Gubbi, Jayavardhana; Marusic, Slaven; Palaniswami, Marimuthu

    2016-07-01

    Analyzing crowd events in a video is key to understanding the behavioral characteristics of people (humans). Detecting crowd events in videos is challenging because of articulated human movements and occlusions. The aim of this paper is to detect the events in a probabilistic framework for automatically interpreting the visual crowd behavior. In this paper, crowd event detection and classification in optical flow manifolds (OFMs) are addressed. A new algorithm to detect walking and running events has been proposed, which uses optical flow vector lengths in OFMs. Furthermore, a new algorithm to detect merging and splitting events has been proposed, which uses Riemannian connections in the optical flow bundle (OFB). The longest vector from the OFB provides a key feature for distinguishing walking and running events. Using a Riemannian connection, the optical flow vectors are parallel transported to localize the crowd groups. The geodesic lengths among the groups provide a criterion for merging and splitting events. Dispersion and evacuation events are jointly modeled from the walking/running and merging/splitting events. Our results show that the proposed approach delivers a comparable model to detect crowd events. Using the performance evaluation of tracking and surveillance 2009 dataset, the proposed method is shown to produce the best results in merging, splitting, and dispersion events, and comparable results in walking, running, and evacuation events when compared with other methods. PMID:26219100

  8. Optical Detection of Lightning from Space

    NASA Technical Reports Server (NTRS)

    Boccippio, Dennis J.; Christian, Hugh J.

    1998-01-01

    Optical sensors have been developed to detect lightning from space during both day and night. These sensors have been fielded in two existing satellite missions and may be included on a third mission in 2002. Satellite-hosted, optically-based lightning detection offers three unique capabilities: (1) the ability to reliably detect lightning over large, often remote, spatial regions, (2) the ability to sample all (IC and CG) lightning, and (3) the ability to detect lightning with uniform (i.e., not range-dependent) sensitivity or detection efficiency. These represent significant departures from conventional RF-based detection techniques, which typically have strong range dependencies (biases) or range limitations in their detection capabilities. The atmospheric electricity team of the NASA Marshall Space Flight Center's Global Hydrology and Climate Center has implemented a three-step satellite lightning research program which includes three phases: proof-of-concept/climatology, science algorithm development, and operational application. The first instrument in the program, the Optical Transient Detector (OTD), is deployed on a low-earth orbit (LEO) satellite with near-polar inclination, yielding global coverage. The sensor has a 1300 x 1300 sq km field of view (FOV), moderate detection efficiency, moderate localization accuracy, and little data bias. The OTD is a proof-of-concept instrument and its mission is primarily a global lightning climatology. The limited spatial accuracy of this instrument makes it suboptimal for use in case studies, although significant science knowledge has been gained from the instrument as deployed.

  9. Optical detection dental disease using polarized light

    DOEpatents

    Everett, Matthew J.; Colston, Jr., Billy W.; Sathyam, Ujwal S.; Da Silva, Luiz B.; Fried, Daniel

    2003-01-01

    A polarization sensitive optical imaging system is used to detect changes in polarization in dental tissues to aid the diagnosis of dental disease such as caries. The degree of depolarization is measured by illuminating the dental tissue with polarized light and measuring the polarization state of the backscattered light. The polarization state of this reflected light is analyzed using optical polarimetric imaging techniques. A hand-held fiber optic dental probe is used in vivo to direct the incident beam to the dental tissue and collect the reflected light. To provide depth-resolved characterization of the dental tissue, the polarization diagnostics may be incorporated into optical coherence domain reflectometry and optical coherence tomography (OCDR/OCT) systems, which enables identification of subsurface depolarization sites associated with demineralization of enamel or bone.

  10. Spectral efficiency of optical direct detection

    NASA Astrophysics Data System (ADS)

    Martinez, Alfonso

    2007-04-01

    The spectral efficiency (channel capacity) of the optical direct-detection channel is studied. The modeling of the optical direct-detection channel as a discrete-time Poisson channel is reviewed. Closed-form integral representations for the entropy of random variables with Poisson and negative binomial distributions are derived. The spectral efficiency achievable with an arbitrary input gamma density is expressed in closed integral form. Simple, nonasymptotic upper and lower bounds to the channel capacity are computed. Numerical results are presented and compared with previous bounds and approximations.

  11. Integrated Micro-Optics for Microfluidic Detection.

    PubMed

    Kazama, Yuto; Hibara, Akihide

    2016-01-01

    A method of embedding micro-optics into a microfluidic device was proposed and demonstrated. First, the usefulness of embedded right-angle prisms was demonstrated in microscope observation. Lateral-view microscopic observation of an aqueous dye flow in a 100-μm-sized microchannel was demonstrated. Then, the embedded right-angle prisms were utilized for multi-beam laser spectroscopy. Here, crossed-beam thermal lens detection of a liquid sample was applied to glucose detection. PMID:26753713

  12. Fibre optic sensors for mine hazard detection

    NASA Astrophysics Data System (ADS)

    Liu, T.; Wang, C.; Wei, Y.; Zhao, Y.; Huo, D.; Shang, Y.; Wang, Z.; Ning, Y.

    2009-07-01

    We report the development of a comprehensive safety monitoring solution for coal mines. A number of fibre optic sensors have been developed and deployed for safety monitoring of mine roof integrity and hazardous gases. The FOS-based mine hazard detection system offers unique advantages of intrinsic safety, multi-location and multi-parameter monitoring. They can be potentially used to build expert systems for mine hazard early detection and prevention.

  13. OPAD data analysis. [Optical Plumes Anomaly Detection

    NASA Technical Reports Server (NTRS)

    Buntine, Wray L.; Kraft, Richard; Whitaker, Kevin; Cooper, Anita E.; Powers, W. T.; Wallace, Tim L.

    1993-01-01

    Data obtained in the framework of an Optical Plume Anomaly Detection (OPAD) program intended to create a rocket engine health monitor based on spectrometric detections of anomalous atomic and molecular species in the exhaust plume are analyzed. The major results include techniques for handling data noise, methods for registration of spectra to wavelength, and a simple automatic process for estimating the metallic component of a spectrum.

  14. Detectivity comparison of bolometric optical antennas

    NASA Astrophysics Data System (ADS)

    Cuadrado, Alexander; López-Alonso, José M.; Martínez-Antón, Juan C.; Ezquerro, Jose M.; González, Francisco J.; Alda, Javier

    2015-08-01

    The practical application of optical antennas in detection devices strongly depends on its ability to produce an acceptable signal-to-noise ratio for the given task. It is known that, due to the intrinsic problems arising from its sub-wavelength dimensions, optical antennas produce very small signals. The quality of these signals depends on the involved transduction mechanism. The contribution of different types of noise should be adapted to the transducer and to the signal extraction regime. Once noise is evaluated and measured, the specific detectivity, D*, becomes the parameter of interest when comparing the performance of antenna coupled devices with other detectors. However, this parameter involves some magnitudes that can be defined in several ways for optical antennas. In this contribution we are interested in the evaluation and comparison of D_ values for several bolometric optical antennas working in the infrared and involving two materials. At the same time, some material and geometrical parameters involved in the definition of noise and detectivity will be discussed to analyze the suitability of D_ to properly account for the performance of optical antennas.

  15. Reset tree-based optical fault detection.

    PubMed

    Lee, Dong-Geon; Choi, Dooho; Seo, Jungtaek; Kim, Howon

    2013-01-01

    In this paper, we present a new reset tree-based scheme to protect cryptographic hardware against optical fault injection attacks. As one of the most powerful invasive attacks on cryptographic hardware, optical fault attacks cause semiconductors to misbehave by injecting high-energy light into a decapped integrated circuit. The contaminated result from the affected chip is then used to reveal secret information, such as a key, from the cryptographic hardware. Since the advent of such attacks, various countermeasures have been proposed. Although most of these countermeasures are strong, there is still the possibility of attack. In this paper, we present a novel optical fault detection scheme that utilizes the buffers on a circuit's reset signal tree as a fault detection sensor. To evaluate our proposal, we model radiation-induced currents into circuit components and perform a SPICE simulation. The proposed scheme is expected to be used as a supplemental security tool. PMID:23698267

  16. Reset Tree-Based Optical Fault Detection

    PubMed Central

    Lee, Dong-Geon; Choi, Dooho; Seo, Jungtaek; Kim, Howon

    2013-01-01

    In this paper, we present a new reset tree-based scheme to protect cryptographic hardware against optical fault injection attacks. As one of the most powerful invasive attacks on cryptographic hardware, optical fault attacks cause semiconductors to misbehave by injecting high-energy light into a decapped integrated circuit. The contaminated result from the affected chip is then used to reveal secret information, such as a key, from the cryptographic hardware. Since the advent of such attacks, various countermeasures have been proposed. Although most of these countermeasures are strong, there is still the possibility of attack. In this paper, we present a novel optical fault detection scheme that utilizes the buffers on a circuit's reset signal tree as a fault detection sensor. To evaluate our proposal, we model radiation-induced currents into circuit components and perform a SPICE simulation. The proposed scheme is expected to be used as a supplemental security tool. PMID:23698267

  17. Optical detection of radon decay in air

    NASA Astrophysics Data System (ADS)

    Sand, Johan; Ihantola, Sakari; Peräjärvi, Kari; Toivonen, Harri; Toivonen, Juha

    2016-02-01

    An optical radon detection method is presented. Radon decay is directly measured by observing the secondary radiolumines cence light that alpha particles excite in air, and the selectivity of coincident photon detection is further enhanced with online pulse-shape analysis. The sensitivity of a demonstration device was 6.5 cps/Bq/l and the minimum detectable concentration was 12 Bq/m3 with a 1 h integration time. The presented technique paves the way for optical approaches in rapid radon detec tion, and it can be applied beyond radon to the analysis of any alpha-active sample which can be placed in the measurement chamber.

  18. Optical detection of radon decay in air

    PubMed Central

    Sand, Johan; Ihantola, Sakari; Peräjärvi, Kari; Toivonen, Harri; Toivonen, Juha

    2016-01-01

    An optical radon detection method is presented. Radon decay is directly measured by observing the secondary radiolumines cence light that alpha particles excite in air, and the selectivity of coincident photon detection is further enhanced with online pulse-shape analysis. The sensitivity of a demonstration device was 6.5 cps/Bq/l and the minimum detectable concentration was 12 Bq/m3 with a 1 h integration time. The presented technique paves the way for optical approaches in rapid radon detec tion, and it can be applied beyond radon to the analysis of any alpha-active sample which can be placed in the measurement chamber. PMID:26867800

  19. Optical sensor for rapid microbial detection

    NASA Astrophysics Data System (ADS)

    Al-Adhami, Mustafa; Tilahun, Dagmawi; Rao, Govind; Kostov, Yordan

    2016-05-01

    In biotechnology, the ability to instantly detect contaminants is key to running a reliable bioprocess. Bioprocesses are prone to be contaminated by cells that are abundant in our environment; detection and quantification of these cells would aid in the preservation of the bioprocess product. This paper discusses the design and development of a portable kinetics fluorometer which acts as a single-excitation, single-emission photometer that continuously measures fluorescence intensity of an indicator dye, and plots it. Resazurin is used as an indicator dye since the viable contaminant cells reduce Resazurin toResorufin, the latter being strongly fluorescent. A photodiode detects fluorescence change by generating current proportional to the intensity of the light that reached it, and a trans-impedance differential op-amp ensures amplification of the photodiodes' signal. A microfluidic chip was designed specifically for the device. It acts as a fully enclosed cuvette, which enhances the Resazurin reduction rate. E. coli in LB media, along with Resazurin were injected into the microfluidic chip. The optical sensor detected the presence of E. coli in the media based on the fluorescence change that occurred in the indicator dye in concentrations as low as 10 CFU/ml. A method was devised to detect and determine an approximate amount of contamination with this device. This paper discusses application of this method to detect and estimate sample contamination. This device provides fast, accurate, and inexpensive means to optically detect the presence of viable cells.

  20. Distributed fiber optic fuel leak detection system

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar; Kempen, C.; Esterkin, Yan; Sun, Sonjian

    2013-05-01

    With the increase worldwide demand for hydrocarbon fuels and the vast development of new fuel production and delivery infrastructure installations around the world, there is a growing need for reliable fuel leak detection technologies to provide safety and reduce environmental risks. Hydrocarbon leaks (gas or liquid) pose an extreme danger and need to be detected very quickly to avoid potential disasters. Gas leaks have the greatest potential for causing damage due to the explosion risk from the dispersion of gas clouds. This paper describes progress towards the development of a fast response, high sensitivity, distributed fiber optic fuel leak detection (HySenseTM) system based on the use of an optical fiber that uses a hydrocarbon sensitive fluorescent coating to detect the presence of fuel leaks present in close proximity along the length of the sensor fiber. The HySenseTM system operates in two modes, leak detection and leak localization, and will trigger an alarm within seconds of exposure contact. The fast and accurate response of the sensor provides reliable fluid leak detection for pipelines, tanks, airports, pumps, and valves to detect and minimize any potential catastrophic damage.

  1. Distributed fiber optic fuel leak detection system

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar; Kempen, C.; Esterkin, Yan; Sun, Sunjian

    2013-05-01

    With the increase worldwide demand for hydrocarbon fuels and the vast development of new fuel production and delivery infrastructure installations around the world, there is a growing need for reliable fuel leak detection technologies to provide safety and reduce environmental risks. Hydrocarbon leaks (gas or liquid) pose an extreme danger and need to be detected very quickly to avoid potential disasters. Gas leaks have the greatest potential for causing damage due to the explosion risk from the dispersion of gas clouds. This paper describes progress towards the development of a fast response, high sensitivity, distributed fiber optic fuel leak detection (HySensTM) system based on the use of an optical fiber that uses a hydrocarbon sensitive fluorescent coating to detect the presence of fuel leaks present in close proximity along the length of the sensor fiber. The HySenseTM system operates in two modes, leak detection and leak localization, and will trigger an alarm within seconds of exposure contact. The fast and accurate response of the sensor provides reliable fluid leak detection for pipelines, tanks, airports, pumps, and valves to detect and minimize any potential catastrophic damage.

  2. Target discrimination strategies in optics detection

    NASA Astrophysics Data System (ADS)

    Sjöqvist, Lars; Allard, Lars; Henriksson, Markus; Jonsson, Per; Pettersson, Magnus

    2013-10-01

    Detection and localisation of optical assemblies used for weapon guidance or sniper rifle scopes has attracted interest for security and military applications. Typically a laser system is used to interrogate a scene of interest and the retro-reflected radiation is detected. Different system approaches for area coverage can be realised ranging from flood illumination to step-and-stare or continuous scanning schemes. Independently of the chosen approach target discrimination is a crucial issue, particularly if a complex scene such as in an urban environment and autonomous operation is considered. In this work target discrimination strategies in optics detection are discussed. Typical parameters affecting the reflected laser radiation from the target are the wavelength, polarisation properties, temporal effects and the range resolution. Knowledge about the target characteristics is important to predict the target discrimination capability. Two different systems were used to investigate polarisation properties and range resolution information from targets including e.g. road signs, optical reflexes, rifle sights and optical references. The experimental results and implications on target discrimination will be discussed. If autonomous operation is required target discrimination becomes critical in order to reduce the number of false alarms.

  3. Frequency skewed optical pulses for range detection

    NASA Astrophysics Data System (ADS)

    Ozharar, Sarper; Gee, Sangyoun; Quinlan, Franklyn; Delfyett, Peter J., Jr.

    2007-04-01

    Frequency skewed optical pulses are generated via both a composite cavity structure in a fiberized semiconductor optical amplifier ring laser and a frequency skew loop outside the laser cavity. The composite cavity technique is similar to rational harmonic mode-locking, however it is based on cavity detuning rather than frequency detuning. These frequency skewed pulses are ideal for range detection applications since their interference results in a range dependent RF signal. The intracavity frequency skewed pulse train showed superior performance in both stability and signal quality.

  4. Gaseous hydrogen leakage optical fibre detection system

    NASA Astrophysics Data System (ADS)

    Trouillet, Alain; Veillas, Colette; Sigronde, E.; Gagnaire, Henri; Clement, Michel

    2004-06-01

    Liquid hydrogen has been intensively used in aerospace applications during the past forty years and is of great interest for fuel cells technologies and future automotive applications. Following upon major explosive risks due to the use of hydrogen in air, previous studies were carried out in our laboratory in order to develop optical fiber sensors for the detection of hydrogen leakage. This communication is aimed towards a prototype optical fiber system designed for the detection of gaseous hydrogen leakage near the conecting flanges of the liquid hydrogen pipes on the test bench of the engine Vulcain of the rocket ARIANE V. Depending on the configuration, the prototype sensor provides a two-level alarm signal and the detection of gaseous hydrogen leakage is possible for concentrations lower than the lower explosive limit in air (between 0.1 and 4%) with alarm response times lower than 10 seconds in a wide range of temperatures between -35°C and 300°C. The sensing principle based on palladium-hydrogen interaction is presented as well as the detection system composed of an optical fiber probe and an optoelectronic device.

  5. Optical imaging module for astigmatic detection system.

    PubMed

    Wang, Wei-Min; Cheng, Chung-Hsiang; Molnar, Gabor; Hwang, Ing-Shouh; Huang, Kuang-Yuh; Danzebrink, Hans-Ulrich; Hwu, En-Te

    2016-05-01

    In this paper, an optical imaging module design for an astigmatic detection system (ADS) is presented. The module is based on a commercial optical pickup unit (OPU) and it contains a coaxial illuminant for illuminating a specimen. Furthermore, the imaging module facilitates viewing the specimen and the detection laser spot of the ADS with a lateral resolution of approximately 1 μm without requiring the removal of an element of the OPU. Two polarizers and one infrared filter are used to eliminate stray laser light in the OPU and stray light produced by the illuminant. Imaging modules designed for digital versatile disks (DVDs) and Blu-ray DVDs were demonstrated. Furthermore, the module can be used for imaging a small cantilever with approximate dimensions of 2 μm (width) × 5 μm (length), and therefore, it has the potential to be used in high-speed atomic force microscopy. PMID:27250434

  6. Fiber optic hydrophones for acoustic neutrino detection

    NASA Astrophysics Data System (ADS)

    Buis, E. J.; Doppenberg, E. J. J.; Lahmann, R.; Toet, P. M.; de Vreugd, J.

    2016-04-01

    Cosmic neutrinos with ultra high energies can be detected acoustically using hydrophones. The detection of these neutrinos may provide crucial information about then GZK mechanism. The flux of these neutrinos, however, is expected to be low, so that a detection volume is required more than a order of magnitude larger than what has presently been realized. With a large detection volume and a large number of hydrophones, there is a need for technology that is cheap and easy to deploy. Fiber optics provide a natural way for distributed sensing. In addition, a sensor has been designed and manufactured that can be produced cost-effectively on an industrial scale. Sensitivity measurements show that the sensor is able to reach the required sea-state zero level. For a proper interpretation of the expected bipolar signals, filtering techniques should be applied to remove the effects of the unwanted resonance peaks.

  7. Optic disc detection using ant colony optimization

    NASA Astrophysics Data System (ADS)

    Dias, Marcy A.; Monteiro, Fernando C.

    2012-09-01

    The retinal fundus images are used in the treatment and diagnosis of several eye diseases, such as diabetic retinopathy and glaucoma. This paper proposes a new method to detect the optic disc (OD) automatically, due to the fact that the knowledge of the OD location is essential to the automatic analysis of retinal images. Ant Colony Optimization (ACO) is an optimization algorithm inspired by the foraging behaviour of some ant species that has been applied in image processing for edge detection. Recently, the ACO was used in fundus images to detect edges, and therefore, to segment the OD and other anatomical retinal structures. We present an algorithm for the detection of OD in the retina which takes advantage of the Gabor wavelet transform, entropy and ACO algorithm. Forty images of the retina from DRIVE database were used to evaluate the performance of our method.

  8. Optical Detection of Life on Exoplanets

    NASA Technical Reports Server (NTRS)

    Heap, Sara

    2009-01-01

    We describe what is known about the atmospheric properties (Teff, lob g, [FelH]) and fundamental properties (mass, age, and metal content) of nearby stars and how they influence the habitable zones and habitable eras of these stars. We then take an observer's point of view to assess the ability of optical telescopes to detect photosynthetic or methanogenic life on planets orbiting these stars.

  9. Renewable Surface Biosensors with Optical Detection

    SciTech Connect

    Bruckner-Lea, Cindy J.; Ackerman, Eric J.; Dockendorff, Brian P.; Holman, David A.; Grate, Jay W.

    2001-04-30

    One major challenge in the development of biosensors is the limited lifetime of a chemically selective surface that includes biomolecules. Renewable surface biosensors address this issue by using fresh aliquots of derivatized microbeads for each analysis. The analyte detection can then occur on the microbeads, or downstream from the microbeads. In this paper, we will describe two types of renewable surface biosensors. The first renewable biosensor system includes on-column optical detection for monitoring the binding of biomolecules onto protein or DNA-derivatized Sepharose beads. The second renewable biosensor system includes detection downstream from the microparticles and is based on the use of derivatized magnetic particles for selective binding. The magnetic particles are fluidically captured and released in a sequential injection system to allow the automation of an Enzyme Linked ImmunoSorbent Assay.

  10. Renewable Surface Biosensors With Optical Detection

    SciTech Connect

    Bruckner-Lea, Cynthia J.; Ackerman, Eric J.; Dockendorff, Brian P.; Holman, David A.; Grate, Jay W.

    2001-12-01

    One major challenge in the development of biosensors is the limited lifetime of a chemically selective surface that includes biomolecules. Renewable surface biosensors address this issue by using fresh aliquots of derivatized microbeads for each analysis. The analyte detection can then occur on the microbeads, or downstream from the microbeads. In this paper, we will describe two types of renewable surface biosensors. The first renewable biosensor system includes on-column optical detection for monitoring the binding of biomolecules onto protein or DNA-derivatized Sepharose beads. The second renewable biosensor system includes detection downstream from the microparticles and is based on the use of derivatized magnetic particles for selective binding. The magnetic particles are fluidically captured and released in a sequential injection system to allow the automation of an Enzyme Linked ImmunoSorbent Assay.

  11. Detecting multiatomic composite states in optical lattices

    NASA Astrophysics Data System (ADS)

    Kuklov, Anatoly; Moritz, Henning

    2007-01-01

    We propose and discuss methods for detecting quasimolecular complexes which are expected to form in strongly interacting optical lattice systems. Particular emphasis is placed on the detection of composite fermions forming in Bose-Fermi mixtures. We argue that, as an indirect indication of the composite fermions and a generic consequence of strong interactions, periodic correlations must appear in the atom shot noise of bosonic absorption images, similar to the bosonic Mott insulator [S. Fölling , Nature (London) 434, 481 (2005)]. The composites can also be detected directly and their quasimomentum distribution measured. This method—an extension of the technique of noise correlation interferometry [E. Altman , Phys. Rev. A 79, 013603 (2004)]—relies on measuring higher order correlations between the bosonic and fermionic shot noise in the absorption images. However, it fails above a certain number of the constituents due to a dramatic increase of uncorrelated noise.

  12. Trace elements profile is associated with insulin resistance syndrome and oxidative damage in thyroid disorders: Manganese and selenium interest in Algerian participants with dysthyroidism.

    PubMed

    Maouche, Naima; Meskine, Djamila; Alamir, Barkahoum; Koceir, Elhadj-Ahmed

    2015-10-01

    The relationship between dysthyroidism and antioxidant trace elements (ATE) status is very subtle during oxidative stress (OS). This relationship is mediated by thyroid hormone (TH) disorder, insulin resistance syndrome (IRS) and inflammation. The aim of this study was to investigate ATE such as selenium (Se), manganese (Mn), zinc (Zn) and copper (Cu) status on thyroid dysfunction, and their interaction with antioxidant enzyme activities, mainly, superoxide dismutase (SOD) and glutathione peroxidase (GPx), TH profile (TSH, T(3), T(4)) and IRS clusters. The study was undertaken on 220 Algerian adults (30-50 years), including 157 women and 63 men who were divided to 4 groups: subclinical hypothyroidism (n = 50), overt hypothyroidism (n = 60), Graves's disease hyperthyroidism (n = 60) and euthyroid controls (n = 50). The IRS was confirmed according to NCEP (National Cholesterol Education Program). Insulin resistance was evaluated by HOMA-IR model. Trace elements were determined by the Flame Atomic Absorption Spectrometry (Flame-AAS) technique. The antioxidant enzymes activity and metabolic parameters were determined by biochemical methods. The TH profile and anti-Thyroperoxidase Antibodies (anti-TPO-Ab) were evaluated by radioimmunoassay. Results showed that the plasma manganese levels were significantly increased in all dysthyroidism groups (p ≤ 0.01). However, the plasma copper and zinc concentrations were maintained normal or not very disturbed vs control group. In contrast, the plasma selenium levels were highly decreased (p ≤ 0.001) and positively correlated with depletion of glutathione peroxidase activity; and associated both with anti-TPO-Ab overexpression and fulminant HS-CRP levels. This study confirms the oxidative stress-inflammation relationship in the dysthyroidism. The thyroid follicles antioxidant protection appears preserved in the cytosol (Cu/Zn-SOD), while it is altered in the mitochondria (Mn-SOD), which gives this cell organelle, a status of

  13. Fiber Optic Thermal Detection of Composite Delaminations

    NASA Technical Reports Server (NTRS)

    Wu, Meng-Chou; Winfree, William P.

    2011-01-01

    A recently developed technique is presented for thermographic detection of delaminations in composites by performing temperature measurements with fiber optic Bragg gratings. A single optical fiber with multiple Bragg gratings employed as surface temperature sensors was bonded to the surface of a composite with subsurface defects. The investigated structure was a 10-ply composite specimen with prefabricated delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared and found to be consistent with the calculations using numerical simulation techniques. Also discussed are methods including various heating sources and patterns, and their limitations for performing in-situ structural health monitoring.

  14. Optical and infrared detection using microcantilevers

    SciTech Connect

    Oden, P.I.; Datskos, P.G.; Warmack, R.J. |; Wachter, E.A.; Thundat, T.

    1996-05-01

    The feasibility of micromechanical optical and infrared (IR) detection using microcantilevers is demonstrated. Microcantilevers provide a simple means for developing single- and multi-element sensors for visible and infrared radiation that are smaller, more sensitive and lower in cost than quantum or thermal detectors. Microcantilevers coated with a heat absorbing layer undergo bending due to the differential stress originating from the bimetallic effect. Bending is proportional to the amount of heat absorbed and can be detected using optical or electrical methods such as resistance changes in piezoresistive cantilevers. The microcantilever sensors exhibit two distinct thermal responses: a fast one ({theta}{sub 1}{sup thermal} < ms) and a slower one ({tau}{sub 2}{sup thermal} {approximately} 10 ms). A noise equivalent temperature difference, NEDT = 90 mK was measured. When uncoated microcantilevers were irradiated by a low-power diode laser ({lambda} = 786 nm) the noise equivalent power, NEP, was found to be 3.5nW/{radical}Hz which corresponds to a specific detectivity, D*, of 3.6 {times} 10{sup 7} cm {center_dot} {radical}Hz/W at a modulation frequency of 20 Hz.

  15. Enhancement of optical detectability with polarization

    NASA Astrophysics Data System (ADS)

    Egan, Walter G.

    1999-07-01

    Low detectability is a major consideration for combat platforms. Exposed surfaces are painted or coated black to minimize optical or near infrared detectability; this is a fallacy in regard to polarization. The percent polarization of a diffuse (non specular) surface is inversely proportional to the surface reflectance (also known as albedo). Thus a dark surface with a reflectance of 2% can have a percent polarization of approximately 100%. (The percent polarization is the ratio of the difference between two orthogonal polarized measurements ratioed to the sum multiplied by 100). Experimental measurements of diffuse surfaces with albedos between 2% and 90% show this inverse relationship to be obeyed from the ultraviolet to the near infrared. Imagery has been obtained on various aircraft coatings that verify the inverse relationship between surface albedo and percent polarization in the green, red and near infrared wavelength bands. The imagery was obtained in the three bands with the Kodak digital cameras, which downloaded on to CD ROMs. Imagery has also been obtained on laboratory samples that verify the inverse relationship between albedo and polarization. The conclusion is that very high polarization of a dark aircraft enhances the detectability such that it is easily recognized optically using polarization. This effect has not been recognized in signature reduction. Imagery will be presented and the inverse relationship between surface albedo and percent polarization will be demonstrated.

  16. Flexible detection optics for light scattering

    NASA Astrophysics Data System (ADS)

    Taratuta, Victor G.; Hurd, Alan J.; Meyer, Robert B.

    1984-05-01

    We have designed and built a compact, modular apparatus for the collection, viewing, and detection of scattered light for less than 1200, based on a commercially available optical bench. The novelty of our instrument is that it has the flexibility of modular design while allowing the user to see exactly what is happening: both the real image of the sample and the spatial coherence of the scattered light can be examined. There is built-in control over polarization, filtering, magnification, and other parameters.

  17. Ultraviolet light detection using an optical microcavity.

    PubMed

    Harker, Audrey; Mehrabani, Simin; Armani, Andrea M

    2013-09-01

    Ultraviolet (UV) light exposure is connected to both physical and psychological diseases. As such, there is significant interest in developing sensors that can detect UV light in the mW/cm2 intensity range with a high signal-to-noise ratio. In this Letter, we demonstrate a UV sensor based on a silica integrated optical microcavity that has a linear operating response in both the forward and backward directions from 14 to 53 mW/cm2. The sensor response agrees with the developed predictive theory based on a thermodynamic model. Additionally, the signal-to-noise ratio is above 100 at physiologically relevant intensity levels. PMID:23988974

  18. Optical detection of microcystin produced by cyanobacteria

    NASA Astrophysics Data System (ADS)

    Al-Ammar, R.; Nabok, A.; Hashim, A.; Smith, T.

    2013-06-01

    Microcystin (MC-LR) produced by cyanobacteria (blue-green algae) was detected in direct immunoassay with specific monoclonal antibody MC10E7 using an optical method of Total Internal Reflection Ellipsometry (TIRE). The minimal detected concentration of MC-LR of 0.1 ng/ml is a remarkable achievement for direct immunoassay against such low molecular weight analyte molecule. The study of binding kinetics of MC-LR to MC10E7 antibody allowed the evaluation of the association constant KA of about 108 (l/Mol) typical for highly specific immune reactions. Concentration of MC-LR in aqueous solutions was reduced using an absorbent made of polyelectrolyte-coated microparticles functionalized with MC10E7 antibodies.

  19. Ionizing radiation detection using microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    DeHaven, Stanton

    Ionizing radiation detecting microstructured optical fibers are fabricated, modeled and experimentally measured for X-ray detection in the 10-40 keV energy range. These fibers operate by containing a scintillator material which emits visible light when exposed to ionizing radiation. An X-ray source characterized with a CdTe spectrometer is used to quantify the X-ray detection efficiency of the fibers. The solid state CdTe detector is considered 100% efficient in this energy range. A liquid filled microstructured optical fiber (MOF) is presented where numerical analysis and experimental observation leads to a geometric theory of photon transmission using total internal reflection. The model relates the quantity and energy of absorbed X-rays to transmitted and measured visible light photons. Experimental measurement of MOF photon counts show good quantitative agreement with calculated theoretical values. This work is extended to a solid organic scintillator, anthracene, which shows improved light output due to its material properties. A detailed description of the experimental approach used to fabricate anthracene MOF is presented. The fabrication technique uses a modified Bridgman-Stockbarger crystal growth technique to grow anthracene single crystals inside MOF. The anthracene grown in the MOF is characterized using spectrophotometry, Raman spectroscopy, and X-ray diffraction. These results show the anthracene grown is a high purity crystal with a structure similar to anthracene grown from the liquid, vapor and melt techniques. The X-ray measurement technique uses the same approach as that for liquid filled MOF for efficiency comparison. A specific fiber configuration associated with the crystal growth allows an order of magnitude improvement in X-ray detection efficiency. The effect of thin film external coatings on the measured efficiency is presented and related to the fiber optics. Lastly, inorganic alkali halide scintillator materials of CsI(Tl), CsI(Na), and

  20. On event-based optical flow detection

    PubMed Central

    Brosch, Tobias; Tschechne, Stephan; Neumann, Heiko

    2015-01-01

    Event-based sensing, i.e., the asynchronous detection of luminance changes, promises low-energy, high dynamic range, and sparse sensing. This stands in contrast to whole image frame-wise acquisition by standard cameras. Here, we systematically investigate the implications of event-based sensing in the context of visual motion, or flow, estimation. Starting from a common theoretical foundation, we discuss different principal approaches for optical flow detection ranging from gradient-based methods over plane-fitting to filter based methods and identify strengths and weaknesses of each class. Gradient-based methods for local motion integration are shown to suffer from the sparse encoding in address-event representations (AER). Approaches exploiting the local plane like structure of the event cloud, on the other hand, are shown to be well suited. Within this class, filter based approaches are shown to define a proper detection scheme which can also deal with the problem of representing multiple motions at a single location (motion transparency). A novel biologically inspired efficient motion detector is proposed, analyzed and experimentally validated. Furthermore, a stage of surround normalization is incorporated. Together with the filtering this defines a canonical circuit for motion feature detection. The theoretical analysis shows that such an integrated circuit reduces motion ambiguity in addition to decorrelating the representation of motion related activations. PMID:25941470

  1. Parallel Optical and Electrochemical DNA Detection

    NASA Astrophysics Data System (ADS)

    Knoll, Wolfgang; Liu, Jianyun; Niu, Lifang; Nielsen, Peter Eigil; Tiefenauer, Louis

    This contribution introduces strategies for the sensitive detection of oligonucleotides as bio-analytes binding from solution to a variety of probe architectures assembled at the (Au-) sensor surface. Detection principles based on surface plasmon optics and electrochemical techniques are compared. In particular, cyclic- and square wave voltammetry (SWV) are applied for the read-out of ferrocene redox labels conjugated to streptavidin that binds to the (biotinylated) DNA targets after hybridizing to the interfacial probe matrix of either DNA or peptide nucleic acid (PNA) strands. By employing streptavidin modified with fluorophores the identical sensor architecture can be used for the recording of hybridization reactions by surface plasmon fluorescence spectroscopy (SPFS). The Langmuir isotherms determined by both techniques, i.e., by SWV and SPFS, give virtually identical affinity constants KA, confirming that the mode of detection has no influence on the hybridization reaction. By using semiconducting nanoparticles as luminescence labels that can be tuned in their bandgap energies over a wide range of emission wavelengths surface plasmon fluorescence microscopy allows for the parallel read-out of multiple analyte binding events simultaneously.

  2. Detection of Optically Faint GEO Debris

    NASA Technical Reports Server (NTRS)

    Seitzer, P.; Lederer, S.; Barker, E.; Cowardin, H.; Abercromby, K.; Silha, J.; Burkhardt, A.

    2014-01-01

    There have been extensive optical surveys for debris at geosynchronous orbit (GEO) conducted with meter-class telescopes, such as those conducted with MODEST (the Michigan Orbital DEbris Survey Telescope, a 0.6-m telescope located at Cerro Tololo in Chile), and the European Space Agency's 1.0-m space debris telescope (SDT) in the Canary Islands. These surveys have detection limits in the range of 18th or 19th magnitude, which corresponds to sizes larger than 10 cm assuming an albedo of 0.175. All of these surveys reveal a substantial population of objects fainter than R = 15th magnitude that are not in the public U.S. Satellite Catalog. To detect objects fainter than 20th magnitude (and presumably smaller than 10 cm) in the visible requires a larger telescope and excellent imaging conditions. This combination is available in Chile. NASA's Orbital Debris Program Office has begun collecting orbital debris observations with the 6.5-m (21.3-ft diameter) "Walter Baade" Magellan telescope at Las Campanas Observatory. The goal is to detect objects as faint as possible from a ground-based observatory and begin to understand the brightness distribution of GEO debris fainter than R = 20th magnitude.

  3. Detecting eavesdropping activity in fiber optic networks

    NASA Astrophysics Data System (ADS)

    MacDonald, Gregory G.

    The secure transmission of data is critical to governments, military organizations, financial institutions, health care providers and other enterprises. The primary method of securing in-transit data is though data encryption. A number of encryption methods exist but the fundamental approach is to assume an eavesdropper has access to the encrypted message but does not have the computing capability to decrypt the message in a timely fashion. Essentially, the strength of security depends on the complexity of the encryption method and the resources available to the eavesdropper. The development of future technologies, most notably quantum computers and quantum computing, is often cited as a direct threat to traditional encryption schemes. It seems reasonable that additional effort should be placed on prohibiting the eavesdropper from coming into possession of the encrypted message in the first place. One strategy for denying possession of the encrypted message is to secure the physical layer of the communications path. Because the majority of transmitted information is over fiber-optic networks, it seems appropriate to consider ways of enhancing the integrity and security of the fiber-based physical layer. The purpose of this research is to investigate the properties of light, as they are manifested in single mode fiber, as a means of insuring the integrity and security of the physical layer of a fiber-optic based communication link. Specifically, the approach focuses on the behavior of polarization in single mode fiber, as it is shown to be especially sensitive to fiber geometry. Fiber geometry is necessarily modified during the placement of optical taps. The problem of detecting activity associated with the placement of an optical tap is herein approached as a supervised machine learning anomaly identification task. The inputs include raw polarization measurements along with additional features derived from various visualizations of the raw data (the inputs are

  4. Optical detection of the superconducting proximity effect

    SciTech Connect

    Greene, L.H.; Abeyta, A.C.; Roshchin, I.V.; Robinson, I.K.; Dorsten, J.F.; Tanzer, T.A.; Bohn, P.W.

    1996-12-31

    The authors present the first detection of a superconducting proximity effect by optical techniques. Raman scattering on n{sup +}-InAs is performed through very thin, high-quality, superconducting Nb films grown directly on the (100) InAs surface. The 6 to 10 nm thick Nb films exhibit {Tc}`s of 2.5 to 5.5 K, as measured by electronic transport, and are flat to {approximately}0.5 nm, as measured by x-ray reflectivity. As the Nb/InAs structure is cooled below the superconducting transition temperature, the magnitude of the unscreened LO phonon mode, associated with the surface charge accumulation layer in the InAs, is observed to be enhanced by more than 40%. This reversible change is observed only when the Nb is in good electrical contact with the InAs.

  5. Submerged turbulence detection with optical satellites

    NASA Astrophysics Data System (ADS)

    Gibson, Carl H.; Keeler, R. Norris; Bondur, Valery G.; Leung, Pak T.; Prandke, H.; Vithanage, D.

    2007-09-01

    During fall periods in 2002, 2003 and 2004 three major oceanographic expeditions were carried out in Mamala Bay, Hawaii. These were part of the RASP Remote Anthropogenic Sensing Program. Ikonos and Quickbird optical satellite images of sea surface glint revealed ~100 m spectral anomalies in km2 averaging patches in regions leading from the Honolulu Sand Island Municipal Outfall diffuser to distances up to 20 km. To determine the mechanisms behind this phenomenon, the RASP expeditions monitored the waters adjacent to the outfall with an array of hydrographic, optical and turbulence microstructure sensors in anomaly and ambient background regions. Drogue tracks and mean turbulence parameters for 2 × 10 4 microstructure patches were analyzed to understand complex turbulence, fossil turbulence and zombie turbulence near-vertical internal wave transport processes. The dominant mechanism appears to be generic to stratified natural fluids including planet and star atmospheres and is termed beamed zombie turbulence maser action (BZTMA). Most of the bottom turbulent kinetic energy is converted to ~ 100 m fossil turbulence waves. These activate secondary (zombie) turbulence in outfall fossil turbulence patches that transmit heat, mass, chemical species, momentum and information vertically to the sea surface for detection in an efficient maser action. The transport is beamed in intermittent mixing chimneys.

  6. Submerged turbulence detection with optical satellites

    NASA Astrophysics Data System (ADS)

    Gibson, Carl H.; Keeler, R. Norris; Bondur, Valery G.; Leung, Pak T.; Prandke, H.; Vithanage, D.

    2013-01-01

    During fall periods in 2002, 2003 and 2004 three major oceanographic expeditions were carried out in Mamala Bay, Hawaii. These were part of the RASP Remote Anthropogenic Sensing Program. Ikonos and Quickbird optical satellite images of sea surface glint revealed !100 m spectral anomalies in km2 averaging patches in regions leading from the Honolulu Sand Island Municipal Outfall diffuser to distances up to 20 km. To determine the mechanisms behind this phenomenon, the RASP expeditions monitored the waters adjacent to the outfall with an array of hydrographic, optical and turbulence microstructure sensors in anomaly and ambient background regions. Drogue tracks and mean turbulence parameters for 2 ! 104 microstructure patches were analyzed to understand complex turbulence, fossil turbulence and zombie turbulence near-vertical internal wave transport processes. The dominant mechanism appears to be generic to stratified natural fluids including planet and star atmospheres and is termed beamed zombie turbulence maser action (BZTMA). Most of the bottom turbulent kinetic energy is converted to ! 100 m fossil turbulence waves. These activate secondary (zombie) turbulence in outfall fossil turbulence patches that transmit heat, mass, chemical species, momentum and information vertically to the sea surface for detection in an efficient maser action. The transport is beamed in intermittent mixing chimneys.

  7. Multimodal optical imaging for detecting breast cancer

    NASA Astrophysics Data System (ADS)

    Patel, Rakesh; Khan, Ashraf; Wirth, Dennis; Kamionek, Michal; Kandil, Dina; Quinlan, Robert; Yaroslavsky, Anna N.

    2012-06-01

    The goal of the study was to evaluate wide-field and high-resolution multimodal optical imaging, including polarization, reflectance, and fluorescence for the intraoperative detection of breast cancer. Lumpectomy specimens were stained with 0.05 mg/ml aqueous solution of methylene blue (MB) and imaged. Wide-field reflectance images were acquired between 390 and 750 nm. Wide-field fluorescence images were excited at 640 nm and registered between 660 and 750 nm. High resolution confocal reflectance and fluorescence images were excited at 642 nm. Confocal fluorescence images were acquired between 670 nm and 710 nm. After imaging, the specimens were processed for hematoxylin and eosin (H&E) histopathology. Histological slides were compared with wide-field and high-resolution optical images to evaluate correlation of tumor boundaries and cellular morphology, respectively. Fluorescence polarization imaging identified the location, size, and shape of the tumor in all the cases investigated. Averaged fluorescence polarization values of tumor were higher as compared to normal tissue. Statistical analysis confirmed the significance of these differences. Fluorescence confocal imaging enabled cellular-level resolution. Evaluation and statistical analysis of MB fluorescence polarization values registered from single tumor and normal cells demonstrated higher fluorescence polarization from cancer. Wide-field high-resolution fluorescence and fluorescence polarization imaging shows promise for intraoperative delineation of breast cancers.

  8. Coherent detection in optical fiber systems.

    PubMed

    Ip, Ezra; Lau, Alan Pak Tao; Barros, Daniel J F; Kahn, Joseph M

    2008-01-21

    The drive for higher performance in optical fiber systems has renewed interest in coherent detection. We review detection methods, including noncoherent, differentially coherent, and coherent detection, as well as a hybrid method. We compare modulation methods encoding information in various degrees of freedom (DOF). Polarization-multiplexed quadrature-amplitude modulation maximizes spectral efficiency and power efficiency, by utilizing all four available DOF, the two field quadratures in the two polarizations. Dual-polarization homodyne or heterodyne downconversion are linear processes that can fully recover the received signal field in these four DOF. When downconverted signals are sampled at the Nyquist rate, compensation of transmission impairments can be performed using digital signal processing (DSP). Linear impairments, including chromatic dispersion and polarization-mode dispersion, can be compensated quasi-exactly using finite impulse response filters. Some nonlinear impairments, such as intra-channel four-wave mixing and nonlinear phase noise, can be compensated partially. Carrier phase recovery can be performed using feedforward methods, even when phase-locked loops may fail due to delay constraints. DSP-based compensation enables a receiver to adapt to time-varying impairments, and facilitates use of advanced forward-error-correction codes. We discuss both single- and multi-carrier system implementations. For a given modulation format, using coherent detection, they offer fundamentally the same spectral efficiency and power efficiency, but may differ in practice, because of different impairments and implementation details. With anticipated advances in analog-to-digital converters and integrated circuit technology, DSP-based coherent receivers at bit rates up to 100 Gbit/s should become practical within the next few years. PMID:18542153

  9. Polarization sensitive optical coherence tomography detection method

    SciTech Connect

    Everett, M J; Sathyam, U S; Colston, B W; DaSilva, L B; Fried, D; Ragadio, J N; Featherstone, J D B

    1999-05-12

    This study demonstrates the potential of polarization sensitive optical coherence tomography (PS-OCT) for non-invasive in vivo detection and characterization of early, incipient caries lesions. PS-OCT generates cross-sectional images of biological tissue while measuring the effect of the tissue on the polarization state of incident light. Clear discrimination between regions of normal and demineralized enamel is first shown in PS-OCT images of bovine enamel blocks containing well-characterized artificial lesions. High-resolution, cross-sectional images of extracted human teeth are then generated that clearly discriminate between the normal and carious regions on both the smooth and occlusal surfaces. Regions of the teeth that appeared to be demineralized in the PS-OCT images were verified using histological thin sections examined under polarized light microscopy. The PS-OCT system discriminates between normal and carious regions by measuring the polarization state of the back-scattered 1310 nm light, which is affected by the state of demineralization of the enamel. Demineralization of enamel increases the scattereing coefficient, thus depolarizing the incident light. This study shows that PS-OCT has great potential for the detection, characterization, and monitoring of incipient caries lesions.

  10. Degradation points detection in optical fiber

    NASA Astrophysics Data System (ADS)

    Salikhov, Aydar I.

    2015-03-01

    In this paper, we propose a new algorithm for monitoring the state of the fiber-optic link using polarization effects. The necessity of this work is because currently in operation is a very large number of fiber-optic cables with expired or expiring operation. This means that they are actively developing microcracks and other local defects. In this paper we propose a method for continuous monitoring of optical fiber communication cables.

  11. Leakage detection using fiber optics distributed temperature monitoring

    NASA Astrophysics Data System (ADS)

    Nikles, Marc; Vogel, Bernhard H.; Briffod, Fabien; Grosswig, Stephan; Sauser, Florian; Luebbecke, Steffen; Bals, Andre; Pfeiffer, Thomas

    2004-07-01

    The monitoring of temperature profiles over long distance by means of optical fibers represents a highly efficient way to perform leakage detection along pipelines, in dams, dykes, or tanks... Different techniques have been developed taking advantages of the fiber geometry and of optical time domain analysis for the localization of the information. Among fiber optics distributed temperature sensing techniques, Brillouin-based systems have demonstrated to have the best potential for applications over distances up to several tens of kilometers. The key features and performances are reviewed in the present article and a 55km pipeline equipped with a fiber optics leakage detection system is presented as a case study.

  12. Chemical detection demonstrated using an evanescent wave graphene optical sensor

    NASA Astrophysics Data System (ADS)

    Maliakal, Ashok; Reith, Leslie; Cabot, Steve

    2016-04-01

    Graphene devices have been constructed on silicon mirrors, and the graphene is optically probed through an evanescent wave interaction in an attenuated total reflectance configuration using an infrared spectrometer. The graphene is electrically biased in order to tune its optical properties. Exposure of the device to the chemicals iodine and ammonia causes observable and reversible changes to graphene's optical absorption spectra in the mid to near infrared range which can be utilized for the purpose of sensing. Electrical current measurements through the graphene are made simultaneously with optical measurements allowing for simultaneous sensing using two separate detection modalities. Our current results reveal sub-ppm detection limits for iodine and approximately 100 ppm detection limits for ammonia. We have also demonstrated that this approach will work at 1.55 μm, which opens up the possibility for graphene optical sensors that leverage commercial telecom light sources.

  13. Fiber-optic testing system having a detection circuit

    NASA Astrophysics Data System (ADS)

    Needham, Francis L.

    1992-05-01

    A system for testing a fiber-optic component with infrared radiation is provided. The testing system has a source of infrared radiation, an optic coupler, a detecting circuit, and an analog tape recorder. The optic coupler directs the infrared radiation onto the fiber-optic component. The detection circuit is electrically connected to the tape recorder. The detection circuit has an amplifier, a potentiometer connected in parallel to the amplifier, and a photoelectric transducer connected in series to the amplifier. These components are mounted on a non-conductive board. A power source supplies voltage and is connected to the amplifier. The circuit operates by having the photoelectric transducer sense the infrared radiation emitted from the tested fiber-optic component and convert the radiation into an electrical signal. The amplifier then amplifies the electrical signal to the voltage necessary for driving the tape recorder.

  14. Fiber-optical testing system having a detection circuit

    NASA Astrophysics Data System (ADS)

    Needham, Francis L.

    1994-01-01

    A system for testing a fiber-optic component with infrared radiation is provided. The testing system has a source of infrared radiation, an optic coupler, a detecting circuit, and an analog tape recorder. The optic coupler directs the infrared radiation onto the fiber-optic component. The detection circuit is electrically connected to the tape recorder. The detection circuit has an amplifier, a potentiometer connected in parallel to the amplifier, and a photoelectric transducer connected in series to the amplifier. These components are mounted on a non-conductive board. A power source supplies voltage and is connected to the amplifier. The circuit operates by having the photoelectric transducer sense the infrared radiation emitted from the tested fiber-optic component and convert the radiation into an electrical signal. The amplifier then amplifies the electrical signal to the voltage necessary for driving the tape recorder.

  15. Adaptive optics assisted Fourier domain OCT with balanced detection

    NASA Astrophysics Data System (ADS)

    Meadway, A.; Bradu, A.; Hathaway, M.; Van der Jeught, S.; Rosen, R. B.; Podoleanu, A. Gh.

    2011-03-01

    Two factors are of importance to optical coherence tomography (OCT), resolution and sensitivity. Adaptive optics improves the resolution of a system by correcting for aberrations causing distortions in the wave-front. Balanced detection has been used in time domain OCT systems by removing excess photon noise, however it has not been used in Fourier domain systems, as the cameras used in the spectrometers saturated before excess photon noise becomes a problem. Advances in camera technology mean that this is no longer the case and balanced detection can now be used to improve the signal to noise ratio in a Fourier domain (FD) OCT system. An FD-OCT system, enhanced with adaptive optics, is presented and is used to show the improvement that balanced detection can provide. The signal to noise ratios of single camera detection and balanced detection are assessed and in-vivo retinal images are acquired to demonstrate better image quality when using balance detection.

  16. Electro-Optical Detection of Single λ-DNA†

    PubMed Central

    Liu, Shuo; Wall, Thomas A.; Ozcelik, Damla; Parks, Joshua W.; Hawkins, Aaron R.; Schmidt, Holger

    2015-01-01

    Single λ-DNA molecules are detected on a nanopore-gated optofluidic chip electrically and optically. Statistical variations in the single particle trajectories are used to predict the intensity distribution of the fluorescence signals. PMID:25533516

  17. Lamb wave detection with a fiber optic angular displacement sensor

    NASA Astrophysics Data System (ADS)

    Garcia, Marlon R.; Sakamoto, João. M. S.; Higuti, Ricardo T.; Kitano, Cláudio

    2015-09-01

    In this work we show that the fiber optic angular displacement sensor is capable of Lamb wave detection, with results comparable to a piezoelectric transducer. Therefore, the fiber optic sensor has a great potential to be used as the Lamb wave ultrasonic receiver and to perform non-destructive and non-contact testing.

  18. Integrated optical biosensor for detection of multivalent proteins

    SciTech Connect

    Kelly, Dan; Grace, Karen M.; Song, Xuedong; Swanson, Basil I.; Frayer, Daniel; Mendes, Sergio B.; Peyghambarian, Nasser

    1999-12-01

    We have developed a simple, highly sensitive and specific optical waveguide sensor for the detection of multivalent proteins. The optical biosensor is based on optically tagged glycolipid receptors embedded within a fluid phospholipid bilayer membrane formed upon the surface of a planar optical waveguide. Binding of multivalent cholera toxin triggers a fluorescence resonance energy transfer that results in a two-color optical change that is monitored by measurement of emitted luminescence above the waveguide surface. The sensor approach is highly sensitive and specific and requires no additional reagents and washing steps. Demonstration of protein-receptor recognition by use of planar optical waveguides provides a path forward for the development of fieldable miniaturized biosensor arrays. (c) 1999 Optical Society of America.

  19. Optical Detection of Anomalous Nitrogen in Comets

    NASA Astrophysics Data System (ADS)

    2003-12-01

    VLT Opens New Window towards Our Origins Summary A team of European astronomers [1] has used the UVES spectrograph on the 8.2-m VLT KUEYEN telescope to perform a uniquely detailed study of Comet LINEAR (C/2000 WM1) . This is the first time that this powerful instrument has been employed to obtain high-resolution spectra of a comet. At the time of the observations in mid-March 2002, Comet LINEAR was about 180 million km from the Sun, moving outwards after its perihelion passage in January. As comets are believed to carry "pristine" material - left-overs from the formation of the solar system, about 4,600 million years ago - studies of these objects are important to obtain clues about the origins of the solar system and the Earth in particular. The high quality of the data obtained of this moving 9th-magnitude object has permitted a determination of the cometary abundance of various elements and their isotopes [2]. Of particular interest is the unambiguous detection and measurement of the nitrogen-15 isotope. The only other comet in which this isotope has been observed is famous Comet Hale-Bopp - this was during the passage in 1997, when it was much brighter than Comet LINEAR. Most interestingly, Comet LINEAR and Comet Hale-Bopp display the same isotopic abundance ratio, about 1 nitrogen-15 atom for each 140 nitrogen-14 atoms ( 14 N/ 15 N = 140 ± 30) . That is about half of the terrestrial value (272). It is also very different from the result obtained by means of radio measurements of Comet Hale-Bopp ( 14 N/ 15 N = 330 ± 75). Optical and radio measurements concern different molecules (CN and HCN, respectively), and this isotopic anomaly must be explained by some differentiation mechanism. The astronomers conclude that part of the cometary nitrogen is trapped in macromolecules attached to dust particles . The successful entry of UVES into cometary research now opens eagerly awaited opportunities for similiar observations in other, comparatively faint comets. These

  20. Optical detection of oil on water

    NASA Technical Reports Server (NTRS)

    Millard, J. P.; Arvesen, J. C.

    1973-01-01

    Three radiometric techniques utilizing sunlight reflected and backscattered from water bodies have potential application for remote sensing of oil spills. Oil on water can be detected by viewing perpendicular polarization component of reflected light or difference between polarization components. Best detection is performed in ultraviolet or far-red portions of spectrum and in azimuth directions toward or opposite sun.

  1. Leakage detection of oil pipeline using distributed fiber optic sensor

    NASA Astrophysics Data System (ADS)

    Shan, Song; Wang, Li; Zhou, Jinfeng

    2007-07-01

    A system of distributed optical fiber sensor has presented based on the optical fiber sensor technology and detected the oil pipeline leakage using Mach-Zehnder optical interferometer. There are two interferential signals from sensor and reference light to put in computer has been analyzed using the analysis software LabVIEW of National Instruments' that can operate for the cross-correlation function, then compare the correlation peak to obtain the disturbance of oil leakage location, the detection precision 200m at around 50km for pipeline in the high speed sampling and data signal processing has obtained.

  2. An Optical Biosensor for Bacillus Cereus Spore Detection

    NASA Astrophysics Data System (ADS)

    Li, Chengquan; Tom, Harry W. K.

    2005-03-01

    We demonstrate a new transduction scheme for optical biosensing. Bacillus cereus is a pathogen that may be found in food and dairy products and is able to produce toxins and cause food poisoning. It is related to Bacillus anthracis (anthrax). A CCD array covered with micro-structured glass coverslip is used to detect the optical resonant shift due to the binding of the antigen (bacillus cereus spore) to the antibody (polyclonal antibody). This novel optical biosensor scheme has the potential for detecting 10˜100 bioagents in a single device as well as the potential to test for antigens with multiple antibody tests to avoid ``false positives.''

  3. Detection of Laser Optic Defects Using Gradient Direction Matching

    SciTech Connect

    Chen, B Y; Kegelmeyer, L M; Liebman, J A; Salmon, J T; Tzeng, J; Paglieroni, D W

    2005-12-14

    That National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) will be the world's largest and most energetic laser. It has thousands of optics and depends heavily on the quality and performance of these optics. Over the past several years, we have developed the NIF Optics Inspection Analysis System that automatically finds defects in a specific optic by analyzing images taken of that optic. This paper describes a new and complementary approach for the automatic detection of defects based on detecting the diffraction ring patterns in downstream optic images caused by defects in upstream optics. Our approach applies a robust pattern matching algorithm for images called Gradient Direction Matching (GDM). GDM compares the gradient directions (the direction of flow from dark to light) of pixels in a test image to those of a specified model and identifies regions in the test image whose gradient directions are most in line with those of the specified model. For finding rings, we use luminance disk models whose pixels have gradient directions all pointing toward the center of the disk. After GDM identifies potential rings locations, we rank these rings by how well they fit the theoretical diffraction ring pattern equation. We perform false alarm mitigation by throwing out rings of low fit. A byproduct of this fitting procedure is an estimate of the size of the defect and its distance from the image plane. We demonstrate the potential effectiveness of this approach by showing examples of rings detected in real images of NIF optics.

  4. Portable multichannel fiber optic biosensor for field detection

    NASA Astrophysics Data System (ADS)

    Golden, Joel P.; Saaski, Elric W.; Shriver-Lake, Lisa C.; Anderson, George P.; Ligler, Frances S.

    1997-04-01

    A compact, portable fiber optic biosensor is developed that enables monitoring of up to four fiber optic probes simultaneously. The sensor employs a novel optical fiber bundle jumper for exciting and collecting fluorescence emission from the evanescent wave fiber optic probes. A single fiber in the center of the bundle couples laser excitation into the sensor probe, while the surrounding fibers collect the returning fluorescent emission light. This design requires no beamsplitter, enabling the detection optics and control circuitry to be reduced to a 4 X 6 in. circuit card. Four of these cards are integrated into a single portable system. Results from detection assays for hazardous biological agents and an environmental pollutant are shown.

  5. Optical detection system for MEMS-type pressure sensor

    NASA Astrophysics Data System (ADS)

    Sareło, K.; Górecka-Drzazga, A.; Dziuban, J. A.

    2015-07-01

    In this paper a special optical detection system designed for a MEMS-type (micro-electro-mechanical system) silicon pressure sensor is presented. The main part of the optical system—a detection unit with a perforated membrane—is bonded to the silicon sensor, and placed in a measuring system. An external light source illuminates the membrane of the pressure sensor. Owing to the light reflected from the deflected membrane sensor, the optical pattern consisting of light points is visible, and pressure can be estimated. The optical detection unit (20   ×   20   ×   20.4 mm3) is fabricated using microengineering techniques. Its dimensions are adjusted to the dimensions of the pressure sensor (5   ×   5 mm2 silicon membrane). Preliminary tests of the optical detection unit integrated with the silicon pressure sensor are carried out. For the membrane sensor from 15 to 60 µm thick, a repeatable detection of the differential pressure in the range of 0 to 280 kPa is achieved. The presented optical microsystem is especially suitable for the pressure measurements in a high radiation environment.

  6. Analysis of quantitative phase detection based on optical information processing

    NASA Astrophysics Data System (ADS)

    Tao, Wang; Tu, Jiang-Chen; Chun, Kuang-Tao; Yu, Han-Wang; Xin, Du

    2009-07-01

    Phase object exists widely in nature, such as biological cells, optical components, atmospheric flow field and so on. The phase detection of objects has great significance in the basic research, nondestructive testing, aerospace, military weapons and other areas. The usual methods of phase object detection include interference method, grating method, schlieren method, and phase-contrast method etc. These methods have their own advantages, but they also have some disadvantages on detecting precision, environmental requirements, cost, detection rate, detection range, detection linearity in various applications, even the most sophisticated method-phase contrast method mainly used in microscopic structure, lacks quantitative analysis of the size of the phase of the object and the relationship between the image contrast and the optical system. In this paper, various phase detection means and the characteristics of different applications are analyzed based on the optical information processing, and a phase detection system based on optical filtering is formed. Firstly the frequency spectrum of the phase object is achieved by Fourier transform lens in the system, then the frequency spectrum is changed reasonably by the filter, at last the image which can represent the phase distribution through light intensity is achieved by the inverse Fourier transform. The advantages and disadvantages of the common used filters such as 1/4 wavelength phase filter, high-pass filter and edge filter are analyzed, and their phase resolution is analyzed in the same optical information processing system, and the factors impacting phase resolution are pointed out. The paper draws a conclusion that there exists an optimal filter which makes the detect accuracy best for any application. At last, we discussed how to design an optimal filter through which the ability of the phase testing of optical information processing system can be improved most.

  7. Simultaneous detection and intensity estimation of an optical image

    NASA Technical Reports Server (NTRS)

    Wang, L.

    1979-01-01

    A statistical model for simultaneous detection and single parameter estimation of a stochastic signal against background noise is obtained. Two strategies, Bayes and maximum likelihood, are discussed. The detection of an optical point source imaged on a photosensitive surface and the estimation of its intensity based on such strategies are examined. An almost optimum estimate is also proposed and its statistical properties are studied.

  8. Improvement of optical systems for detection of smokes

    NASA Astrophysics Data System (ADS)

    Panin, V. F.; Dashkovskii, A. G.

    2015-04-01

    The theory of electromagnetic radiation dispersion by polydisperse particles is analyzed. Methods of reliable optical indication of smokes to identify Fire Danger are considered. The conventional method of optical smoke detection implies measuring optical characteristics of the environment under control. After that the results obtained are converted into microphysical parameters which can be compared to the known microphysical properties of smokes.The calculated optical portrait of smokes is offered. The portrait of smokes is the field of representation points in coordinates of the degree of diffusion radiation polarization for two diffusion angles. Each of the spots indicates one of the numerous realizations of smokes. The direct match of the representation spots in the optical increases the probability of smoke A different way to protect optical system is to use the device with mutually orthogonal polarizers of the light source and detector. If hindrance is nonspherical aerosol, the signal from the device is used to correct the signals from smoke detectors.

  9. Fiber optic approach for detecting corrosion

    NASA Astrophysics Data System (ADS)

    Kostecki, Roman; Ebendorff-Heidepriem, Heike; Davis, Claire; McAdam, Grant; Wang, Tianyu; Monro, Tanya M.

    2016-04-01

    Corrosion is a multi-billion dollar problem faced by industry. The ability to monitor the hidden metallic structure of an aircraft for corrosion could result in greater availability of existing aircraft fleets. Silica exposed-core microstructured optical fiber sensors are inherently suited towards this application, as they are extremely lightweight, robust, and suitable both for distributed measurements and for embedding in otherwise inaccessible corrosion-prone areas. By functionalizing the fiber with chemosensors sensitive to corrosion by-products, we demonstrate in-situ kinetic measurements of accelerated corrosion in simulated aluminum aircraft joints.

  10. Optic disc detection and boundary extraction in retinal images.

    PubMed

    Basit, A; Fraz, Muhammad Moazam

    2015-04-10

    With the development of digital image processing, analysis and modeling techniques, automatic retinal image analysis is emerging as an important screening tool for early detection of ophthalmologic disorders such as diabetic retinopathy and glaucoma. In this paper, a robust method for optic disc detection and extraction of the optic disc boundary is proposed to help in the development of computer-assisted diagnosis and treatment of such ophthalmic disease. The proposed method is based on morphological operations, smoothing filters, and the marker controlled watershed transform. Internal and external markers are used to first modify the gradient magnitude image and then the watershed transformation is applied on this modified gradient magnitude image for boundary extraction. This method has shown significant improvement over existing methods in terms of detection and boundary extraction of the optic disc. The proposed method has optic disc detection success rate of 100%, 100%, 100% and 98.9% for the DRIVE, Shifa, CHASE_DB1, and DIARETDB1 databases, respectively. The optic disc boundary detection achieved an average spatial overlap of 61.88%, 70.96%, 45.61%, and 54.69% for these databases, respectively, which are higher than currents methods. PMID:25967336

  11. Optically selective, acoustically resonant gas detecting transducer

    NASA Technical Reports Server (NTRS)

    Dimeff, J. (Inventor)

    1977-01-01

    A gas analyzer is disclosed which responds to the resonant absorption or emission spectrum of a specific gas by producing an acoustic resonance in a chamber containing a sample of that gas, and which measures the amount of that emission or absorption by measuring the strength of that acoustic resonance, e.g., the maximum periodic pressure, velocity or density achieved. In the preferred embodiment, a light beam is modulated periodically at the acoustical resonance frequency of a closed chamber which contains an optically dense sample of the gas of interest. Periodic heating of the absorbing gas by the light beam causes a cyclic expansion, movement, and pressure within the gas. An amplitude is reached where the increased losses were the cyclic radiation energy received. A transducing system is inclined for converting the pressure variations of the resonant gas into electronic readout signals.

  12. Pyridine Vapors Detection by an Optical Fibre Sensor

    PubMed Central

    Elosua, Cesar; Bariain, Candido; Matias, Ignacio R.; Rodriguez, Antonio; Colacio, Enriquie; Salinas-Castillo, Alfonso; Segura-Carretero, Antonio; Fernandez-Gutiérrez, Alberto

    2008-01-01

    An optical fibre sensor has been implemented towards pyridine vapors detection; to achieve this, a novel vapochromic material has been used, which, in solid state, suffers a change in colour from blue to pink-white in presence of pyridine vapours. This complex is added to a solution of PVC (Poly Vinyl Chloride), TBP (Tributylphosphate) and tetrahydrofuran (THF), forming a plasticized matrix; by dip coating technique, the sensing material is fixed onto a cleaved ended optical fibre. The fabrication process was optimized in terms of number of dips and dipping speed, evaluating the final devices by dynamic range. Employing a reflection set up, the absorbance spectra and changes in the reflected optical power of the sensors were registered to determine their response. A linear relation between optical power versus vapor concentration was obtained, with a detection limit of 1 ppm (v/v).

  13. Amplifier Noise Based Optical Steganography with Coherent Detection

    NASA Astrophysics Data System (ADS)

    Wu, Ben; Chang, Matthew P.; Caldwell, Naomi R.; Caldwell, Myles E.; Prucnal, Paul R.

    2014-12-01

    We summarize the principle and experimental setup of optical steganography based on amplified spontaneous emission (ASE) noise. Using ASE noise as the signal carrier, optical steganography effectively hides a stealth channel in both the time domain and the frequency domain. Coherent detection is used at the receiver of the stealth channel. Because ASE noise has short coherence length and random phase, it only interferes with itself within a very short range. Coherent detection requires the stealth transmitter and stealth receiver to precisely match the optical delay,which generates a large key space for the stealth channel. Several methods to further improve optical steganography, signal to noise ratio, compatibility with the public channel, and applications of the stealth channel are also summarized in this review paper.

  14. LLNL electro-optical mine detection program

    SciTech Connect

    Anderson, C.; Aimonetti, W.; Barth, M.; Buhl, M.; Bull, N.; Carter, M.; Clark, G.; Fields, D.; Fulkerson, S.; Kane, R.

    1994-09-30

    Under funding from the Advanced Research Projects Agency (ARPA) and the US Marine Corps (USMC), Lawrence Livermore National Laboratory (LLNL) has directed a program aimed at improving detection capabilities against buried mines and munitions. The program has provided a national test facility for buried mines in arid environments, compiled and distributed an extensive data base of infrared (IR), ground penetrating radar (GPR), and other measurements made at that site, served as a host for other organizations wishing to make measurements, made considerable progress in the use of ground penetrating radar for mine detection, and worked on the difficult problem of sensor fusion as applied to buried mine detection. While the majority of our effort has been concentrated on the buried mine problem, LLNL has worked with the U.S.M.C. on surface mine problems as well, providing data and analysis to support the COBRA (Coastal Battlefield Reconnaissance and Analysis) program. The original aim of the experimental aspect of the program was the utilization of multiband infrared approaches for the detection of buried mines. Later the work was extended to a multisensor investigation, including sensors other than infrared imagers. After an early series of measurements, it was determined that further progress would require a larger test facility in a natural environment, so the Buried Object Test Facility (BOTF) was constructed at the Nevada Test Site. After extensive testing, with sensors spanning the electromagnetic spectrum from the near ultraviolet to radio frequencies, possible paths for improvement were: improved spatial resolution providing better ground texture discrimination; analysis which involves more complicated spatial queueing and filtering; additional IR bands using imaging spectroscopy; the use of additional sensors other than IR and the use of data fusion techniques with multi-sensor data; and utilizing time dependent observables like temperature.

  15. Tumor margin detection using optical biopsy techniques

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Liu, Cheng-hui; Li, Jiyou; Li, Zhongwu; Zhou, Lixin; Chen, Ke; Pu, Yang; He, Yong; Zhu, Ke; Li, Qingbo; Alfano, Robert R.

    2014-03-01

    The aim of this study is to use the Resonance Raman (RR) and fluorescence spectroscopic technique for tumor margin detection with high accuracy based on native molecular fingerprints of breast and gastrointestinal (GI) tissues. This tumor margins detection method utilizes advantages of RR spectroscopic technique in situ and in real-time to diagnose tumor changes providing powerful tools for clinical guiding intraoperative margin assessments and postoperative treatments. The tumor margin detection procedures by RR spectroscopy were taken by scanning lesion from center or around tumor region in ex-vivo to find the changes in cancerous tissues with the rim of normal tissues using the native molecular fingerprints. The specimens used to analyze tumor margins include breast and GI carcinoma and normal tissues. The sharp margin of the tumor was found by the changes of RR spectral peaks within 2 mm distance. The result was verified using fluorescence spectra with 300 nm, 320 nm and 340 nm excitation, in a typical specimen of gastric cancerous tissue within a positive margin in comparison with normal gastric tissues. This study demonstrates the potential of RR and fluorescence spectroscopy as new approaches with labeling free to determine the intraoperative margin assessment.

  16. Spectrally balanced detection for optical frequency domain imaging.

    PubMed

    Chen, Yueli; de Bruin, Daniel M; Kerbage, Charles; de Boer, Johannes F

    2007-12-10

    In optical frequency domain imaging (OFDI) or swept-source optical coherence tomography, balanced detection is required to suppress relative intensity noise (RIN). A regular implementation of balanced detection by combining reference and sample arm signal in a 50/50 coupler and detecting the differential output with a balanced receiver is however, not perfect. Since the splitting ratio of the 50/50 coupler is wavelength dependent, RIN is not optimally canceled at the edges of the wavelength sweep. The splitting ratio has a nearly linear shift of 0.4% per nanometer. This brings as much as +/-12% deviation at the margins of wavelength-swept range centered at 1060nm. We demonstrate a RIN suppression of 33dB by spectrally corrected balanced detection, 11dB more that regular balanced detection. PMID:19550929

  17. Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers.

    PubMed

    Cole, Russell H; Gartner, Zev J; Abate, Adam R

    2016-01-01

    Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein. PMID:27214249

  18. The optical detection unit for Baikal-GVD neutrino telescope

    NASA Astrophysics Data System (ADS)

    Avrorin, A. D.; Avrorin, A. V.; Aynutdinov, V. M.; Bannash, R.; Belolaptikov, I. A.; Bogorodsky, D. Yu.; Brudanin, V. B.; Budnev, N. M.; Danilchenko, I. A.; Domogatsky, G. V.; Doroshenko, A. A.; Dyachok, A. N.; Dzhilkibaev, Zh.-A. M.; Fialkovsky, S. V.; Gafarov, A. R.; Gaponenko, O. N.; Golubkov, K. V.; Gress, T. I.; Honz, Z.; Kebkal, K. G.; Kebkal, O. G.; Konischev, K. V.; Konstantinov, E. N.; Korobchenko, A. V.; Koshechkin, A. P.; Koshel, F. K.; Kozhin, A. V.; Kulepov, V. F.; Kuleshov, D. A.; Ljashuk, V. I.; Milenin, M. B.; Mirgazov, R. A.; Osipova, E. R.; Panfilov, A. I.; Pan'kov, L. V.; Perevalov, A. A.; Pliskovsky, E. N.; Rozanov, M. I.; Rubtzov, V. Yu.; Rjabov, E. V.; Shaybonov, B. A.; Sheifler, A. A.; Skurihin, A. V.; Smagina, A. A.; Suvorova, O. V.; Tabolenko, V. A.; Tarashansky, B. A.; Yakovlev, S. A.; Zagorodnikov, A. V.; Zhukov, V. A.; Zurbanov, V. L.

    2016-07-01

    The first stage of the GVD-cluster composed of five strings was deployed in April 2014. Each string consists of two sections with 12 optical modules per section. A section is the basic detection unit of the Baikal neutrino telescope. We will describe the section design, review its basic elements - optical modules, FADC readout units, slow control and calibration systems, and present selected results for section in-situ tests in Lake Baikal.

  19. Spin microscope based on optically detected magnetic resonance

    SciTech Connect

    Berman, Gennady P.; Chernobrod, Boris M.

    2009-11-10

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of impaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  20. Spin microscope based on optically detected magnetic resonance

    SciTech Connect

    Berman, Gennady P.; Chernobrod, Boris M.

    2010-06-29

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  1. Spin microscope based on optically detected magnetic resonance

    SciTech Connect

    Berman, Gennady P.; Chernobrod, Boris M.

    2010-07-13

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  2. Spin microscope based on optically detected magnetic resonance

    SciTech Connect

    Berman, Gennady P.; Chernobrod, Boris M.

    2009-10-27

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  3. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P.; Chernobrod, Boris M.

    2007-12-11

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  4. Detection of optical properties in small region by diffuse reflectance

    NASA Astrophysics Data System (ADS)

    Wang, Lijun; Li, Shengcai; Wang, Kai; Zhu, Zongping; Wang, Wei

    2015-11-01

    The optical properties of small and highly absorbing tissues can be determined by measurement of spatially resolved diffuse reflectance at short source-detector separations. Spatial resolution and number of measuring point influence the inverting precision of optical property directly from the experimental diffuse reflectance. To increase spatial resolution and number of measuring point, a high-resolution and multiple points detection system is designed. A special optical fiber array probe is employed. Its spatial resolution is 0.125mm. The system is proved to be reliable by comparing the experimental result of diffuse reflectance from small region 0.125mm-1.25mm with that of numerical simulation. The inverting method based on Monte Carlo simulation is designed, by which optical properties can be achieved by building optical parameter date base and training artificial neural network (ANN).

  5. Microstructured Optical Fiber for X-ray Detection

    NASA Technical Reports Server (NTRS)

    DeHaven, Stanton L.

    2009-01-01

    A novel scintillating optical fiber is presented using a composite micro-structured quartz optical fiber. Scintillating materials are introduced into the multiple inclusions of the fiber. This creates a composite optical fiber having quartz as a cladding with an organic scintillating material core. X-ray detection using these fibers is compared to a collimated cadmium telluride (CdTe) detector over an energy range from 10 to 40 keV. Results show a good correlation between the fiber count rate trend and that of the CdTe detector.

  6. MICROSTRUCTURED OPTICAL FIBER FOR X-RAY DETECTION

    SciTech Connect

    DeHaven, S. L.

    2010-02-22

    A novel scintillating optical fiber is presented using a composite micro-structured quartz optical fiber. Scintillating materials are introduced into the multiple inclusions of the fiber. This creates a composite optical fiber having quartz as a cladding with an organic scintillating material core. X-ray detection using these fibers is compared to a collimated cadmium telluride (CdTe) detector over an energy range from 10 to 40 keV. Results show a good correlation between the fiber count rate trend and that of the CdTe detector.

  7. Airborne optical detection of oil on water.

    NASA Technical Reports Server (NTRS)

    Millard, J. P.; Arvesen, J. C.

    1972-01-01

    Airborne measurements were made over controlled oil-spill test sites to evaluate various techniques, utilizing reflected sunlight, for detecting oil on water. The results of these measurements show that (1) maximum contrast between oil and water is in the UV and red portions of the spectrum; (2) minimum contrast is in the blue-green; (3) differential polarization appears to be a very promising technique; (4) no characteristic absorption bands, which would permit one oil to be distinguished from another, were discovered in the spectral regions measured; (5) sky conditions greatly influence the contrast between oil and water; and (6) highest contrast was achieved under overcast sky conditions.

  8. Approximate nearest neighbour field based optic disk detection.

    PubMed

    Ramakanth, S Avinash; Babu, R Venkatesh

    2014-01-01

    Approximate Nearest Neighbour Field maps are commonly used by computer vision and graphics community to deal with problems like image completion, retargetting, denoising, etc. In this paper, we extend the scope of usage of ANNF maps to medical image analysis, more specifically to optic disk detection in retinal images. In the analysis of retinal images, optic disk detection plays an important role since it simplifies the segmentation of optic disk and other retinal structures. The proposed approach uses FeatureMatch, an ANNF algorithm, to find the correspondence between a chosen optic disk reference image and any given query image. This correspondence provides a distribution of patches in the query image that are closest to patches in the reference image. The likelihood map obtained from the distribution of patches in query image is used for optic disk detection. The proposed approach is evaluated on five publicly available DIARETDB0, DIARETDB1, DRIVE, STARE and MESSIDOR databases, with total of 1540 images. We show, experimentally, that our proposed approach achieves an average detection accuracy of 99% and an average computation time of 0.2 s per image. PMID:24290957

  9. Pipeline leakage detection using distributed fibre optical temperature sensing

    NASA Astrophysics Data System (ADS)

    Grosswig, S.; Hurtig, E.; Luebbecke, S.; Vogel, B.

    2005-05-01

    The leakage detection system based on the distributed fibre optical temperature measurement method is an analysing method for continuous detection and localization of leakages at pipelines in the steady and unsteady operation states according to the German rules for pipelines TRbF 301/TRFL which is valid in Germany since April 2003. The leakage detection system is useable under the precondition that there is a sufficient large temperature gradient between the leakage area and the unaffected environment. This can be caused by the medium itself or through a physical effect due to the leakage, e.g. gas expansion, evaporation. It's a very sensitive method, so also creeping leakages can be detected.

  10. Fingerprint fake detection by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Meissner, Sven; Breithaupt, Ralph; Koch, Edmund

    2013-03-01

    The most established technique for the identification at biometric access control systems is the human fingerprint. While every human fingerprint is unique, fingerprints can be faked very easily by using thin layer fakes. Because commercial fingerprint scanners use only a two-dimensional image acquisition of the finger surface, they can only hardly differentiate between real fingerprints and fingerprint fakes applied on thin layer materials. A Swept Source OCT system with an A-line rate of 20 kHz and a lateral and axial resolution of approximately 13 μm, a centre wavelength of 1320 nm and a band width of 120 nm (FWHM) was used to acquire fingerprints and finger tips with overlying fakes. Three-dimensional volume stacks with dimensions of 4.5 mm x 4 mm x 2 mm were acquired. The layering arrangement of the imaged finger tips and faked finger tips was analyzed and subsequently classified into real and faked fingerprints. Additionally, sweat gland ducts were detected and consulted for the classification. The manual classification between real fingerprints and faked fingerprints results in almost 100 % correctness. The outer as well as the internal fingerprint can be recognized in all real human fingers, whereby this was not possible in the image stacks of the faked fingerprints. Furthermore, in all image stacks of real human fingers the sweat gland ducts were detected. The number of sweat gland ducts differs between the test persons. The typical helix shape of the ducts was observed. In contrast, in images of faked fingerprints we observe abnormal layer arrangements and no sweat gland ducts connecting the papillae of the outer fingerprint and the internal fingerprint. We demonstrated that OCT is a very useful tool to enhance the performance of biometric control systems concerning attacks by thin layer fingerprint fakes.

  11. Optical and SAR data integration for automatic change pattern detection

    NASA Astrophysics Data System (ADS)

    Mishra, B.; Susaki, J.

    2014-09-01

    Automatic change pattern mapping in urban and sub-urban area is important but challenging due to the diversity of urban land use pattern. With multi-sensor imagery, it is possible to generate multidimensional unique information of Earth surface features that allow developing a relationship between a response of each feature to synthetic aperture radar (SAR) and optical sensors to track the change automatically. Thus, a SAR and optical data integration framework for change detection and a relationship for automatic change pattern detection were developed. It was carried out in three steps: (i) Computation of indicators from SAR and optical images, namely: normalized difference ratio (NDR) from multi-temporal SAR images and the normalized difference vegetation index difference (NDVI) from multi-temporal optical images, (ii) computing the change magnitude image from NDR and ΔNDVI and delineating the change area and (iii) the development of an empirical relationship, for automatic change pattern detection. The experiment was carried out in an outskirts part of Ho Chi Minh City, one of the fastest growing cities in the world. The empirical relationship between the response of surface feature to optical and SAR imagery has successfully delineated six changed classes in a very complex urban sprawl area that was otherwise impossible with multi-spectral imagery. The improvement of the change detection results by making use of the unique information on both sensors, optical and SAR, is also noticeable with a visual inspection and the kappa index was increased by 0.13 (0.75 to 0.88) in comparison to only optical images.

  12. Optical biopsy - a new armamentarium to detect disease using light

    NASA Astrophysics Data System (ADS)

    Pu, Yang; Alfano, Robert R.

    2015-03-01

    Optical spectroscopy has been considered a promising method for cancer detection for past thirty years because of its advantages over the conventional diagnostic methods of no tissue removal, minimal invasiveness, rapid diagnoses, less time consumption and reproducibility since the first use in 1984. It offers a new armamentarium. Human tissue is mainly composed of extracellular matrix of collagen fiber, proteins, fat, water, and epithelial cells with key molecules in different structures. Tissues contain a number of key fingerprint native endogenous fluorophore molecules, such as tryptophan, collagen, elastin, reduced nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD) and porphyrins. It is well known that abnormalities in metabolic activity precede the onset of a lot of main diseases: carcinoma, diabetes mellitus, atherosclerosis, Alzheimer, and Parkinson's disease, etc. Optical spectroscopy may help in detecting various disorders. Conceivably the biochemical or morphologic changes that cause the spectra variations would appear earlier than the histological aberration. Therefore, "optical biopsy" holds a great promise as clinical tool for diagnosing early stage of carcinomas and other deceases by combining with available photonic technology (e.g. optical fibers, photon detectors, spectrographs spectroscopic ratiometer, fiber-optic endomicroscope and nasopharyngoscope) for in vivo use. This paper focuses on various methods available to detect spectroscopic changes in tissues, for example to distinguish cancerous prostate tissues and/or cells from normal prostate tissues and/or cells. The methods to be described are fluorescence, stokes shift, scattering, Raman, and time-resolved spectroscopy will be reviewed. The underlying physical and biological basis for these optical approaches will be discussed with examples. The idea is to present some of the salient works to show the usefulness and methods of Optical Biopsy for cancer detection and

  13. Assessments of phenomenologies for multi-optical mine detection

    NASA Astrophysics Data System (ADS)

    Letalick, Dietmar; Sjökvist, Stefan; Uppsäll, Magnus; Menning, Dennis; Andersson, Pierre; Grönwall, Christina

    2007-04-01

    This paper presents the Swedish land mine and UXO detection project "Multi Optical Mine Detection System," MOMS, and the research carried out so far. The goal for MOMS is to provide knowledge and competence for fast detection of mines, especially surface laid mines, by the use of both active and passive optical sensors. A main activity was to collect information and gain knowledge about phenomenology; i.e. features or characteristics that can give a detectable signature or contrast between object and background, and to carry out a phenomenology assessment. A large effort has also been put into a scene description to support phenomenology assessment and provide a framework for further experimental campaigns. Also, some preliminary experimental results are presented and discussed.

  14. Violence detection based on histogram of optical flow orientation

    NASA Astrophysics Data System (ADS)

    Yang, Zhijie; Zhang, Tao; Yang, Jie; Wu, Qiang; Bai, Li; Yao, Lixiu

    2013-12-01

    In this paper, we propose a novel approach for violence detection and localization in a public scene. Currently, violence detection is considerably under-researched compared with the common action recognition. Although existing methods can detect the presence of violence in a video, they cannot precisely locate the regions in the scene where violence is happening. This paper will tackle the challenge and propose a novel method to locate the violence location in the scene, which is important for public surveillance. The Gaussian Mixed Model is extended into the optical flow domain in order to detect candidate violence regions. In each region, a new descriptor, Histogram of Optical Flow Orientation (HOFO), is proposed to measure the spatial-temporal features. A linear SVM is trained based on the descriptor. The performance of the method is demonstrated on the publicly available data sets, BEHAVE and CAVIAR.

  15. Detection of Abnormal Events via Optical Flow Feature Analysis

    PubMed Central

    Wang, Tian; Snoussi, Hichem

    2015-01-01

    In this paper, a novel algorithm is proposed to detect abnormal events in video streams. The algorithm is based on the histogram of the optical flow orientation descriptor and the classification method. The details of the histogram of the optical flow orientation descriptor are illustrated for describing movement information of the global video frame or foreground frame. By combining one-class support vector machine and kernel principal component analysis methods, the abnormal events in the current frame can be detected after a learning period characterizing normal behaviors. The difference abnormal detection results are analyzed and explained. The proposed detection method is tested on benchmark datasets, then the experimental results show the effectiveness of the algorithm. PMID:25811227

  16. New Optical Methods for Liveness Detection on Fingers

    PubMed Central

    Dolezel, Michal; Vana, Jan; Brezinova, Eva; Yim, Jaegeol; Shim, Kyubark

    2013-01-01

    This paper is devoted to new optical methods, which are supposed to be used for liveness detection on fingers. First we describe the basics about fake finger use in fingerprint recognition process and the possibilities of liveness detection. Then we continue with introducing three new liveness detection methods, which we developed and tested in the scope of our research activities—the first one is based on measurement of the pulse, the second one on variations of optical characteristics caused by pressure change, and the last one is based on reaction of skin to illumination with different wavelengths. The last part deals with the influence of skin diseases on fingerprint recognition, especially on liveness detection. PMID:24151584

  17. Surface-bonded fiber optic Sagnac sensors for ultrasound detection.

    PubMed

    Jang, Tae Seong; Lee, Seung Seok; Kim, Young Gil

    2004-04-01

    This paper describes a fiber optic sensor suitable for remote sensing and multi-point detection of ultrasound. This ultrasound sensor is based on the surface-bonded fiber optic Sagnac interferometer with the output fringe visibility of 1; it consists of a laser source, an ordinary single mode fiber delay line, a fiber coupler, a phase modulator and polarization controllers. For the validation of the sensor, surface acoustic waves and Lamb waves are excited by illuminating a steel specimen with an array of Q-switched Nd:YAG laser-generated line sources and the measurement of laser-generated ultrasonic waves are performed on the specimen surface using the surface-mounting fiber optic Sagnac sensor. The surface-bonded fiber optic sensor developed in this study has a simple configuration for detection of ultrasonic waves. Effectiveness of surface-bonded fiber optic Sagnac sensors for remote sensing of ultrasound and in situ monitoring of structures is investigated. The capability of multi-point detection of ultrasound by this Sagnac sensor is also discussed. PMID:15047393

  18. Integrated optical biosensor for rapid detection of bacteria

    NASA Astrophysics Data System (ADS)

    Mathesz, Anna; Valkai, Sándor; Újvárosy, Attila; Aekbote, Badri; Sipos, Orsolya; Stercz, Balázs; Kocsis, Béla; Szabó, Dóra; Dér, András

    2016-02-01

    In medical diagnostics, rapid detection of pathogenic bacteria from body fluids is one of the basic issues. Most state-of-the-art methods require optical labeling, increasing the complexity, duration and cost of the analysis. Therefore, there is a strong need for developing selective sensory devices based on label-free techniques, in order to increase the speed, and reduce the cost of detection. In a recent paper, we have shown that an integrated optical Mach-Zehnder interferometer, a highly sensitive all-optical device made of a cheap photopolymer, can be used as a powerful lab-on-a-chip tool for specific, labelfree detection of proteins. By proper modifications of this technique, our interferometric biosensor was combined with a microfluidic system allowing the rapid and specific detection of bacteria from solutions, having the surface of the sensor functionalized by bacterium-specific antibodies. The experiments proved that the biosensor was able to detect Escherichia coli bacteria at concentrations of 106 cfu/ml within a few minutes, that makes our device an appropriate tool for fast, label-free detection of bacteria from body fluids such as urine or sputum. On the other hand, possible applications of the device may not be restricted to medical microbiology, since bacterial identification is an important task in microbial forensics, criminal investigations, bio-terrorism threats and in environmental studies, as well.

  19. Contactless ultrasound detection using an optical ring resonator

    NASA Astrophysics Data System (ADS)

    Kim, Kyu Hyun; Luo, Wei; Zhang, Cheng; Guo, L. Jay; Fan, Xudong

    2016-03-01

    We develop an air-couple ultrasound detector based on an optical fluidic ring resonator (OFRR) suspended on a Ushaped holder. The OFRR is a glass capillary with an outer diameter of approximately 130 μm and a wall thickness in the order of 1~10 μm. The circular cross section of the OFRR supports the high-Q whispering gallery mode (WGM) that circulates along the circumference. Incoming ultrasound pressure results in a small refractive index change in the glass wall and geometrical change in the OFRR shape, both of which in turn lead to a spectral shift in the WGM that can be sensitively detected owing to WGM with high optical Q-factors (>107). Due to the suspension nature of the OFRR, the ultrasound detection can be carried out in air, which is advantageous in comparison with other ultrasound detections that require acoustic coupling media such water, gel or solid. The sensitivity can be tuned and optimized by changing the diameter and wall thickness. Besides the optical detection, we also demonstrate optomechanical ultrasound mixing, in which optomechanical vibration is first excited within the OFRR that subsequently modulates the ultrasound wave. Our work will lead to the development of a new type of air-coupled ultrasound detector that can be used for photo-acoustic imaging, non-invasive ultrasound detection of external objects, and ultrasound detection/characterization of internal objects (such as particles and liquids) flowing inside the capillary.

  20. Integrated optical biosensor for rapid detection of bacteria

    NASA Astrophysics Data System (ADS)

    Mathesz, Anna; Valkai, Sándor; Újvárosy, Attila; Aekbote, Badri; Sipos, Orsolya; Stercz, Balázs; Kocsis, Béla; Szabó, Dóra; Dér, András

    2015-12-01

    In medical diagnostics, rapid detection of pathogenic bacteria from body fluids is one of the basic issues. Most state-of-the-art methods require optical labeling, increasing the complexity, duration and cost of the analysis. Therefore, there is a strong need for developing selective sensory devices based on label-free techniques, in order to increase the speed, and reduce the cost of detection. In a recent paper, we have shown that an integrated optical Mach-Zehnder interferometer, a highly sensitive all-optical device made of a cheap photopolymer, can be used as a powerful lab-on-a-chip tool for specific, labelfree detection of proteins. By proper modifications of this technique, our interferometric biosensor was combined with a microfluidic system allowing the rapid and specific detection of bacteria from solutions, having the surface of the sensor functionalized by bacterium-specific antibodies. The experiments proved that the biosensor was able to detect Escherichia coli bacteria at concentrations of 106 cfu/ml within a few minutes, that makes our device an appropriate tool for fast, label-free detection of bacteria from body fluids such as urine or sputum. On the other hand, possible applications of the device may not be restricted to medical microbiology, since bacterial identification is an important task in microbial forensics, criminal investigations, bio-terrorism threats and in environmental studies, as well.

  1. Capillary electrophoresis microchip detecting system based on embedded optical fiber

    NASA Astrophysics Data System (ADS)

    Yan, Weiping; Li, Yuanyuan; Ma, Lingzhi

    2007-12-01

    Microchip capillary electrophoresis(CE) has been recognized as a powerful tool for biochemical analyses due to its smaller size, faster separation and lower sample requirement. According to the principle of laser-induced fluorescence, the detecting system of CE microchip embedded optical fiber is discussed in this paper as well as its small volume and simple detection optical circuit. The system was composed with semiconductor laser (532nm), high voltage control system, photon counter, PC and CE chip embedded optical fibers. With the constructed detection system, different samples and different concentrations were detected, including Rhodamine B, Rhodamine 6G, and mingling solution of Rhodamine B and Rhodamine 6G. The lowest detected concentration is 1×10 -6mol/L for Rhodamine B, and 1×10 -5mol/L for Rhodamine 6G, respectively. The separation of the mingling solution of Rhodamine B and Rhodamine 6G was completed, whose concentration were both about 1×10 -4mol/L. The results show that the constructed detection system possesses some advantages, such as compact structure, higher sensitivity and repetition, which are beneficial to the development of microminiaturization and integration of micro CE chip.

  2. Characterization of fiber optic Cerenkov radiation sensor for detecting neutrons

    NASA Astrophysics Data System (ADS)

    Jang, K. W.; Yagi, T.; Pyeon, C. H.; Shin, S. H.; Yoo, W. J.; Misawa, T.; Lee, B.

    2013-09-01

    Cerenkov radiation can be observed easily as a shimmer of blue light from the water in boiling- and pressurized-water reactors, or spent fuel storage pools. In this research, we fabricated the fiber-optic Cerenkov radiation sensor using a Gdfoil, rutile crystal and optical fiber for detecting neutrons. Also, the reference sensor for measuring background gammarays was fabricated with the rutile crystal and optical fiber. The neutron fluxes could be obtained by measuring the signal difference between two sensors. To characterize the fiber-optic Cerenkov radiation sensor, we measured neutron fluxes using a Cf-252 neutron source according to depths of polyethylene. As the results, the counts of fiber-optic Cerenkov radiation sensor were higher than those of reference sensor due to additional interactions between Gd-foil and neutrons. Also, the counts of Cerenkov radiation decreased with increasing polyethylene thickness. It is anticipated that the novel and simple fiber-optic Cerenkov radiation sensor using the Cerenkov effect can be widely used to detect the neutrons in hazardous nuclear facilities.

  3. Optical detection of nanoparticle-enhanced human papillomavirus genotyping microarrays.

    PubMed

    Li, Xue Zhe; Kim, Sookyung; Cho, Wonhyung; Lee, Seung-Yop

    2013-02-01

    In this study, we propose a new detection method of nanoparticle-enhanced human papillomavirus genotyping microarrays using a DVD optical pick-up with a photodiode. The HPV genotyping DNA chip was labeled using Au/Ag core-shell nanoparticles, prepared on a treatment glass substrate. Then, the bio information of the HPV genotyping target DNA was detected by measuring the difference of the optical signals between the DNA spots and the background parts for cervical cancer diagnosis. Moreover the approximate linear relationship between the concentration of the HPV genotyping target DNA and the optical signal depending on the density of Au/Ag core-shell nanoparticles was obtained by performing a spot finding algorithm. It is shown that the nanoparticle-labeled HPV genotyping target DNA can be measured and quantified by collecting the low-cost photodiode signal on the treatment glass chip, replacing high-cost fluorescence microarray scanners using a photomultiplier tube. PMID:23413051

  4. Real-Time Detection of Optical Transients with RAPTOR

    NASA Astrophysics Data System (ADS)

    Borozdin, Konstantin N.; Brumby, Steven P.; Galassi, Mark C.; McGowan, Katherine; Starr, Daniel; Vestrand, Thomas; White, Robert; Wozniak, Przemek; Wren, James A.

    2002-12-01

    Fast variability of optical objects is an interesting though poorly explored subject in modern astronomy. Real-time data processing and identification of transient celestial events in the images is very important for such study as it allows rapid follow-up with more sensitive instruments. We discuss an approach which we have developed for the RAPTOR project, a pioneering closed-loop system combining real-time transient detection with rapid follow-up. RAPTOR's data processing pipeline is able to identify and localize an optical transient within seconds after the observation. The testing we performed so far have been confirming the effectiveness of our method for the optical transient detection. The software pipeline we have developed for RAPTOR can easily be applied to the data from other experiments.

  5. Automated detection of optical counterparts to GRBs with RAPTOR

    SciTech Connect

    Wozniak, P. R.; Vestrand, W. T.; Evans, S.; White, R.; Wren, J.

    2006-05-19

    The RAPTOR system (RAPid Telescopes for Optical Response) is an array of several distributed robotic telescopes that automatically respond to GCN localization alerts. Raptor-S is a 0.4-m telescope with 24 arc min. field of view employing a 1k x 1k Marconi CCD detector, and has already detected prompt optical emission from several GRBs within the first minute of the explosion. We present a real-time data analysis and alert system for automated identification of optical transients in Raptor-S GRB response data down to the sensitivity limit of {approx} 19 mag. Our custom data processing pipeline is designed to minimize the time required to reliably identify transients and extract actionable information. The system utilizes a networked PostgreSQL database server for catalog access and distributes email alerts with successful detections.

  6. A synchronous phase detection system for an optical interferometric sensor

    NASA Astrophysics Data System (ADS)

    Bush, I. J.

    1982-05-01

    A system has been developed to accurately detect phase produced in optical interferometric sensors. The system employs optical heterodyning, and it synchronously detects optical phase by feeding an error signal back to a phase modulator in the reference leg of the interferometer. This system is seen to have properties similar to a phase-locked loop used for the demodulation of FM signals. The system model is second order and nonlinear, but a linear approximation serves to accurately describe the system in synchronous operation and is corroborated with well-matched empirical data. The complete model is simulated via computer techniques and is needed to describe the system's parameters that lead to loss and reacquisition of synchronization.

  7. Channel simulation for direct-detection optical communication systems

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.

    1974-01-01

    A technique is described for simulating the random modulation imposed by atmospheric scintillation and transmitter pointing jitter on a direct-detection optical communication system. The system is capable of providing signal fading statistics which obey log-normal, beta, Rayleigh, Ricean, or chi-square density functions. Experimental tests of the performance of the channel simulator are presented.

  8. Channel simulation for direct detection optical communication systems

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.

    1974-01-01

    A technique is described for simulating the random modulation imposed by atmospheric scintillation and transmitter pointing jitter on a direct detection optical communication system. The system is capable of providing signal fading statistics which obey log normal, beta, Rayleigh, Ricean or chi-squared density functions. Experimental tests of the performance of the Channel Simulator are presented.

  9. Optical Detection of Organic Chemical Biosignatures at Hydrothermal Vents

    NASA Technical Reports Server (NTRS)

    Conrad, P. G.; Lane, A. L.; Bhartia, R.; Hug, W. H.

    2004-01-01

    We have developed a non-contact, optical life detection instrument that can detect organic chemical biosignatures in a number of different environments, including dry land, shallow aqueous, deep marine or in ice. Hence, the instrument is appropriate as a biosignature survey tool both for Mars exploration or in situ experiments in an ice-covered ocean such as one might wish to explore on Europa. Here, we report the results we obtained on an expedition aboard the Russian oceanographic vessel Akademik Mstislav Keldysh to hydrothermal vent sites in the Pacific Ocean using our life detection instrument MCDUVE, a multichannel, deep ultraviolet excitation fluorescence detector. MCDUVE detected organic material distribution on rocks near the vent, as well as direct detection of organisms, both microbial and microscopic. We also were able to detect organic material issuing directly from vent chimneys, measure the organic signature of the water column as we ascended, and passively observe the emission of light directly from some vents.

  10. Optical protein detection based on magnetic clusters rotation.

    PubMed

    Ramiandrisoa, Donatien; Brient-Litzler, Elodie; Daynes, Aurélien; Compain, Eric; Bibette, Jérôme; Baudry, Jean

    2015-09-25

    In this paper we present a simple method to quantify aggregates of 200nm magnetic particles. This method relies on the optical and magnetic anisotropy of particle aggregates, whereas dispersed particles are optically isotropic. We orientate aggregates by applying short pulses of a magnetic field, and we measure optical density variation directly linked to this reorientation. By computing the scattering efficiency of doublets and singlets, we demonstrate the absolute quantification of a few % of doublets in a well dispersed suspension. More generally, these optical variations are related to the aggregation state of the sample. This method can be easily applied to an agglutination assay, where target proteins induce aggregation of colloidal particles. By observing only aligned clusters, we increase sensitivity and we reduce the background noise as compared to a classical agglutination assay: we obtain a detection limit on the C-reactive protein of less than 3pM for a total assay time of 10min. PMID:25849116

  11. Multivariate optical element platform for compressed detection of fluorescence markers

    NASA Astrophysics Data System (ADS)

    Priore, Ryan J.; Swanstrom, Joseph A.

    2014-05-01

    The success of a commercial fluorescent diagnostic assay is dependent on the selection of a fluorescent biomarker; due to the broad nature of fluorescence biomarker emission profiles, only a small number of fluorescence biomarkers may be discriminated from each other as a function of excitation source. Multivariate Optical Elements (MOEs) are thin-film devices that encode a broad band, spectroscopic pattern allowing a simple broadband detector to generate a highly sensitive and specific detection for a target analyte. MOEs have historically been matched 1:1 to a discrete analyte or class prediction; however, MOE filter sets are capable of sensing projections of the original sparse spectroscopic space enabling a small set of MOEs to discriminate a multitude of target analytes. This optical regression can offer real-time measurements with relatively high signal-to-noise ratios that realize the advantages of multiplexed detection and pattern recognition in a simple optical instrument. The specificity advantage of MOE-based sensors allows fluorescent biomarkers that were once incapable of discrimination from one another via optical band pass filters to be employed in a common assay panel. A simplified MOE-based sensor may ultimately reduce the requirement for highly trained operators as well as move certain life science applications like disease prognostication from the laboratory to the point of care. This presentation will summarize the design and fabrication of compressed detection MOE filter sets for detecting multiple fluorescent biomarkers simultaneously with strong spectroscopic interference as well as comparing the detection performance of the MOE sensor with traditional optical band pass filter methodologies.

  12. Fiber-Optic Based Compact Gas Leak Detection System

    NASA Technical Reports Server (NTRS)

    deGroot, Wim A.

    1995-01-01

    A propellant leak detection system based on Raman scattering principles is introduced. The proposed system is flexible and versatile as the result of the use of optical fibers. It is shown that multiple species can be monitored simultaneously. In this paper oxygen, nitrogen, carbon monoxide, and hydrogen are detected and monitored. The current detection sensitivity for both hydrogen and carbon monoxide is 1% partial pressure at ambient conditions. The sensitivity for oxygen and nitrogen is 0.5% partial pressure. The response time to changes in species concentration is three minutes. This system can be used to monitor multiple species at several locations.

  13. MEMS-based extreme adaptive optics for planet detection

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce; Graham, James; Oppenheimer, Ben; Poyneer, Lisa; Sivaramakrishnan, Anand; Veran, Jean-Pierre

    2006-01-01

    The next major step in the study of extrasolar planets will be the direct detection, resolved from their parent star, of a significant sample of Jupiter-like extrasolar giant planets. Such detection will open up new parts of the extrasolar planet distribution and allow spectroscopic characterization of the planets themselves. Detecting Jovian planets at 5-50 AU scale orbiting nearby stars requires adaptive optics systems and coronagraphs an order of magnitude more powerful than those available today - the realm of "Extreme" adaptive optics. We present the basic requirements and design for such a system, the Gemini Planet Imager (GPI.) GPI will require a MEMS-based deformable mirror with good surface quality, 2-4 micron stroke (operated in tandem with a conventional low-order "woofer" mirror), and a fully-functional 48-actuator-diameter aperture.

  14. Spectrally efficient optical transmission based on Stokes vector direct detection.

    PubMed

    Li, An; Che, Di; Chen, Vivian; Shieh, William

    2014-06-30

    We propose a novel detection scheme called Stokes vector direct detection (SV-DD) to realize high electrical spectral efficiency and cost-effective optical communication for short and medium reach. With SV-DD, the signal is modulated in only one polarization and combined with the carrier in the orthogonal polarization for fiber transmission. At reception, the combined signal is detected in Stokes space by three or four photo-detectors. Compared with conventional DD technique, SV-DD is resilient to both chromatic dispersion and signal-to-signal beat noise. Furthermore, SV-DD does not require polarization tracking or narrow band optical filtering for carrier extraction. In this paper, we present for the first time the numerical analysis and experimental demonstration of single-carrier SV-DD. We report 62.5-Gb/s data rate single-carrier SV-DD transmission over 160-km SSMF using 12.5-Gbaud 32-QAM modulation. PMID:24977825

  15. MEMS-based extreme adaptive optics for planet detection

    SciTech Connect

    Macintosh, B A; Graham, J R; Oppenheimer, B; Poyneer, L; Sivaramakrishnan, A; Veran, J

    2005-11-18

    The next major step in the study of extrasolar planets will be the direct detection, resolved from their parent star, of a significant sample of Jupiter-like extrasolar giant planets. Such detection will open up new parts of the extrasolar planet distribution and allow spectroscopic characterization of the planets themselves. Detecting Jovian planets at 5-50 AU scale orbiting nearby stars requires adaptive optics systems and coronagraphs an order of magnitude more powerful than those available today--the realm of ''Extreme'' adaptive optics. We present the basic requirements and design for such a system, the Gemini Planet Imager (GPI.) GPI will require a MEMS-based deformable mirror with good surface quality, 2-4 micron stroke (operated in tandem with a conventional low-order ''woofer'' mirror), and a fully-functional 48-actuator-diameter aperture.

  16. Planet detectability by an adaptive optics stellar coronagraph

    NASA Astrophysics Data System (ADS)

    Nakajima, T.

    1994-04-01

    We show the possibilities for imaging Jupiter-like planets around nearby bright stars, assuming the availability of stellar coronagraphs coupled with modest adaptive optics mounted on large ground-based telescopes. The adaptive optics sharpens the point-spread function (PSF) of the planet, permits the use of an occulting disk smaller than the seeing disk, reduces the PSF envelope of the bright star, and therefore enhances the contrast between the planet and background. We have generated the PSF of the planet and the PSF envelope of the main star, using Monte Carlo simulations based on the Kolmogorov theory of turbulence. We calculate the signal-to-noise ratio of a model planet as a function of the angular separation based on photon statistics and realistic assumptions on the system performance. We have derived a criterion for optimizing the combination of the degree of adaptive compensation and the telescope diameter. It is found that a stellar coronagraph with modest adaptive optics mounted on a large ground-based telescope will be capable of detecting Jupiter-like planets around nearby bright stars such as alpha Cen, Sirius, and Procyon at wavelengths between 0.7 and 2.2 micrometers. Near-infrared observations are preferred because usable telescopes and isoplanatic angles are larger at infrared wavelengths than optical wavelengths for a given adaptive optics system. We have also found seven other target stars around which planets will be above the detection limit.

  17. Ultrafast Radiation Detection by Modulation of an Optical Probe Beam

    SciTech Connect

    Vernon, S P; Lowry, M E

    2006-02-22

    We describe a new class of radiation sensor that utilizes optical interferometry to measure radiation-induced changes in the optical refractive index of a semiconductor sensor medium. Radiation absorption in the sensor material produces a transient, non-equilibrium, electron-hole pair distribution that locally modifies the complex, optical refractive index of the sensor medium. Changes in the real (imaginary) part of the local refractive index produce a differential phase shift (absorption) of an optical probe used to interrogate the sensor material. In contrast to conventional radiation detectors where signal levels are proportional to the incident energy, signal levels in these optical sensors are proportional to the incident radiation energy flux. This allows for reduction of the sensor form factor with no degradation in detection sensitivity. Furthermore, since the radiation induced, non-equilibrium electron-hole pair distribution is effectively measured ''in place'' there is no requirement to spatially separate and collect the generated charges; consequently, the sensor risetime is of the order of the hot-electron thermalization time {le} 10 fs and the duration of the index perturbation is determined by the carrier recombination time which is of order {approx} 600 fs in, direct-bandgap semiconductors, with a high density of recombination defects; consequently, the optical sensors can be engineered with sub-ps temporal response. A series of detectors were designed, and incorporated into Mach Zehnder and Fabry-Perot interferometer-based detection systems: proof of concept, lower detection sensitivity, Mach-Zehnder detectors were characterized at beamline 6.3 at SSRL; three generations of high sensitivity single element and imaging Fabry-Perot detectors were measured at the LLNL Europa facility. Our results indicate that this technology can be used to provide x-ray detectors and x-ray imaging systems with single x-ray sensitivity and S/N {approx} 30 at x

  18. Periodic optical variability of radio-detected ultracool dwarfs

    SciTech Connect

    Harding, L. K.; Golden, A.; Singh, Navtej; Sheehan, B.; Butler, R. F.; Hallinan, G.; Boyle, R. P.; Zavala, R. T.

    2013-12-20

    A fraction of very low mass stars and brown dwarfs are known to be radio active, in some cases producing periodic pulses. Extensive studies of two such objects have also revealed optical periodic variability, and the nature of this variability remains unclear. Here, we report on multi-epoch optical photometric monitoring of six radio-detected dwarfs, spanning the ∼M8-L3.5 spectral range, conducted to investigate the ubiquity of periodic optical variability in radio-detected ultracool dwarfs. This survey is the most sensitive ground-based study carried out to date in search of periodic optical variability from late-type dwarfs, where we obtained 250 hr of monitoring, delivering photometric precision as low as ∼0.15%. Five of the six targets exhibit clear periodicity, in all cases likely associated with the rotation period of the dwarf, with a marginal detection found for the sixth. Our data points to a likely association between radio and optical periodic variability in late-M/early-L dwarfs, although the underlying physical cause of this correlation remains unclear. In one case, we have multiple epochs of monitoring of the archetype of pulsing radio dwarfs, the M9 TVLM 513–46546, spanning a period of 5 yr, which is sufficiently stable in phase to allow us to establish a period of 1.95958 ± 0.00005 hr. This phase stability may be associated with a large-scale stable magnetic field, further strengthening the correlation between radio activity and periodic optical variability. Finally, we find a tentative spin-orbit alignment of one component of the very low mass binary, LP 349–25.

  19. Automated spoof-detection for fingerprints using optical coherence tomography.

    PubMed

    Darlow, Luke Nicholas; Webb, Leandra; Botha, Natasha

    2016-05-01

    Fingerprint recognition systems are prevalent in high-security applications. As a result, the act of spoofing these systems with artificial fingerprints is of increasing concern. This research presents an automatic means for spoof-detection using optical coherence tomography (OCT). This technology is able to capture a 3D representation of the internal structure of the skin and is thus not limited to a 2D surface scan. The additional information afforded by this representation means that accurate spoof-detection can be achieved. Two features were extracted to detect the presence of (1) an additional thin layer on the surface of the skin and (2) a thicker additional layer or a complete artificial finger. An analysis of these features showed that they are highly separable, resulting in 100% accuracy regarding spoof-detection, with no false rejections of real fingers. This is the first attempt at fully automated spoof-detection using OCT. PMID:27140346

  20. Optical detection of magnetic nanoparticles in colloidal suspensions

    NASA Astrophysics Data System (ADS)

    Gimenez, Alejandro J.; Ramirez-Wong, Diana G.; Favela-Camacho, Sarai E.; Sanchez, Isaac C.; Yáñez-Limón, J. M.; Luna-Bárcenas, Gabriel

    2016-03-01

    This study reports the change of light transmittance and light scattering dispersion by colloidal suspensions of magnetic nanoparticles. Optical changes were observed during the application of transversal magnetic fields to magnetic nanoparticles and nanowires at concentrations spanning from 20 μg/mL to 2 ng/mL. Results show that light scattering modulation is a simple, fast and inexpensive method for detection of magnetic nanoparticles at low concentrations. Frequency and time response of the optical modulation strongly depends on the geometry of the particles. In this regard, light transmittance and scattering measurements may prove useful in characterizing the morphology of suspended nanoparticles.

  1. A fibre optic chemical sensor for the detection of cocaine

    NASA Astrophysics Data System (ADS)

    Nguyen, T. Hien; Sun, Tong; Grattan, Kenneth T. V.; Hardwick, S. A.

    2010-09-01

    A fibre-optic chemical sensor for the detection of cocaine has been developed, based on a molecularly imprinted polymer (MIP) containing a fluorescein moiety as the signalling group. The fluorescent MIP was formed and covalently attached to the distal end of an optical fibre. The sensor exhibited an increase in fluorescence intensity in response to cocaine in the concentration range of 0 - 500 μM in aqueous acetonitrile mixtures with good reproducibility over 24 h. Selectivity for cocaine over others drugs has also been demonstrated.

  2. Distributed fiber optic system for oil pipeline leakage detection

    NASA Astrophysics Data System (ADS)

    Paranjape, R.; Liu, N.; Rumple, C.; Hara, Elmer H.

    2003-02-01

    We present a novel approach for the detection of leakage in oil pipelines using methods of fiber optic distributed sensors, a presence-of-oil based actuator, and Optical Time Domain Reflectometry (OTDR). While the basic concepts of our approach are well understood, the integration of the components into a complete system is a real world engineering design problem. Our focus has been on the development of the actuator design and testing using installed dark fiber. Initial results are promising, however environmental studies into the long term effects of exposure to the environment are still pending.

  3. Jade detection and analysis based on optical coherence tomography images

    NASA Astrophysics Data System (ADS)

    Chang, Shoude; Mao, Youxin; Chang, Guangming; Flueraru, Costel

    2010-06-01

    Optical coherence tomography is a fundamentally new type of optical sensing technology that can perform high-resolution, cross sectional sensing of the internal structure of materials and biological samples. This work briefly describes its capability of exploring and analyzing the internal structures and textures of various jades. With a depth resolution of 4 μm in jade and penetration range of 5 mm in jade, swept-source OCT could be used as a new powerful instrument to generate 3-D volume data of jade, which is important for applications in jade industry and artwork, particularly for jade detection and classification, counterfeit recognition, and guided artistic carving.

  4. Detecting ionizing radiation with optical fibers down to biomedical doses

    NASA Astrophysics Data System (ADS)

    Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; De Natale, P.; Gagliardi, G.

    2013-10-01

    We report on a passive ionizing radiation sensor based on a fiber-optic resonant cavity interrogated by a high resolution interferometric technique. After irradiation in clinical linear accelerators, we observe significant variations of the fiber thermo-optic coefficient. Exploiting this effect, we demonstrate an ultimate detection limit of 160 mGy with an interaction volume of only 6 × 10-4 mm3. Thanks to its reliability, compactness, and sensitivity at biomedical dose levels, our system lends itself to real applications in radiation therapy procedures as well as in radiation monitoring and protection in medicine, aerospace, and nuclear power plants.

  5. Optical spectroscopy for the detection of ischemic tissue injury

    DOEpatents

    Demos, Stavros; Fitzgerald, Jason; Troppmann, Christoph; Michalopoulou, Andromachi

    2009-09-08

    An optical method and apparatus is utilized to quantify ischemic tissue and/or organ injury. Such a method and apparatus is non-invasive, non-traumatic, portable, and can make measurements in a matter of seconds. Moreover, such a method and apparatus can be realized through optical fiber probes, making it possible to take measurements of target organs deep within a patient's body. Such a technology provides a means of detecting and quantifying tissue injury in its early stages, before it is clinically apparent and before irreversible damage has occurred.

  6. Optical fiber null coupler sensor for damage detection using ultrasonic

    NASA Astrophysics Data System (ADS)

    Xuan, HaiFeng; Liao, Yanbiao; Zhang, Ming; Lai, Shu R.

    2005-02-01

    A novel optical fiber null coupler (OFNC) sensor based on acousto-optic interaction is developed, which can be used in the structure health monitoring of the medical materials. The OFNC sensors can be response to 10MHz supersonic wave, and their signal-to noise ratio are higher then Piezo Ceramic Transducers(PZT). A kind of Perspex with a 1mm hole is employed as the sample, where the OFNC sensor is glued on, and the reflected signal of ultrasonic wave by the hole is detected .

  7. Plastic optical fiber sensor for gastric ph detection

    NASA Astrophysics Data System (ADS)

    Baldini, Francesco; Bracci, Susanna; Cosi, Franco

    1994-02-01

    An optical fiber sensor for gastric pH detection is described, making use of plastic fibers as light carriers and a proper electronic system for both source driving and signal processing. The use of a suitable microprocessor and an internal buffer allows the realization of a portable and reliable device, fed by batteries. The indicators, bromophenol blue (BPB) or thymol blue (TB), are immobilized on controlled pore glass (CPG) fixed at the end of plastic optical fibers following a proprietary process. The realized optrode, satisfying clinical requirements, was tested `in vitro.' A precision of

  8. Method and means for detecting optically transmitted signals and establishing optical interference pattern between electrodes

    DOEpatents

    Kostenbauder, A.G.

    1988-06-28

    A photodetector for detecting signal pulses transmitted in an optical carrier signal relies on the generation of electron-hole pairs and the diffusion of the generated electrons and holes to the electrodes on the surface of the semiconductor detector body for generating photovoltaic pulses. The detector utilizes the interference of optical waves for generating an electron-hole grating within the semiconductor body, and, by establishing an electron-hole pair maximum at one electrode and a minimum at the other electrode, a detectable voltaic pulse is generated across the electrode. 4 figs.

  9. Method and means for detecting optically transmitted signals and establishing optical interference pattern between electrodes

    DOEpatents

    Kostenbauder, Adnah G.

    1988-01-01

    A photodetector for detecting signal pulses transmitted in an optical carrier signal relies on the generation of electron-hole pairs and the diffusion of the generated electrons and holes to the electrodes on the surface of the semiconductor detector body for generating photovoltaic pulses. The detector utilizes the interference of optical waves for generating an electron-hole grating within the semiconductor body, and, by establishing an electron-hole pair maximum at one electrode and a minimum at the other electrode, a detectable voltaic pulse is generated across the electrode.

  10. Optical detection of radio waves through a nanomechanical transducer.

    PubMed

    Bagci, T; Simonsen, A; Schmid, S; Villanueva, L G; Zeuthen, E; Appel, J; Taylor, J M; Sørensen, A; Usami, K; Schliesser, A; Polzik, E S

    2014-03-01

    Low-loss transmission and sensitive recovery of weak radio-frequency and microwave signals is a ubiquitous challenge, crucial in radio astronomy, medical imaging, navigation, and classical and quantum communication. Efficient up-conversion of radio-frequency signals to an optical carrier would enable their transmission through optical fibres instead of through copper wires, drastically reducing losses, and would give access to the set of established quantum optical techniques that are routinely used in quantum-limited signal detection. Research in cavity optomechanics has shown that nanomechanical oscillators can couple strongly to either microwave or optical fields. Here we demonstrate a room-temperature optoelectromechanical transducer with both these functionalities, following a recent proposal using a high-quality nanomembrane. A voltage bias of less than 10 V is sufficient to induce strong coupling between the voltage fluctuations in a radio-frequency resonance circuit and the membrane's displacement, which is simultaneously coupled to light reflected off its surface. The radio-frequency signals are detected as an optical phase shift with quantum-limited sensitivity. The corresponding half-wave voltage is in the microvolt range, orders of magnitude less than that of standard optical modulators. The noise of the transducer--beyond the measured 800 pV Hz-1/2 Johnson noise of the resonant circuit--consists of the quantum noise of light and thermal fluctuations of the membrane, dominating the noise floor in potential applications in radio astronomy and nuclear magnetic imaging. Each of these contributions is inferred to be 60 pV Hz-1/2 when balanced by choosing an electromechanical cooperativity of ~150 with an optical power of 1 mW. The noise temperature of the membrane is divided by the cooperativity. For the highest observed cooperativity of 6,800, this leads to a projected noise temperature of 40 mK and a sensitivity limit of 5 pV Hz-1/2. Our approach to

  11. Fiber-optic radiation sensor for detection of tritium

    NASA Astrophysics Data System (ADS)

    Jang, K. W.; Cho, D. H.; Yoo, W. J.; Seo, J. K.; Heo, J. Y.; Park, J.-Y.; Lee, B.

    2011-10-01

    The objective of this study is to develop the radiation sensor, which is composed of a scintillator, an optical fiber bundle and a light measuring device to detect the tritium in real-time. In this study, we have fabricated fiber-optic radiation sensors using inorganic scintillators and plastic optical fiber bundles. Each scintillator interacts with electron or beta ray and generates 455-550 nm wavelength of scintillation photons. An optical fiber bundle is usually made of plastic or glass, which is used to guide the light signal from a scintillating probe to light measuring device. For the purpose of selecting the best scintillator with a high efficiency, fiber-optic sensors manufactured using three kinds of inorganic scintillator such as Gd 2O 2S:Tb, Y 3Al 5O 12:Ce and CsI:Tl, and they are tested with a metal hydride type of tritium source. In addition, the scintillation photons are measured as a function of distance between a fiber-optic sensor and source. Finally, we have measured the amounts of scintillation photon with different activities of tritium source and compared the measured results with those obtained using a surface activity monitor.

  12. A two-level detection algorithm for optical fiber vibration

    NASA Astrophysics Data System (ADS)

    Bi, Fukun; Ren, Xuecong; Qu, Hongquan; Jiang, Ruiqing

    2015-09-01

    Optical fiber vibration is detected by the coherent optical time domain reflection technique. In addition to the vibration signals, the reflected signals include clutters and noises, which lead to a high false alarm rate. The "cell averaging" constant false alarm rate algorithm has a high computing speed, but its detection performance will be declined in nonhomogeneous environments such as multiple targets. The "order statistics" constant false alarm rate algorithm has a distinct advantage in multiple target environments, but it has a lower computing speed. An intelligent two-level detection algorithm is presented based on "cell averaging" constant false alarm rate and "order statistics" constant false alarm rate which work in serial way, and the detection speed of "cell averaging" constant false alarm rate and performance of "order statistics" constant false alarm rate are conserved, respectively. Through the adaptive selection, the "cell averaging" is applied in homogeneous environments, and the two-level detection algorithm is employed in nonhomogeneous environments. Our Monte Carlo simulation results demonstrate that considering different signal noise ratios, the proposed algorithm gives better detection probability than that of "order statistics".

  13. Real-time detection of optical transients with RAPTOR

    SciTech Connect

    Borozdin, K. N.; Brumby, Steven P.; Galassi, M. C.; McGowan, K. E.; Starr, D. L.; Vestrand, W. T.; White, R. R.; Wozniak, P. R.; Wren, J.

    2002-01-01

    Fast variability of optical objects is an interesting though poorly explored subject in modern astronomy. Real-time data processing and identification of transient, celestial events in the images is very important, for such study as it allows rapid follow-up with more sensitive instruments, We discuss an approach which we have chosen for the RAPTOR project which is a pioneering close-loop system combining real-time transient detection with rapid follow-up. Our data processing pipeline is able to identify and localize an optical transient within seconds after the observation. We describe the challenges we met, solutions we found and some results obtained in our search for fast optical transients. The software pipeline we have developed for RAPTOR can easily be applied to the data from other experiments.

  14. Partially Nondestructive Continuous Detection of Individual Traveling Optical Photons

    NASA Astrophysics Data System (ADS)

    Hosseini, Mahdi; Beck, Kristin M.; Duan, Yiheng; Chen, Wenlan; Vuletić, Vladan

    2016-01-01

    We report the continuous and partially nondestructive measurement of optical photons. For a weak light pulse traveling through a slow-light optical medium (signal), the associated atomic-excitation component is detected by another light beam (probe) with the aid of an optical cavity. We observe strong correlations of gsp (2 )=4.4 (5 ) between the transmitted signal and probe photons. The observed (intrinsic) conditional nondestructive quantum efficiency ranges between 13% and 1% (65% and 5%) for a signal transmission range of 2% to 35%, at a typical time resolution of 2.5 μ s . The maximal observed (intrinsic) device nondestructive quantum efficiency, defined as the product of the conditional nondestructive quantum efficiency and the signal transmission, is 0.5% (2.4%). The normalized cross-correlation function violates the Cauchy-Schwarz inequality, confirming the nonclassical character of the correlations.

  15. Improvements in NDIR gas detection within the same optical chamber

    NASA Astrophysics Data System (ADS)

    Martinez-Anton, Juan Carlos; Silva-Lopez, Manuel

    2011-10-01

    Non-dispersive infrared (NDIR) is a well known technique for gas concentration monitoring. Lead salt photoconductors and thermopile detectors are typically used. Together with gas filter correlation (GFC) they are the basis for a reference standard in environmental gas monitoring like carbon monoxide determination and other gas species. To increase gas sensitivity, a multi-pass optical cavity is often used. In this contribution we propose a new optical design that allows for auto-reference multiple gas detection. It basically consists of an array of White's cell multi-pass camera that allows multiple channels with independent lengths inside the same volume. We explore its performance for carbon monoxide detection and based on recent commercial developments in infrared detector and emitter technologies.

  16. Resonant optical transducers for in-situ gas detection

    DOEpatents

    Bond, Tiziana C; Cole, Garrett; Goddard, Lynford

    2016-06-28

    Configurations for in-situ gas detection are provided, and include miniaturized photonic devices, low-optical-loss, guided-wave structures and state-selective adsorption coatings. High quality factor semiconductor resonators have been demonstrated in different configurations, such as micro-disks, micro-rings, micro-toroids, and photonic crystals with the properties of very narrow NIR transmission bands and sensitivity up to 10.sup.-9 (change in complex refractive index). The devices are therefore highly sensitive to changes in optical properties to the device parameters and can be tunable to the absorption of the chemical species of interest. Appropriate coatings applied to the device enhance state-specific molecular detection.

  17. Optical detection of parasitic protozoa in sol-gel matrices

    NASA Astrophysics Data System (ADS)

    Livage, Jacques; Barreau, J. Y.; Da Costa, J. M.; Desportes, I.

    1994-10-01

    Whole cell parasitic protozoa have been entrapped within sol-gel porous silica matrices. Stationary phase promastigote cells of Leishmania donovani infantum are mixed with a silica sol before gelation occurs. They remain trapped within the growing oxide network and their cellular organization appears to be well preserved. Moreover protozoa retain their antigenic properties in the porous gel. They are still able to detect parasite specific antibodies in serum samples from infected patients via an enzyme linked immunosorbent assay (ELISA). Antigen- antibody associations occurring in the gel are optically detected via the reactions of a peroxidase conjugate with ortho-phenylenediamine leading to the formation of a yellow coloration. A clear-cut difference in optical density is measured between positive and negative sera. Such an entrapment of antigenic species into porous sol-gel matrices avoids the main problems due to non specific binding and could be advantageously used in diagnostic kits.

  18. Detection of small-amplitude optical variability in galactic nuclei

    NASA Astrophysics Data System (ADS)

    McNeil, Stephen R.

    2004-10-01

    A new photometry technique is developed for the detection of small-amplitude optical variability in galactic nuclei. This technique utilizes the surface brightness profiles of galaxies and checks for nuclear variations by matching up the bulge profiles (assumed to be constant). With this method optical variability is measured down to two hundredths of a magnitude. The method is tested on the following six galaxies using a B-Johnson and an R- Cousins filter: M51, M101, M81, M94, NGC4395, and NGC3982. These galaxies constitute a sampling of normal, LINER, and Seyfert galaxies. Although normal and LINER galaxies are thought to have no optical variability in their nucleus, our study concludes that most galaxies show some optical variability over the timescales of months and years. A study on deconvolution is also carried out as a possible way to improve the new technique. However, none of the tested algorithms improved the ability to detect small-amplitude nuclear variations down to hundredths of a magnitude.

  19. Passive optical detection of meteorological parameters in launch vehicle environments.

    PubMed

    Krause, F R; Su, M Y; Klugman, E H

    1970-05-01

    New optical detection systems are being developed which combine conventional passive photometry with advanced data processing and statistical analysis methods. These crossed-beam detection systems can continuously monitor meteorological parameters in rocket or aircraft environments. The outputs from several photometers are analyzed by cross correlation techniques to retrieve the transit times or transit distance of light emitting, absorbing, or scattering particles between the photometer lines of sight. These transit times and distances are then transformed into wind components and turbulence levels for preselected altitudes. A continuous near real time display of these meteorological parameters is also under development. PMID:20076328

  20. Automated choroidal neovascularization detection algorithm for optical coherence tomography angiography

    PubMed Central

    Liu, Li; Gao, Simon S.; Bailey, Steven T.; Huang, David; Li, Dengwang; Jia, Yali

    2015-01-01

    Optical coherence tomography angiography has recently been used to visualize choroidal neovascularization (CNV) in participants with age-related macular degeneration. Identification and quantification of CNV area is important clinically for disease assessment. An automated algorithm for CNV area detection is presented in this article. It relies on denoising and a saliency detection model to overcome issues such as projection artifacts and the heterogeneity of CNV. Qualitative and quantitative evaluations were performed on scans of 7 participants. Results from the algorithm agreed well with manual delineation of CNV area. PMID:26417524

  1. Optical detection of meteoroidal impacts on the Moon

    PubMed

    Ortiz; Sada; Bellot Rubio LR; Aceituno; Aceituno; Gutierrez; Thiele

    2000-06-22

    Impacts of meteoroids on the Moon should cause detectable optical flashes, but the population of objects that are big enough is very low, and hitherto no unambiguous impact flashes have been recorded. The flux of meteoroids associated with the Leonid meteor shower of 18 November 1999 was predicted to produce observable flashes on the night side of the Moon. Here we report the unambiguous detection of five such impact flashes, three of which were seen simultaneously by other observers. We also observed a possible impact flash on 16 July 1999. All of the flashes were of very brief duration (<0.02 s), as expected for high-speed impacts. PMID:10879526

  2. Coherent optical ultrasound detection with rare-earth ion dopants.

    PubMed

    Tay, Jian Wei; Ledingham, Patrick M; Longdell, Jevon J

    2010-08-10

    We describe theoretical and experimental demonstration for optical detection of ultrasound using a spectral hole engraved in cryogenically cooled rare-earth ion-doped solids. Our method utilizes the dispersion effects due to the spectral hole to perform phase-to-amplitude modulation conversion. Like previous approaches using spectral holes, it has the advantage of detection with large étendue. The method also has the benefit that high sensitivity can be obtained with moderate absorption contrast for the spectral holes. PMID:20697433

  3. Development of optical automatic positioning and wafer defect detection system

    NASA Astrophysics Data System (ADS)

    Tien, Chuen-Lin; Lai, Qun-Huang; Lin, Chern-Sheng

    2016-02-01

    The data of a wafer with defects can provide engineers with very important information and clues to improve the yield rate and quality in manufacturing. This paper presents a microscope automatic positioning and wafer detection system with human-machine interface based on image processing and fuzzy inference algorithms. In the proposed system, a XY table is used to move the position of each die on 6 inch or 8 inch wafers. Then, a high-resolution CCD and one set of two-axis optical linear encoder are used to accurately measure the position on the wafer. Finally, the developed human-machine interface is used to display the current position of an actual wafer in order to complete automatic positioning, and a wafer map database can be created. In the process of defect detection, CCD is used for image processing, and during preprocessing, it is required to filter noise, acquire the defect characteristics, define the defective template, and then take the characteristic points of the defective template as the reference input for fuzzy inference. A high-accuracy optical automatic positioning and wafer defect detection system is thus constructed. This study focused on automatic detection of spots, scratches, and bruises, and attempted to reduce the time to detect defective die and improve the accuracy of determining the defects of semiconductor devices.

  4. Optical sensors for the detection of trace chloroform.

    PubMed

    Fong, Jonathan K; Pena, Justin K; Xue, Zi-Ling; Alam, Maksudul M; Sampathkumaran, Uma; Goswami, Kisholoy

    2015-02-01

    Optical thin film sensors have been developed to detect chloroform in aqueous and nonaqueous solutions. These sensors utilize a modified Fujiwara reaction, one of the only known methods for detecting halogenated hydrocarbons in the visible spectrum. The modified Fujiwara reagents, 2,2'-dipyridyl and tetra-n-butyl ammonium hydroxide (n-Bu4NOH or TBAH), are encapsulated in an ethyl cellulose (EC) or sol-gel film. Upon exposure of the EC sensor film to HCCl3 in petroleum ether, a colored product is produced within the film, which is analyzed spectroscopically, yielding a detection limit of 0.830 ppm (parts per million v/v or μL/L hereinafter) and a quantification limit of 2.77 ppm. When the chloroform concentration in pentane is ≥5 ppm, the color change of the EC sensor is visible to the naked eye. In aqueous chloroform solution, reaction in the sol-gel sensor film turns the sensor from colorless to dark yellow/brown, also visible to the naked eye, with a detection limit of 500 ppm. This is well below the solubility of chloroform in water (ca. 5,800 ppm). To our knowledge, these are the first optical quality thin film sensors using Fujiwara reactions for halogenated hydrocarbon detection. PMID:25549694

  5. Detection of biological molecules using chemical amplification and optical sensors

    SciTech Connect

    Antwerp, W.P. van; Mastrototaro, J.J.

    2000-01-04

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  6. Detection of biological molecules using chemical amplification and optical sensors

    DOEpatents

    Van Antwerp, William Peter; Mastrototaro, John Joseph

    2000-01-01

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  7. Detection of biological molecules using chemical amplification and optical sensors

    DOEpatents

    Van Antwerp, William Peter; Mastrototaro, John Joseph

    2004-10-12

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal.

  8. Optical detection of the Casimir force between macroscopic objects.

    PubMed

    Petrov, Victor; Petrov, Mikhail; Bryksin, Valeriy; Petter, Juergen; Tschudi, Theo

    2006-11-01

    We report the optical detection of mechanical deformation of a macroscopic object induced by the Casimir force. An adaptive holographic interferometer based on a photorefractive BaTiO3:Co crystal was used to measure periodical nonlinear deformations of a thin pellicle caused by an oscillating Casimir force. A reasonable agreement between the experimental and calculated values of the first and second harmonics of the Casimir force oscillations has been obtained. PMID:17041670

  9. Optical Detection of Preneoplastic Lesions of the Central Airways

    PubMed Central

    van der Leest, C.; Amelink, A.; van Klaveren, R. J.; Hoogsteden, H. C.; Sterenborg, H. J. C. M.; Aerts, J. G. J. V.

    2012-01-01

    Current routine diagnosis of premalignant lesions of the central airways is hampered due to a limited sensitivity (white light bronchoscopy) and resolution (computer tomography (CT), positron emission tomography (PET)) of currently used techniques. To improve the detection of these subtle mucosal abnormalities, novel optical imaging bronchoscopic techniques have been developed over the past decade. In this review we highlight the technological developments in the field of endoscopic imaging, and describe their advantages and disadvantages in clinical use. PMID:22550600

  10. Integrated optic/nanofluidic fluorescent detection device with plasmonic excitation

    NASA Astrophysics Data System (ADS)

    Varsanik, J. S.; Bernstein, J. J.

    2013-09-01

    Integrated optic/microfluidic devices have proven to be useful tools in many sensing applications. However, the resolution and sensitivity of existing devices is limited by the processes and materials chosen for their fabrication. A procedure for the production of a new family of low-noise, high-resolution integrated microfluidic optical detection devices is presented, along with results from a prototype device. The device architecture is presented, highlighting design choices made in fluidics and optical integration to minimize scattered light. Diffused waveguides were fabricated, characterized, and modeled. A plasmonic resonator is designed, simulated, and integrated into the system to achieve electric field enhancement and localization to sub-micron dimensions. The device was tested to demonstrate both field enhancement and localization. The procedure that was developed enables the creation of integrated devices capable of high-resolution detection of fluorescent samples. The interrogation region was 200 nm long in the direction of flow, achieving sub-wavelength resolution in an integrated device. Furthermore, discrete fluorescent particles 20 nm in diameter were individually detected, demonstrating the high resolution and sensitivity capabilities of this family of devices.

  11. Optical Path Switching Based Differential Absorption Radiometry for Substance Detection

    NASA Technical Reports Server (NTRS)

    Sachse, Glen W. (Inventor)

    2000-01-01

    A system and method are provided for detecting one or more substances. An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. The first wavelength band and second wavelength band are unique. Further, spectral absorption of a substance of interest is different at the first wavelength band as compared to the second wavelength band. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

  12. A Novel Optical Biosensing System Using Mach-Zehnder-Type Optical Waveguide for Influenza Virus Detection.

    PubMed

    Sakamoto, Hiroaki; Minpou, Yuma; Sawai, Takayuki; Enami, Yasufumi; Suye, Shin-Ichiro

    2016-02-01

    In order to minimize the damage from viral epidemics, early detection of the causative agent of a viral epidemic and prevention of its immediate spread are urgent social demands. Therefore, in this study, we evaluated the utility of a Mach-Zehnder-type optical waveguide as a sensing device for influenza virus detection. However, it is impossible to detect a 100-nm-size virus using a sol-gel optical biosensor because sol-gel glass has a pore size of only a few nanometers, which makes it impossible for the virus to diffuse into the silica thin film. In order to construct the influenza-specific Mach-Zehnder optical biosensor for influenza detection, a stable antibody immobilization method with resulting high density on the sol-gel surface is strongly required. In this study, the sol-gel glass surface was modified with amino and carboxyl groups, and an anti-H1N1/HA1 antibody was covalently immobilized using a cross-linking agent. We successfully prepared a carboxyl-modified sol-gel surface, using NHS/EDC as the cross-linker, for antibody immobilization, and confirmed the detection of influenza virus using the antibody-immobilized sol-gel glass. After treatment with a 100 μg/mL influenza virus solution for 15 min, a peak wavelength shift (~24 nm) was observed in the output light spectrum. PMID:26498024

  13. A survey on object detection in optical remote sensing images

    NASA Astrophysics Data System (ADS)

    Cheng, Gong; Han, Junwei

    2016-07-01

    Object detection in optical remote sensing images, being a fundamental but challenging problem in the field of aerial and satellite image analysis, plays an important role for a wide range of applications and is receiving significant attention in recent years. While enormous methods exist, a deep review of the literature concerning generic object detection is still lacking. This paper aims to provide a review of the recent progress in this field. Different from several previously published surveys that focus on a specific object class such as building and road, we concentrate on more generic object categories including, but are not limited to, road, building, tree, vehicle, ship, airport, urban-area. Covering about 270 publications we survey (1) template matching-based object detection methods, (2) knowledge-based object detection methods, (3) object-based image analysis (OBIA)-based object detection methods, (4) machine learning-based object detection methods, and (5) five publicly available datasets and three standard evaluation metrics. We also discuss the challenges of current studies and propose two promising research directions, namely deep learning-based feature representation and weakly supervised learning-based geospatial object detection. It is our hope that this survey will be beneficial for the researchers to have better understanding of this research field.

  14. Optical Fiber Nanotips Coated with Molecular Beacons for DNA Detection

    PubMed Central

    Giannetti, Ambra; Barucci, Andrea; Cosi, Franco; Pelli, Stefano; Tombelli, Sara; Trono, Cosimo; Baldini, Francesco

    2015-01-01

    Optical fiber sensors, thanks to their compactness, fast response and real-time measurements, have a large impact in the fields of life science research, drug discovery and medical diagnostics. In recent years, advances in nanotechnology have resulted in the development of nanotools, capable of entering the single cell, resulting in new nanobiosensors useful for the detection of biomolecules inside living cells. In this paper, we provide an application of a nanotip coupled with molecular beacons (MBs) for the detection of DNA. The MBs were characterized by hybridization studies with a complementary target to prove their functionality both free in solution and immobilized onto a solid support. The solid support chosen as substrate for the immobilization of the MBs was a 30 nm tapered tip of an optical fiber, fabricated by chemical etching. With this set-up promising results were obtained and a limit of detection (LOD) of 0.57 nM was reached, opening up the possibility of using the proposed nanotip to detect mRNAs inside the cytoplasm of living cells. PMID:25919369

  15. Reusable fiber optic immunofluorosensor for rapid detection of pesticides

    NASA Astrophysics Data System (ADS)

    Anis, Nabil A.; Valdes, James J.; Thompson, Roy G.; Menking, Darrell E.; Wong, Rosie B.; Eldefrawi, Mohyee E.

    1993-05-01

    Quartz fibers coated with acetylcholinesterase (AChE) or antibody (Ab) are used as biosensors utilizing total reflectance fluorescence for the rapid detection of pesticides. The enzyme biosensor was constructed by immobilizing fluorescein isothiocyanate (FITC)-tagged eel electric organ AChE on quartz fibers. The fluorescent signal was generated by hydrolysis of acetylcholine (ACh) that is present in the perfusate. Organophosphate (OP) and carbamate anticholinesterase (AntiChE) insecticides inhibited AChE and reduced the fluorescent quenching resulting from AChE hydrolysis. A parathion biosensor was constructed by immobilizing casein-parathion on the quartz fibers, that bound rabbit antiparathion antibody. The optical signal was generated by perfusing the fibers with fluorescein-labeled goat antirabbit IgG. Free parathion inhibited the binding of antiparathion Abs and reduced the optical signal and provided the basis for detection of parathion. Another immunosensor developed detected the herbicide PursuitR by utilizing the reversible binding of a fluorescein-Pursuit derivative to antiPursuit Abs immobilized on the fiber. Unlabeled Pursuit competed effectively and displaced the bound fluorescent compound in a dose-dependent manner. The sensor discriminated effectively between Pursuit-like and structurally unrelated herbicides. The immunosensor offers the advantage of continuous monitoring, ease of operation, speed of detection, low cost, stability, specificity, matrix transparency, and reusability.

  16. Comparison of direct and heterodyne detection optical intersatellite communication links

    NASA Technical Reports Server (NTRS)

    Chen, C. C.; Gardner, C. S.

    1987-01-01

    The performance of direct and heterodyne detection optical intersatellite communication links are evaluated and compared. It is shown that the performance of optical links is very sensitive to the pointing and tracking errors at the transmitter and receiver. In the presence of random pointing and tracking errors, optimal antenna gains exist that will minimize the required transmitter power. In addition to limiting the antenna gains, random pointing and tracking errors also impose a power penalty in the link budget. This power penalty is between 1.6 to 3 dB for a direct detection QPPM link, and 3 to 5 dB for a heterodyne QFSK system. For the heterodyne systems, the carrier phase noise presents another major factor of performance degradation that must be considered. In contrast, the loss due to synchronization error is small. The link budgets for direct and heterodyne detection systems are evaluated. It is shown that, for systems with large pointing and tracking errors, the link budget is dominated by the spatial tracking error, and the direct detection system shows a superior performance because it is less sensitive to the spatial tracking error. On the other hand, for systems with small pointing and tracking jitters, the antenna gains are in general limited by the launch cost, and suboptimal antenna gains are often used in practice. In which case, the heterodyne system has a slightly higher power margin because of higher receiver sensitivity.

  17. Flow cytometer using a fiber optic detection system

    NASA Astrophysics Data System (ADS)

    Kanda, Masahiko; Nakata, Motomi; Osoegawa, Misako; Niwa, Shinichirou; Yamashita, Tatsuo; Suzuki, Shingo; Murayama, Koji

    2001-05-01

    A flow cytometer with a new hybrid flow cell has been developed. The hybrid flow cell was constructed closed-type quarts curvets which produces a parabolic profile of flow velocities. It was involved a fiber-optic detecting unit for a high sensitivity collection and had a jet nozzle and a PZT device for droplet formation aimed to cell sorting. A optical fiber that consists of a glass core and have a core diameter of 200 micrometers with NA of 0.5 have been successfully used for the collection of side scatter and fluorescent signals. Two detecting fibers mounted in a hybrid flow cell with pith of 250 micrometers are designed to individually detect fluorescent signals excited by 2 lasers, which are a compact air-cooled AR laser (488 nm: 20 mW) and a semiconductor laser (640 nm: 15 mW). As a result, a sensitivity of our flow cytometer is 300 MESF determined using fluorescein-labeled beads and 2 scatter and 6 fluorescent signals could successfully be detected. Typical patterns of cell cycle were observed with Daudi human Burkitt Lymphoma cell lines stained with PL. Furthermore, the alignment requirements are more simplified because of a hybrid flow cell stably mounted.

  18. Optically Resonant Nanophotonic Devices for Label-Free Biomolecular Detection

    NASA Astrophysics Data System (ADS)

    Goddard, Julie; Mandal, Sudeep; Erickson, David

    Optical devices, such as surface plasmon resonance chips and waveguide-based Mach-Zehnder interferometers, have long been successfully used as label-free biomolecular sensors. Recently, however, there has been increased interest in developing new approaches to biomolecular detection that can improve on the limit of detection, specificity, and multiplexibility of these early devices and address emerging challenges in pathogen detection, disease diagnosis, and drug discovery. As we describe in this chapter, planar optically resonant nanophotonic devices (such as ring resonators, whispering gallery modes, and photonic crystal cavities) are one method that shows promise in significantly advancing the technology. Here we first provide a short review of these devices focusing on a handful of approaches illustrative of the state of the art. We then frame the major challenge to improving the technology as being the ability to provide simultaneously spatial localization of the electromagnetic energy and biomolecular binding events. We then introduce our “Nanoscale Optofluidic Sensor Arrays” which represents our approach to addressing this challenge. It is demonstrated how these devices serve to enable multiplexed detection while localizing the electromagnetic energy to a volume as small as a cubic wavelength. Challenges involved in the targeted immobilization of biomolecules over such a small area are discussed and our solutions presented. In general, we have tried to write this chapter with the novice in mind, providing details on the fabrication and immobilization methods that we have used and how one might adapt our approach to their designs.

  19. Coherent Detection of High-Rate Optical PPM Signals

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor; Fernandez, Michela Munoz

    2006-01-01

    A method of coherent detection of high-rate pulse-position modulation (PPM) on a received laser beam has been conceived as a means of reducing the deleterious effects of noise and atmospheric turbulence in free-space optical communication using focal-plane detector array technologies. In comparison with a receiver based on direct detection of the intensity modulation of a PPM signal, a receiver based on the present method of coherent detection performs well at much higher background levels. In principle, the coherent-detection receiver can exhibit quantum-limited performance despite atmospheric turbulence. The key components of such a receiver include standard receiver optics, a laser that serves as a local oscillator, a focal-plane array of photodetectors, and a signal-processing and data-acquisition assembly needed to sample the focal-plane fields and reconstruct the pulsed signal prior to detection. The received PPM-modulated laser beam and the local-oscillator beam are focused onto the photodetector array, where they are mixed in the detection process. The two lasers are of the same or nearly the same frequency. If the two lasers are of different frequencies, then the coherent detection process is characterized as heterodyne and, using traditional heterodyne-detection terminology, the difference between the two laser frequencies is denoted the intermediate frequency (IF). If the two laser beams are of the same frequency and remain aligned in phase, then the coherent detection process is characterized as homodyne (essentially, heterodyne detection at zero IF). As a result of the inherent squaring operation of each photodetector, the output current includes an IF component that contains the signal modulation. The amplitude of the IF component is proportional to the product of the local-oscillator signal amplitude and the PPM signal amplitude. Hence, by using a sufficiently strong local-oscillator signal, one can make the PPM-modulated IF signal strong enough to

  20. Biomimetic/Optical Sensors for Detecting Bacterial Species

    NASA Technical Reports Server (NTRS)

    Homer, Margie; Ksendzov, Alexander; Yen, Shiao-Pin; Ryan, Margaret; Lazazzera, Beth

    2006-01-01

    Biomimetic/optical sensors have been proposed as means of real-time detection of bacteria in liquid samples through real-time detection of compounds secreted by the bacteria. Bacterial species of interest would be identified through detection of signaling compounds unique to those species. The best-characterized examples of quorum-signaling compounds are acyl-homoserine lactones and peptides. Each compound, secreted by each bacterium of an affected species, serves as a signal to other bacteria of the same species to engage in a collective behavior when the population density of that species reaches a threshold level analogous to a quorum. A sensor according to the proposal would include a specially formulated biomimetic film, made of a molecularly imprinted polymer (MIP), that would respond optically to the signaling compound of interest. The MIP film would be integrated directly onto an opticalwaveguide- based ring resonator for optical readout. Optically, the sensor would resemble the one described in Chemical Sensors Based on Optical Ring Resonators (NPO-40601), NASA Tech Briefs, Vol. 29, No. 10 (October 2005), page 32. MIPs have been used before as molecular- recognition compounds, though not in the manner of the present proposal. Molecular imprinting is an approach to making molecularly selective cavities in a polymer matrix. These cavities function much as enzyme receptor sites: the chemical functionality and shape of a cavity in the polymer matrix cause the cavity to bind to specific molecules. An MIP matrix is made by polymerizing monomers in the presence of the compound of interest (template molecule). The polymer forms around the template. After the polymer solidifies, the template molecules are removed from the polymer matrix by decomplexing them from their binding sites and then dissolving them, leaving cavities that are matched to the template molecules in size, shape, and chemical functionality. The cavities thus become molecular-recognition sites

  1. Miniature endoscopic optical coherence tomography for calculus detection.

    PubMed

    Kao, Meng-Chun; Lin, Chun-Li; Kung, Che-Yen; Huang, Yi-Fung; Kuo, Wen-Chuan

    2015-08-20

    The effective treatment of periodontitis involves the detection and removal of subgingival dental calculus. However, subgingival calculus is more difficult to detect than supragingival calculus because it is firmly attached to root surfaces within periodontal pockets. To achieve a smooth root surface, clinicians often remove excessive amounts of root structure because of decreased visibility. In addition, enamel pearl, a rare type of ectopic enamel formation on the root surface, can easily be confused with dental calculus in the subgingival environment. In this study, we developed a fiber-probe swept-source optical coherence tomography (SSOCT) technique and combined it with the quantitative measurement of an optical parameter [standard deviation (SD) of the optical coherence tomography (OCT) intensity] to differentiate subgingival calculus from sound enamel, including enamel pearl. Two-dimensional circumferential images were constructed by rotating the miniprobe (0.9 mm diameter) while acquiring image lines, and the adjacent lines in each rotation were stacked to generate a three-dimensional volume. In OCT images, compared to sound enamel and enamel pearls, dental calculus showed significant differences (P<0.001) in SD values. Finally, the receiver operating characteristic curve had a high capacity (area under the curve=0.934) for discriminating between healthy regions (including enamel pearl) and dental calculus. PMID:26368780

  2. Fault analysis and detection in large active optical systems

    NASA Astrophysics Data System (ADS)

    Cox, Charles D.; Furber, Mark E.; Jordan, David C.; Blaszak, David D.

    1995-05-01

    Active optical systems are complex systems that may be expected to operate in hostile environments such as space. The ability of such a system either to tolerate failures of components or to reconfigure to accommodate failed components could significantly increase the useful lifetime of the system. Active optical systems often contain hundreds of actuators and sensor channels but have an inherent redundancy, i.e., more actuators or sensor channels than the minimum needed to achieve the required performance. A failure detection and isolation system can be used to find and accommodate failures. One type of failure is the failure of an actuator. The effect of actuator failure on the ability of a deformable mirror to correct aberrations is analyzed using a finite-element model of the deformable mirror, and a general analytical procedure for determining the effect of actuator failures on system performance is given. The application of model-based failure detection, isolation and identification algorithms to active optical systems is outlined.

  3. Optical Flow Estimation for Flame Detection in Videos

    PubMed Central

    Mueller, Martin; Karasev, Peter; Kolesov, Ivan; Tannenbaum, Allen

    2014-01-01

    Computational vision-based flame detection has drawn significant attention in the past decade with camera surveillance systems becoming ubiquitous. Whereas many discriminating features, such as color, shape, texture, etc., have been employed in the literature, this paper proposes a set of motion features based on motion estimators. The key idea consists of exploiting the difference between the turbulent, fast, fire motion, and the structured, rigid motion of other objects. Since classical optical flow methods do not model the characteristics of fire motion (e.g., non-smoothness of motion, non-constancy of intensity), two optical flow methods are specifically designed for the fire detection task: optimal mass transport models fire with dynamic texture, while a data-driven optical flow scheme models saturated flames. Then, characteristic features related to the flow magnitudes and directions are computed from the flow fields to discriminate between fire and non-fire motion. The proposed features are tested on a large video database to demonstrate their practical usefulness. Moreover, a novel evaluation method is proposed by fire simulations that allow for a controlled environment to analyze parameter influences, such as flame saturation, spatial resolution, frame rate, and random noise. PMID:23613042

  4. Integration of waveguides for optical detection in microfabricated analytical devices

    NASA Astrophysics Data System (ADS)

    Kutter, Joerg P.; Mogensen, Klaus B.; Friis, Peter; Jorgensen, Anders M.; Petersen, Nickolaj J.; Telleman, Pieter; Huebner, Joerg

    2000-08-01

    Buried optical channel waveguides integrated with a fluidic channel network on a planar microdevice are presented. The waveguides were fabricated using silica-on-silicon technology with the goal to replace bulk optical elements and facilitate various optical detection techniques for miniaturized total analysis systems or lab-on-a-chip systems. Waveguide structures with core layers doped with germanium were employed for fluorescence measurements, while waveguides with nitrogen- only doped core layers were used for absorbance measurements. By the elimination of germanium oxygen deficiency centers transmission of light down to 210nm was possible, allowing absorance measurements in the mid and far UV region (210 to 280nm), which is the region where a large number of different molecules absorb light. Robust, alignment-free microdevices, which can easily be hooked up to a number of light sources and detectors were used for fluorescence measurements of two dyes, fluorescein and Bodipy, and absorbance measurements of a stres-reducing drug, propranolol. The lowest detected concentrations were 250pM for fluorescein, 100nM for Bodipy and 12(mu) M for propranolol.

  5. Optical flow estimation for flame detection in videos.

    PubMed

    Mueller, Martin; Karasev, Peter; Kolesov, Ivan; Tannenbaum, Allen

    2013-07-01

    Computational vision-based flame detection has drawn significant attention in the past decade with camera surveillance systems becoming ubiquitous. Whereas many discriminating features, such as color, shape, texture, etc., have been employed in the literature, this paper proposes a set of motion features based on motion estimators. The key idea consists of exploiting the difference between the turbulent, fast, fire motion, and the structured, rigid motion of other objects. Since classical optical flow methods do not model the characteristics of fire motion (e.g., non-smoothness of motion, non-constancy of intensity), two optical flow methods are specifically designed for the fire detection task: optimal mass transport models fire with dynamic texture, while a data-driven optical flow scheme models saturated flames. Then, characteristic features related to the flow magnitudes and directions are computed from the flow fields to discriminate between fire and non-fire motion. The proposed features are tested on a large video database to demonstrate their practical usefulness. Moreover, a novel evaluation method is proposed by fire simulations that allow for a controlled environment to analyze parameter influences, such as flame saturation, spatial resolution, frame rate, and random noise. PMID:23613042

  6. Detecting single DNA molecule interactions with optical microcavities (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Vollmer, Frank

    2015-09-01

    Detecting molecules and their interactions lies at the heart of all biosensor devices, which have important applications in health, environmental monitoring and biomedicine. Achieving biosensing capability at the single molecule level is, moreover, a particularly important goal since single molecule biosensors would not only operate at the ultimate detection limit by resolving individual molecular interactions, but they could also monitor biomolecular properties which are otherwise obscured in ensemble measurements. For example, a single molecule biosensor could resolve the fleeting interaction kinetics between a molecule and its receptor, with immediate applications in clinical diagnostics. We have now developed a label-free biosensing platform that is capable of monitoring single DNA molecules and their interaction kinetics[1], hence achieving an unprecedented sensitivity in the optical domain, Figure 1. We resolve the specific contacts between complementary oligonucleotides, thereby detecting DNA strands with less than 2.4 kDa molecular weight. Furthermore we can discern strands with single nucleotide mismatches by monitoring their interaction kinetics. Our device utilizes small glass microspheres as optical transducers[1,2, 3], which are capable of increasing the number of interactions between a light beam and analyte molecules. A prism is used to couple the light beam into the microsphere. Ourr biosensing approach resolves the specific interaction kinetics between single DNA fragments. The optical transducer is assembled in a simple three-step protocol, and consists of a gold nanorod attached to a glass microsphere, where the surface of the nanorod is further modified with oligonucleotide receptors. The interaction kinetics of an oligonucleotide receptor with DNA fragments in the surrounding aqueous solution is monitored at the single molecule level[1]. The light remains confined inside the sphere where it is guided by total internal reflections along a

  7. High resolution underwater fiber optic threat detection system

    NASA Astrophysics Data System (ADS)

    Berger, Alexander; Hermesh, Shalmon; Durets, Eugene; Kempen, Lothar U.

    2006-10-01

    Current underwater protection systems are complex expensive devices consisting of multiple electronic sensing elements. The detection and identification of divers and small submerged watercraft requires very high image resolution. The high price of an array of conventional piezoelectric transducers and associated electronic components makes this solution feasible for localized implementations, but the protection of large stretches of coastline requires a different approach. We present a novel multichannel sonar design that augments current active sonar transducers with a passive fiber-optic multichannel acoustic emission sensing array. The system provides continuous monitoring of the acoustic wave reflections emitted by a single projector, yielding information about the size and shape of approaching objects. A novel fiber hydrophone enclosure is utilized to dramatically enhance the sensor response to the sonar frequency, while suppressing out-of-band sound sources and noise. The ability of a fiber hydrophone to respond to acoustic emissions is based on established fiber Bragg grating sensing techniques. In this approach, the energy of an acoustic wave is converted into the modulation of the in-fiber optical transducer's optical properties. The obtained results demonstrate significant response of the designed fiber optic hydrophone to the incident acoustic wave over the frequency domain from 1-80 kHz. Our approach allows selective tuning of the sensor to a particular acoustic frequency, as well as potential extension of the spectral response to 300- 400kHz.2

  8. A Fiber Optic Probe for the Detection of Cataracts

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Dhadwal, Harbans S.

    1993-01-01

    A compact fiber optic probe developed for on-orbit science experiments was used to detect the onset of cataracts, a capability that could eliminate physicians' guesswork and result in new drugs to 'dissolve' or slow down the cataract formation before surgery is necessary. The probe is based upon dynamic light scattering (DLS) principles. It has no moving parts, no apertures, and requires no optical alignment. It is flexible and easy to use. Results are presented for excised but intact human eye lenses. In a clinical setting, the device can be easily incorporated into a slit-lamp apparatus (ophthalmoscope) for complete eye diagnostics. In this set-up, the integrated fiber optic probe, the size of a pencil, delivers a low power cone of laser light into the eye of a patient and guides the light which is backscattered by the protein molecules of the lens through a receiving optical fiber to a photo detector. The non-invasive DLS measurements provide rapid determination of protein crystalline size and its size distribution in the eye lens.

  9. Research on key problems for LAMOST optical fiber detection system

    NASA Astrophysics Data System (ADS)

    Wang, Mengxin; Chen, Jianjun; Luo, Ali; Chen, Xiaoran

    2014-07-01

    The large sky area multi-object fiber spectroscopic telescope (LAMOST) is an innovative reflecting schmidt telescope, promising a very high spectrum acquiring rate of several ten-thousands of spectra per night. By using the parallel controllable fiber positioning technique, LAMOST makes reconfiguration of fibers accurately according to the positions of objects in minutes and fine adjusting the fibers. During telescope observation period, each optical fiber unit positional accuracy directly determines the quality of subsequent spectrum acqusition, yet for real-time optical fiber positional accuracy, there only exists an internal information feedback which focus on the corresponding stepper motor driving conditions, however, this available information is not comprehensive, it can not offer the actual positional information for each fiber unit. Considering the LAMOST on-site environment, a novel real-time optical fiber positional accuracy detection system which can be integrated in the existing observation and control system need to be developed to solve this problem. During the observation interval, this system can offer a comprehensive and effective information feedback about the focal optical fiber positional accuracy. Based on this feedback, the observation assistants can properly adjust the observation strategies to ensure the effectiveness and accuracy of acquired spectrum. Furthermore, this fiber positional accuracy feedback can provide prior spectral quality information to the spectral processing personnel and optimal the spectrum processing efficiency.

  10. Optical cloud detection from a disposable airborne sensor

    NASA Astrophysics Data System (ADS)

    Nicoll, Keri; Harrison, R. Giles; Brus, David

    2016-04-01

    In-situ measurement of cloud droplet microphysical properties is most commonly made from manned aircraft platforms due to the size and weight of the instrumentation, which is both costly and typically limited to sampling only a few clouds. This work describes the development of a small, lightweight (<200g), disposable, optical cloud sensor which is designed for use on routine radiosonde balloon flights and also small unmanned aerial vehicle (UAV) platforms. The sensor employs the backscatter principle, using an ultra-bright LED as the illumination source, with a photodiode detector. Scattering of the LED light by cloud droplets generates a small optical signal which is separated from background light fluctuations using a lock-in technique. The signal to noise obtained permits cloud detection using the scattered LED light, even in daytime. During recent field tests in Pallas, Finland, the retrieved optical sensor signal has been compared with the DMT Cloud and Aerosol Spectrometer (CAS) which measures cloud droplets in the size range from 0.5 to 50 microns. Both sensors were installed at the hill top observatory of Sammaltunturi during a field campaign in October and November 2015, which experienced long periods of immersion inside cloud. Preliminary analysis shows very good agreement between the CAPS and the disposable cloud sensor for cloud droplets >5micron effective diameter. Such data and calibration of the sensor will be discussed here, as will simultaneous balloon launches of the optical cloud sensor through the same cloud layers.

  11. Extended linear detection range for optical tweezers using image-plane detection scheme

    NASA Astrophysics Data System (ADS)

    Hajizadeh, Faegheh; Masoumeh Mousavi, S.; Khaksar, Zeinab S.; Reihani, S. Nader S.

    2014-10-01

    Ability to measure pico- and femto-Newton range forces using optical tweezers (OT) strongly relies on the sensitivity of its detection system. We show that the commonly used back-focal-plane detection method provides a linear response range which is shorter than that of the restoring force of OT for large beads. This limits measurable force range of OT. We show, both theoretically and experimentally, that utilizing a second laser beam for tracking could solve the problem. We also propose a new detection scheme in which the quadrant photodiode is positioned at the plane optically conjugate to the object plane (image plane). This method solves the problem without need for a second laser beam for the bead sizes that are commonly used in force spectroscopy applications of OT, such as biopolymer stretching.

  12. Spatially resolved detection of complex ferromagnetic dynamics using optically detected nitrogen-vacancy spins

    NASA Astrophysics Data System (ADS)

    Wolfe, C. S.; Manuilov, S. A.; Purser, C. M.; Teeling-Smith, R.; Dubs, C.; Hammel, P. C.; Bhallamudi, V. P.

    2016-06-01

    We demonstrate optical detection of a broad spectrum of ferromagnetic excitations using nitrogen-vacancy (NV) centers in an ensemble of nanodiamonds. Our recently developed approach exploits a straightforward CW detection scheme using readily available diamond detectors, making it easily implementable. The NV center is a local detector, giving the technique spatial resolution, which here is defined by our laser spot, but in principle can be extended far into the nanoscale. Among the excitations, we observe the propagating dipolar and dipolar-exchange spinwaves, as well as dynamics associated with the multi-domain state of the ferromagnet at low fields. These results offer an approach, distinct from commonly used optically detected magnetic resonance techniques, for spatially resolved spectroscopic study of magnetization dynamics at the nanoscale.

  13. Optical detection of blade flutter. [in YF-100 turbofan engine

    NASA Technical Reports Server (NTRS)

    Nieberding, W. C.; Pollack, J. L.

    1977-01-01

    The paper examines the capabilities of photoelectric scanning (PES) and stroboscopic imagery (SI) as optical monitoring tools for detection of the onset of flutter in the fan blades of an aircraft gas turbine engine. Both optical techniques give visual data in real time as well as video-tape records. PES is shown to be an ideal flutter monitor, since a single cathode ray tube displays the behavior of all the blades in a stage simultaneously. Operation of the SI system continuously while searching for a flutter condition imposes severe demands on the flash tube and affects its reliability, thus limiting its use as a flutter monitor. A better method of operation is to search for flutter with the PES and limit the use of SI to those times when the PES indicates interesting blade activity.

  14. Generation and detection of atomic spin entanglement in optical lattices

    NASA Astrophysics Data System (ADS)

    Dai, Han-Ning; Yang, Bing; Reingruber, Andreas; Xu, Xiao-Fan; Jiang, Xiao; Chen, Yu-Ao; Yuan, Zhen-Sheng; Pan, Jian-Wei

    2016-08-01

    Ultracold atoms in optical lattices hold promise for the creation of entangled states for quantum technologies. Here we report on the generation, manipulation and detection of atomic spin entanglement in an optical superlattice. Using a spin-dependent superlattice, atomic spins in the left or right sites can be individually addressed and coherently manipulated with near-unity fidelities by microwave pulses. The spin entanglement of the two atoms in the double wells of the superlattice is generated via the dynamical evolution governed by spin superexchange. By monitoring the collisional atom loss with in situ absorption imaging we measure the spin correlations of the atoms inside the double wells and obtain a lower bound on the entanglement fidelity of 0.79 +/- 0.06, and a violation of a Bell's inequality S = 2.21 +/- 0.08.

  15. Detection of defects in optics based on scanning

    NASA Astrophysics Data System (ADS)

    Zhou, Bin; Bai, Jian; Liang, Yiyong; Wang, Kaiwei; Lu, Qianbo; Zhang, Sai

    2015-08-01

    In this paper, a method to detect internal pocks and bubbles of optical elements based on laser line source scanning is proposed. In dark field environment, a laser line source is used to illuminate from one side of the glass under test, a high-resolution CCD camera is used to take pictures in front of the glass sample. Images which contain information of defects are acquired through rough scanning and accurate scanning. Accurate three-dimensional coordinates of the internal defects are acquired after image processing, which descript the characteristic information of internal defects quantificationally. Compared with the microscope imaging measurement, this proposed detection of defects in optics based on laser line source scanning has a relative aberration smaller than 2%. In addition, the detection time is approximately reduced to 20 minutes from 1 hour dramatically. The analysis indicates that the error of the position of defects is much smaller than the size of them, which means the position of the defects can be acquired accurately by this approach.

  16. Optical solid-state detection of organophosphates using organophosphorus hydrolase.

    PubMed

    White, Brandy J; Harmon, H James

    2005-04-15

    We have developed a sensor surface for optical detection of organophosphates based on reversible inhibition of organophosphorus hydrolase (OPH) by copper complexed meso-tri(4-sulfonato phenyl) mono(4-carboxy phenyl) porphyrin (CuC1TPP). OPH immobilized onto glass microscope slides retains catalytic activity for more than 232 days. CuC1TPP is a reversible, competitive inhibitor of OPH, binding at the active site of the immobilized enzyme. The absorbance spectrum of the porphyrin-enzyme complex is measured via planar waveguide evanescent wave absorbance spectroscopy using a blue LED as a light source and an Ocean Optics USB2000 as the spectrophotometer. The characteristics of the absorbance spectrum of CuC1TPP are specific and different when the porphyrin is bound to the enzyme or is bound non-specifically to the surface of the slide. Addition of a substrate of OPH such as one of the organophosphates paraoxon, coumaphos, diazinon, or malathion displaces the porphyrin from the enzyme resulting in reduced absorbance intensity at 412 nm. Absorbance changes at 412 nm show log-linear dependence on substrate concentration. Paraoxon concentrations between 7 parts per trillion (ppt) and 14 parts per million (ppm) were investigated and a 3:1 S/N detection limit of 7 ppt was determined. Concentrations of 700 ppt to 40 ppm were investigated for diazinon, malathion, and coumaphos with detection limits of 800 ppt, 1 part per billion, and 250 ppt, respectively. This optical technique does not require the addition of reagents or solutions other than the sample and absorbance spectra can be collected in less than 6 s. PMID:15741066

  17. Optical biosensors for bacteria detection by a peptidomimetic antimicrobial compound.

    PubMed

    Tenenbaum, Elena; Segal, Ester

    2015-11-21

    In this work we present a label-free optical biosensor for rapid bacteria detection using a novel peptide-mimetic compound, as the recognition element. The biosensor design is based on an oxidized porous silicon (PSiO2) nanostructure used as the optical transducer, functionalized with the sequence K-[C12K]7 (referred to as K-7α12), which is a synthetic antimicrobial peptide. This compound is a member of a family of oligomers of acylated lysines (OAKs), mimicking the hydrophobicity and charge of natural antimicrobial peptides. The OAK is tethered to the PSiO2 film and the changes in the reflectivity spectrum are monitored upon exposure to Escherichia coli (E. coli) bacterial suspensions and their lysates. We show that capture of bacterial cell fragments induces predictable changes in the reflectivity spectrum, proportional to E. coli concentrations, thereby enabling rapid, sensitive and reproducible detection of E. coli at concentrations as low as 10(3) cells per mL. While for intact bacterial cells, the K-7α12-tethered PSiO2 shows a poor capturing ability, resulting in an insignificant optical response. The biosensor performance is also studied upon exposure to model Gram positive and negative bacterial lysates, suggesting preferential capture of E. coli cell fragments in the presented scheme. These OAK-based biosensors offer significant advantages in comparison with conventional antibody-based assays, in terms of their simple and cost-effective production, while providing numerous possible sequence combinations for designing new detection schemes. PMID:26456237

  18. Dental caries detection by optical spectroscopy: a polarized Raman approach with fibre-optic coupling

    NASA Astrophysics Data System (ADS)

    Ko, A. C.-T.; Choo-Smith, L.-P.; Werner, J.; Hewko, M.; Sowa, M. G.; Dong, C.; Cleghorn, B.

    2006-09-01

    Incipient dental caries lesions appear as white spots on the tooth surface; however, accurate detection of early approximal lesions is difficult due to limited sensitivity of dental radiography and other traditional diagnostic tools. A new fibre-optic coupled spectroscopic method based on polarized Raman spectroscopy (P-RS) with near-IR laser excitation is introduced which provides contrast for detecting and characterizing incipient caries. Changes in polarized Raman spectra are observed in PO 4 3- vibrations arising from hydroxyapatite of mineralized tooth tissue. Demineralization-induced morphological/orientational alteration of enamel crystallites is believed to be responsible for the reduction of Raman polarization anisotropy observed in the polarized Raman spectra of caries lesions. Supporting evidence obtained by polarized Raman spectral imaging is presented. A specially designed fibre-optic coupled setup for simultaneous measurement of parallel- and cross-polarized tooth Raman spectra is demonstrated in this study.

  19. Spectral domain optical coherence tomography with dual-balanced detection

    NASA Astrophysics Data System (ADS)

    Bo, En; Liu, Xinyu; Chen, Si; Luo, Yuemei; Wang, Nanshuo; Wang, Xianghong; Liu, Linbo

    2016-03-01

    We developed a spectral domain optical coherence tomography (SD-OCT) system employing dual-balanced detection (DBD) for direct current term suppression and SNR enhancement, especially for auto-autocorrelation artifacts reduction. The DBD was achieved by using a beam splitter to building a free-space Michelson interferometer, which generated two interferometric spectra with a phase difference of π. These two phase-opposed spectra were guided to the spectrometer through two single mode fibers of the 8 fiber v-groove array and acquired by ultizing the upper two lines of a three-line CCD camera. We rotated this fiber v-groove array by 1.35 degrees to focus two spectra onto the first and second line of the CCD camera. Two spectra were aligned by optimum spectrum matching algorithm. By subtracting one spectrum from the other, this dual-balanced detection system achieved a direct current term suppression of ~30 dB, SNR enhancement of ~3 dB, and auto-autocorrelation artifacts reduction of ~10 dB experimentally. Finally we respectively validated the feasibility and performance of dual-balanced detection by imaging a glass plate and swine corneal tissue ex vivo. The quality of images obtained using dual-balanced detection was significantly improved with regard to the conventional single-detection (SD) images.

  20. A Method of Detecting Fire Smoke by Using Optical Flow

    NASA Astrophysics Data System (ADS)

    Terada, Kenji; Miyahara, Hiroyuki; Nii, Yasutoshi

    In this paper, the authors propose a method for detecting fire smoke by using the optical flow. This method is not influenced against the image obtainment environment. About 60,000 fires have occurred every year in Japan. To be most important to the fires is an early period fire fighting. At present, the automatic devices of detectiong fires is needed. The alarms which can detect smoke and heat are utilized to house fires. However, these alarms are not useful for the outside of house such as the incendiary or woodland fire. This method is able to detect such a flame that becomes a fire is the early period. First, the region of the flame in the images obtained from the observation camera is detected. Next, the characteristic quantity that expresses the smoke is extracted. This characteristic is not influenced to the motion such as the cloud, leaf and moving objects. In other words, the only smoke can be detected, from the range which looks like the flame in the image.

  1. Magneto-optical contrast in liquid-state optically detected NMR spectroscopy.

    PubMed

    Pagliero, Daniela; Meriles, Carlos A

    2011-12-01

    We use optical Faraday rotation (OFR) to probe nuclear spins in real time at high-magnetic field in a range of diamagnetic sample fluids. Comparison of OFR-detected NMR spectra reveals a correlation between the relative signal amplitude and the fluid Verdet constant, which we interpret as a manifestation of the variable detuning between the probe beam and the sample optical transitions. The analysis of chemical-shift-resolved, optically detected spectra allows us to set constraints on the relative amplitudes of hyperfine coupling constants, both for protons at chemically distinct sites and other lower-gyromagnetic-ratio nuclei including carbon, fluorine, and phosphorous. By considering a model binary mixture we observe a complex dependence of the optical response on the relative concentration, suggesting that the present approach is sensitive to the solvent-solute dynamics in ways complementary to those known in inductive NMR. Extension of these experiments may find application in solvent suppression protocols, sensitivity-enhanced NMR of metalloproteins in solution, the investigation of solvent-solute interactions, or the characterization of molecular orbitals in diamagnetic systems. PMID:22100736

  2. Optical beat interference noise reduction in OFDMA optical access link using self-homodyne balanced detection

    NASA Astrophysics Data System (ADS)

    Jung, Sang-Min; Won, Yong-Yuk; Han, Sang-Kook

    2013-12-01

    A Novel technique for reducing the OBI noise in optical OFDMA-PON uplink is presented. OFDMA is a multipleaccess/ multiplexing scheme that can provide multiplexing operation of user data streams onto the downlink sub-channels and uplink multiple access by means of dividing OFDM subcarriers as sub-channels. The main issue of high-speed, single-wavelength upstream OFDMA-PON arises from optical beating interference noise. Because the sub-channels are allocated dynamically to multiple access users over same nominal wavelength, it generates the optical beating interference among upstream signals. In this paper, we proposed a novel scheme using self-homodyne balanced detection in the optical line terminal (OLT) to reduce OBI noise which is generated in the uplink transmission of OFDMA-PON system. When multiple OFDMA sub-channels over the same nominal wavelength are received at the same time in the proposed architecture, OBI noises can be removed using balanced detection. Using discrete multitone modulation (DMT) to generate real valued OFDM signals, the proposed technique is verified through experimental demonstration.

  3. Fiber Optic Thermographic Detection of Flaws in Composites

    NASA Technical Reports Server (NTRS)

    Wu, Meng-Chou; Winfree, William P.

    2009-01-01

    Optical fibers with multiple Bragg gratings bonded to surfaces of structures were used for thermographic detection of subsurface defects in structures. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The obtained data were analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with the simulation results.

  4. Detection of biological molecules using chemical amplification and optical sensors

    DOEpatents

    Van Antwerp, William Peter; Mastrototaro, John Joseph

    2001-01-01

    Methods are provided for the determination of the concentration of biological levels of polyhydroxylated compounds, particularly glucose. The methods utilize an amplification system that is an analyte transducer immobilized in a polymeric matrix, where the system is implantable and biocompatible. Upon interrogation by an optical system, the amplification system produces a signal capable of detection external to the skin of the patient. Quantitation of the analyte of interest is achieved by measurement of the emitted signal. Specifically, the analyte transducer immobilized in a polymeric matrix can be a boronic acid moiety.

  5. Dual collection mode optical microscope with single-pixel detection

    NASA Astrophysics Data System (ADS)

    Rodríguez, A. D.; Clemente, P.; Fernández-Alonso, Mercedes; Tajahuerce, E.; Lancis, J.

    2015-07-01

    In this work we have developed a single-pixel optical microscope that provides both re ection and transmission images of the sample under test by attaching a diamond pixel layout DMD to a commercial inverted microscope. Our system performs simultaneous measurements of re ection and transmission modes. Besides, in contrast with a conventional system, in our single-element detection system both images belong, unequivocally, to the same plane of the sample. Furthermore, we have designed an algorithm to modify the shape of the projected patterns that improves the resolution and prevents the artifacts produced by the diamond pixel architecture.

  6. Depth resolved detection of lipid using spectroscopic optical coherence tomography

    PubMed Central

    Fleming, Christine P.; Eckert, Jocelyn; Halpern, Elkan F.; Gardecki, Joseph A.; Tearney, Guillermo J.

    2013-01-01

    Optical frequency domain imaging (OFDI) can identify key components related to plaque vulnerability but can suffer from artifacts that could prevent accurate identification of lipid rich regions. In this paper, we present a model of depth resolved spectral analysis of OFDI data for improved detection of lipid. A quadratic Discriminant analysis model was developed based on phantom compositions known chemical mixtures and applied to a tissue phantom of a lipid-rich plaque. We demonstrate that a combined spectral and attenuation model can be used to predict the presence of lipid in OFDI images. PMID:24009991

  7. Optical frequency standards for gravitational wave detection using satellite velocimetry

    NASA Astrophysics Data System (ADS)

    Vutha, Amar

    2015-04-01

    Satellite Doppler velocimetry, building on the work of Kaufmann and Estabrook and Wahlquist, is a complementary technique to interferometric methods of gravitational wave detection. This method is based on the fact that the gravitational wave amplitude appears in the apparent Doppler shift of photons propagating from an emitter to a receiver. This apparent Doppler shift can be resolved provided that a frequency standard, capable of quickly averaging down to a high stability, is available. We present a design for a space-capable optical atomic frequency standard, and analyze the sensitivity of satellite Doppler velocimetry for gravitational wave astronomy in the milli-hertz frequency band.

  8. Detecting single DNA molecule interactions with optical microcavities (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Vollmer, Frank

    2015-09-01

    Detecting molecules and their interactions lies at the heart of all biosensor devices, which have important applications in health, environmental monitoring and biomedicine. Achieving biosensing capability at the single molecule level is, moreover, a particularly important goal since single molecule biosensors would not only operate at the ultimate detection limit by resolving individual molecular interactions, but they could also monitor biomolecular properties which are otherwise obscured in ensemble measurements. For example, a single molecule biosensor could resolve the fleeting interaction kinetics between a molecule and its receptor, with immediate applications in clinical diagnostics. We have now developed a label-free biosensing platform that is capable of monitoring single DNA molecules and their interaction kinetics[1], hence achieving an unprecedented sensitivity in the optical domain, Figure 1. We resolve the specific contacts between complementary oligonucleotides, thereby detecting DNA strands with less than 2.4 kDa molecular weight. Furthermore we can discern strands with single nucleotide mismatches by monitoring their interaction kinetics. Our device utilizes small glass microspheres as optical transducers[1,2, 3], which are capable of increasing the number of interactions between a light beam and analyte molecules. A prism is used to couple the light beam into the microsphere. Ourr biosensing approach resolves the specific interaction kinetics between single DNA fragments. The optical transducer is assembled in a simple three-step protocol, and consists of a gold nanorod attached to a glass microsphere, where the surface of the nanorod is further modified with oligonucleotide receptors. The interaction kinetics of an oligonucleotide receptor with DNA fragments in the surrounding aqueous solution is monitored at the single molecule level[1]. The light remains confined inside the sphere where it is guided by total internal reflections along a

  9. Optical leak detection of oxygen using IR-laser diodes

    NASA Technical Reports Server (NTRS)

    Disimile, P. J.; Fox, C.; Toy, N.

    1991-01-01

    The ability to accurately measure the concentration of gaseous oxygen and its corresponding flow rate is becoming of greater importance. The technique being presented is based on the principal of light attenuation due to the absorption of radiation by the A-band of oxygen which is located in the 759-770 nm wavelength range. With an ability to measure the change in the light transmission to 0.05 percent, a sensitive optical leak detection system which has a rapid time response is possible. In this research program, the application of laser diode technology and its ability to be temperature tuned to a selected oxygen absorption spectral peak has allowed oxygen concentrations as low as 16,000 ppm to be detected.

  10. Detection of tunnel excavation using fiber optic reflectometry: experimental validation

    NASA Astrophysics Data System (ADS)

    Linker, Raphael; Klar, Assaf

    2013-06-01

    Cross-border smuggling tunnels enable unmonitored movement of people and goods, and pose a severe threat to homeland security. In recent years, we have been working on the development of a system based on fiber- optic Brillouin time domain reflectometry (BOTDR) for detecting tunnel excavation. In two previous SPIE publications we have reported the initial development of the system as well as its validation using small-scale experiments. This paper reports, for the first time, results of full-scale experiments and discusses the system performance. The results confirm that distributed measurement of strain profiles in fiber cables buried at shallow depth enable detection of tunnel excavation, and by proper data processing, these measurements enable precise localization of the tunnel, as well as reasonable estimation of its depth.

  11. Detecting high-frequency gravitational waves with optically levitated sensors.

    PubMed

    Arvanitaki, Asimina; Geraci, Andrew A

    2013-02-15

    We propose a tunable resonant sensor to detect gravitational waves in the frequency range of 50-300 kHz using optically trapped and cooled dielectric microspheres or microdisks. The technique we describe can exceed the sensitivity of laser-based gravitational wave observatories in this frequency range, using an instrument of only a few percent of their size. Such a device extends the search volume for gravitational wave sources above 100 kHz by 1 to 3 orders of magnitude, and could detect monochromatic gravitational radiation from the annihilation of QCD axions in the cloud they form around stellar mass black holes within our galaxy due to the superradiance effect. PMID:25166367

  12. A remote fiber optic dosimeter network for detecting hydrazine vapor

    SciTech Connect

    Klimcak, C.; Radhakrishnan, G.; Jaduszliwer, B.

    1995-12-31

    A fiber optic chemical dosimeter has been developed for use in the remote detection of vapors of toxic amine rocket fuels (hydrazine and its substituted derivatives) that are used as Air Force and civilian launch sites. The dosimeter employs a colorimetric indicating reagent immobilized in a porous sol-gel cladding on multimode fiber. This reagent reacts selectively with the fuel vapor to produce a strongly absorbing cladding that introduces light propagation losses in the fiber; these losses indicate the presence of hydrazine (N{sub 2}H{sub 4}) vapor. The absorption occurs over a broad spectral range ideally suited for interrogation by semiconductor diode lasers. The authors have shown that the dosimeter yields an average hydrazine detectivity of 2.3 exposures of the dosimeter to laboratory air have not adversely affected the dosimeter. Additionally, its response to ammonia vapor has been determined to be 9,200 times smaller than its response to hydrazine vapor.

  13. A porous silicon optical microcavity for sensitive bacteria detection

    NASA Astrophysics Data System (ADS)

    Li, Sha; Huang, Jianfeng; Cai, Lintao

    2011-10-01

    A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (~10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml - 1 at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml - 1. The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

  14. UV LED fiber optic detection System for DNA and protein

    NASA Astrophysics Data System (ADS)

    Belz, Mathias; Klein, Felix A.; Habhegger, Heidi

    2007-02-01

    Concentrations of DNA and proteins are traditionally detected at 260/280nm using laboratory spectrophotometers. Recently, AlGaN/GaN ultraviolet Light Emitting Diodes (LED) became available in the 250 nm to 350 nm wavelength region. An inexpensive fiber optic detection system based on these UV LEDs and photodiodes has been developed. It allows concentration measurements of such popular biochemistry samples. Measurement stability and noise will be discussed. The performance of the system in comparison to a standard spectrophotometer will be evaluated. In particular, the effect of decreasing the spectral resolution from usually used 2-3 nm to 10-20 nm Full Width Half Maximum (FWHM) is simulated and experimentally confirmed.

  15. Amylin Detection with a Miniature Optical-Fiber Based Sensor

    NASA Astrophysics Data System (ADS)

    Liu, Zhaowen; Ann, Matsko; Hughes, Adam; Reeves, Mark

    We present results of a biosensor based on shifts in the localized surface plasmon resonance of gold nanoparticles self-assembled on the end of an optical fiber. This system allows for detection of protein expression in low sensing volumes and for scanning in cell cultures and tissue samples. Positive and negative controls were done using biotin/avidin and the BSA/Anti-BSA system. These demonstrate that detection is specific and sensitive to nanomolar levels. Sensing of amylin, an important protein for pancreatic function, was performed with polyclonal and monoclonal antibodies. The measured data demonstrates the difference in sensitivity to the two types of antibodies, and titration experiments establish the sensitivity of the sensor. Further experiments demonstrate that the sensor can be regenerated and then reused.

  16. Ultrasensitive detection of mode splitting in active optical microcavities

    SciTech Connect

    He, Lina; Oezdemir, Sahin Kaya; Zhu Jiangang; Yang Lan

    2010-11-15

    Scattering-induced mode splitting in active microcavities is demonstrated. Below the lasing threshold, quality factor enhancement by optical gain allows resolving, in the wavelength-scanning transmission spectrum, of resonance dips of the split modes which otherwise would not be detected in a passive resonator. In the lasing regime, mode splitting manifests itself as two lasing modes with extremely narrow linewidths. Mixing these lasing modes in a detector leads to a heterodyne beat signal whose frequency corresponds to the mode-splitting amount. Lasing regime not only allows ultra-high sensitivity for mode-splitting measurements but also provides an easily accessible scheme by eliminating the need for wavelength scanning around resonant modes. Mode splitting in active microcavities has an immediate impact in enhancing the sensitivity of subwavelength scatterer detection and in studying light-matter interactions in a strong-coupling regime.

  17. Detection alternatives for pulse position modulation (PPM) optical communication

    NASA Astrophysics Data System (ADS)

    Mecherle, G. Stephen

    1986-01-01

    An analysis is conducted for alternative optical communication detection strategies employing pulse position modulation (PPM). In cases without error correcting codes, the M-ary maximum count strategy is noted to furnish the best performance on the basis of its maximum a posteriori character. In cases with error correcting codes, the decoder has the additional option of hard or soft decisioning and each of the unencoded detection schemes can interface directly with a hard decision decoder. Illustrative hard decision coding gains are evaluated for M-ary Reed-Solomon and binary BCH codes with an APD receiver. The performance of rate-1/2 Reed-Solomon codes is compared for Delta-max and threshold soft decision strategies with an APD receiver.

  18. TiO2 optical sensor for amino acid detection

    NASA Astrophysics Data System (ADS)

    Tereshchenko, Alla; Viter, Roman; Konup, Igor; Ivanitsa, Volodymyr; Geveliuk, Sergey; Ishkov, Yuriy; Smyntyna, Valentyn

    2013-11-01

    A novel optical sensor based on TiO2 nanoparticles for Valine detection has been developed. In the presented work, commercial TiO2 nanoparticles (Sigma Aldrich, particle size 32 nm) were used as sensor templates. The sensitive layer was formed by a porphyrin coating on a TiO2 nanostructured surface. As a result, an amorphous layer between the TiO2 nanostructure and porphyrin was formed. Photoluminescence (PL) spectra were measured in the range of 370-900 nm before and after porphyrin application. Porphyrin adsorption led to a decrease of the main TiO2 peak at 510 nm and the emergence of an additional peak of high intensity at 700 nm. Absorption spectra (optical density vs. wavelenght, measured from 300 to 1100 nm) showed IR shift Sorret band of prophiryn after deposition on metal oxide. Adsorption of amino acid quenched PL emission, related to porphyrin and increased the intensity of the TiO2 emission. The interaction between the sensor surface and the amino acid leads to the formation of new complexes on the surface and results in a reduction of the optical activity of porphyrin. Sensitivity of the sensor to different concentrations of Valine was calculated. The developed sensor can determine the concentration of Valine in the range of 0.04 to 0.16 mg/ml.

  19. Optical Cluster Detection in the Post-SDSS Era

    NASA Astrophysics Data System (ADS)

    Koester, Benjamin

    2011-01-01

    Near the conclusion of the first Sloan Digital Sky Survey, the development of optical cluster detection algorithms, quantification of their selection functions, and mass and redshift calibration hit full swing. Catalogs typically include thousands of massive (>1x1014 Msun) clusters reaching z 0.5, with selection functions that are routinely calibrated with realistic mock galaxy simulations, and cluster mass proxies that are cross-calibrated against X-ray, weak-lensing, dynamical, and SZ observations. All of this is folded into analyses that offer cosmological constraints competitive with catalogs created at other wavelengths. In this talk, these developments are reviewed from the perspective of the MaxBCG cluster catalog. The lessons learned from optical cluster-finding efforts are then turned to the next generation of optical/NIR surveys soon to come online, using the Dark Energy Survey (DES) as an example. In DES, this past experience guides the coordination of vast resources that will culminate in well-understood cluster catalogs specifically tailored to cosmological applications reaching z 1.

  20. Breast cancer detection using phase contrast diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Liang, Xiaoping; Zhang, Qizhi; Li, Changqing; Grobmyer, Stephen R.; Fajardo, Laurie L.; Jiang, Huabei

    2007-02-01

    In this report, a phase-contrast diffuse optical tomography system, which can measure the refractive indices of human breast masses in vivo, is described. To investigate the utility of phase-contrast diffuse optical tomography (PCDOT) for differentiation of malignant and benign breast masses in humans, and to compare PCDOT with conventional diffuse optical tomography (DOT) for analysis of breast masses in humans. 35 breast masses were imaged in 33 patients (mean age = 51 years; range 22-80 years) using PCDOT. Images characterizing the tissue refractive index, absorption and scattering of breast masses were obtained with a finite element-based reconstruction algorithm. The accuracies of absorption and scattering images were compared with images of refractive index in light of the pathology results. Absorption and scattering images were unable to accurately discriminate benign from malignant lesions. Malignant lesions tended to have decreased refractive index allowing them to discriminate from benign lesions in most cases. The sensitivity, specificity, false positive value, and overall accuracy for refractive index were 81.8%, 70.8%, 29.2%, and 74.3%, respectively. Overall we show that benign and malignant breast masses in humans demonstrate different refractive index and differences in refractive index properties can be used to discriminate benign from malignant masses in patients with high accuracy. This opens up a new avenue for improved breast cancer detection using NIR diffusing light.

  1. Fiber optic confocal microscope: In vivo precancer detection

    NASA Astrophysics Data System (ADS)

    Carlson, Kristen Dawn

    Cancer is a significant public health problem worldwide. Many cancers originate as precancerous lesions in the epithelium which, when removed in sufficient time, can prevent progression to cancer. However, current detection techniques are typically time-consuming and expensive, limiting their acceptance and accessibility. Optical techniques, such as confocal microscopy, have significant potential to provide clinicians with real-time, high-resolution images of cells and tissue without tissue removal. These images of cell morphology and tissue architecture can be used to characterize tissue and determine the presence or extent of precancer and cancer. This dissertation explores the instrumentation and application of fiber optic reflectance confocal microscopy for in vivo precancer detection. The first part of the dissertation presents in vivo imaging of suspicious lesions in the human uterine cervix and oral mucosa using a fiber bundle based confocal microscope with a complex glass miniature objective lens. Images are analyzed quantitatively and qualitatively to determine the potential of this technology in vivo. An analysis of nuclear density from images of 30 cervical epithelium sites shows differentiation between normal and precancerous sites. Similarly, images from 20 oral mucosa sites demonstrate changes in nuclear density and tissue architecture indicative of progression of precancer and cancer. In addition to this multi-fiber confocal microscope used with a glass objective lens for the clinical studies, imaging of tissue samples has been accomplished with the same confocal system using an injection molded plastic miniature objective lens demonstrating comparable optical quality for a significantly less expensive optical component. Finally, a benchtop prototype of a single fiber confocal microscope using a gimbaled two-axis MEMS scanner has been designed and constructed. Imaging of a resolution target and cellular samples demonstrates sufficient resolution and

  2. Optical techniques for millimeter-wave detection and imaging

    NASA Astrophysics Data System (ADS)

    Schuetz, Christopher Arnim

    The benefits of imaging using regions of the electromagnetic spectrum outside the visible range have been known for decades. Infrared and radio frequency imaging techniques have achieved great successes in both military and civilian applications. However, there remains a range of the spectrum between these two regimes that remains relatively unexplored. Millimeter waves, or the range of wavelengths between one millimeter and one centimeter, have remained relatively unexplored as an imaging technology, largely due to the lack of sufficiently sensitive, practical detectors for passive imaging in this regime. At these short wavelengths, the diffraction limit imposed by the limited extent of the imaging aperture significantly limits attainable image resolution. Recent developments in semiconductor low-noise amplifiers have demonstrated many desirable applications for such imaging technology, but have, as yet, not been able to demonstrate the economical, small-format imagers necessary to make such imagers practical in most of the conceived applications. In this regard, I present a new approach to millimeter-wave detection based on optical modulation with subsequent carrier suppression. This approach demonstrates promise in achieving the goal of economical, high-resolution imagers with sufficient sensitivity for passive millimeter-wave imaging. In this thesis, I explain the operational requirements of such detectors, provide theoretical background for their operation, and describe current experimental results obtained using commercially available components in the 35 GHz. In addition, I describe successful efforts to fabricate modulators with improved modulation bandwidths for detection in the 95 GHz atmospheric window. These demonstration systems have attained sufficient single pixel performance to detect thermal emission with a noise equivalent temperature difference (NETD) approaching 1K/ Hz at both 35 and 95 GHz. The NETDs attained correspond to sub-picowatt noise

  3. Pressure and Temperature Spin Crossover Sensors with Optical Detection

    PubMed Central

    Linares, Jorge; Codjovi, Epiphane; Garcia, Yann

    2012-01-01

    Iron(II) spin crossover molecular materials are made of coordination centres switchable between two states by temperature, pressure or a visible light irradiation. The relevant macroscopic parameter which monitors the magnetic state of a given solid is the high-spin (HS) fraction denoted nHS, i.e., the relative population of HS molecules. Each spin crossover material is distinguished by a transition temperature T1/2 where 50% of active molecules have switched to the low-spin (LS) state. In strongly interacting systems, the thermal spin switching occurs abruptly at T1/2. Applying pressure induces a shift from HS to LS states, which is the direct consequence of the lower volume for the LS molecule. Each material has thus a well defined pressure value P1/2. In both cases the spin state change is easily detectable by optical means thanks to a thermo/piezochromic effect that is often encountered in these materials. In this contribution, we discuss potential use of spin crossover molecular materials as temperature and pressure sensors with optical detection. The ones presenting smooth transitions behaviour, which have not been seriously considered for any application, are spotlighted as potential sensors which should stimulate a large interest on this well investigated class of materials. PMID:22666041

  4. A dual-detector optical receiver for PDM signals detection

    NASA Astrophysics Data System (ADS)

    Chen, Guanyu; Yu, Yu; Zhang, Xinliang

    2016-05-01

    We propose and fabricate a silicon based dual-detector optical receiver, which consists of a two dimensional (2D) grating coupler (GC) and two separate germanium photodetectors (Ge PDs). The 2D GC performs polarization diversity, and thus demultiplexing and detection for polarization division multiplexed (PDM) signals can be achieved. Through a specific design with double-sides illumination, the space charge density can be reduced and the responsivity and saturation power can be improved significantly. The measured dark current, responsivity and bandwidth are 0.86 μA, 1.06 A/W and 36 GHz under 3 V reverse biased voltage, respectively. Both DC currents and eye diagrams are measured for the proposed device and the results validate its performance successfully. The power penalty between the single and dual polarized signals is about 1.9 dB under 10 and 20 Gb/s cases for both the two Ge PDs. The proposed direct detection (DD) for PDM signals with high speed, high responsivity and large saturation power is cost-effective and promising for short reach optical communication.

  5. A dual-detector optical receiver for PDM signals detection

    PubMed Central

    Chen, Guanyu; Yu, Yu; Zhang, Xinliang

    2016-01-01

    We propose and fabricate a silicon based dual-detector optical receiver, which consists of a two dimensional (2D) grating coupler (GC) and two separate germanium photodetectors (Ge PDs). The 2D GC performs polarization diversity, and thus demultiplexing and detection for polarization division multiplexed (PDM) signals can be achieved. Through a specific design with double-sides illumination, the space charge density can be reduced and the responsivity and saturation power can be improved significantly. The measured dark current, responsivity and bandwidth are 0.86 μA, 1.06 A/W and 36 GHz under 3 V reverse biased voltage, respectively. Both DC currents and eye diagrams are measured for the proposed device and the results validate its performance successfully. The power penalty between the single and dual polarized signals is about 1.9 dB under 10 and 20 Gb/s cases for both the two Ge PDs. The proposed direct detection (DD) for PDM signals with high speed, high responsivity and large saturation power is cost-effective and promising for short reach optical communication. PMID:27198501

  6. Organic vapor detection with fiber optic bead arrays

    NASA Astrophysics Data System (ADS)

    Stitzel, Shannon E.; Albert, Keith J.; Walt, David R.

    1999-12-01

    The need for small, fast responding detection systems is growing and fiber-optic bead arrays offer a different approach to small sensor design. Sensor arrays are fabricated by inserting self-encoded microspheres into microwells etched into the distal face of an imaging fiber. Each imaging fiber is 0.5 - 1 mm in outer diameter and consists of 5,000 - 10,000 individually clad, 3 - 4 micrometers diameter optical fibers bundled together. The bundles are coherent, allowing each microsphere in a well to be addressed as an individual sensor. Microsphere sensors are silica or polymer beads (approximately 3 micrometers in diameter) impregnated with solvatochromic dyes. These dyes alter their fluorescence emission spectra in response to changes in vapor polarity, allowing analytes to be discriminated based on their signature fluorescence response over time. A computational network is trained to recognize these response patterns for each sensor type, allowing for identification of specific organic vapors. Each sensor type is cross- reactive, and has unique fluorescence response patterns to different analytes. The sensor types can be identified based on their unique responses, allowing their position to be registered by observing the identity of the response pattern toward a known standard. Such encoding enables array fabrication to be simplified since sensors can be randomly dispersed throughout the array, instead of specifically patterned within the array. Possible applications for bead array detectors include environmental and industrial monitoring, land mine detection, and medical diagnostics.

  7. Single-target molecule detection with nonbleaching multicolor optical immunolabels.

    PubMed

    Schultz, S; Smith, D R; Mock, J J; Schultz, D A

    2000-02-01

    We introduce and demonstrate the use of colloidal silver plasmon-resonant particles (PRPs) as optical reporters in typical biological assays. PRPs are ultrabright, nanosized optical scatterers, which scatter light elastically and can be prepared with a scattering peak at any color in the visible spectrum. PRPs are readily observed individually with a microscope configured for dark-field microscopy, with white-light illumination of typical power. Here we illustrate the use of PRPs, surface coated with standard ligands, as target-specific labels in an in situ hybridization and an immunocytology assay. We propose that PRPs can replace or complement established labels, such as those based on radioactivity, fluorescence, chemiluminescence, or enzymatic/colorimetric detection that are used routinely in biochemistry, cell biology, and medical diagnostic applications. Moreover, because PRP labels are nonbleaching and bright enough to be rapidly identified and counted, an ultrasensitive assay format based on single-target molecule detection is now practical. We also present the results of a model sandwich immunoassay for goat anti-biotin antibody, in which the number of PRP labels counted in an image constitutes the measured signal. PMID:10655473

  8. A dual-detector optical receiver for PDM signals detection.

    PubMed

    Chen, Guanyu; Yu, Yu; Zhang, Xinliang

    2016-01-01

    We propose and fabricate a silicon based dual-detector optical receiver, which consists of a two dimensional (2D) grating coupler (GC) and two separate germanium photodetectors (Ge PDs). The 2D GC performs polarization diversity, and thus demultiplexing and detection for polarization division multiplexed (PDM) signals can be achieved. Through a specific design with double-sides illumination, the space charge density can be reduced and the responsivity and saturation power can be improved significantly. The measured dark current, responsivity and bandwidth are 0.86 μA, 1.06 A/W and 36 GHz under 3 V reverse biased voltage, respectively. Both DC currents and eye diagrams are measured for the proposed device and the results validate its performance successfully. The power penalty between the single and dual polarized signals is about 1.9 dB under 10 and 20 Gb/s cases for both the two Ge PDs. The proposed direct detection (DD) for PDM signals with high speed, high responsivity and large saturation power is cost-effective and promising for short reach optical communication. PMID:27198501

  9. Optical beamforming networks employing phase modulation and direct detection

    NASA Astrophysics Data System (ADS)

    Xue, Xiaoxiao; Zheng, Xiaoping; Zhang, Hanyi; Zhou, Bingkun

    2011-06-01

    We propose a novel dispersion-based optical beamforming network scheme employing phase modulation and direct detection. Optical phase modulators have the advantages of simple-structure, low loss and absence of bias. Dispersion-induced phase-to-intensity conversion is utilized to facilitate direct detection. A structure of wideband dispersive device (WDD) cascaded with periodic dispersive device (PDD) is introduced to enhance the system flexibility, so that the delay adjustability and RF response can be properly designed respectively by choosing appropriate dispersions of the WDD and PDD. A concept-proof system with a wideband chirped fiber grating (CFG) as the WDD and two multiband CFGs (MCFG1 and MCFG2) as the PDD separately is built to demonstrate the basic idea. The delay tuning range is 0-1.8 ns with increment of 164.2 ps. The passband center is 30 GHz for MCFG1 and 20 GHz for MCFG2, and the fractional bandwidth is 51.8%. The shot-noise-limited spurious-free dynamic range is also analyzed and measured to be 105.7 dB ṡ Hz2/3 when the average photocurrent is 2.7 mA.

  10. Design and study on optic fiber sensor detection system

    NASA Astrophysics Data System (ADS)

    Jiang, Xuemei; Liu, Quan; Liang, Xiaoyu; Lin, Haiyan

    2005-11-01

    With the development of industry and agriculture, the environmental pollution becomes more and more serious. Various kinds of poisonous gas are the important pollution sources. Various kinds of poisonous gas, such as the carbon monoxide, sulfureted hydrogen, sulfur dioxide, methane, acetylene are threatening human normal life and production seriously especially today when industry and various kinds of manufacturing industries develop at full speed. The acetylene is a kind of gas with very lively chemical property, extremely apt to burn, resolve and explode, and it is great to destroy things among these poisonous gases. Comparing with other inflammable and explosive gas, the explosion range of the acetylene is heavier. Therefore carrying on monitoring acetylene pollution sources scene in real time, grasping the state of pollution taking place and development in time, have very important meanings. Aim at the above problems, a set of optical fiber detection system of acetylene gas based on the characteristic of spectrum absorption of acetylene is presented in this paper, which has reference channel and is for on-line and real-time detection. In order to eliminate the effect of other factors on measurement precision, the double light sources, double light paths and double cells are used in this system. Because of the use of double wavelength compensating method, this system can eliminate the disturbance in the optical paths, the problem of instability is solved and the measurement precision is greatly enhanced. Some experimental results are presented at the end of this paper.

  11. Optical weed detection and evaluation using reflection measurements

    NASA Astrophysics Data System (ADS)

    Vrindts, Els; De Baerdemaeker, Josse

    1999-01-01

    For the site-specific application of herbicides, the automatic detection and evaluation of weeds is necessary. Since reflectance of crop, weeds and soil differs in visual and near IR wavelengths, there is a potential for using reflection measurements at different wavelengths to distinguish between them. Diffuse reflectance spectra of crop and weed leaves were used to evaluate the possibilities of weed detection with reflection measurements. Fourteen different weed species and four crops were included in the dataset. Classification of the spectra in crop, weeds and soil is possible, based on 3 to 7 narrow wavelength bands. The spectral analysis was repeated for reflectance measurements of canopies. Sugarbeet and Maize and 7 weed species were included in the measurements. The classification into crop and weeds was still possible, suing a limited number of wavelength band ratios. This suggest that reflection measurements at a limited number of wavelength bands could be used to detect and treat weeds in a field. This is a great environmental benefit, as agrochemicals will only be used where they are needed. The possibilities of using optical reflectance for weed detection and treatment in the field are discussed.

  12. Configuration of electro-optic fire source detection system

    NASA Astrophysics Data System (ADS)

    Fabian, Ram Z.; Steiner, Zeev; Hofman, Nir

    2007-04-01

    The recent fighting activities in various parts of the world have highlighted the need for accurate fire source detection on one hand and fast "sensor to shooter cycle" capabilities on the other. Both needs can be met by the SPOTLITE system which dramatically enhances the capability to rapidly engage hostile fire source with a minimum of casualties to friendly force and to innocent bystanders. Modular system design enable to meet each customer specific requirements and enable excellent future growth and upgrade potential. The design and built of a fire source detection system is governed by sets of requirements issued by the operators. This can be translated into the following design criteria: I) Long range, fast and accurate fire source detection capability. II) Different threat detection and classification capability. III) Threat investigation capability. IV) Fire source data distribution capability (Location, direction, video image, voice). V) Men portability. ) In order to meet these design criteria, an optimized concept was presented and exercised for the SPOTLITE system. Three major modular components were defined: I) Electro Optical Unit -Including FLIR camera, CCD camera, Laser Range Finder and Marker II) Electronic Unit -including system computer and electronic. III) Controller Station Unit - Including the HMI of the system. This article discusses the system's components definition and optimization processes, and also show how SPOTLITE designers successfully managed to introduce excellent solutions for other system parameters.

  13. Optical Monitoring and Detection of Spinal Cord Ischemia

    PubMed Central

    Mesquita, Rickson C.; D’Souza, Angela; Bilfinger, Thomas V.; Galler, Robert M.; Emanuel, Asher; Schenkel, Steven S.; Yodh, Arjun G.; Floyd, Thomas F.

    2013-01-01

    Spinal cord ischemia can lead to paralysis or paraparesis, but if detected early it may be amenable to treatment. Current methods use evoked potentials for detection of spinal cord ischemia, a decades old technology whose warning signs are indirect and significantly delayed from the onset of ischemia. Here we introduce and demonstrate a prototype fiber optic device that directly measures spinal cord blood flow and oxygenation. This technical advance in neurological monitoring promises a new standard of care for detection of spinal cord ischemia and the opportunity for early intervention. We demonstrate the probe in an adult Dorset sheep model. Both open and percutaneous approaches were evaluated during pharmacologic, physiological, and mechanical interventions designed to induce variations in spinal cord blood flow and oxygenation. The induced variations were rapidly and reproducibly detected, demonstrating direct measurement of spinal cord ischemia in real-time. In the future, this form of hemodynamic spinal cord diagnosis could significantly improve monitoring and management in a broad range of patients, including those undergoing thoracic and abdominal aortic revascularization, spine stabilization procedures for scoliosis and trauma, spinal cord tumor resection, and those requiring management of spinal cord injury in intensive care settings. PMID:24358279

  14. Liquid crystals as optical amplifiers for bacterial detection.

    PubMed

    Zafiu, C; Hussain, Z; Küpcü, S; Masutani, A; Kilickiran, P; Sinner, E-K

    2016-06-15

    Interactions of bacteria with target molecules (e.g. antibiotics) or other microorganisms are of growing interest. The first barrier for targeting gram-negative bacteria is layer of a Lipopolysaccharides (LPS). Liquid crystal (LC) based sensors covered with LPS monolayers, as presented in this study, offer a simple model to study and make use of this type of interface for detection and screening. This work describes in detail the production and application of such sensors based on three different LPS that have been investigated regarding their potential to serve as sensing layer to detect bacteria. The LPS O127:B8 in combination with a LC based sensor was identified to be most useful as biomimetic sensing surface. This LPS/LC combination interacts with three different bacteria species, one gram-positive and two gram-negative species, allowing the detection of bacterial presence regardless from their viability. It could be shown that even very low bacterial cell numbers (minimum 500 cell ml(-1)) could be detected within minutes (maximum 15 min). The readout mechanism is the adsorption of bacterial entities on surface bond LPS molecules with the LC serving as an optical amplifier. PMID:26827146

  15. Fiber optic system design for vehicle detection and analysis

    NASA Astrophysics Data System (ADS)

    Nedoma, Jan; Zboril, Ondrej; Fajkus, Marcel; Zavodny, Petr; Kepak, Stanislav; Bednarek, Lukas; Martinek, Radek; Vasinek, Vladimir

    2016-04-01

    Fiber optic interferometers belong to a group of highly sensitive and precise devices enabling to measure small changes in the deformation shapes, changes in pressure, temperature, vibration and so on. The basis of their activity is to evaluate the number of fringes over time, not changes in the intensity of the optical signal. The methodology described in the article is based on using the interferometer to monitor traffic density. The base of the solution is a Mach-Zehnder interferometer operating with single-mode G.652 optical fiber at the wavelength of 1550 nm excited by a DFB laser. The power distribution of the laser light into the individual arms of the interferometer is in the ratio 1:1. Realized measuring scheme was terminated by an optical receiver including InGaAs PIN photodiode. Registered signal from the photodetector was through 8 Hz high pass filter fed to the measuring card that captures the analog input voltage using an application written in LabView development environment. The interferometer was stored in a waterproof box and placed at the side of the road. Here panned individual transit of cars in his environs. Vertically across the road was placed in contact removable belt simulating a retarder, which was used when passing cars to create sufficient vibration response detecting interferometer. The results demonstrated that the individual vehicles passing around boxing showed characteristic amplitude spectra, which was unique for each object, and had sufficient value signal to noise ratio (SNR). The signal was processed by applications developed for the amplitude-frequency spectrum. Evaluated was the maximum amplitude of the signal and compared to the noise. The results were verified by repeated transit of the different types of cars.

  16. Detection of plasmonic nanoparticles with full field-OCT: optical and photothermal detection

    PubMed Central

    Nahas, Amir; Varna, Mariana; Fort, Emmanuel; Boccara, A. Claude

    2014-01-01

    Detecting the signal backscattered by nanoparticles immersed in highly scattering media such as biological tissue remains a challenge. In this article we report on the use of Full Field OCT (FF-OCT) to slice in depth in phantoms and in tissues in order a) to selectively observe the particles through the backscattered light at suitable wavelengths, and b) to detect the effects of the time-dependent response to full field optical heating through the strong absorption cross-section of these plasmonic nanoparticles. The analysis of the thermal wave behavior leads to the localization of the heat sources even when FF-OCT signals cannot reach the heated area. PMID:25360370

  17. Optical system and method for gas detection and monitoring

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A. (Inventor); Korman, Valentin (Inventor); Witherow, William K. (Inventor); Hendrickson, Adam Gail (Inventor); Sinko, John Elihu (Inventor)

    2011-01-01

    A free-space optical path of an optical interferometer is disposed in an environment of interest. A light beam is guided to the optical interferometer using a single-mode optical fiber. The light beam traverses the interferometer's optical path. The light beam guided to the optical path is combined with the light beam at the end of the optical path to define an output light. A temporal history of the output light is recorded.

  18. Streak detection and analysis pipeline for optical images

    NASA Astrophysics Data System (ADS)

    Virtanen, J.; Granvik, M.; Torppa, J.; Muinonen, K.; Poikonen, J.; Lehti, J.; Säntti, T.; Komulainen, T.; Flohrer, T.

    2014-07-01

    We describe a novel data processing and analysis pipeline for optical observations of moving objects, either of natural (asteroids, meteors) or artificial origin (satellites, space debris). The monitoring of the space object populations requires reliable acquisition of observational data to support the development and validation of population models, and to build and maintain catalogues of orbital elements. The orbital catalogues are, in turn, needed for the assessment of close approaches (for asteroids, with the Earth; for satellites, with each other) and for the support of contingency situations or launches. For both types of populations, there is also increasing interest to detect fainter objects corresponding to the small end of the size distribution. We focus on the low signal-to-noise (SNR) detection of objects with high angular velocities, resulting in long and faint object trails, or streaks, in the optical images. The currently available, mature image processing algorithms for detection and astrometric reduction of optical data cover objects that cross the sensor field-of-view comparably slowly, and, particularly for satellites, within a rather narrow, predefined range of angular velocities. By applying specific tracking techniques, the objects appear point-like or as short trails in the exposures. However, the general survey scenario is always a 'track-before-detect' problem, resulting in streaks of arbitrary lengths. Although some considerations for low-SNR processing of streak-like features are available in the current image processing and computer vision literature, algorithms are not readily available yet. In the ESA-funded StreakDet (Streak detection and astrometric reduction) project, we develop and evaluate an automated processing pipeline applicable to single images (as compared to consecutive frames of the same field) obtained with any observing scenario, including space-based surveys and both low- and high-altitude populations. The algorithmic

  19. Research on fiber-optic sensors for methane detection based on Harmonic detection

    NASA Astrophysics Data System (ADS)

    Wang, Shutao; Huang, Liang; Zhou, Zhishuang; Zhu, Zhihui

    2010-10-01

    In this paper, a sylstem of fiber-optic gas sensor based methane absorption spectra is studied. The system have made great improvement and in-depth analysis in methane spectral absorption,a weak optical signal extraction and processing and gas measurement accuracy.The system consists of light source, Photonic Crystal Fiber, air chamber, photoelectric detectors and signal processing components and so on. According to the Lambert-Beer law, spectrum absorption intensity is closely relate with the concentration of the gas. In order to ensure the system at a high resolution and sensitivity,The system used distributed feedback semiconductor laser (DFBLD) as a light source .It bring useful information of the optical signal to PIN Photodetector which then convert the optical signal to electrical signals after optical interacting with the methane gas,then send the electrical signal to lock-in amplifier.the harmonic detection of gas concentration was achieved by the light modulator, And then compared the harmonic component. Finally, the signal expected was produced through the A / D converter digital in the computer.

  20. Optical detection of sepsis markers using liquid crystal based biosensors

    NASA Astrophysics Data System (ADS)

    McCamley, Maureen K.; Artenstein, Andrew W.; Opal, Steven M.; Crawford, Gregory P.

    2007-02-01

    A liquid crystal based biosensor for the detection and diagnosis of sepsis is currently in development. Sepsis, a major clinical syndrome with a significant public health burden in the US due to a large elderly population, is the systemic response of the body to a localized infection and is defined as the combination of pathologic infection and physiological changes. Bacterial infections are responsible for 90% of cases of sepsis in the US. Currently there is no bedside diagnostic available to positively identify sepsis. The basic detection scheme employed in a liquid crystal biosensor contains attributes that would find value in a clinical setting, especially for the early detection of sepsis. Utilizing the unique properties of liquid crystals, such as birefringence, a bedside diagnostic is in development which will optically report the presence of biomolecules. In a septic patient, an endotoxin known as lipopolysaccharide (LPS) is released from the outer membrane of Gram-negative bacteria and can be found in the blood stream. It is hypothesized that this long chained molecule will cause local disruptions to the open surface of a sensor containing aligned liquid crystal. The bulk liquid crystal ampli.es these local changes at the surface due to the presence of the sepsis marker, providing an optical readout through polarizing microscopy images. Liquid crystal sensors consisting of both square and circular grids, 100-200 μm in size, have been fabricated and filled with a common liquid crystal material, 5CB. Homeotropic alignment was confirmed using polarizing microscopy. The grids were then contacted with either saline only (control), or saline with varying concentrations of LPS. Changes in the con.guration of the nematic director of the liquid crystal were observed through the range of concentrations tested (5mg/mL - 1pg/mL) which have been confirmed by a consulting physician as clinically relevant levels.

  1. Damage detection and characterization using fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Glisic, Branko; Sigurdardottir, Dorotea; Yao, Yao; Hubbell, David

    2013-04-01

    Fiber optic sensors (FOS) have significantly evolved and have reached their market maturity during the last decade. Their widely recognized advantages are high precision, long-term stability, and durability. But in addition to these advantageous performances, FOS technologies allow for affordable instrumentation of large areas of structure enabling global large-scale monitoring based on long-gauge sensors and integrity monitoring based on distributed sensors. These two approaches are particularly suitable for damage detection and characterization, i.e., damage localization and to certain extent quantification and propagation, as illustrated by two applications presented in detail in this paper: post-tensioned concrete bridge and segmented concrete pipeline. Early age cracking was detected, localized and quantified in the concrete deck of a pedestrian bridge using embedded long-gauge FOS. Post-tensioning of deck closed the cracks; however, permanent weakening in a bridge joint occurred due to cracking and it was identified and quantified. The damage was confirmed using embedded distributed FOS and a separate load test of the bridge. Real-size concrete pipeline specimens and surrounding soil were equipped with distributed FOS and exposed to permanent ground displacement in a large-scale testing facility. Two tests were performed on different pipeline specimens. The sensors bonded on the pipeline specimens successfully detected and localized rupture of pipeline joints, while the sensors embedded in the soil were able to detect and localize the failure plane. Comparison with strain-gauges installed on the pipeline and visual inspection after the test confirmed accurate damage detection and characterization.

  2. Passive radiation detection using optically active CMOS sensors

    NASA Astrophysics Data System (ADS)

    Dosiek, Luke; Schalk, Patrick D.

    2013-05-01

    Recently, there have been a number of small-scale and hobbyist successes in employing commodity CMOS-based camera sensors for radiation detection. For example, several smartphone applications initially developed for use in areas near the Fukushima nuclear disaster are capable of detecting radiation using a cell phone camera, provided opaque tape is placed over the lens. In all current useful implementations, it is required that the sensor not be exposed to visible light. We seek to build a system that does not have this restriction. While building such a system would require sophisticated signal processing, it would nevertheless provide great benefits. In addition to fulfilling their primary function of image capture, cameras would also be able to detect unknown radiation sources even when the danger is considered to be low or non-existent. By experimentally profiling the image artifacts generated by gamma ray and β particle impacts, algorithms are developed to identify the unique features of radiation exposure, while discarding optical interaction and thermal noise effects. Preliminary results focus on achieving this goal in a laboratory setting, without regard to integration time or computational complexity. However, future work will seek to address these additional issues.

  3. Detection of early seizures by diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Hajihashemi, M. Reza; Zhou, Junli; Carney, Paul R.; Jiang, Huabei

    2015-03-01

    In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Besides, preclinical seizure experiments need to be conducted in awake animals with images reconstructed and displayed in real-time. We demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking brain activities with high spatiotemporal resolution. We developed methods to conduct seizure experiments in fully awake rats using a subject-specific helmet and a restraining mechanism. For the first time, we detected early hemodynamic responses with heterogeneous patterns several minutes preceding the electroencephalographic seizure onset, supporting the presence of a "pre-seizure" state both in anesthetized and awake rats. Using a novel time-series analysis of scattering images, we show that the analysis of scattered diffuse light is a sensitive and reliable modality for detecting changes in neural activity associated with generalized seizure. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways.

  4. Detection of atherosclerotic vascular tissue from optical coherence tomography images

    NASA Astrophysics Data System (ADS)

    Prakash, Ammu; Hewko, Mark; Sowa, Mike; Sherif, Sherif

    2012-10-01

    Atherosclerotic coronary artery disease continues to be one of the major causes of mortality. Prevention, diagnosis and treatment of atherosclerotic coronary artery disease are dependent on the detection of high risk atherosclerotic plaque. As age is one of the most important risk factors, atherosclerosis worsens steadily with increasing age. Automatic characterization of atherosclerotic plaque using the optical coherence tomography (OCT) images provides a powerful tool to classify patients with high risk plaque. In this study we develop an automatic classifier to detect atherosclerotic plaque in young and old Watanabe heritable hyperlipidemic (WHHL) rabbits, using OCT images without reliance on visual inspection. Our classifier based on texture analysis technique may provide an efficient tool for detecting invisible changes in tissue structure. We extracted a set of 22 statistical textural features for each image using the spatial gray level dependence matrix (SGLDM) method. An optimal scalar feature selection process was carried to select the best discriminating features that employ the Fisher discriminant ratio (FDR) criterion, and cross correlation measure between the pairs of features. Using these optimal features, we formed a combination of 5 best classification features using an exhaustive search method. A combined feature set was finally employed for the classification of plaque. We obtained correct classification rate and validation of 76.67% and 75% respectively.

  5. Noninvasive detection of plant nutrient stress using fiber optic spectrophotometry

    NASA Astrophysics Data System (ADS)

    Chen, Jun-Wei; Asundi, Anand K.; Liew, Oi Wah; Boey, William S. L.

    2001-05-01

    In a previous paper, we described the use of fiber optic spectrophotometry as a non-destructive and sensitive method to detect early symptoms of plant nutrient deficiency. We report further developments of our work on Brassica chinensis var parachinensis (Bailey) showing reproducibility of our data collected at a different seasonal period. Plants at the mid-log growth phase were subjected to nutrient stress by transferring them to nitrate- and calcium- deficient nutrient solution in a standing aerated hydroponic system. After tracking changes in leaf reflectance by FOSpectr for nine days, the plants were returned to complete nutrient solution and their recovery was monitored for a further nine days. The responses of nutrient stressed plants were compared with those grown under complete nutrient solution over the 18-day trial period. We also compared the sensitivity of FOSpectr detection against plant growth measurements vis-a-vis average leaf number and leaf width and show that the former method gave an indication of nutrient stress much earlier than the latter. In addition, this work indicated that while normal and nutrient-stressed plants could not be distinguished within the first 7 days by tracking plant growth indicators, stressed plants did show a clear decline in average leaf number and leaf width in later stages of growth even after the plants were returned to complete nutrient solution. The results further reinforce the need for early detection of nutrient stress, as late remedial action could not reverse the loss in plant growth in later stages of plant development.

  6. A portable cell-based optical detection device for rapid detection of Listeria and Bacillus toxins

    NASA Astrophysics Data System (ADS)

    Banerjee, Pratik; Banada, Padmapriya P.; Rickus, Jenna L.; Morgan, Mark T.; Bhunia, Arun K.

    2005-11-01

    A mammalian cell-based optical biosensor was built to detect pathogenic Listeria and Bacillus species. This sensor measures the ability of the pathogens to infect and induce cytotoxicity on hybrid lymphocyte cell line (Ped-2E9) resulting in the release of alkaline phosphatase (ALP) that can be detected optically using a portable spectrophotometer. The Ped-2E9 cells were encapsulated in collagen gel matrices and grown in 48-well plates or in specially designed filtration tube units. Toxin preparations or bacterial cells were introduced and ALP release was assayed after 3-5 h. Pathogenic L. monocytogenes strains or the listeriolysin toxins preparation showed cytotoxicity ranging from 55% - 92%. Toxin preparations (~20 μg/ml) from B. cereus strains showed 24 - 98% cytotoxicity. In contrast, a non-pathogenic L. innocua (F4247) and a B. substilis induced only 2% and 8% cytotoxicity, respectively. This cell-based detection device demonstrates its ability to detect the presence of pathogenic Listeria and Bacillus species and can potentially be used onsite for food safety or in biosecurity application.

  7. Detection of crevice corrosion of metallic alloys by optical interferometry

    SciTech Connect

    Habib, K.

    1999-11-01

    In the present investigation, an optical corrosion-meter has been developed for materials testing and evaluation of different corrosion phenomena. The idea of the optical corrosion-meter was established based on principles of 3D-holographic interferometry for measuring microsurface dissolution, i.e. mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e. corrosion current of metallic samples in aqueous solutions. In the present work, an early stage of crevice corrosion of a titanium alloy, a carbon steel and a pure aluminum in seawater was monitored in situ by the optical corrosion-meter during the cyclic polarization test. The observations of crevice corrosion were basically interferometric perturbations detected only on the surface of the titanium alloy and the carbon steel underneath a crevice assembly, made of Teflon bolt, Teflon nut, and Teflon washer. The crevice assembly used on all tested samples to create a differential aeration cell between the surface of the sample and areas underneath the crevice assembly in seawater. Each Teflon washer contained radial grooves and had 20 plateaus which formed crevices ( shield areas) when pressed against the surface of the sample. The interferometric perturbations interpreted as a localized corrosion in a form of an early crevice corrosion of a depth ranged between 0.3 pm to several micrometers. Consequently, results of the present work indicate that holographic interferometry is very useful technique as a 3D-interferometric microscope for monitoring crevice corrosion at the initiation stage of the phenomenon for different metallic samples in aqueous solutions.

  8. Super Smooth Optics for Extra-Solar Planet Detection

    NASA Technical Reports Server (NTRS)

    Terrile, Richard J.; Ftaclas, Christ

    1989-01-01

    The goal of imaging planets around the nearby stars has important scientific significance but requires the use of advanced methods of controlling diffracted and scattered light. Over the last three years we have undertaken a study of coronagraphic methods of controlling diffracted light and of figuring hyper-contrast optics. Progress in these two general areas have led to a proposed space-based, 1.9 meter diameter coronagraphic telescope designed specifically for very high performance in the imaging of faint objects near bright sources. This instrument, called the Circumstellar Imaging Telescope (CIT), relies on a new high efficiency coronagraph design and the careful control of scattered light by extremely smooth optics. The high efficiency coronagraph uses focal plane apodization in order to concentrate diffracted light more efficiently in the pupil. This allows convenient removal of the diffracted light by masking off parts of the telescope pupil while not sacrificing the center of the field. Reductions of diffracted light by factors exceeding 1000 are not only possible but are required in order to detect extra-solar planets. Laboratory experiments with this new design have confirmed the theoretical diffraction reductions to the limits of the optics used (factors of about 300) . The extremely high efficiency of this coronagraph puts strong constraints on the narrow angle scattered light due to figure errors in the telescope mirror. Since planets orbiting nearby stars are expected at angular distances of about 1 arcsecond, it is in this small angular range in which scattering must be controlled. The figure errors responsible for scattering in this range come from mid-spatial frequencies corresponding to correlation lengths of about 10 cm on the primary mirror. A primary mirror about 15 times smoother than the Hubble Space Telescope mirror is required for the CIT. Laboratory experiments indicate that small test mirrors can be fabricated with existing technology

  9. Multi-optical mine detection: results from a field trial

    NASA Astrophysics Data System (ADS)

    Letalick, Dietmar; Tolt, Gustav; Sjökvist, Stefan K.; Nyberg, Sten; Grönwall, Christina; Andersson, Pierre; Linderhed, Anna; Forssell, Göran; Larsson, Håkan; Uppsäll, Magnus

    2006-05-01

    As a part of the Swedish mine detection project MOMS, an initial field trial was conducted at the Swedish EOD and Demining Centre (SWEDEC). The purpose was to collect data on surface-laid mines, UXO, submunitions, IED's, and background with a variety of optical sensors, for further use in the project. Three terrain types were covered: forest, gravel road, and an area which had recovered after total removal of all vegetation some years before. The sensors used in the field trial included UV, VIS, and NIR sensors as well as thermal, multi-spectral, and hyper-spectral sensors, 3-D laser radar and polarization sensors. Some of the sensors were mounted on an aerial work platform, while others were placed on tripods on the ground. This paper describes the field trial and the presents some initial results obtained from the subsequent analysis.

  10. Optical fibre-based detection of DNA hybridization.

    PubMed

    Hine, Anna V; Chen, Xianfeng; Hughes, Marcus D; Zhou, Kaiming; Davies, Edward; Sugden, Kate; Bennion, Ian; Zhang, Lin

    2009-04-01

    A dual-peak LPFG (long-period fibre grating), inscribed in an optical fibre, has been employed to sense DNA hybridization in real time, over a 1 h period. One strand of the DNA was immobilized on the fibre, while the other was free in solution. After hybridization, the fibre was stripped and repeated detection of hybridization was achieved, so demonstrating reusability of the device. Neither strand of DNA was fluorescently or otherwise labelled. The present paper will provide an overview of our early-stage experimental data and methodology, examine the potential of fibre gratings for use as biosensors to monitor both nucleic acid and other biomolecular interactions and then give a summary of the theory and fabrication of fibre gratings from a biological standpoint. Finally, the potential of improving signal strength and possible future directions of fibre grating biosensors will be addressed. PMID:19290879

  11. Optical detection of the spin transition by reflectivity: application to ?

    NASA Astrophysics Data System (ADS)

    Morscheidt, W.; Jeftic, J.; Codjovi, E.; Linares, J.; Bousseksou, A.; Constant-Machado, H.; Varret, F.

    1998-08-01

    Apparatus for measuring a reflected light signal on crystalline or powder samples of thermochromic materials, such as `spin-crossover' materials, has been developed in conjunction with a helium cryostat enabling measurements from cryogenic to ambient temperatures. Depending on the intensity and wavelength of the incident light and optical properties of the sample, reflectivity measurements provide information about a relatively thin surface layer of the investigated compound. The thermal spin transition or photoexcitation from the low-spin state, which is usually coloured, to the high-spin state, which is white or transparent, is detected by a change in the relative intensity as shown on examples of 0957-0233/9/8/025/img10 crystalline powders (btr = bis - triazole). To compare the situation in the bulk, simultaneous magnetic measurements were performed.

  12. Brain metastasis detection by resonant Raman optical biopsy method

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Liu, Cheng-hui; Cheng, Gangge; Zhou, Lixin; Zhang, Chunyuan; Pu, Yang; Li, Zhongwu; Liu, Yulong; Li, Qingbo; Wang, Wei; Alfano, Robert R.

    2014-03-01

    Resonant Raman (RR) spectroscopy provides an effective way to enhance Raman signal from particular bonds associated with key molecules due to changes on a molecular level. In this study, RR is used for detection of human brain metastases of five kinds of primary organs of lung, breast, kidney, rectal and orbital in ex-vivo. The RR spectra of brain metastases cancerous tissues were measured and compared with those of normal brain tissues and the corresponding primary cancer tissues. The differences of five types of brain metastases tissues in key bio-components of carotene, tryptophan, lactate, alanine and methyl/methylene group were investigated. The SVM-KNN classifier was used to categorize a set of RR spectra data of brain metastasis of lung cancerous tissues from normal brain tissue, yielding diagnostic sensitivity and specificity at 100% and 75%, respectively. The RR spectroscopy may provide new moleculebased optical probe tools for diagnosis and classification of brain metastatic of cancers.

  13. Detecting nanoparticles in tissue using an optical iterative technique

    PubMed Central

    Yariv, Inbar; Rahamim, Gilad; Shliselberg, Elad; Duadi, Hamootal; Lipovsky, Anat; Lubart, Rachel; Fixler, Dror

    2014-01-01

    Determining the physical penetration depth of nanoparticles (NPs) into tissues is a challenge that many researchers have been facing in recent years. This paper presents a new noninvasive method for detecting NPs in tissue using an optical iterative technique based on the Gerchberg-Saxton (G-S) algorithm. At the end of this algorithm the reduced scattering coefficient (µs'), of a given substance, can be estimated from the standard deviation (STD) of the retrieved phase of the remitted light. Presented in this paper are the results of a tissue simulation which indicate a linear ratio between the STD and the scattering components. A linear ratio was also observed in the tissue-like phantoms and in ex vivo experiments with and without NPs (Gold nanorods and nano Methylene Blue). The proposed technique is the first step towards determining the physical penetration depth of NPs. PMID:25426317

  14. Remote measurement of microwave distribution based on optical detection

    NASA Astrophysics Data System (ADS)

    Ji, Zhong; Ding, Wenzheng; Yang, Sihua; Chen, Qun; Xing, Da

    2016-01-01

    In this letter, we present the development of a remote microwave measurement system. This method employs an arc discharge lamp that serves as an energy converter from microwave to visible light, which can propagate without transmission medium. Observed with a charge coupled device, quantitative microwave power distribution can be achieved when the operators and electronic instruments are in a distance from the high power region in order to reduce the potential risk. We perform the experiments using pulsed microwaves, and the results show that the system response is dependent on the microwave intensity over a certain range. Most importantly, the microwave distribution can be monitored in real time by optical observation of the response of a one-dimensional lamp array. The characteristics of low cost, a wide detection bandwidth, remote measurement, and room temperature operation make the system a preferred detector for microwave applications.

  15. Optical Confirmation of a Neutrino-Detected Supernova

    NASA Astrophysics Data System (ADS)

    Robinson, L. J.; Roth, J.; Sky Publishing Corp. Team

    1999-12-01

    The next nearby supernova is likely to be first detected by neutrino observatories. At best, they will determine its position to within some tens of square degrees. Since the supernova has a 50:50 chance of being mv < 6, even at maximum, a thorough optical search for the putative star will almost certainly be needed. To aid in the immediate search for the supernova, Sky Publishing Corp. has established AstroAlert, a worldwide e-mail network of some 2,000 amateur and other small-telescope users. The announcement of a probable supernova will be made by the Supernova Neutrino Early Warning System and automatically forwarded to participants through AstroAlert. Details of the AstroAlert network will be described as well as protocols for validating the ``guest" star and obtaining its precise position.

  16. Optimum detection of an optical image on a photoelectric surface

    NASA Technical Reports Server (NTRS)

    Helstrom, C. W.; Wang, L.

    1972-01-01

    The detection of an optical image in the presence of uniform background light is based on a likelihood ratio formed of the numbers of photoelectrons emitted from small elements of a photoelectric surface onto which the image is focused. When diffraction is negligible and the surface has unit quantum efficiency, this detector is equipollent with the optimum detector of the image forming light. Its performance is compared with that of the threshold detector and that of a detector basing its decisions on the total number of photoelectrons from a finite area of the image. The illuminance of the image is postulated to have a Gaussian spatial distribution. All three detectors exhibit nearly the same reliability.

  17. Optical detection of chemical warfare agents and toxic industrial chemicals

    NASA Astrophysics Data System (ADS)

    Webber, Michael E.; Pushkarsky, Michael B.; Patel, C. Kumar N.

    2004-12-01

    We present an analytical model evaluating the suitability of optical absorption based spectroscopic techniques for detection of chemical warfare agents (CWAs) and toxic industrial chemicals (TICs) in ambient air. The sensor performance is modeled by simulating absorption spectra of a sample containing both the target and multitude of interfering species as well as an appropriate stochastic noise and determining the target concentrations from the simulated spectra via a least square fit (LSF) algorithm. The distribution of the LSF target concentrations determines the sensor sensitivity, probability of false positives (PFP) and probability of false negatives (PFN). The model was applied to CO2 laser based photoacosutic (L-PAS) CWA sensor and predicted single digit ppb sensitivity with very low PFP rates in the presence of significant amount of interferences. This approach will be useful for assessing sensor performance by developers and users alike; it also provides methodology for inter-comparison of different sensing technologies.

  18. Oil spill disasters detection and monitoring by optical satellite data

    NASA Astrophysics Data System (ADS)

    Livia Grimaldi, Caterina Sara; Coviello, Irina; Lacava, Teodosio; Pergola, Nicola; Tramutoli, Valerio

    2010-05-01

    Marine oil spill disasters may be related to natural hazards, when storms and hurricanes cause the sinking of tankers carrying crude or refined oil, as well as to human action, as illegal discharges, assessment errors (failures or collisions) or acts of warfare. Their consequence has a devastating effects on the marine and coastal environment. In order to reduce the environmental impact of such kind of hazard, giving to local authorities necessary information of pollution entity and evolution, timely detection and continuously updated information are fundamental. Satellite remote sensing can give a significant contribution in such a direction. Nowadays, SAR (Synthetic Aperture Radar) technology has been recognized as the most efficient for oil spill detection and description, thanks to the high spatial resolution and all-time/weather capability of the present operational sensors. Anyway, the actual SARs revisiting time does not allow a rapid detection and near real-time monitoring of these phenomena at global scale. The COSMO-Skymed Italian dual-mission (expected in the 2010) will overcome this limitation improving the temporal resolution until 12 hours by a SAR constellation of four satellites, but several open questions regarding costs and global delivery policy of such data, might prevent their use in an operational context. Passive optical sensors, on board meteorological satellites, thanks to their high temporal resolution (from a few hours to 15 minutes, depending on the characteristics of the platform/sensor), may represent, at this moment, a suitable SAR alternative/complement for oil spill detection and monitoring. Up to now, some techniques have been proposed for mapping known oil spill discharges monitoring using optical satellite data, on the other hand, reliable satellite methods for an automatic and timely detection of oil spill are still currently missing. Existing methods, in fact, can localize the presence of an oil spill only after an alert and

  19. Damage detection in bridges through fiber optic structural health monitoring

    NASA Astrophysics Data System (ADS)

    Doornink, J. D.; Phares, B. M.; Wipf, T. J.; Wood, D. L.

    2006-10-01

    A fiber optic structural health monitoring (SHM) system was developed and deployed by the Iowa State University (ISU) Bridge Engineering Center (BEC) to detect gradual or sudden damage in fracture-critical bridges (FCBs). The SHM system is trained with measured performance data, which are collected by fiber optic strain sensors to identify typical bridge behavior when subjected to ambient traffic loads. Structural responses deviating from the trained behavior are considered to be signs of structural damage or degradation and are identified through analytical procedures similar to control chart analyses used in statistical process control (SPC). The demonstration FCB SHM system was installed on the US Highway 30 bridge near Ames, IA, and utilizes 40 fiber bragg grating (FBG) sensors to continuously monitor the bridge response when subjected to ambient traffic loads. After the data is collected and processed, weekly evaluation reports are developed that summarize the continuous monitoring results. Through use of the evaluation reports, the bridge owner is able to identify and estimate the location and severity of the damage. The information presented herein includes an overview of the SHM components, results from laboratory and field validation testing on the system components, and samples of the reduced and analyzed data.

  20. Preparation and optical performance detection of acid-leaching optical fiber image bundle

    NASA Astrophysics Data System (ADS)

    Zhou, Dechun; Yu, Fengxia; Tan, Fang; Lu, Jingjuan

    2009-05-01

    This article determines three kinds of materials: core and clad glass,cladding glass,acid-leaching glass and the match ability of physical and chemical performances of these materials is described.. The quantitative relationship between concentration, temperature, acid type and resolution time are studied to determine a series of suitable technical parameters. Many effective methods are identified to improve optical properties through a lager number of detecting and analyzing the properties of fiber image bundle, which lays a good foundation for wider application.

  1. Distributed optical microsensors for hydrogen leak detection and related applications

    NASA Astrophysics Data System (ADS)

    Hunter, Scott R.; Patton, James F.; Sepaniak, Michael J.; Datskos, Panos G.; Smith, D. Barton

    2010-04-01

    Significant advances have recently been made to develop optically interrogated microsensor based chemical sensors with specific application to hydrogen vapor sensing and leak detection in the hydrogen economy. We have developed functionalized polymer-film and palladium/silver alloy coated microcantilever arrays with nanomechanical sensing for this application. The uniqueness of this approach is in the use of independent component analysis (ICA) and the classification techniques of neural networks to analyze the signals produced by an array of microcantilever sensors. This analysis identifies and quantifies the amount of hydrogen and other trace gases physisorbed on the arrays. Selectivity is achieved by using arrays of functionalized sensors with a moderate distribution of specificity among the sensing elements. The device consists of an array of beam-shaped transducers with molecular recognition phases (MRPs) applied to one surface of the transducers. Bending moments on the individual transducers can be detected by illuminating them with a laser or an LED and then reading the reflected light with an optical position sensitive detector (PSD) such as a CCD. Judicious selection of MRPs for the array provides multiple isolated interaction surfaces for sensing the environment. When a particular chemical agent binds to a transducer, the effective surface stresses of its modified and uncoated sides change unequally and the transducer begins to bend. The extent of bending depends upon the specific interactions between the microcantilever's MRP and the analyte. Thus, the readout of a multi-MRP array is a complex multidimensional signal that can be analyzed to deconvolve a multicomponent gas mixture. The use of this sensing and analysis technique in unattended networked arrays of sensors for various monitoring and surveillance applications is discussed.

  2. 3D defect detection using optical wide-field microscopy

    NASA Astrophysics Data System (ADS)

    Tympel, Volker; Schaaf, Marko; Srocka, Bernd

    2007-06-01

    We report a method to detect signed differences in two similar data sets representing 3-dimensional intensity profiles recorded by optical wide-field microscopes. The signed differences describe missing or unexpected intensity values, defined as defects. In technical applications like wafer and mask inspection, data sets often represent surfaces. The reported method is able to describe the size and position especially in relation to the neighboring surface and is called Three-Dimension-Aberration (TDA)-Technology. To increase the tool performance and to handle different sizes of defects a scaled bottom-up method is implemented and started with high reduced data sets for the search of large defects. Each analysis contains three steps. The first step is a correlation to calculate the displacement vector between the similar data sets. In the second step a new data set is created. The new data set consists of intensity differences. Extreme values in the data set represent the position of defects. By the use of linear and non-linear filters the stability of detection can be improved. If all differences are below a threshold the bottom-up method starts with the next larger scaled data set. In the other case it is assumed that the defect is detected and step three starts with the detection of the convex hull of the defect and the search of the neighboring surface. As a result the defect is described by a parameter set including the relative position. Because of the layered structure of the data set and the bottom-up technique the method is suitable for multi-core processor architectures.

  3. Cloud Detection of Optical Satellite Images Using Support Vector Machine

    NASA Astrophysics Data System (ADS)

    Lee, Kuan-Yi; Lin, Chao-Hung

    2016-06-01

    Cloud covers are generally present in optical remote-sensing images, which limit the usage of acquired images and increase the difficulty of data analysis, such as image compositing, correction of atmosphere effects, calculations of vegetation induces, land cover classification, and land cover change detection. In previous studies, thresholding is a common and useful method in cloud detection. However, a selected threshold is usually suitable for certain cases or local study areas, and it may be failed in other cases. In other words, thresholding-based methods are data-sensitive. Besides, there are many exceptions to control, and the environment is changed dynamically. Using the same threshold value on various data is not effective. In this study, a threshold-free method based on Support Vector Machine (SVM) is proposed, which can avoid the abovementioned problems. A statistical model is adopted to detect clouds instead of a subjective thresholding-based method, which is the main idea of this study. The features used in a classifier is the key to a successful classification. As a result, Automatic Cloud Cover Assessment (ACCA) algorithm, which is based on physical characteristics of clouds, is used to distinguish the clouds and other objects. In the same way, the algorithm called Fmask (Zhu et al., 2012) uses a lot of thresholds and criteria to screen clouds, cloud shadows, and snow. Therefore, the algorithm of feature extraction is based on the ACCA algorithm and Fmask. Spatial and temporal information are also important for satellite images. Consequently, co-occurrence matrix and temporal variance with uniformity of the major principal axis are used in proposed method. We aim to classify images into three groups: cloud, non-cloud and the others. In experiments, images acquired by the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and images containing the landscapes of agriculture, snow area, and island are tested. Experiment results demonstrate the detection

  4. Improved Detection Sensitivity of Line-Scanning Optical Coherence Microscopy

    PubMed Central

    Chen, Yu; Huang, Shu-Wei; Zhou, Chao; Potsaid, Benjamin; Fujimoto, James G.

    2012-01-01

    Optical coherence microscopy (OCM) is a promising technology for high-resolution cellular-level imaging in human tissues. Line-scanning OCM is a new form of OCM that utilizes line-field illumination for parallel detection. In this study, we demonstrate improved detection sensitivity by using an achromatic design for line-field generation. This system operates at 830-nm wavelength with 82-nm bandwidth. The measured axial resolution is 3.9 μm in air (corresponding to ~2.9 μm in tissue), and the transverse resolutions are 2.1 μm along the line-field illumination direction and 1.7 μm perpendicular to line illumination direction. The measured sensitivity is 98 dB with 25 line averages, resulting in an imaging speed of ~2 frames/s (516 lines/s). Real-time, cellular-level imaging of scattering tissues is demonstrated using human-colon specimens. PMID:22685379

  5. Improved coded optical communication error rates using joint detection receivers

    NASA Astrophysics Data System (ADS)

    Dutton, Zachary; Guha, Saikat; Chen, Jian; Habif, Jonathan; Lazarus, Richard

    2012-02-01

    It is now known that coherent state (laser light) modulation is sufficient to reach the ultimate quantum limit (the Holevo bound) for classical communication capacity. However, all current optical communication systems are fundamentally limited in capacity because they perform measurements on single symbols at a time. To reach the Holevo bound, joint quantum measurements over long symbol blocks will be required. We recently proposed and demonstrated the ``conditional pulse nulling'' (CPN) receiver -- which acts jointly on the time slots of a pulse-position-modulation (PPM) codeword by employing pulse nulling and quantum feedforward -- and demonstrated a 2.3 dB improvement in error rate over direct detection (DD). In a communication system coded error rates are made arbitrary small by employing an outer code (such as Reed-Solomon (RS)). Here we analyze RS coding of PPM errors with both DD and CPN receivers and calculate the outer code length requirements. We find the improved PPM error rates with the CPN translates into >10 times improvement in the required outer code length at high rates. This advantage also translates increase the range for a given coding complexity. In addition, we present results for outer coded error rates of our recently proposed ``Green Machine'' which realizes a joint detection advantage for binary phase shift keyed (BPSK) modulation.

  6. A PC-aided optical foetal heart rate detection system.

    PubMed

    Oweis, Rami J; As'ad, Hala; Aldarawsheh, Amany; Al-Khdeirat, Rawan; Lwissy, Kaldoun

    2014-01-01

    Safe monitoring of foetal heart rate is a valuable tool for the healthy evolution and wellbeing of both foetus and mother. This paper presents a non-invasive optical technique that allows for foetal heart rate detection using a photovoltaic infrared (IR) detector placed on the mother's abdomen. The system presented here consists of a photoplethysmography (PPG) circuit, abdomen circuit and a personal computer equipped with MATLAB. A near IR beam having a wavelength of 880 nm is transmitted through the mother's abdomen and foetal tissue. The received abdominal signal that conveys information pertaining to the mother and foetal heart rate is sensed by a low noise photodetector. The PC receives the signal through the National Instrumentation Data Acquisition Card (NIDAQ). After synchronous detection of the abdominal and finger PPG signals, the designed MATLAB-based software saves, analyses and extracts information related to the foetal heart rate. Extraction is carried out using recursive least squares adaptive filtration. Measurements on eight pregnant women with gestational periods ranging from 35-39 weeks were performed using the proposed system and CTG. Results show a correlation coefficient of 0.978 and a correlation confidence interval between 88-99.6%. The t test results in a p value of 0.034, which is less than 0.05. Low power, low cost, high signal-to-noise ratio, reduction of ambient light effect and ease of use are the main characteristics of the proposed system. PMID:24195701

  7. Optical fiber Fabry-Perot interferometer for microorganism growth detection

    NASA Astrophysics Data System (ADS)

    Liu, Xiaohui; Jiang, Mingshun; Sui, Qingmei; Luo, Shuyang; Geng, Xiangyi

    2016-07-01

    An optical fiber Fabry-Perot interferometer (FPI) based on hollow-core photonic crystal fiber (HCPCF) for microorganism growth detection is proposed and demonstrated. The FPI is formed by splicing both ends of a short section of HCPCF to SMFs and cleaving the SMF pigtail to a proper length. By measuring the fringe contrast of interference pattern, the refractive index (RI) changes of analyte during microorganism growth can be obtained. RI response of the sensor was investigated theoretically and experimentally. It shows linear response with sensitivity of -136 dB/RIU and good repeatability. Temperature response was also tested and the result confirms the low temperature cross-sensitivity of the sensor. Detection of yeast growth in liquid medium by the FPI sensor was conducted and the result shows the characteristic of typical yeast growth curve. With its advantages of high RI sensitivity, low temperature cross-sensitivity, capability for real-time measurement and so on, this FPI sensor has great potential in biosensing.

  8. The Direct Detectability of Giant Exoplanets in the Optical

    NASA Astrophysics Data System (ADS)

    Greco, Johnny P.; Burrows, Adam

    2015-08-01

    Motivated by the possibility that a coronagraph will be put on the Wide-field Infrared Survey Telescope (WFIRST)/Astrophysics Focused Telescope Assets (AFTA), we explore the direct detectability of extrasolar giant planets (EGPs) in the optical. We quantify a planet's detectability by the fraction of its orbit for which it is in an observable configuration ({f}{obs}). Using a suite of Monte Carlo experiments, we study the dependence of {f}{obs} upon the inner working angle (IWA) and minimum achievable contrast ({C}{min}) of the direct-imaging observatory; the planet's phase function, geometric albedo, single-scattering albedo, radius, and distance from Earth; and the semimajor axis distribution of EGPs. We calculate phase functions for a given geometric or single-scattering albedo, assuming various scattering mechanisms. We find that the Lambertian phase function can predict significantly larger {f}{obs}s with respect to the more realistic Rayleigh phase function. For observations made with WFIRST/AFTA's baseline capabilities ({C}{min}˜ {10}-9, {IWA}˜ 0\\buildrel{\\prime\\prime}\\over{.} 2), Jupiter-like planets orbiting stars within 10, 30, and 50 pc of Earth have volume-averaged observability fractions of ˜12%, 3%, and 0.5%, respectively. At 10 pc, such observations yield {f}{obs}\\gt 1% for low- to modest-eccentricity planets with semimajor axes in the range ˜2-10 AU. If {C}{min}={10}-10, this range extends to ˜35 AU. We find that, in all but the most optimistic configurations, the probability for detection in a blind search is low (< 5%). However, with orbital parameter constraints from long-term radial-velocity campaigns and Gaia astrometry, the tools we develop in this work can be used to determine both the most promising systems to target and when to observe them.

  9. Optical Myography: Detecting Finger Movements by Looking at the Forearm.

    PubMed

    Nissler, Christian; Mouriki, Nikoleta; Castellini, Claudio

    2016-01-01

    One of the crucial problems found in the scientific community of assistive/rehabilitation robotics nowadays is that of automatically detecting what a disabled subject (for instance, a hand amputee) wants to do, exactly when she wants to do it, and strictly for the time she wants to do it. This problem, commonly called "intent detection," has traditionally been tackled using surface electromyography, a technique which suffers from a number of drawbacks, including the changes in the signal induced by sweat and muscle fatigue. With the advent of realistic, physically plausible augmented- and virtual-reality environments for rehabilitation, this approach does not suffice anymore. In this paper, we explore a novel method to solve the problem, which we call Optical Myography (OMG). The idea is to visually inspect the human forearm (or stump) to reconstruct what fingers are moving and to what extent. In a psychophysical experiment involving ten intact subjects, we used visual fiducial markers (AprilTags) and a standard web camera to visualize the deformations of the surface of the forearm, which then were mapped to the intended finger motions. As ground truth, a visual stimulus was used, avoiding the need for finger sensors (force/position sensors, datagloves, etc.). Two machine-learning approaches, a linear and a non-linear one, were comparatively tested in settings of increasing realism. The results indicate an average error in the range of 0.05-0.22 (root mean square error normalized over the signal range), in line with similar results obtained with more mature techniques such as electromyography. If further successfully tested in the large, this approach could lead to vision-based intent detection of amputees, with the main application of letting such disabled persons dexterously and reliably interact in an augmented-/virtual-reality setup. PMID:27148039

  10. Optical Myography: Detecting Finger Movements by Looking at the Forearm

    PubMed Central

    Nissler, Christian; Mouriki, Nikoleta; Castellini, Claudio

    2016-01-01

    One of the crucial problems found in the scientific community of assistive/rehabilitation robotics nowadays is that of automatically detecting what a disabled subject (for instance, a hand amputee) wants to do, exactly when she wants to do it, and strictly for the time she wants to do it. This problem, commonly called “intent detection,” has traditionally been tackled using surface electromyography, a technique which suffers from a number of drawbacks, including the changes in the signal induced by sweat and muscle fatigue. With the advent of realistic, physically plausible augmented- and virtual-reality environments for rehabilitation, this approach does not suffice anymore. In this paper, we explore a novel method to solve the problem, which we call Optical Myography (OMG). The idea is to visually inspect the human forearm (or stump) to reconstruct what fingers are moving and to what extent. In a psychophysical experiment involving ten intact subjects, we used visual fiducial markers (AprilTags) and a standard web camera to visualize the deformations of the surface of the forearm, which then were mapped to the intended finger motions. As ground truth, a visual stimulus was used, avoiding the need for finger sensors (force/position sensors, datagloves, etc.). Two machine-learning approaches, a linear and a non-linear one, were comparatively tested in settings of increasing realism. The results indicate an average error in the range of 0.05–0.22 (root mean square error normalized over the signal range), in line with similar results obtained with more mature techniques such as electromyography. If further successfully tested in the large, this approach could lead to vision-based intent detection of amputees, with the main application of letting such disabled persons dexterously and reliably interact in an augmented-/virtual-reality setup. PMID:27148039

  11. Influence of the Spot Size of the Probe Beam on the Detected THz Power Using Electro-Optic Detection Method

    NASA Astrophysics Data System (ADS)

    Metbulut, Mukaddes Meliz; Güllü, Hasan Hüseyin; Altan, Hakan

    We compared the detected THz power through electro-optic detection for different spot sizes of a probe beam on the < 110 > ZnTe crystal. We find that there is a proportional relationship between the detected THz power and spot size of the probe beam by theoretically analyzing its effect on the intensity profile of the terahertz beam.

  12. Optical galaxy cluster detection across a wide redshift range

    SciTech Connect

    Hao, Jiangang

    2009-04-01

    The past decade is one of the most exciting period in the history of physics and astronomy. The discovery of cosmic acceleration dramatically changed our understanding about the evolution and constituents of the Universe. To accommodate the new acceleration phase into our well established Big Bang cosmological scenario under the frame work of General Relativity, there must exist a very special substance that has negative pressure and make up about 73% of the total energy density in our Universe. It is called Dark Energy. For the first time people realized that the vast majority of our Universe is made of things that are totally different from the things we are made of. Therefore, one of the major endeavors in physics and astronomy in the coming years is trying to understand, if we can, the nature of dark energy. Understanding dark energy cannot be achieved from pure logic. We need empirical evidence to finally determine about what is dark energy. The better we can constrain the energy density and evolution of the dark energy, the closer we will get to the answer. There are many ways to constrain the energy density and evolution of dark energy, each of which leads to degeneracy in certain directions in the parameter space. Therefore, a combination of complimentary methods will help to reduce the degeneracies and give tighter constraints. Dark energy became dominate over matter in the Universe only very recently (at about z ~ 1.5) and will affect both the cosmological geometry and large scale structure formation. Among the various experiments, some of them constrain the dark energy mainly via geometry (such as CMB, Supernovae) while some others provides constraints from both structures and geometry (such as BAO, Galaxy Clusters) Galaxy clusters can be used as a sensitive probe for cosmology. A large cluster catalog that extends to high redshift with well measured masses is indispensable for precisely constraining cosmological parameters. Detecting clusters in optical

  13. Coherent detection and digital signal processing for fiber optic communications

    NASA Astrophysics Data System (ADS)

    Ip, Ezra

    The drive towards higher spectral efficiency in optical fiber systems has generated renewed interest in coherent detection. We review different detection methods, including noncoherent, differentially coherent, and coherent detection, as well as hybrid detection methods. We compare the modulation methods that are enabled and their respective performances in a linear regime. An important system parameter is the number of degrees of freedom (DOF) utilized in transmission. Polarization-multiplexed quadrature-amplitude modulation maximizes spectral efficiency and power efficiency as it uses all four available DOF contained in the two field quadratures in the two polarizations. Dual-polarization homodyne or heterodyne downconversion are linear processes that can fully recover the received signal field in these four DOF. When downconverted signals are sampled at the Nyquist rate, compensation of transmission impairments can be performed using digital signal processing (DSP). Software based receivers benefit from the robustness of DSP, flexibility in design, and ease of adaptation to time-varying channels. Linear impairments, including chromatic dispersion (CD) and polarization-mode dispersion (PMD), can be compensated quasi-exactly using finite impulse response filters. In practical systems, sampling the received signal at 3/2 times the symbol rate is sufficient to enable an arbitrary amount of CD and PMD to be compensated for a sufficiently long equalizer whose tap length scales linearly with transmission distance. Depending on the transmitted constellation and the target bit error rate, the analog-to-digital converter (ADC) should have around 5 to 6 bits of resolution. Digital coherent receivers are naturally suited for the implementation of feedforward carrier recovery, which has superior linewidth tolerance than phase-locked loops, and does not suffer from feedback delay constraints. Differential bit encoding can be used to prevent catastrophic receiver failure due

  14. Non-invasive Optical Molecular Imaging for Cancer Detection

    NASA Astrophysics Data System (ADS)

    Luo, Zhen

    Cancer is a leading cause of death worldwide. It remains the second most common cause of death in the US, accounting for nearly 1 out of every 4 deaths. Improved fundamental understanding of molecular processes and pathways resulting in cancer development has catalyzed a shift towards molecular analysis of cancer using imaging technologies. It is expected that the non-invasive or minimally invasive molecular imaging analysis of cancer can significantly aid in improving the early detection of cancer and will result in reduced mortality and morbidity associated with the disease. The central hypothesis of the proposed research is that non-invasive imaging of changes in metabolic activity of individual cells, and extracellular pH within a tissue will improve early stage detection of cancer. The specific goals of this research project were to: (a) develop novel optical imaging probes to image changes in choline metabolism and tissue pH as a function of progression of cancer using clinically isolated tissue biopsies; (b) correlate changes in tissue extracellular pH and metabolic activity of tissues as a function of disease state using clinically isolated tissue biopsies; (c) provide fundamental understanding of relationship between tumor hypoxia, acidification of the extracellular space and altered cellular metabolism with progression of cancer. Three novel molecular imaging probes were developed to detect changes in choline and glucose metabolism and extracellular pH in model systems and clinically isolated cells and biopsies. Glucose uptake and metabolism was measured using a fluorescence analog of glucose, 2-NBDG (2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose), while choline metabolism was measured using a click chemistry analog of choline, propargyl choline, which can be in-situ labeled with a fluorophore Alexa-488 azide via a click chemistry reaction. Extracellular pH in tissue were measured by Alexa-647 labeled pHLIP (pH low insertion peptide

  15. Optimization of detection sensitivity for a Fiber Optic Intrusion Detection System (FOIDS) using design of experiments.

    SciTech Connect

    Miller, Larry D.; Mack, Thomas Kimball; Mitchiner, Kim W.; Varoz, Carmella A.

    2010-06-01

    The Fiber Optic Intrusion Detection System (FOIDS)1 is a physical security sensor deployed on fence lines to detect climb or cut intrusions by adversaries. Calibration of detection sensitivity can be time consuming because, for example, the FiberSenSys FD-332 has 32 settings that can be adjusted independently to provide a balance between a high probability of detection and a low nuisance alarm rate. Therefore, an efficient method of calibrating the FOIDS in the field, other than by trial and error, was needed. This study was conducted to: x Identify the most significant settings for controlling detection x Develop a way of predicting detection sensitivity for given settings x Develop a set of optimal settings for validation The Design of Experiments (DoE) 2-4 methodology was used to generate small, planned test matrixes, which could be statistically analyzed to yield more information from the test data. Design of Experiments is a statistical methodology for quickly optimizing performance of systems with measurable input and output variables. DoE was used to design custom screening experiments based on 11 FOIDS settings believed to have the most affect on WKH types of fence perimeter intrusions were evaluated: simulated cut intrusions and actual climb intrusions. Two slightly different two-level randomized fractional factorial designed experiment matrixes consisting of 16 unique experiments were performed in the field for each type of intrusion. Three repetitions were conducted for every cut test; two repetitions were conducted for every climb test. Total number of cut tests analyzed was 51; the total number of climb tests was 38. This paper discusses the results and benefits of using Design of Experiments (DoE) to calibrate and optimize the settings for a FOIDS sensor

  16. Automated optic disk boundary detection by modified active contour model.

    PubMed

    Xu, Juan; Chutatape, Opas; Chew, Paul

    2007-03-01

    This paper presents a novel deformable-model-based algorithm for fully automated detection of optic disk boundary in fundus images. The proposed method improves and extends the original snake (deforming-only technique) in two aspects: clustering and smoothing update. The contour points are first self-separated into edge-point group or uncertain-point group by clustering after each deformation, and these contour points are then updated by different criteria based on different groups. The updating process combines both the local and global information of the contour to achieve the balance of contour stability and accuracy. The modifications make the proposed algorithm more accurate and robust to blood vessel occlusions, noises, ill-defined edges and fuzzy contour shapes. The comparative results show that the proposed method can estimate the disk boundaries of 100 test images closer to the groundtruth, as measured by mean distance to closest point (MDCP) <3 pixels, with the better success rate when compared to those obtained by gradient vector flow snake (GVF-snake) and modified active shape models (ASM). PMID:17355059

  17. In situ CTE measurements and damage detection using optical metrology

    NASA Astrophysics Data System (ADS)

    Rajaram, Satish; Cuadra, Jefferson; Saralaya, Raghav; Bartoli, Ivan; Kontsos, Antonios

    2016-02-01

    This paper presents a methodology to make coefficient of thermal expansion measurements through the combined use of two non-contact and full field optical metrology methods including digital image correlation and infrared thermography. In this context, active Infrared Thermography techniques combined with contact and non-contact deformation measurement methods have already been reported to measure materials’ thermal expansion. In addition, such techniques have been reported to be capable to detect surface and subsurface defects from changes in homogenous heat diffusion due to damage. Based on this knowledge, it is hypothesized in this article that the material response induced by thermal loading and quantified by coefficient of thermal expansion measurements could be further used as an indicator of damage. To validate the hypothesis three measurements were performed. The first established the effectiveness of using deformation and thermal full field data for coefficient of thermal expansion measurements. The second intended to demonstrate the advantage of using such full field data in order to provide site-specific measurements of thermal expansion. Finally damage was a priori induced to a metallic specimen, and the measured variations of local CTE confirmed the potential of using the described approach as a means of damage quantification in materials and structures.

  18. An integrated optic hydrogen sensor for fast detection of hydrogen

    NASA Astrophysics Data System (ADS)

    Alam, M. Z.; Moreno, J.; Aitchison, J. S.; Mojahedi, M.

    2007-09-01

    Hydrogen is used as the main propellant for space shuttles, as an energy source in fuel cells, in oil refineries, and for many other applications. Hydrogen is extremely volatile, easily flammable, and highly explosive. Storage and handling of hydrogen is a challenging task and a good hydrogen sensor is highly desirable. An ideal hydrogen sensor should be fast, reversible, highly selective, compact in size, easy to fabricate, and cheap in price. Unfortunately such a sensor to date is not available. In this paper we propose a multi-channel integrated optical sensor for detection of hydrogen. The sensor consists of a high index waveguide on a low index substrate and uses Pd or Pd alloy thin film as the sensing medium. Since a single channel hydrogen sensor will be affected by the presence of other gases and the variations of temperature, humidity, and input power; a multi-channel sensing scheme and differential measurements are proposed to correct for some of these effects. All the components of the multi-channel sensor can be realized using planar technology and the complete sensor can be fabricated on a single chip. The sensor is compact and the response time is expected to be very short. The concept of multi-channel sensing presented in this work is very general and can be extended to other gas sensors as well.

  19. Online technique for detecting state of onboard fiber optic gyroscope.

    PubMed

    Miao, Zhiyong; Xu, Dingjie; He, Kunpeng; Pang, Shuwan; Tian, Chunmiao

    2015-02-01

    Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of "state of health" for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data. PMID:25725877

  20. Online technique for detecting state of onboard fiber optic gyroscope

    NASA Astrophysics Data System (ADS)

    Miao, Zhiyong; Xu, Dingjie; He, Kunpeng; Pang, Shuwan; Tian, Chunmiao

    2015-02-01

    Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of "state of health" for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data.

  1. Optical fiber waveguide sensor for the colorimetric detection of ammonia

    NASA Astrophysics Data System (ADS)

    Schmitt, Katrin; Rist, Jonas; Peter, Carolin; Wöllenstein, Jürgen

    2011-06-01

    We present the development and characterization of a fiber-optic colorimetric gas sensor combined with the electronic circuitry for measurement control and RFID communication. The gas sensor detects ammonia using a 300 μm polyolefin fiber coated with a gas-sensitive polymer film. The spectral and time-dependent sensitivity of various polymer films was tested in transmission measurements. Light from a standard LED at λ = 590 nm was coupled into the polyolefin fiber through the front face. A prototype of the gas sensor with the direct coupling method was tested under realistic measurement conditions, i.e. battery-driven and in a completely autonomous mode. The sensor system showed good sensitivity to the ammonia concentrations and response times in the order of minutes. The achievable power consumption was below 100μW.The films contained the pH-sensitive dyes bromocresol purple or bromophenol blue embedded in either ethyl cellulose or polyvinyl butyral, and optionally tributyl phosphate as plasticizer. The bromophenol blue based films showed a strong reaction to ammonia, with saturation concentrations around 1000 ppm and response times of about 15 seconds to 100ppm. The colorimetric reaction was simulated using a simple kinetic model which was in good agreement with the experimental results.

  2. Sequence Detection for PPM Optical Communication With ISI

    NASA Technical Reports Server (NTRS)

    Moision, Bruce; Srinivasan, Meera; Lee, Clement

    2006-01-01

    A method of sequence detection has been proposed to mitigate the effects of inter-slot interference and inter-symbol interference (both denoted ISI) in the reception of M-ary pulse-position modulation (PPM) optical signals. The method would make it possible to reduce the error rate for a given slot duration, to use a shorter slot duration (and, hence, to communicate at a higher rate) without exceeding a given error rate, or to use a lower-bandwidth (and, hence, less-expensive) receiver to receive a signal of a given slot width without exceeding a given error rate. In M-ary PPM, a symbol period is divided into M time slots, each of duration T(sub s), and a symbol consists of a binary sequence ones and zeros represented by pulses or the absence of pulses, respectively, in the time slots. At the transmitter, the bit stream is used to modulate a laser, the output of which is constant (either full power or zero power, representing 1 or 0, respectively) during each time slot. However, the signal becomes attenuated (signal photons are lost) in propagation from the transmitter to the receiver and noise enters at the receiver, complicating the problem of determining the timing of the symbol periods and slots and identifying the symbols.

  3. Detecting Bacterial Surface Organelles on Single Cells Using Optical Tweezers.

    PubMed

    Zakrisson, Johan; Singh, Bhupender; Svenmarker, Pontus; Wiklund, Krister; Zhang, Hanqing; Hakobyan, Shoghik; Ramstedt, Madeleine; Andersson, Magnus

    2016-05-10

    Bacterial cells display a diverse array of surface organelles that are important for a range of processes such as intercellular communication, motility and adhesion leading to biofilm formation, infections, and bacterial spread. More specifically, attachment to host cells by Gram-negative bacteria are mediated by adhesion pili, which are nanometers wide and micrometers long fibrous organelles. Since these pili are significantly thinner than the wavelength of visible light, they cannot be detected using standard light microscopy techniques. At present, there is no fast and simple method available to investigate if a single cell expresses pili while keeping the cell alive for further studies. In this study, we present a method to determine the presence of pili on a single bacterium. The protocol involves imaging the bacterium to measure its size, followed by predicting the fluid drag based on its size using an analytical model, and thereafter oscillating the sample while a single bacterium is trapped by an optical tweezer to measure its effective fluid drag. Comparison between the predicted and the measured fluid drag thereby indicate the presence of pili. Herein, we verify the method using polymer coated silica microspheres and Escherichia coli bacteria expressing adhesion pili. Our protocol can in real time and within seconds assist single cell studies by distinguishing between piliated and nonpiliated bacteria. PMID:27088225

  4. Optical heterodyne detection for cavity ring-down spectroscopy

    DOEpatents

    Levenson, Marc D.; Paldus, Barbara A.; Zare, Richard N.

    2000-07-25

    A cavity ring-down system for performing cavity ring-down spectroscopy (CRDS) using optical heterodyne detection of a ring-down wave E.sub.RD during a ring-down phase or a ring-up wave E.sub.RU during a ring up phase. The system sends a local oscillator wave E.sub.LO and a signal wave E.sub.SIGNAL to the cavity, preferably a ring resonator, and derives an interference signal from the combined local oscillator wave E.sub.LO and the ring-down wave E.sub.RD (or ring-up wave E.sub.RU). The local oscillator wave E.sub.LO has a first polarization and the ring-down wave E.sub.RD has a second polarization different from the first polarization. The system has a combining arrangement for combining or overlapping local oscillator wave E.sub.LO and the ring-down wave E.sub.RD at a photodetector, which receives the interference signal and generates a heterodyne current I.sub.H therefrom. Frequency and phase differences between the waves are adjustable.

  5. Online technique for detecting state of onboard fiber optic gyroscope

    SciTech Connect

    Miao, Zhiyong; He, Kunpeng Pang, Shuwan; Xu, Dingjie; Tian, Chunmiao

    2015-02-15

    Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of “state of health” for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data.

  6. Displacement response, detection limit, and dynamic range of fiber-optic lever sensors

    NASA Technical Reports Server (NTRS)

    He, Gang; Cuomo, Frank W.

    1991-01-01

    The authors present the evaluation of the displacement response, detection limit, and dynamic range of fiber-optic lever sensors in a general format to establish their dependence on fiber sizes, optoelectronic detector specifications, input power, and other relevant parameters. The formations for the normalized reflected optical power change are derived for the evaluation of the optimal sensor response, the linearity range, and the minimum detectable displacement. The theoretical models are verified by an experiment which determines sensor response, modulation index, reflected optical power change, and linear response range through dynamic measurement. The application of this theoretical model to the study of a fiber-optic microphone for acoustic pressure detection is considered.

  7. Frequency interleaving towards spectrally efficient directly detected optical OFDM for next-generation optical access networks.

    PubMed

    Mehedy, Lenin; Bakaul, Masuduzzaman; Nirmalathas, Ampalavanapillai

    2010-10-25

    In this paper, we theoretically analyze and demonstrate that spectral efficiency of a conventional direct detection based optical OFDM system (DDO-OFDM) can be improved significantly using frequency interleaving of adjacent DDO-OFDM channels where OFDM signal band of one channel occupies the spectral gap of other channel and vice versa. We show that, at optimum operating condition, the proposed technique can effectively improve the spectral efficiency of the conventional DDO-OFDM system as much as 50%. We also show that such a frequency interleaved DDO-OFDM system, with a bit rate of 48 Gb/s within 25 GHz bandwidth, achieves sufficient power budget after transmission over 25 km single mode fiber to be used in next-generation time-division-multiplexed passive optical networks (TDM-PON). Moreover, by applying 64- quadrature amplitude modulation (QAM), the system can be further scaled up to 96 Gb/s with a power budget sufficient for 1:16 split TDM-PON. PMID:21164657

  8. A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images

    PubMed Central

    Belghith, Akram; Bowd, Christopher; Weinreb, Robert N.; Zangwill, Linda M.

    2014-01-01

    Glaucoma is an ocular disease characterized by distinctive changes in the optic nerve head (ONH) and visual field. Glaucoma can strike without symptoms and causes blindness if it remains without treatment. Therefore, early disease detection is important so that treatment can be initiated and blindness prevented. In this context, important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, an essential element for glaucoma detection and monitoring. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy subjects. In this paper, we present a new framework for detection of glaucoma progression using 3D SD-OCT images. In contrast to previous works that the retinal nerve fiber layer (RNFL) thickness measurement provided by commercially available spectral-domain optical coherence tomograph, we consider the whole 3D volume for change detection. To integrate a priori knowledge and in particular the spatial voxel dependency in the change detection map, we propose the use of the Markov Random Field to handle a such dependency. To accommodate the presence of false positive detection, the estimated change detection map is then used to classify a 3D SDOCT image into the “non-progressing” and “progressing” glaucoma classes, based on a fuzzy logic classifier. We compared the diagnostic performance of the proposed framework to existing methods of progression detection. PMID:25606299

  9. A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images

    NASA Astrophysics Data System (ADS)

    Belghith, Akram; Bowd, Christopher; Weinreb, Robert N.; Zangwill, Linda M.

    2014-03-01

    Glaucoma is an ocular disease characterized by distinctive changes in the optic nerve head (ONH) and visual field. Glaucoma can strike without symptoms and causes blindness if it remains without treatment. Therefore, early disease detection is important so that treatment can be initiated and blindness prevented. In this context, important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, an essential element for glaucoma detection and monitoring. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy subjects. In this paper, we present a new framework for detection of glaucoma progression using 3D SD-OCT images. In contrast to previous works that the retinal nerve fiber layer (RNFL) thickness measurement provided by commercially available spectral-domain optical coherence tomograph, we consider the whole 3D volume for change detection. To integrate a priori knowledge and in particular the spatial voxel dependency in the change detection map, we propose the use of the Markov Random Field to handle a such dependency. To accommodate the presence of false positive detection, the estimated change detection map is then used to classify a 3D SDOCT image into the "non-progressing" and "progressing" glaucoma classes, based on a fuzzy logic classifier. We compared the diagnostic performance of the proposed framework to existing methods of progression detection.

  10. In vivo detection of experimental optic neuritis by pupillometry.

    PubMed

    Shindler, Kenneth S; Revere, Karen; Dutt, Mahasweta; Ying, Gui-Shuang; Chung, Daniel C

    2012-07-01

    Optic neuritis is an inflammatory demyelination of optic nerve often occurring in multiple sclerosis (MS) patients. Mice with experimental autoimmune encephalomyelitis (EAE), an MS model, develop optic neuritis, but it is detected histologically after sacrifice, limiting the ability to monitor progression or treatment in vivo. We examined whether pupillary light responses measured by pupillometry can identify eyes with optic neuritis in EAE mice. C57BL/6 mice were exposed to unilateral light flashes of increasing intensity at 10 s intervals (4.7, 37, and 300 μW/cm(2)). Pupillary responses were recorded with a commercially available pupillometer. EAE was then induced by immunization with myelin oligodendrocyte glycoprotein. Pupillometry was repeated up to 17 days post-immunization, and responses were correlated with optic nerve inflammation. By day 17 post-immunization, 90% of EAE eyes had optic nerve inflammation. EAE eyes had significantly reduced pupillary constriction compared to control eyes. Mice exhibited more than a 25% decrease in pupillary constriction in at least one eye by days 13-15 post-immunization. In some eyes, pupil responses decreased prior to onset of detectable inflammation. Results show that pupillometry detects decreased optic nerve function in experimental optic neuritis, even in the absence of histological detection. Measuring pupillary constriction allows in vivo identification and functional assessment of eyes with optic neuritis that will be useful in evaluating potential therapies over time. Furthermore, results demonstrate that decreased visual function occurs early in optic neuritis, before optic nerve inflammation reaches its peak level. PMID:22561341

  11. Optical detection and characterization of ice crystals in LACIS

    NASA Astrophysics Data System (ADS)

    Kiselev, Alexei; Clauß, Tina; Niedermeier, Dennis; Hartmann, Susan; Wex, Heike; Stratmann, Frank

    2010-05-01

    Tropospheric ice and mixed phase clouds are an integral part of the earth system and their microphysical and radiative properties are strongly coupled e.g. through the complexities of the ice nucleation process. Therefore the investigation of influences of different aerosol particles which act as ice nuclei (IN) on the freezing behaviour of cloud droplets is important and still poses unresolved questions. The Leipzig Aerosol and Cloud Interaction Simulator (LACIS) is used to investigate the IN activity of different natural and artificial aerosol particles (mineral dust, soot etc.) in heterogeneous freezing processes (immersion or deposition freezing). A critical part of LACIS is the particle detection system allowing for size-resolved counting of activated seed particles and discrimination between ice crystals and water droplets. Recently, two instruments have been developed to provide these measurements at the LACIS facility. The Thermally-stabilized Optical Particle Spectrometer (TOPS) is measuring the particle size based on the intensity of light scattered by individual particles into a near-forward (15° to 45°) direction. Two symmetrical forward scattering channels allow for optical determination of the sensing volume, thus reducing the coincidence counting error and the edge zone effect. The backscatter channel (162° to 176°) equipped with a rotatable cross polarizer allows for establishing the change in linear polarization state of the scattered light. The backscatter elevation angle is limited so that the linear depolarization of light scattered by spherical particles of arbitrary size is zero. Any detectable signal in the depolarization channel can be therefore attributed to non-spherical particles (ice crystals). With consideration of the signal in the backscatter channel the separate counting of water drops and ice particle is possible. The Leipzig Ice Scattering Apparatus (LISA) is a modified version of the Small Ice Detector (SID3), developed at the

  12. Detection of dermal systemic sclerosis using noncontact optical coherence elastography

    NASA Astrophysics Data System (ADS)

    Liu, Chih-Hao; Du, Yong; Singh, Manmohan; Li, Jiasong; Wu, Chen; Han, Zhaolong; Raghunathan, Raksha; Hsu, Thomas; Noorani, Shezaan; Hicks, M. John; Mohan, Chandra; Larin, Kirill V.

    2016-03-01

    Systemic sclerosis (SSc) is a connective tissue disease that results in excessive accumulation of collagen in the skin and internal organs. Overall, SSc is a rare disorder, but has a high mortality, particularly in last decade of life. To improve the survival rate, an accurate and early diagnosis is crucial. Currently, the modified Rodnan skin score (mRSS) is the gold standard for evaluating SSc progression based on clinical palpation at 17 sites on the body. However, this procedure can be time consuming, and the assessed score may be biased by the experience of the clinician, causing inter- and intraobserver variabilities. Moreover, the instrinsic elasticity of skin may further bias the mRSS assessment in the early stages of SSc, such as oedematous. To overcome these limitations, there is a need for a rapid, accurate, and objective assessment technique. Optical coherence elastography (OCE) is a novel, rapidly emerging technique, which can assess mechanical contrast in tissues with micrometer spatial resolution. In this work, we demonstrate the first use of OCE to assess the mechanical properties of control and SSc-like diseased skin non-invasively. A focused air-pulse induced an elastic wave in the skin, which was detected by a home-built OCE system. The elastic wave propagated significantly faster in SSc skin compared to healthy skin. The Young's modulus of the SSc skin was significantly higher than that of normal skin (P<0.05). Thus, OCE was able to objectively differentiate healthy and fibrotic skin completely noninvasively and is a promising and potentially useful new technology for quantifying skin involvement in SSc.

  13. Time resolved optical detection for white matter lesion detection: preclinical tests on macaque brains and MRI co-registration

    NASA Astrophysics Data System (ADS)

    Planat-Chrétien, A.; Berger, M.; Hervé, L.; Watroba, L.; Demilly, J.; Flament, J.; Stimmer, L.; Aubourg, P.; Dinten, J.-M.

    2015-07-01

    We conducted a preclinical assessment on young macaques aimed at detecting white matter lesions. We present the protocol we implemented to achieve the lesions detection using a bedside non-invasive optical-based Time-Resolved instrumentation we have optimized for this purpose. We validated the reconstructed 3D absorption map with co-registration of MRI data.

  14. Distributed Fiber-Optic Sensors for Vibration Detection.

    PubMed

    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

  15. EVALUATION OF OPTICAL DETECTION METHODS FOR WATERBORNE SUSPENSIONS

    EPA Science Inventory

    Turbidimeters and optical paricle counters (OPCs) are used to monitor particulate matter in water. The response from these instruments is governed by the optical properties of the suspension and the instrument design. The recommended design criteria for turbidimeters allows for l...

  16. Optical path switching based differential absorption radiometry for substance detection

    NASA Technical Reports Server (NTRS)

    Sachse, Glen W. (Inventor)

    2003-01-01

    An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

  17. Optical path switching based differential absorption radiometry for substance detection

    NASA Technical Reports Server (NTRS)

    Sachse, Glen W. (Inventor)

    2005-01-01

    An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.

  18. Coherent (photon) vs incoherent (current) detection of multidimensional optical signals from single molecules in open junctions

    SciTech Connect

    Agarwalla, Bijay Kumar; Hua, Weijie; Zhang, Yu; Mukamel, Shaul; Harbola, Upendra

    2015-06-07

    The nonlinear optical response of a current-carrying single molecule coupled to two metal leads and driven by a sequence of impulsive optical pulses with controllable phases and time delays is calculated. Coherent (stimulated, heterodyne) detection of photons and incoherent detection of the optically induced current are compared. Using a diagrammatic Liouville space superoperator formalism, the signals are recast in terms of molecular correlation functions which are then expanded in the many-body molecular states. Two dimensional signals in benzene-1,4-dithiol molecule show cross peaks involving charged states. The correlation between optical and charge current signal is also observed.

  19. Nuisance alarm suppression techniques for fibre-optic intrusion detection systems

    NASA Astrophysics Data System (ADS)

    Mahmoud, Seedahmed S.; Visagathilagar, Yuvaraja; Katsifolis, Jim

    2012-02-01

    The suppression of nuisance alarms without degrading sensitivity in fibre-optic intrusion detection systems is important for maintaining acceptable performance. Signal processing algorithms that maintain the POD and minimize nuisance alarms are crucial for achieving this. A level crossings algorithm is presented for suppressing torrential rain-induced nuisance alarms in a fibre-optic fence-based perimeter intrusion detection system. Results show that rain-induced nuisance alarms can be suppressed for rainfall rates in excess of 100 mm/hr, and intrusion events can be detected simultaneously during rain periods. The use of a level crossing based detection and novel classification algorithm is also presented demonstrating the suppression of nuisance events and discrimination of nuisance and intrusion events in a buried pipeline fibre-optic intrusion detection system. The sensor employed for both types of systems is a distributed bidirectional fibre-optic Mach Zehnder interferometer.

  20. Evaluating the Accuracy of Optic Nerve Detections in Retina Imaging Using Complementary Methods

    SciTech Connect

    Karnowski, Thomas Paul; Aykac, Deniz; Chaum, Edward; Giancardo, Luca; Tobin Jr, Kenneth William

    2009-01-01

    The detection of the optic nerve in retina images is a key element of detecting the anatomical structure of the retina. In this work we report on the fusion of two complementary optic nerve detection methods. The methods are complementary in the sense that they use different fundamental queues for locating the optic nerve. By fusing the methods through applying simple distance-based threshold, a confidence level may be assigned to the quality of the optic nerve detection. In a practical screening system this metric can be used to determine if the images should be immediately reviewed by a physician or if further automatic processing is feasible. We report on the results for two different data sets and show that the use of the threshold improves detection quality.

  1. Magneto-optic detection system with noise cancellation

    NASA Technical Reports Server (NTRS)

    Lewicki, G. W.; Guisinger, J. E. (Inventor)

    1973-01-01

    In a magneto-optic readout system, a polarized beam of light from a laser is subjected to the magneto-optical effect of a magnetic record medium, and then passed through an analyzer which resolves the beam into two orthogonal vector components so oriented that the two components are of equal amplitude when the angle of rotation due to the magneto-optic effect is zero. Separate photodetectors produce two output signals which are proportional to the amplitudes of the vector components. The two output signals are combined in a differential amplifier through separate logarithmic transfer circuits to produce an output signal proportional to the ratio of the two original detector signals.

  2. Fiber-Optic Sensor Would Detect Movements Of Shaft

    NASA Technical Reports Server (NTRS)

    Roschak, Edmund J.

    1989-01-01

    Fiber-optic sensor senses both rotational speed and axial displacement of shaft in motor, pump, or other rotating machine. Does not require magnetic materials, notches, or grooves in shaft. Required modification of shaft is etching or plating surface to make ring black around half circumference and reflective around other half along short length at one end or some other convenient location. Triangular bundle of sending and receiving optical fibers aimed at black/reflective ring on shaft. Frequency and amplitude of output pulses of fiber-optic probe indicates rotational frequency and axial position of shaft.

  3. Interference-free optical detection for Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet (Inventor); Fischer, David G (Inventor); Kojima, Jun (Inventor)

    2012-01-01

    An architecture for spontaneous Raman scattering (SRS) that utilizes a frame-transfer charge-coupled device (CCD) sensor operating in a subframe burst gating mode to realize time-resolved combustion diagnostics is disclosed. The technique permits all-electronic optical gating with microsecond shutter speeds (<5 .mu.s), without compromising optical throughput or image fidelity. When used in conjunction with a pair of orthogonally-polarized excitation lasers, the technique measures time-resolved vibrational Raman scattering that is minimally contaminated by problematic optical background noise.

  4. Electro-optic detection of continuous-wave mid-infrared radiation

    NASA Astrophysics Data System (ADS)

    Cao, Hua; Nahata, Ajay

    2002-10-01

    We demonstrate coherent detection of continuous-wave mid-infrared radiation. This radiation is produced by use of conventional difference-frequency mixing and detected via the linear electro-optic effect. The detection process allows for the simultaneous measurement of the amplitude and phase properties of the infrared field. Both processes require an amplitude-modulated optical beam that is derived from the superimposed output of two single-frequency lasers. With appropriate choice of lasers and nonlinear optical crystals, the technique may be applied to any wavelength throughout the far and mid infrared.

  5. Optical reflectance assay for the detection of biofilm formation.

    PubMed

    Broschat, Shira L; Loge, Frank J; Peppin, Jason D; White, David; Call, Douglas R; Kuhn, Edward

    2005-01-01

    We describe the protocol for an inexpensive and nondestructive optical reflectance assay for the measurement of biofilm formation. Reflectance data are obtained using an Ocean Optics (Dunedin, Florida) USB 2000 spectrometer with a polychromatic light source. A fiber optic cable is used both for illumination and collection, and Ocean Optics OOIBase32 Platinum software is used for preliminary processing of the data. Differences in reflectance data collected at times ranging from 2 to 24 h distinguish between cell attachment and volume growth for two strains of Enterococci. Confocal scanning laser microscopy imaging is used to confirm these results. Phase contrast microscopy images are also obtained in conjunction with reflectance measurements for several different biofilm specimens. The experiments consider biofilm formation on glass and polystyrene substrata, but the method can be used for many other abiotic substrata of interest, both opaque and nonopaque. PMID:16178660

  6. Distributed fiber optic acoustic sensor for leak detection

    NASA Astrophysics Data System (ADS)

    Kurmer, John P.; Kingsley, Stuart A.; Laudo, John S.; Krak, Stephen J.

    1992-01-01

    Leaks in dielectric fluid-filled, high-voltage distribution lines can cause significant problems for the electric power industry. Often, these lines run over long distance and are difficult to access. Operators may know that a leak exists because additional fluid is required to maintain pipe pressure; however, locating the leak is often a significant challenge. A system that could monitor and locate leaks within the electrical distribution pipe lines would be highly desirable. We present a distributed fiber optic acoustic sensor technology that could be used to measure and locate leaks within fluid-filled, high-voltage distribution lines. In this application, the optical fiber sensor is placed inside the fluid-filled pipe and can potentially locate leaks to within several meters. The fiber optic acoustic sensor is designed such that it can listen to the sound produced by the fluid as it escapes from the pipe into the surrounding soil. The fluid inside the pipe is typically maintained at a pressure of 200 psi and escapes at high velocity when a leak occurs. The distributed fiber optic sensing system being developed is based upon the Sagnac interferometer and is unusual in that range information is not obtained by the more common method of optical time domain reflectometry or optical frequency domain reflectometry, but by essentially a CW technique which works in the frequency domain. It is also unusual in that the signal processing technique actually looks for the absence of a signal.

  7. Hadamard precoding for PAPR reduction in optical direct detection OFDM systems

    NASA Astrophysics Data System (ADS)

    Wang, Zhong-Peng; Xiao, Jiang-Nan; Li, Fan; Chen, Lin

    2011-09-01

    The high peak-to-average power ration (PAPR) values of optical orthogond frequency division multiplexing (OFDM) signal limit the system nonlinear tolerance (NLT). In this paper, a novel method based on Hadamard precoding is proposed to reduce the peak-to-average power ratio in optical direct detection OFDM system. The proposed scheme is successfully applied to an experimental system of optical direct-detection OFDM signal transmission through fiber. In this experiment, the 2.5 Gbit/s binary phase shift keying (BPSK) optical OFDM signals with Hadamard precoding are generated and transmitted though a single mode fiber. The experimental results show that the proposed scheme can reduce PAPR by almost 1.5 dB. Meantime the received sensitivity is improved by 2 dB with 100 km fiber transmission compared with that of an ordinary optical direct detection OFDM system.

  8. Remote detection of single emitters via optical waveguides

    NASA Astrophysics Data System (ADS)

    Then, Patrick; Razinskas, Gary; Feichtner, Thorsten; Haas, Philippe; Wild, Andreas; Bellini, Nicola; Osellame, Roberto; Cerullo, Giulio; Hecht, Bert

    2014-05-01

    The integration of lab-on-a-chip technologies with single-molecule detection techniques may enable new applications in analytical chemistry, biotechnology, and medicine. We describe a method based on the reciprocity theorem of electromagnetic theory to determine and optimize the detection efficiency of photons emitted by single quantum emitters through truncated dielectric waveguides of arbitrary shape positioned in their proximity. We demonstrate experimentally that detection of single quantum emitters via such waveguides is possible, confirming the predicted behavior of the detection efficiency. Our findings blaze the trail towards efficient lensless single-emitter detection compatible with large-scale optofluidic integration.

  9. Detection of multipath effect using a self-pumped optical phase-conjugate filter.

    PubMed

    Li, Y; Ha, B; Eichmann, G; Kanterakis, E G; Caviris, N P

    1991-05-15

    A new optical Fourier domain filtering scheme that combines the conventional optical space-invariant linear filtering with a self-pumped nonlinear-optical phase-conjugation technique is proposed. The new method is used for a real-time detection and channel evaluation of the multipath information needed in radar, sonar, and communication signal-processing applications. Preliminary experimental demonstrations are included. PMID:19774056

  10. Automatic Detection of Optic Disc in Retinal Image by Using Keypoint Detection, Texture Analysis, and Visual Dictionary Techniques

    PubMed Central

    Bayır, Şafak

    2016-01-01

    With the advances in the computer field, methods and techniques in automatic image processing and analysis provide the opportunity to detect automatically the change and degeneration in retinal images. Localization of the optic disc is extremely important for determining the hard exudate lesions or neovascularization, which is the later phase of diabetic retinopathy, in computer aided eye disease diagnosis systems. Whereas optic disc detection is fairly an easy process in normal retinal images, detecting this region in the retinal image which is diabetic retinopathy disease may be difficult. Sometimes information related to optic disc and hard exudate information may be the same in terms of machine learning. We presented a novel approach for efficient and accurate localization of optic disc in retinal images having noise and other lesions. This approach is comprised of five main steps which are image processing, keypoint extraction, texture analysis, visual dictionary, and classifier techniques. We tested our proposed technique on 3 public datasets and obtained quantitative results. Experimental results show that an average optic disc detection accuracy of 94.38%, 95.00%, and 90.00% is achieved, respectively, on the following public datasets: DIARETDB1, DRIVE, and ROC. PMID:27110272

  11. Image processing techniques applied to the detection of optic disk: a comparison

    NASA Astrophysics Data System (ADS)

    Kumari, Vijaya V.; Narayanan, Suriya N.

    2010-02-01

    In retinal image analysis, the detection of optic disk is of paramount importance. It facilitates the tracking of various anatomical features and also in the extraction of exudates, drusens etc., present in the retina of human eye. The health of retina crumbles with age in some people during the presence of exudates causing Diabetic Retinopathy. The existence of exudates increases the risk for age related macular Degeneration (AMRD) and it is the leading cause for blindness in people above the age of 50.A prompt diagnosis when the disease is at the early stage can help to prevent irreversible damages to the diabetic eye. Screening to detect diabetic retinopathy helps to prevent the visual loss. The optic disk detection is the rudimentary requirement for the screening. In this paper few methods for optic disk detection were compared which uses both the properties of optic disk and model based approaches. They are uniquely used to give accurate results in the retinal images.

  12. Fiber-optic-based surface plasmon resonance (SPR) sensors for the detection of toxic nerve agents

    NASA Astrophysics Data System (ADS)

    Prakash, Anna M. C.; Kim, Yoon-Chang; Banerji, Soame; Masson, Jean-Francois; Booksh, Karl S.

    2004-03-01

    Analytical instruments capable of detecting nerve agents in battlefield conditions where speed, accuracy and ease of operation are a must in today's military. Fast detection and decontamination of nerve agents in very low concentrations is the primary focus of our research. The method presented here focuses on optimizing polymer stabilized sensing elements on the surface of SPR fiber-optic probes. A number of polymers & polymer supported metal complexes capable of reversibly binding to the species of interest & which have robust operation in hostile environments are incorporated with the fiber optic sensing elements. An optical technique, such as Surface Plasmon Resonance (SPR), better suited to rapid data collection without sample pretreatment is employed. The approach using polymer-based optical fibers with off-the-shelf SPR system components has been tested for the detection of Pinacolyl methylphosphonate (PMP), a simulant for nerve agent Soman. Surface initiated polymeric sensors have higher sensitivity toward detecting PMP than bulk-polymerized sensors.

  13. Surface-enhanced nonlinear optical effects and detection of adsorbed molecular monolayers

    SciTech Connect

    Shen, Y.R.; Chen, C.K.; Heinz, T.F.; Ricard, D.

    1981-01-01

    The observation of a number of surface-enhanced nonlinear optical effects is discussed. The feasibility of using second-harmonic generation to detect the adsorption of molecular monolayers on a metal surface in an electrolytic solution is shown.

  14. Photon Counting System for High-Sensitivity Detection of Bioluminescence at Optical Fiber End.

    PubMed

    Iinuma, Masataka; Kadoya, Yutaka; Kuroda, Akio

    2016-01-01

    The technique of photon counting is widely used for various fields and also applicable to a high-sensitivity detection of luminescence. Thanks to recent development of single photon detectors with avalanche photodiodes (APDs), the photon counting system with an optical fiber has become powerful for a detection of bioluminescence at an optical fiber end, because it allows us to fully use the merits of compactness, simple operation, highly quantum efficiency of the APD detectors. This optical fiber-based system also has a possibility of improving the sensitivity to a local detection of Adenosine triphosphate (ATP) by high-sensitivity detection of the bioluminescence. In this chapter, we are introducing a basic concept of the optical fiber-based system and explaining how to construct and use this system. PMID:27424915

  15. Fibre optic systems for gas detection principals, progress and prospects

    NASA Astrophysics Data System (ADS)

    Culshaw, Brian

    2010-11-01

    Gas sensing is evolving into an important application contributing particularly to environmental and safety monitoring. Fibre optic sensing will have an important role to play as the need for gas measurements increase. This paper seeks to overview of the optical techniques which are compatible with fibre optic technology and present a limited snapshot of the applications. Fibre optic techniques offer intrinsic safety, reliability and very long interrogation distances over the fibre link together with prospects for highly multiplexed and distributed systems. There are two basic approaches for fibre sensing targeted at gas measurements. The first involves some intermediate compound in contact with the end of the fibre (or deposited along the fibre) whose optical properties change with the presence of the gas of interest, usually measured spectroscopically. The second involves direct absorption spectroscopy typically in the near infrared. Former techniques are invariably responsive to a number of gas species and are usually difficult to calibrate accurately. The latter techniques are highly gas specific and can be accurately calibrated. However both approaches have their application sectors depending upon particular measurement requirements. The paper presents a brief overview of the principles of both these techniques and analyses some of their applications.

  16. Application of signal detection theory to optics. [image evaluation and restoration

    NASA Technical Reports Server (NTRS)

    Helstrom, C. W.

    1973-01-01

    Basic quantum detection and estimation theory, applications to optics, photon counting, and filtering theory are studied. Recent work on the restoration of degraded optical images received at photoelectrically emissive surfaces is also reported, the data used by the method are the numbers of electrons ejected from various parts of the surface.

  17. QUANTITATIVE DETECTION OF ENVIRONMENTALLY IMPORTANT DYES USING DIODE LASER/FIBER-OPTIC RAMAN

    EPA Science Inventory

    A compact diode laser/fiber-optic Raman spectrometer is used for quantitative detection of environmentally important dyes. This system is based on diode laser excitation at 782 mm, fiber optic probe technology, an imaging spectrometer, and state-of-the-art scientific CCD camera. ...

  18. Guided Wave and Damage Detection in Composite Laminates Using Different Fiber Optic Sensors

    PubMed Central

    Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

    2009-01-01

    Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH0) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent. PMID:22412347

  19. Detection of avian influenza antigens in proximity fiber, droplet, and optical waveguide microfluidics

    NASA Astrophysics Data System (ADS)

    Yoon, Jeong-Yeol; Heinze, Brian C.; Gamboa, Jessica; You, David J.

    2009-05-01

    Virus antigens of avian influenza subtype H3N2 were detected on two different microfluidic platforms: microchannel and droplet. Latex immunoagglutination assays were performed using 920-nm highly carboxylated polystyrene beads that are conjugated with antibody to avian influenza virus. The bead suspension was merged with the solutions of avian influenza virus antigens in a Y-junction of a microchannel made by polydimethylsiloxane soft lithography. The resulting latex immunoagglutinations were measured with two optical fibers in proximity setup to detect 45° forward light scattering. Alternatively, 10 μL droplets of a bead suspension and an antigen solution were merged on a superhydrophobic surface (water contact angle = 155°), whose movement was guided by a metal wire, and 180° back light scattering is measured with a backscattering optical probe. Detection limits were 0.1 pg mL-1 for both microchannel with proximity fibers and droplet microfluidics, thanks to the use of micro-positioning stages to help generate reproducible optical signals. Additionally, optical waveguide was tested by constructing optical waveguide channels (filled with mineral oil) within a microfluidic device to detect the same light scattering. Detection limit was 0.1 ng mL-1 for an optical waveguide device, with a strong potential of improvement in the near future. The use of optical waveguide enabled smaller device setup, easier operation, smaller standard deviations and broader linear range of assay than proximity fiber microchannel and droplet microfluidics. Total assay time was less than 10 min.

  20. Optical Detection of core-gold nanoshells inside biosystems

    NASA Astrophysics Data System (ADS)

    D'Acunto, Mario; Dinarelli, Simone; Cricenti, Antonio; Luce, Marco

    2016-02-01

    Metal nanoshells having a dielectric core with a thin gold layer are generating new interest due to the unique optical, electric and magnetic properties exhibited by the local field enhancement near the metal - dielectric core interface. These nanoshells possess strong, highly tunable local plasmon resonances with frequencies dependent upon the nanoshell shape and core material. These unique characteristics have applications in biosensing, optical communication and medicine. In this paper, we developed a theoretical, numerical and experimental approach based on a scanning near optical microscope to identify nanoshells inside mouse cells. Taking advantage of the characteristic near-infrared transparency window of many biological systems, i.e. the low light absorption coefficient of biological systems between 750-1100 nm, we were able to identify a 100-150 nm diameter barium titanate-gold nanoshell inside the h9c2 mouse cells.

  1. Pathogen detection using evanescent-wave fiber optic biosensor

    NASA Astrophysics Data System (ADS)

    Ferreira, Aldo P.; Werneck, Marcelo M.; Ribeiro, R. M.; Lins, U. G.

    1999-07-01

    This paper describes a real time optical biosensor that utilizes the evanescent field technique for monitoring microorganisms in hospital environment. The biosensor monitors interactions between the analytic (bacteria) and the evanescent field of an optical fiber passing through the culture media where the bacteria grows. The objective is to monitor atmospheres in hospital areas for the Staphylococcus aureus and Streptococcus pneumonia. The results lead us the conclusion that this kind of sensor presents quick response, good performance, easy of construction and low cost. We expect that the sensor will be of great help in controlling the hospital environment.

  2. Quantum Dots Microstructured Optical Fiber for X-Ray Detection

    NASA Technical Reports Server (NTRS)

    DeHaven, Stan; Williams, Phillip; Burke, Eric

    2015-01-01

    Microstructured optical fibers containing quantum dots scintillation material comprised of zinc sulfide nanocrystals doped with magnesium sulfide are presented. These quantum dots are applied inside the microstructured optical fibers using capillary action. The x-ray photon counts of these fibers are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The results of the fiber light output and associated effects of an acrylate coating and the quantum dot application technique are discussed.

  3. Optical design of an optical coherence tomography and multispectral fluorescence imaging endoscope to detect early stage ovarian cancer

    NASA Astrophysics Data System (ADS)

    Tate, Tyler; Keenan, Molly; Swan, Elizabeth; Black, John; Utzinger, Urs; Barton, Jennifer

    2014-12-01

    The five year survival rate for ovarian cancer is over 90% if early detection occurs, yet no effective early screening method exists. We have designed and are constructing a dual modality Optical Coherence Tomography (OCT) and Multispectral Fluorescence Imaging (MFI) endoscope to optically screen the Fallopian tube and ovary for early stage cancer. The endoscope reaches the ovary via the natural pathway of the vagina, cervix, uterus and Fallopian tube. In order to navigate the Fallopian tube the endoscope must have an outer diameter of 600 μm, be highly flexible, steerable, tracking and nonperforating. The imaging systems consists of six optical subsystems, two from OCT and four from MFI. The optical subsystems have independent and interrelated design criteria. The endoscope will be tested on realistic tissue models and ex vivo tissue to prove feasibility of future human trials. Ultimately the project aims to provide women the first effective ovarian cancer screening technique.

  4. Research on vision-based error detection system for optic fiber winding

    NASA Astrophysics Data System (ADS)

    Lu, Wenchao; Li, Huipeng; Yang, Dewei; Zhang, Min

    2011-11-01

    Optic fiber coils are the hearts of fiber optic gyroscopes (FOGs). To detect the irresistible errors during the process of winding of optical fibers, such as gaps, climbs and partial rises between fibers, when fiber optic winding machines are operated, and to enable fully automated winding, we researched and designed this vision-based error detection system for optic fiber winding, on the basis of digital image collection and process[1]. When a Fiber-optic winding machine is operated, background light is used as illumination system to strength the contrast of images between fibers and background. Then microscope and CCD as imaging system and image collecting system are used to receive the analog images of fibers. After that analog images are shifted into digital imagines, which can be processed and analyzed by computers. Canny edge detection and a contour-tracing algorithm are used as the main image processing method. The distances between the fiber peaks were then measured and compared with the desired values. If these values fall outside of a predetermined tolerance zone, an error is detected and classified either as a gap, climb or rise. we used OpenCV and MATLAB database as basic function library and used VC++6.0 as the platform to show the results. The test results showed that the system was useful, and the edge detection and contour-tracing algorithm were effective, because of the high rate of accuracy. At the same time, the results of error detection are correct.

  5. Direct detection of optical phase conjugation in a colloidal medium.

    PubMed

    López-Mariscal, Carlos; Gutiérrez-Vega, Julio C; McGloin, David; Dholakia, Kishan

    2007-05-14

    Degenerate four-wave mixing is demonstrated using an artificial Kerr medium and is evidenced by directly observing the phase conjugation of a vortex signal beam. The nonlinear susceptibility is produced by a refractive index grating created in a suspension of dielectric microscopic particles optically confined in the intensity grating distribution of two interfering laser beams. PMID:19546937

  6. New radiological material detection technologies for nuclear forensics: Remote optical imaging and graphene-based sensors.

    SciTech Connect

    Harrison, Richard Karl; Martin, Jeffrey B.; Wiemann, Dora K.; Choi, Junoh; Howell, Stephen W.

    2015-09-01

    We developed new detector technologies to identify the presence of radioactive materials for nuclear forensics applications. First, we investigated an optical radiation detection technique based on imaging nitrogen fluorescence excited by ionizing radiation. We demonstrated optical detection in air under indoor and outdoor conditions for alpha particles and gamma radiation at distances up to 75 meters. We also contributed to the development of next generation systems and concepts that could enable remote detection at distances greater than 1 km, and originated a concept that could enable daytime operation of the technique. A second area of research was the development of room-temperature graphene-based sensors for radiation detection and measurement. In this project, we observed tunable optical and charged particle detection, and developed improved devices. With further development, the advancements described in this report could enable new capabilities for nuclear forensics applications.

  7. Meeting current public health needs: optical biosensors for pathogen detection and analysis

    NASA Astrophysics Data System (ADS)

    Yang, Minghui; Sapsford, Kim E.; Sergeev, Nikolay; Sun, Steven; Rasooly, Avraham

    2009-02-01

    Pathogen detection and analysis is critical for medicine, food safety, agriculture, public health and biosecurity. Many current microbial detection approaches are based on century-old culturing methods which, while reliable, are slow, provide relatively little information about the pathogens and are not adaptable to high throughput operations. Optical biodetection represents a potential alternative. Most ELISA and chromatography systems are based on optical methods that are also used for analysis of molecular interactions, such as DNA hybridization and protein-protein interactions (e.g. microarrays or SPR biosensors). Various optical biosensor platforms have been developed that have many of the characteristics essential for modern pathogen molecular analysis including sensitivity, speed of analysis, multi-channel capability, relative simplicity and low cost. Here we provide several examples of the use of optical biosensor technology for pathogen detection and analysis including high throughput DNA microarray analysis, SPR-based rapid direct detection of bacterial toxins, CCD-based fluorescent activity analysis of microbial toxins and a simple ECL-based CCD detection system. However, while effective for molecular analysis, most of these technologies are not as sensitive as traditional culturing methods for detecting microorganisms. There is a need to combine optical biosensors with traditional methods to speed culture-based detection and to provide more information regarding the pathogens.

  8. Light-scattering detection of quantum phases of ultracold atoms in optical lattices

    SciTech Connect

    Ye Jinwu; Zhang, J. M.; Liu, W. M.; Zhang Keye; Li Yan; Zhang Weiping

    2011-05-15

    Ultracold atoms loaded on optical lattices can provide unprecedented experimental systems for the quantum simulations and manipulations of many quantum phases. However, so far, how to detect these quantum phases effectively remains an outstanding challenge. Here, we show that the optical Bragg scattering of cold atoms loaded on optical lattices can be used to detect many quantum phases, which include not only the conventional superfluid and Mott insulating phases, but also other important phases, such as various kinds of charge density wave (CDW), valence bond solid (VBS), CDW supersolid (CDW-SS) and Valence bond supersolid (VB-SS).

  9. Spectrally resolved detection in transient-reflectivity measurements of coherent optical phonons in diamond

    NASA Astrophysics Data System (ADS)

    Nakamura, Kazutaka G.; Ohya, Kazuma; Takahashi, Hiroshi; Tsuruta, Tetsuya; Sasaki, Hiroya; Uozumi, Shin-ichi; Norimatsu, Katsura; Kitajima, Masahiro; Shikano, Yutaka; Kayanuma, Yosuke

    2016-07-01

    Coherent optical phonons in bulk solid systems play a crucial role in understanding and designing light-matter interactions and can be detected by the transient-reflectivity measurement. In this paper, we demonstrate spectrally resolved detection of coherent optical phonons in diamond from ultrashort infrared pump-probe measurements using optical bandpass filters. We show that this enhances the sensitivity approximately 35 times in measuring the coherent oscillations in the transient reflectivity compared with the commonly used spectrally integrated measurement. To explain this observation, we discuss its mechanism.

  10. Functionalization of optical nanotip arrays with an electrochemical microcantilever for multiplexed DNA detection.

    PubMed

    Descamps, Emeline; Duroure, Nathalie; Deiss, Frédérique; Leichlé, Thierry; Adam, Catherine; Mailley, Pascal; Aït-Ikhlef, Ali; Livache, Thierry; Nicu, Liviu; Sojic, Neso

    2013-08-01

    Optical nanotip arrays fabricated on etched fiber bundles were functionalized with DNA spots. Such unconventional substrates (3D and non-planar) are difficult to pattern with standard microfabrication techniques but, using an electrochemical cantilever, up to 400 spots were electrodeposited on the nanostructured optical surface in 5 min. This approach allows each spot to be addressed individually and multiplexed fluorescence detection is demonstrated. Finally, remote fluorescence detection was performed by imaging through the optical fiber bundle itself after hybridisation with the complementary sequence. PMID:23695411

  11. Fusion of optical flow based motion pattern analysis and silhouette classification for person tracking and detection

    NASA Astrophysics Data System (ADS)

    Tangelder, Johan W. H.; Lebert, Ed; Burghouts, Gertjan J.; van Zon, Kasper; den Uyl, Marten J.

    2014-10-01

    This paper presents a novel approach to detect persons in video by combining optical flow based motion analysis and silhouette based recognition. A new fast optical flow computation method is described, and its application in a motion based analysis framework unifying human tracking and detection is outlined. Our optical flow algorithm represents optical flow by grid based motion vectors, which are computed very efficiently and robustly applying template matching. We model the motion patterns of the tracked human and non-human objects by the positions, velocities, motion magnitudes, and motion directions of their optical flow vectors, and build a random forest on these features. For recognition, the random forest computes a normalized score measuring the similarity of a track to a human track. Using edge detection on a motion image for each motion blob its silhouette is computed. Recognition scores are computed, which measure the similarity of the silhouettes with human silhouettes. The optical flow classifier and the silhouette classifier are used as a combined classifier. We analyze the ROC curve to set different decision thresholds on the recognition score for different scenarios. The experiments on the VIRAT test set demonstrate that for human detection the combination of the optical flow based motion method with one based on human silhouette analysis, obtains superior results, compared to the constituent methods.

  12. Subwavelength-resolution photoacoustic microscopy for label-free detection of optical absorption in vivo

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Maslov, Konstantin; Wang, Lihong V.

    2011-03-01

    Mainstream optical microscopy technologies normally detect fluorescence or scattering, which may require undesirable labeling, but cannot directly sense optical absorption, which provides essential biological functional information. Here we reported in vivo and label-free subwavelength-resolution photoacoustic microscopy (SW-PAM) by using a waterimmersion optical objective with a 1.23 NA. Capable of detecting nonfluorescent endogenous pigments, SW-PAM provides exquisitely high optical-absorption contrast. And, as a result of background-free detection, the sensitivity of SW-PAM to optical absorption reaches 100%. SW-PAM was demonstrated with wide-field optical microscopy by imaging gold nanospheres, ex vivo cells, and in vivo vasculature and melanoma. It was shown that SW-PAM has approached the ultimate diffraction-limited optical resolution-220 nm resolution at 532 nm wavelength. Subcellular organelles, such as melanosomes, can be resolved by SW-PAM. Vasculature and early-stage melanoma were imaged with 21:1 and 34:1 contrasts, respectively, without labeling. For all these applications, SW-PAM has contrasts orders of magnitude higher than wide-field optical microscopy. Therefore, SW-PAM is expected to join the mainstream microscopy technologies.

  13. Seven-year-long crack detection monitoring by Brillouin-based fiber optic strain sensor

    NASA Astrophysics Data System (ADS)

    Imai, Michio

    2015-03-01

    As an optical fiber is able to act as a sensing medium, a Brillouin-based sensor provides continuous strain information along an optical fiber. The sensor has been used in a wide range of civil engineering applications because no other tool can satisfactorily detect discontinuity such as a crack. Cracking generates a local strain change on the embedded optical fiber, thus Brillouin optical correlation domain analysis (BOCDA), which offers a high spatial resolution by stimulated Brillouin scattering, is expected to detect a fine crack on concrete structures. The author installed the surface-mounted optical fiber on a concrete deck and periodically monitored strain distribution for seven years. This paper demonstrates how a BOCDA-based strain sensor can be employed to monitor cracks in a concrete surface. Additionally, focusing on another advantage of the sensor, the natural frequency of the deck is successfully measured by dynamic strain history.

  14. OMCat: Catalogue of Serendipitous Sources Detected with the XMM-Newton Optical Monitor

    NASA Technical Reports Server (NTRS)

    Kuntz, K. D.; Harrus, Ilana; McGlynn, Thomas A.; Mushotsky, Richard F.; Snowden, Steven L.

    2007-01-01

    The Optical Monitor Catalogue of serendipitous sources (OMCat) contains entries for every source detected in the publically available XMM-Newton Optical Monitor (OM) images taken in either the imaging or "fast" modes. Since the OM records data simultaneously with the X-ray telescopes on XMM-Newton, it typically produces images in one or more near-UV/optical bands for every pointing of the observatory. As of the beginning of 2006, the public archive had covered roughly 0.5% of the sky in 2950 fields. The OMCat is not dominated by sources previously undetected at other wavelengths; the bulk of objects have optical counterparts. However, the OMCat can be used to extend optical or X-ray spectral energy distributions for known objects into the ultraviolet, to study at higher angular resolution objects detected with GALEX, or to find high-Galactic-latitude objects of interest for UV spectroscopy.

  15. Colorless ONU implementation for WDM-PON using direct-detection optical OFDM

    NASA Astrophysics Data System (ADS)

    Feng, Min; Luo, Qing-long; Bai, Cheng-lin

    2013-03-01

    A novel architecture for the colorless optical network unit (ONU) is proposed and experimentally demonstrated with direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM). In this architecture, polarization-division multiplexing is used to reduce the cost at ONU. In optical line terminal (OLT), quadrature amplitude modulation (QAM) intensity-modulated OFDM signal with x-polarization at 10 Gbit/s is transmitted as downstream. At each ONU, the optical OFDM signal is demodulated with direct detection, and γ-polarization signal is modulated for upstream on-off keying (OOK) data at 5 Gbit/s. Simulation results show that the power penalty is negligible for both optical OFDM downstream and the on-off keying upstream signals after over 50 km single-mode fiber (SMF) transmission.

  16. Applications of optically detected MRI for enhanced contrast and penetration in metal

    NASA Astrophysics Data System (ADS)

    Ruangchaithaweesuk, Songtham; Yu, Dindi S.; Garcia, Nissa C.; Yao, Li; Xu, Shoujun

    2012-10-01

    We report quantitative measurements using optically detected magnetic resonance imaging (MRI) for enhanced pH contrast and flow inside porous metals. Using a gadolinium chelate as the pH contrast agent, we show the response is 0.6 s-1 mM-1 per pH unit at the ambient magnetic field for the pH range 6-8.5. A stopped flow scheme was used to directly measure T1 relaxation time to determine the relaxivity. Flow profiles and images were obtained for a series of porous metals with different average pore sizes. The signal amplitudes and spatial distributions were compared. A clogged region in one of the samples was revealed using optically detected MRI but not optical imaging or scanning electron microscopy. These applications will significantly broaden the impact of optically detected MRI in chemical imaging and materials research.

  17. Optic Disc and Optic Cup Segmentation Methodologies for Glaucoma Image Detection: A Survey.

    PubMed

    Almazroa, Ahmed; Burman, Ritambhar; Raahemifar, Kaamran; Lakshminarayanan, Vasudevan

    2015-01-01

    Glaucoma is the second leading cause of loss of vision in the world. Examining the head of optic nerve (cup-to-disc ratio) is very important for diagnosing glaucoma and for patient monitoring after diagnosis. Images of optic disc and optic cup are acquired by fundus camera as well as Optical Coherence Tomography. The optic disc and optic cup segmentation techniques are used to isolate the relevant parts of the retinal image and to calculate the cup-to-disc ratio. The main objective of this paper is to review segmentation methodologies and techniques for the disc and cup boundaries which are utilized to calculate the disc and cup geometrical parameters automatically and accurately to help the professionals in the glaucoma to have a wide view and more details about the optic nerve head structure using retinal fundus images. We provide a brief description of each technique, highlighting its classification and performance metrics. The current and future research directions are summarized and discussed. PMID:26688751

  18. Optic Disc and Optic Cup Segmentation Methodologies for Glaucoma Image Detection: A Survey

    PubMed Central

    Almazroa, Ahmed; Burman, Ritambhar; Raahemifar, Kaamran; Lakshminarayanan, Vasudevan

    2015-01-01

    Glaucoma is the second leading cause of loss of vision in the world. Examining the head of optic nerve (cup-to-disc ratio) is very important for diagnosing glaucoma and for patient monitoring after diagnosis. Images of optic disc and optic cup are acquired by fundus camera as well as Optical Coherence Tomography. The optic disc and optic cup segmentation techniques are used to isolate the relevant parts of the retinal image and to calculate the cup-to-disc ratio. The main objective of this paper is to review segmentation methodologies and techniques for the disc and cup boundaries which are utilized to calculate the disc and cup geometrical parameters automatically and accurately to help the professionals in the glaucoma to have a wide view and more details about the optic nerve head structure using retinal fundus images. We provide a brief description of each technique, highlighting its classification and performance metrics. The current and future research directions are summarized and discussed. PMID:26688751

  19. Optical detection of glucose concentration in samples with scattering particles.

    PubMed

    Lin, Li-Han; Lo, Yu-Lung; Liao, Chia-Chi; Lin, Jian-Xiang

    2015-12-10

    An optical-based method is proposed for measuring the glucose concentration of samples containing scattering particles. In the proposed approach, a Stokes-Mueller reflection-based polarimetry technique is used to solve the Mueller matrices of a turbid glucose sample with circular birefringence and depolarization properties given six incident lights with different polarization states. Using an error function defined as the difference between the simulated output Stokes vectors and the experimental ones, a genetic algorithm is used to inversely derive the optical rotation and depolarization parameters of the experimental sample corresponding to the glucose concentration and scattering depolarization effect, respectively. The validity of the proposed method is demonstrated using glucose samples containing 0.02 ml and 0.04 ml lipofundin, respectively. PMID:26836866

  20. DETECTION OF MOLECULAR MONOLAYERS BY OPTICAL. SECOND HARMONIC GENERATION

    SciTech Connect

    Chen, C. K.; Heinz, T. F.; Ricard, D.; Shen, Y. R.

    1980-12-01

    Second harmonic generation is shown to be sensitive enough to detect molecular monolayers adsorbed on a silver surface. Adsorption of AgCl and pyridine on silver during and after an electrolytic cycle can be easily observed,

  1. An evaluation of fiber optic intrusion detection systems in interior applications

    SciTech Connect

    Vigil, J.T.

    1994-03-01

    This report discusses the testing and evaluation of four commercially available fiber optic intrusion detection systems. The systems were tested under carpet-type matting and in a vaulted ceiling application. This report will focus on nuisance alarm data and intrusion detection results. Tests were conducted in a mobile office building and in a bunker.

  2. Broadband field-resolved terahertz detection via laser induced air plasma with controlled optical bias.

    PubMed

    Li, Chia-Yeh; Seletskiy, Denis V; Yang, Zhou; Sheik-Bahae, Mansoor

    2015-05-01

    We report a robust method of coherent detection of broadband THz pulses using terahertz induced second-harmonic (TISH) generation in a laser induced air plasma together with a controlled second harmonic optical bias. We discuss a role of the bias field and its phase in the process of coherent detection. Phase-matching considerations subject to plasma dispersion are also examined. PMID:25969238

  3. The Detection of Helicobacter hepaticus Using Whispering-Gallery Mode Microcavity Optical Sensors

    PubMed Central

    Anderson, Mark E.; O’Brien, Emily C.; Grayek, Emily N.; Hermansen, James K.; Hunt, Heather K.

    2015-01-01

    Current bacterial detection techniques are relatively slow, require bulky instrumentation, and usually require some form of specialized training. The gold standard for bacterial detection is culture testing, which can take several days to receive a viable result. Therefore, simpler detection techniques that are both fast and sensitive could greatly improve bacterial detection and identification. Here, we present a new method for the detection of the bacteria Helicobacter hepaticus using whispering-gallery mode (WGM) optical microcavity-based sensors. Due to minimal reflection losses and low material adsorption, WGM-based sensors have ultra-high quality factors, resulting in high-sensitivity sensor devices. In this study, we have shown that bacteria can be non-specifically detected using WGM optical microcavity-based sensors. The minimum detection for the device was 1 × 104 cells/mL, and the minimum time of detection was found to be 750 s. Given that a cell density as low as 1 × 103 cells/mL for Helicobacter hepaticus can cause infection, the limit of detection shown here would be useful for most levels where Helicobacter hepaticus is biologically relevant. This study suggests a new approach for H. hepaticus detection using label-free optical sensors that is faster than, and potentially as sensitive as, standard techniques. PMID:26262647

  4. Detection, Evaluation, and Optimization of Optical Signals Generated by Fiber Optic Bragg Gratings Under Dynamic Excitations

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory; Lekki, John; Lock, James A.

    2002-01-01

    The dynamic response of a fiber optic Bragg grating to mechanical vibrations is examined both theoretically and experimentally. The theoretical expressions describing the consequences of changes in the grating's reflection spectrum are derived for partially coherent beams in an interferometer. The analysis is given in terms of the dominant wavelength, optical bandwidth, and optical path difference of the interfering signals. Changes in the reflection spectrum caused by a periodic stretching and compression of the grating were experimentally measured using an unbalanced Michelson interferometer, a Michelson interferometer with a non-zero optical path difference. The interferometer's sensitivity to changes in dominant wavelength of the interfering beams was measured as a function of interferometer unbalance and was compared to theoretical predictions. The theoretical analysis enables the user to determine the optimum performance for an unbalanced interferometer.

  5. NASA/GSFC program in direct detection optical communications for intersatellite links

    NASA Technical Reports Server (NTRS)

    Fitzmaurice, M.; Bruno, R.

    1989-01-01

    NASA-Goddard has undertaken the development of direct-detection optical communications for space applications at the Gbps data rate channel capability level. The primary challenges to optical communications designers lie in the development of reliable optical power sources, as well as of high performance pointing/acquisition/tracking systems required by the narrow widths of the transmitted optical beams. GaAlAs diodes and their arrays are currently the most attractive technology for optical transmitters; pioneering work has also been conducted on dichroic and grating techniques for combining the power of several laser diodes. Attention is given to the performance obtained for an optical link acquisition and submicroradian tracking/pointing system.

  6. Brillouin optical correlation domain reflectometry with lock-in detection scheme

    NASA Astrophysics Data System (ADS)

    Yao, Yuguo; Kishi, Masato; Hotate, Kazuo

    2016-07-01

    We propose a Brillouin optical correlation domain reflectometry (BOCDR) technique with a lock-in detection scheme in this paper. By designing a new system using the lock-in detection scheme and amplifying a small spontaneous Brillouin signal with a lock-in amplifier, a Brillouin scattering spectrum with a stable shape is obtained. By further introducing a periodical on/off phase modulation for chopping for lock-in detection, the undesired optical background spectrum is effectively reduced, and a 20 cm section with 7,000 µε strain is clearly measured.

  7. Measurement of aerosol optical depth and sub-visual cloud detection using the optical depth sensor (ODS)

    NASA Astrophysics Data System (ADS)

    Toledo, D.; Rannou, P.; Pommereau, J.-P.; Sarkissian, A.; Foujols, T.

    2016-02-01

    A small and sophisticated optical depth sensor (ODS) has been designed to work in the atmosphere of Mars. The instrument measures alternatively the diffuse radiation from the sky and the attenuated direct radiation from the Sun on the surface. The principal goals of ODS are to retrieve the daily mean aerosol optical depth (AOD) and to detect very high and optically thin clouds, crucial parameters in understanding the Martian meteorology and climatology. The detection of clouds is undertaken at twilight, allowing the detection and characterization of clouds with opacities below 0.03 (sub-visual clouds). In addition, ODS is capable to retrieve the aerosol optical depth during nighttime from moonlight measurements. Recently, ODS has been selected at the METEO meteorological station on board the ExoMars 2018 Lander. In order to study the performance of ODS under Mars-like conditions as well as to evaluate the retrieval algorithms for terrestrial measurements, ODS was deployed in Ouagadougou (Africa) between November 2004 and October 2005, a Sahelian region characterized by its high dust aerosol load and the frequent occurrence of Saharan dust storms. The daily average AOD values retrieved by ODS were compared with those provided by a CIMEL sunphotometer of the AERONET (Aerosol Robotic NETwork) network localized at the same location. Results represent a good agreement between both ground-based instruments, with a correlation coefficient of 0.77 for the whole data set and 0.94 considering only the cloud-free days. From the whole data set, a total of 71 sub-visual cirrus (SVC) were detected at twilight with opacities as thin as 1.10-3 and with a maximum of occurrence at altitudes between 14 and 20 km. Although further optimizations and comparisons of ODS terrestrial measurements are required, results indicate the potential of these measurements to retrieve the AOD and detect sub-visual clouds.

  8. Measurement of aerosol optical depth and sub-visual cloud detection using the optical depth sensor (ODS)

    NASA Astrophysics Data System (ADS)

    Toledo, D.; Rannou, P.; Pommereau, J.-P.; Sarkissian, A.; Foujols, T.

    2015-09-01

    A small and sophisticated optical depth sensor (ODS) has been designed to work in the atmosphere of Earth and Mars. The instrument measures alternatively the diffuse radiation from the sky and the attenuated direct radiation from the sun on the surface. The principal goals of ODS are to retrieve the daily mean aerosol optical depth (AOD) and to detect very high and optically thin clouds, crucial parameters in understanding the Martian and Earth meteorology and climatology. The detection of clouds is undertaken at twilight, allowing the detection and characterization of clouds with opacities below 0.03 (sub-visual clouds). In addition, ODS is capable to retrieve the aerosol optical depth during night-time from moonlight measurements. In order to study the performance of ODS under Mars-like conditions as well as to evaluate the retrieval algorithms for terrestrial measurements, ODS was deployed in Ouagadougou (Africa) between November 2004 and October 2005, a sahelian region characterized by its high dust aerosol load and the frequent occurrence of Saharan dust storms. The daily average AOD values retrieved by ODS were compared with those provided by a CIMEL Sun-photometer of the AERONET (Aerosol Robotic NETwork) network localized at the same location. Results represent a good agreement between both ground-based instruments, with a correlation coefficient of 0.79 for the whole data set and 0.96 considering only the cloud-free days. From the whole dataset, a total of 71 sub-visual cirrus (SVC) were detected at twilight with opacities as thin as 1.10-3 and with a maximum of occurrence at altitudes between 14 and 20 km. Although further analysis and comparisons are required, results indicate the potential of ODS measurements to detect sub-visual clouds.

  9. Optical fluorescence biosensor for plant water stress detection

    NASA Astrophysics Data System (ADS)

    Chong, Jenny P. C.; Liew, O. W.; Li, B. Q.; Asundi, A. K.

    2007-05-01

    Precision farming in arable agriculture and horticulture allows conservative use of resources that are applied according to plant needs. The growing concern for sustainability in crop production has accentuated the significance of our work to develop a rapid, sensitive and non-destructive spectroscopic method for real-time monitoring of plant water stress. Elucidation of crop water status before the onset of irreversible cellular damage is critical for effective water management to ensure maximum crop yield and profit margin. A two-component bio-sensing system comprising transgenic 'Indicator Plants' and a spectrometer-linked stereoscopic microscope was developed to detect early signs of water stress before the permanent wilting point is reached. The 'Indicator Plants' are transgenic Petunia hybrida genetically engineered with a drought-responsive promoter-linked enhanced green fluorescent protein marker gene (EGFP). No EGFP fluorescence was detected prior to induction of dehydration stress. Fluorescence emission intensity increased with dehydration period and was found mainly in the stems, leaf veins and leaf tips. While fluorescence emission above endogenous background was detectable after 2 hours of water stress treatment, the plants reached permanent wilting point after 6 hours, showing that our system was able to detect water stress prior to plant entry into the stage of irreversible damage. Future work will be geared towards overcoming biological and instrument-related difficulties encountered in our initial detection system.

  10. Optically Detected Ferromagnetic Resonance in Metallic Ferromagnets Via Off-Resonant Detection of Nitrogen Vacancy Centers in Diamond

    NASA Astrophysics Data System (ADS)

    Page, Michael R.; Bhallamudi, Vidya P.; Schulze, Joe; Purser, Carola M.; Manuilov, Sergei; Wolfe, Christopher; Brangham, Jack T.; Yang, Fengyuan; Hammel, P. Chris

    We report optical detection of ferromagnetic resonance in thin film metallic ferromagnets using a recently discovered approach employing nitrogen vacancy centers in nanodiamonds. While conventional optically detected magnetic resonance measures magnetic fields through their impact on the magnetic resonance frequency of the nitrogen vacancy center, we measure a change in the nitrogen vacancy center photoluminescence at the ferromagnet's resonance condition without need to work at the NV resonance frequency. This measurement technique allows sensitive, local detection of ferromagnetic resonance and can enable the study of magnetic dynamics at the nanoscale in a wide range of materials. While this measurement protocol was first reported in the study of ferromagnetic resonance in YIG, here we demonstrate the measurement in commonly used metallic ferromagnets to establish the generality of the technique and open the possibility of measuring nanoscale patterned devices and magnetic textures based on metallic ferromagnets of both commercial and scientific interest.

  11. Activatable Optical Probes for the Detection of Enzymes

    PubMed Central

    Drake, Christopher R.; Miller, David C.; Jones, Ella F.

    2013-01-01

    The early detection of many human diseases is crucial if they are to be treated successfully. Therefore, the development of imaging techniques that can facilitate early detection of disease is of high importance. Changes in the levels of enzyme expression are known to occur in many diseases, making their accurate detection at low concentrations an area of considerable active research. Activatable fluorescent probes show immense promise in this area. If properly designed they should exhibit no signal until they interact with their target enzyme, reducing the level of background fluorescence and potentially endowing them with greater sensitivity. The mechanisms of fluorescence changes in activatable probes vary. This review aims to survey the field of activatable probes, focusing on their mechanisms of action as well as illustrating some of the in vitro and in vivo settings in which they have been employed. PMID:23519774

  12. Role of condenser iris in optical tweezer detection system.

    PubMed

    Samadi, Akbar; Reihani, S Nader S

    2011-10-15

    Optical tweezers have proven to be very useful in various scientific fields, from biology to nanotechnology. In this Letter we show, both by theory and experiment, that the interference intensity pattern at the back focal plane of the condenser consists of two distinguishable areas with anticorrelated intensity changes when the bead is moved in the axial direction. We show that the space angle defining the border of two areas linearly depends on the NA of the objective. We also propose a new octant photodiode, which could significantly improve the axial resolution compared to the commonly used quadrant photodiode technique. PMID:22002384

  13. The application of signal detection theory to optics

    NASA Technical Reports Server (NTRS)

    Helstrom, C. W.

    1971-01-01

    The restoration of images focused on a photosensitive surface is treated from the standpoint of maximum likelihood estimation, taking into account the Poisson distributions of the observed data, which are the numbers of photoelectrons from various elements of the surface. A detector of an image focused on such a surface utilizes a certain linear combination of those numbers as the optimum detection statistic. Methods for calculating the false alarm and detection probabilities are proposed. It is shown that measuring noncommuting observables in an ideal quantum receiver cannot yield a lower Bayes cost than that attainable by a system measuring only commuting observables.

  14. Detecting T Tauri disks with optical long-baseline interferometry.

    NASA Astrophysics Data System (ADS)

    Malbet, F.; Bertout, C.

    1995-10-01

    We present synthetic images of disks around T Tauri stars. We calculate visibility curves in order to study the possibility of directly detecting thermal emission from T Tauri disks. Total fluxes of T Tauri disks are compared to the sensitivity of VISA, the interferometric sub-array of the European Very Large Telescope. We conclude that thermal emission from circumstellar disk around T Tauri stars is detectable with current or soon-to-be interferometric techniques at wavelengths longer than 2.2μm.

  15. Optical tomograph optimized for tumor detection inside highly absorbent organs

    NASA Astrophysics Data System (ADS)

    Boutet, Jérôme; Koenig, Anne; Hervé, Lionel; Berger, Michel; Dinten, Jean-Marc; Josserand, Véronique; Coll, Jean-Luc

    2011-05-01

    This paper presents a tomograph for small animal fluorescence imaging. The compact and cost-effective system described in this article was designed to address the problem of tumor detection inside highly absorbent heterogeneous organs, such as lungs. To validate the tomograph's ability to detect cancerous nodules inside lungs, in vivo tumor growth was studied on seven cancerous mice bearing murine mammary tumors marked with Alexa Fluor 700. They were successively imaged 10, 12, and 14 days after the primary tumor implantation. The fluorescence maps were compared over this time period. As expected, the reconstructed fluorescence increases with the tumor growth stage.

  16. Detection of Chamber Conditioning Through Optical Emission and Impedance Measurements

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, Meyya

    2001-01-01

    During oxide etch processes, buildup of fluorocarbon residues on reactor sidewalls can cause run-to-run drift and will necessitate some time for conditioning and seasoning of the reactor. Though diagnostics can be applied to study and understand these phenomena, many of them are not practical for use in an industrial reactor. For instance, measurements of ion fluxes and energy by mass spectrometry show that the buildup of insulating fluorocarbon films on the reactor surface will cause a shift in both ion energy and current in an argon plasma. However, such a device cannot be easily integrated into a processing system. The shift in ion energy and flux will be accompanied by an increase in the capacitance of the plasma sheath. The shift in sheath capacitance can be easily measured by a common commercially available impedance probe placed on the inductive coil. A buildup of film on the chamber wall is expected to affect the production of fluorocarbon radicals, and thus the presence of such species in the optical emission spectrum of the plasma can be monitored as well. These two techniques are employed on a GEC (Gaseous Electronics Conference) Reference Cell to assess the validity of optical emission and impedance monitoring as a metric of chamber conditioning. These techniques are applied to experimental runs with CHF3 and CHF3/O2/Ar plasmas, with intermediate monitoring of pure argon plasmas as a reference case for chamber conditions.

  17. Theory of force detection using optically levitated nanoparticles

    NASA Astrophysics Data System (ADS)

    Rodenburg, Brandon; Neukirch, Levi; Pettit, Robert; Vamivakas, Nick; Bhattacharya, Mishkat

    2016-05-01

    Levitated nanoparticles offer the potential of being incredibly well isolated from the environment. This isolation makes such systems excellent candidates for tests of quantum mechanics at the macroscale and as versatile platforms for ultrasensitive metrology. Systems involving an optical cavity mode to provide the trapping field, as well as cooling mechanism of the particle's center of mass motion are well understood theoretically and provide a canonical system for the field of quantum optomechanics. However, techniques based on measurement based parametric cooling and feedback stabilization have made it possible to trap and manipulate a nanoparticle without the need for an optical cavity, even at extremely high vacuum where gas damping cannot stabilize the motion of the particle. For these cavityless systems, a fully quantum theory has recently been developed. In this talk we will present recent work that we have carried out to apply this theory to the use of such devices as force sensors, including a discussion of the ultimate limits placed on the sensitivity by the sources of fundamental quantum noise. Office of Naval Research.

  18. Laboratory Studies of Nonlinear Optical Signals for Caries Detection.

    PubMed

    Terrer, E; Panayotov, I V; Slimani, A; Tardivo, D; Gillet, D; Levallois, B; Fejerskov, O; Gergely, C; Cuisinier, F J G; Tassery, H; Cloitre, T

    2016-05-01

    Multiphoton confocal microscopy and nonlinear spectroscopy are used to investigate the caries process in dentin. Although dentin is a major calcified tissue of the teeth, its organic phase comprises type I collagen fibers. Caries drive dentin demineralization and collagen denaturation. Multiphoton microscopy is a powerful imaging technique: the biological materials are transparent to infrared frequencies and can be excited to penetration depths inaccessible to 1-photon confocal microscopy. The laser excitation greatly reduces photodamage to the sole focal region, and the signal-to-noise ratio is improved significantly. The method has been used to follow pathologic processes involving collagen fibrosis or collagen destruction based on their 2-photon excited fluorescence (2PEF) emission and second harmonic generation (SHG). Combining multiphoton imaging with nonlinear spectroscopy, we demonstrate that both 2PEF and SHG intensity of human dentin are strongly modified during the tooth caries process, and we show that the ratio between SHG and 2PEF signals is a reliable parameter to follow dental caries. The ratio of the SHG/2PEF signals measured by nonlinear optical spectroscopy provides valuable information on the caries process, specifically on the degradation of the organic matrix of dentin. The goal is to bring these nonlinear optical signals to clinical application for caries diagnosis. PMID:26826107

  19. Detecting and characterizing infrasound signals with optical fiber infrasound sensors

    NASA Astrophysics Data System (ADS)

    Walker, Kristoffer; Zumberge, Mark; Berger, Jonathan; Hedlin, Michael; Arrowsmith, Stephen

    2005-04-01

    Optical Fiber Infrasound Sensors (OFIS) are long compliant tubes wrapped with two optical fibers that interferometrically measure the differential pressure variation along the length of the tube. Because each sensor averages spatially along the length of the tube, the frequency response of the recorded pressure variation is a function of the orientation of the OFIS sensor relative to the back azimuth and incidence angle of the incoming wave. We have exploited this property to investigate the ability of various OFIS geometries to determine the back azimuth of infrasound signals. We have found that an OFIS comprised of two orthogonal 89-m-long arms having their centers separated by 63 m can resolve the back azimuth of most infrasound signals with a good signal-to-noise ratio. We find a good match between the back azimuths determined with our technique and those determined for the same signals recorded on the co-located pipe array I57US with the Progressive Multichannel Cross-Correlation technique. Based on these results and additional synthetic tests, we have built and are testing a larger OFIS with several arms that will be able to resolve signals from all directions and with small signal-to-noise ratios.

  20. Linear polarization detection of polarization-sensitive optical coherence tomography in the early detection of the application of dental caries

    NASA Astrophysics Data System (ADS)

    Li, Lei; Zeng, Nan; Yang, Lifeng

    2010-11-01

    Polarization-Sensitive Optical Coherence Tomography (PS-OCT) is an important functional OCT. By extracting the polarization properties from PS-OCT signals we can obtain more information about the structural and optical features of tissues or materials. Dental caries is one of the most prevalent chronic diseases of people worldwide. The primary caries detection and the structure transformation of the enamel and dentin between sound and broken teeth are given serious attention by dentists. In this paper, using our Fourier-domain polarization-sensitive optical coherence tomography (FD-PS-OCT) setup by three incident linear polarization states and two detection states, we can get the 9 Mueller matrix elements from M11to M33 of the decay areas of the artificial caries measured. We also applied our polarized sensitive Monte Carlo program in the simulation of the PS-OCT detection process. We used a sphere-cylinder scattering model as an approximation of anisotropic tissues to describe the optical properties of tooth. By comparing the Mueller matrix elements of both experimental and simulation results, especially the diagonal elements (M11, M22 and M33), we reach the point that the main structural change of the caries that affects its scattering features is the expanded diameter of the enamel rods and dentinal tubules caused by the acid corrosion due to caries lesion.

  1. FIBER OPTIC FLUOROIMMUNOSENSOR FOR THE DETECTION OF POLYCHLORINATED BIPHENYLS

    EPA Science Inventory

    There currently exists a critical and growing need for cost-effective, real-time, and in situ methods for detection of environmental pollutants such as polychlorinated biphenyls (PCBs). erein reported is a evanescent wave Fluoroimmunosensor for measurement of PCBS. 2,4-5-Trichlor...

  2. Enabling accurate photodiode detection of multiple optical traps by spatial filtering

    NASA Astrophysics Data System (ADS)

    Ott, Dino; Reihani, S. Nader S.; Oddershede, Lene B.

    2014-09-01

    Dual and multiple beam optical tweezers allow for advanced trapping geometries beyond single traps, however, these increased manipulation capabilities, usually complicate the detection of position and force. The accuracy of position and force measurements is often compromised by crosstalk between the detected signals, this crosstalk leading to a systematic error on the measured forces and distances. In dual-beam optical trapping setups, the two traps are typically orthogonal polarized and crosstalk can be minimized by inserting polarization optics in front of the detector, however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Moreover, the restriction to two orthogonal polarisation states limits the number of detectable traps to two. Here, we present an easy-to-implement simple method to efficiently eliminate cross-talk in dual beam setups.1 The technique is based on spatial filtering and is highly compatible with standard back-focal-plane photodiode based detection. The reported method significantly improves the accuracy of force-distance measurements, e.g., of single molecules, hence providing much more scientific value for the experimental efforts. Furthermore, it opens the possibility for fast and simultaneous photodiode based detection of multiple holographically generated optical traps.

  3. Detection of apparent skin motion using optical flow analysis: Blood pulsation signal obtained from optical flow sequence

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuki; Maekawa, Tsuyoshi; Miike, Hidetoshi

    1997-02-01

    A skin motion imaging system with two modes of operation, diffusive and specular reflections, was developed. The system consists of image capturing and processing elements. Using optical flow analyses of skin motion at the wrist, we have detected successfully a blood pulsation signal that concurs with the electrocardiogram. The signal provides information not only about blood pulsation, but also about blood circulation and the biomechanical properties of the skin. This system may have other applications in the future, such as noncontact blood pulsation detection and evaluation of the biomechanical properties of skin, for example.

  4. Electro-optical detection probability of optical devices determined by bidirectional laser retro-reflection cross section

    NASA Astrophysics Data System (ADS)

    Laurenzis, Martin; Christnacher, Frank; Matwyschuk, Alexis; Schertzer, Stephane; Hengy, Sebastien

    2015-05-01

    A good measure for the probability to detect a sniper telescopic sight is the effective bi-directional laser retro-reflection cross section. This angular (bi-directional) property of an optical device can be measured and can be used for a fist estimation of its probability to be detected by an active imaging. In the present paper, the authors give examples for resolved and non-resolved sensing of a telescopic sight under mono-static and bi-static conditions. As a result of these measurements, the resolved sensing under mono-static conditions shows the highest signal response in a wide angular range.

  5. Alkali Halide Microstructured Optical Fiber for X-Ray Detection

    NASA Technical Reports Server (NTRS)

    DeHaven, S. L.; Wincheski, R. A.; Albin, S.

    2014-01-01

    Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. The results and associated materials difference are discussed.

  6. Fiber-optic laser sensor for mine detection and verification

    NASA Astrophysics Data System (ADS)

    Bohling, Christian; Scheel, Dirk; Hohmann, Konrad; Schade, Wolfgang; Reuter, Matthias; Holl, Gerhard

    2006-06-01

    What we believe to be a new optical approach for the identification of mines and explosives by analyzing the surface materials and not only bulk is developed. A conventional manually operated mine prodder is upgraded by laser-induced breakdown spectroscopy (LIBS). In situ and real-time information of materials that are in front of the prodder are obtained during the demining process in order to optimize the security aspects and the speed of demining. A Cr4+:Nd3+:YAG microchip laser is used as a seed laser for an ytterbium-fiber amplifier to generate high-power laser pulses at 1064 nm with pulse powers up to Ep=1 mJ, a repetition rate of frep.=2-20 kHz and a pulse duration of tp=620 ps. The recorded LIBS signals are analyzed by applying neural networks for the data analysis.

  7. Fiber-optic laser sensor for mine detection and verification.

    PubMed

    Bohling, Christian; Scheel, Dirk; Hohmann, Konrad; Schade, Wolfgang; Reuter, Matthias; Holl, Gerhard

    2006-06-01

    What we believe to be a new optical approach for the identification of mines and explosives by analyzing the surface materials and not only bulk is developed. A conventional manually operated mine prodder is upgraded by laser-induced breakdown spectroscopy (LIBS). In situ and real-time information of materials that are in front of the prodder are obtained during the demining process in order to optimize the security aspects and the speed of demining. A Cr4+:Nd3+:YAG microchip laser is used as a seed laser for an ytterbium-fiber amplifier to generate high-power laser pulses at 1064 nm with pulse powers up to E(p) = 1 mJ, a repetition rate of f(rep.) = 2-20 kHz and a pulse duration of t(p) = 620 ps. The recorded LIBS signals are analyzed by applying neural networks for the data analysis. PMID:16724144

  8. Alkali halide microstructured optical fiber for X-ray detection

    SciTech Connect

    DeHaven, S. L. E-mail: russel.a.wincheski@nasa.gov; Wincheski, R. A. E-mail: russel.a.wincheski@nasa.gov; Albin, S.

    2015-03-31

    Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. The results and associated materials difference are discussed.

  9. ELECTRO-OPTICAL DETECTION OF CHARGED PARTICLE BEAMS.

    SciTech Connect

    SEMERTZIDIS,Y.K.CASTILLO,V.LARSEN,R.C.LAZARUS,D.M.MAGURNO,B.SRINIVASAN-RAO,T.TSANG,T.USACK,V.,ET AL.

    2003-03-01

    We have made the first observation of a charged particle beam by means of its electro-optical effect on the propagation of laser light in a birefringent crystal at the Brookhaven National Laboratory Accelerator Test Facility. Polarized infrared light was coupled to a LiNbO{sub 3} crystal through a polarization maintaining fiber of 4 micron diameter. An electron beam in 10 ps bunches of 1 mm diameter was scanned across the crystal. The modulation of the laser light during passage of the electron beam was observed using a photodiode with 45 GHz bandwidth. The fastest rise time measured, 120 ps, was made in the single shot mode and was limited by the bandwidth of the oscilloscope and the associated electronics. Both polarization dependent and polarization independent effects were observed. This technology holds promise of greatly improved spatial and temporal resolution of charged particle beams.

  10. Detecting early stage osteoarthritis by optical coherence tomography?

    PubMed Central

    Jahr, Holger; Brill, Nicolai; Nebelung, Sven

    2015-01-01

    Abstract Osteoarthritis (OA) is the most common chronic disease of our joints, manifested by a dynamically increasing degeneration of hyaline articular cartilage (AC). While currently no therapy can reverse this process, the few available treatment options are hampered by the inability of early diagnosis. Loss of cartilage surface, or extracellular matrix (ECM), integrity is considered the earliest sign of OA. Despite the increasing number of imaging modalities surprisingly few imaging biomarkers exist. In this narrative review, recent developments in optical coherence tomography are critically evaluated for their potential to assess different aspects of AC quality as biomarkers of OA. Special attention is paid to imaging surface irregularities, ECM organization and the evaluation of posttraumatic injuries by light-based modalities. PMID:26862954

  11. Optical image sensors and their application in radon detection

    NASA Astrophysics Data System (ADS)

    Griffin, Ryan H.; Tarr, N. Garry

    2013-10-01

    This paper reports on the development and testing of a direct reading radon detector assembled from consumer electronics at very low cost. An electrostatic concentrator constructed by metalizing a plastic funnel is used to focus charged radon progeny onto the exposed surface of an optical image sensor from a webcam. Alpha particles emitted by the collected progeny strike the image sensor, generating sufficient charge to completely saturate one or more pixels The high voltage required by the concentrator is generated using a simple Cockcroft-Walton charge pump. A personal computer is used to analyze the webcam data. Alpha particles were counted at a rate of 5.2 counts/ hour at a radon concentration of 159 Bq/ m3.

  12. Micromachined force-balance feedback accelerometer with optical displacement detection

    DOEpatents

    Nielson, Gregory N.; Langlois, Eric; Baker, Michael; Okandan, Murat; Anderson, Robert

    2014-07-22

    An accelerometer includes a proof mass and a frame that are formed in a handle layer of a silicon-on-an-insulator (SOI). The proof mass is separated from the frame by a back-side trench that defines a boundary of the proof mass. The accelerometer also includes a reflector coupled to a top surface of the proof mass. An optical detector is located above the reflector at the device side. The accelerometer further includes at least one suspension spring. The suspension spring has a handle anchor that extends downwards from the device side to the handle layer to mechanically support upward and downward movement of the proof mass relative to a top surface of the proof mass.

  13. Retroreflective imaging system for optical labeling and detection of microorganisms.

    PubMed

    Bergen, Mark H; Nichols, Jacqueline; Collier, Christopher M; Jin, Xian; Raja, Balakrishnan; Roberts, Deborah J; Ruchhoeft, Paul; Willson, Richard C; Holzman, Jonathan F

    2014-06-10

    A retroreflective imaging system for imaging microscopic targets over macroscopic sampling areas is introduced. Detection of microorganism-bound retroreflector (RR) targets across millimeter-scale samples is implemented according to retroreflection directionality, collimation, and contrast design characteristics. Retroreflection directionality is considered for corner-cube (CC) and spherical geometries. Spherical-RRs improve directionality and reliability. Retroreflection collimation is considered for spherical-RRs. Retroreflective images for micro-CC-RRs and micro-spherical-RRs with varying refractive indices show optimal results for high refractive index BaTiO3 micro-spherical-RRs. A differential imaging technique improves retroreflection contrast by 35 dB. High refractive index micro-spherical-RRs and differential imaging, together, can detect microscopic RR targets across macroscopic areas. PMID:24921128

  14. An optical radar for airborne use over natural waters. [for underwater target detection

    NASA Technical Reports Server (NTRS)

    Levis, C. A.; Swarner, W. G.; Prettyman, C.; Reinhardt, G. W.

    1975-01-01

    An optical radar for detecting targets in natural waters was built and tested in the Gulf of Mexico. The transmitter consists of a Q switched neodymium glass laser, with output amplified and doubled in KDP to 0.53 micrometer wavelength. The receiver incorporates a noval optical spatial filter to reduce the dynamic range required of the photodetector to a reasonable value. Detection of targets to a depth of 26 meters (84 feet) was achieved with a considerable sensitivity margin. The sensitivity of the radar is highly dependent on the optical attenuation coefficient. In general, measured returns fell between the values predicted on the basis of monopath and multipath attenuation. By means of simple physical arguments, a radar equation for the system was derived. To validate this theoretical model, measurements of optical attenuation and of water surface behavior were also instrumented, and some of these results are given.

  15. Orbital debris detection program highlights from the Air Force Maui Optical Station

    NASA Astrophysics Data System (ADS)

    Houchard, Jeff E.; Kervin, Paul W.; Africano, John L.; Kuo, Shiao D.; Medrano, Robert S.; Lambert, John V.

    1994-06-01

    The Air Force Maui Optical Station (AMOS) conducted searches, measurements, and analyses of the orbital debris environment for the Air Force Space Command and the Phillips Laboratory since May 1991 in support of the Air Force Orbital Debris Measurements Program. The objective of this program was to detect orbiting low earth objects not currently in the United States Space Command Space Surveillance Center catalog. Once objects were detected, further objectives were to track, catalog, and maintain those objects locally, to determine statistics on detected objects, and perform relevant analyses. AMOS has developed a prototype surveillance system for the detection and tracking of orbital debris. In addition to this surveillance activity, AMOS has also automated the post-processing videotape streak detection process and is automating the analysis process. Both the optical tracking of orbital debris and the automatic streak detection process were thought to be virtually impossible only a few years ago. The AMOS program employed wide field of view optical telescopes using the Maui Groundbased Electro-Optical Deep Space Surveillance site and AMOS narrow field of view tracking telescopes, both located at the Maui Space Surveillance Site.

  16. Asynchronous detection of optical code division multiple access signals using a bandwidth-efficient and wavelength-aware receiver.

    PubMed

    Fok, Mable P; Deng, Yanhua; Prucnal, Paul R

    2010-04-01

    We experimentally demonstrate what we believe to be a novel detection scheme for interfacing asynchronous optical code division multiple access (CDMA) signals with an electronic clock and data recovery system that operates only at the baseband bandwidth. This allows using a large optical bandwidth expansion factor in which the optical chip rate is much larger than the bandwidth of the optoelectronic receiver. The received optical CDMA signal is launched into a four-wave-mixing-based wavelength-aware all-optical front end that rejects multiaccess interference, followed by an amplitude-noise suppression stage comprised of a semiconductor optical amplifier. The clean signal is then converted into a non-return-to-zero-like signal by a baseband receiver. Using the proposed detection scheme, asynchronous transmission and detection of optical CDMA signals is implemented. With the novel detection scheme, the classic CDMA near-far problem is mitigated, and error-free detection is easily obtained. PMID:20364229

  17. Optical architecture design for detection of absorbers embedded in visceral fat

    PubMed Central

    Francis, Robert; Florence, James; MacFarlane, Duncan

    2014-01-01

    Optically absorbing ducts embedded in scattering adipose tissue can be injured during laparoscopic surgery. Non-sequential simulations and theoretical analysis compare optical system configurations for detecting these absorbers. For absorbers in deep scattering volumes, trans-illumination is preferred instead of diffuse reflectance. For improved contrast, a scanning source with a large area detector is preferred instead of a large area source with a pixelated detector. PMID:24877008

  18. Optical architecture design for detection of absorbers embedded in visceral fat.

    PubMed

    Francis, Robert; Florence, James; MacFarlane, Duncan

    2014-05-01

    Optically absorbing ducts embedded in scattering adipose tissue can be injured during laparoscopic surgery. Non-sequential simulations and theoretical analysis compare optical system configurations for detecting these absorbers. For absorbers in deep scattering volumes, trans-illumination is preferred instead of diffuse reflectance. For improved contrast, a scanning source with a large area detector is preferred instead of a large area source with a pixelated detector. PMID:24877008

  19. Advances in Optical Adjunctive Aids for Visualisation and Detection of Oral Malignant and Potentially Malignant Lesions

    PubMed Central

    Bhatia, Nirav; Lalla, Yastira; Vu, An N.; Farah, Camile S.

    2013-01-01

    Traditional methods of screening for oral potentially malignant disorders and oral malignancies involve a conventional oral examination with digital palpation. Evidence indicates that conventional examination is a poor discriminator of oral mucosal lesions. A number of optical aids have been developed to assist the clinician to detect oral mucosal abnormalities and to differentiate benign lesions from sinister pathology. This paper discusses advances in optical technologies designed for the detection of oral mucosal abnormalities. The literature regarding such devices, VELscope and Identafi, is critically analysed, and the novel use of Narrow Band Imaging within the oral cavity is also discussed. Optical aids are effective in assisting with the detection of oral mucosal abnormalities; however, further research is required to evaluate the usefulness of these devices in differentiating benign lesions from potentially malignant and malignant lesions. PMID:24078812

  20. Label-Free Optical Detection of Biomolecular Translocation through Nanopore Arrays

    PubMed Central

    2015-01-01

    In recent years, nanopores have emerged as exceptionally promising single-molecule sensors due to their ability to detect biomolecules at subfemtomole levels in a label-free manner. Development of a high-throughput nanopore-based biosensor requires multiplexing of nanopore measurements. Electrical detection, however, poses a challenge, as each nanopore circuit must be electrically independent, which requires complex nanofluidics and embedded electrodes. Here, we present an optical method for simultaneous measurements of the ionic current across an array of solid-state nanopores, requiring no additional fabrication steps. Proof-of-principle experiments are conducted that show simultaneous optical detection and characterization of ssDNA and dsDNA using an array of pores. Through a comparison with electrical measurements, we show that optical measurements are capable of accessing equivalent transmembrane current information. PMID:25232895

  1. Automatic Detection of the Optic Disc of the Retina: A Fast Method.

    PubMed

    Jamshidi, M; Rabbani, H; Amini, Z; Kafieh, R; Ommani, A; Lakshminarayanan, V

    2016-01-01

    Localizing the optic disc (OD) in retinal fundus images is of critical importance and many techniques have been developed for OD detection. In this paper, we present the results obtained from two fast methods, correlation and least square, to approximate the location of optic cup. These methods are simple and are not complex, while most of the OD detection algorithms are. The methods were tested on two groups of data (a total of 100 color fundus images) and were 98% successful in the detection of the optic cup. An algorithm using the vessel mask of fundus images is proposed to be run after correlation to ensure that the localization of OD in all images is successful. It was tested on 40 of the test images and had a 100% rate of success. PMID:27014613

  2. Polarization-based balanced detection for spectral-domain optical coherence tomography.

    PubMed

    Black, Adam J; Akkin, Taner

    2015-08-20

    We present a new design for spectral-domain optical coherence tomography that allows balanced detection using a single camera. The design uses polarization optics to encode the light in reference and sample arms. Two parallel and highly aligned spectra, which carry out-of-phase interference signals, in-phase common noise, and auto-interference terms, are focused on the camera, which performs the digital balanced detection for each wavelength. The optical system is characterized and tested for tissue imaging. Results demonstrate consistent signal gains in depth and suppression of DC and sample auto-interference. The design could be further amended for polarization-sensitive imaging and might demonstrate a market for manufacturing dual-line cameras with analog-balanced detection capability. PMID:26368760

  3. Automatic Detection of the Optic Disc of the Retina: A Fast Method

    PubMed Central

    Jamshidi, M.; Rabbani, H.; Amini, Z.; Kafieh, R.; Ommani, A.; Lakshminarayanan, V.

    2016-01-01

    Localizing the optic disc (OD) in retinal fundus images is of critical importance and many techniques have been developed for OD detection. In this paper, we present the results obtained from two fast methods, correlation and least square, to approximate the location of optic cup. These methods are simple and are not complex, while most of the OD detection algorithms are. The methods were tested on two groups of data (a total of 100 color fundus images) and were 98% successful in the detection of the optic cup. An algorithm using the vessel mask of fundus images is proposed to be run after correlation to ensure that the localization of OD in all images is successful. It was tested on 40 of the test images and had a 100% rate of success. PMID:27014613

  4. A new look at coding for APD-based direct-detection optical channels

    NASA Technical Reports Server (NTRS)

    Herro, Mark A.; Hu, Laizhao

    1988-01-01

    Coding for avalanche-photodiode (APD)-based direct-detection optical channels is investigated using a simple channel model that clearly points out the difference between the signal-dependent optical noise channel model and the additive white Gaussian noise channel model. Coding and modulation are viewed as a single entity, and the coding/modulation gain (CMG) is used to analyze and construct good codes for APD-based optical receivers. It is shown that the structure of block codes, when used in conjunction with on-off keying signaling, renders these codes fairly inefficient with respect to obtaining reasonable CMG on the optical channel. In contrast, codes (or modulations) that use fewer channel ones (pulses) than information ones per block can offer substantial CMG on the optical channel. For bandwidth-constrained applications, it is proposed that pulse-position modulation be used with more than one pulse per word to obtain reasonable CMG while consuming small amounts of bandwidth.

  5. Detection of inherent and laser-induced scatter in optical materials

    SciTech Connect

    Sheehan, L.; Kozlowski, M.

    1995-07-05

    As Lawrence Livermore National Laboratory moves forward with the design of the National Ignition Facility (NIF) in the Inertial Confinement Fusion (ICF) program, issues relating to the detection and measurement of laser-induced damage on large optics must be addressed. Currently, microscopy is used to evaluate surface quality and measure damage thresholds on small witness samples. In order to evaluate large areas, an automated system was constructed which can scan optics with dimensions as large as 1 meter and weighing as much as 400 pounds. The use of microscopy as the main test diagnostic has been replaced with an optical scatter detection system. Now large areas can be rastered, and maps can be generated, reflecting inherent and laser-induced scatter in multilayer optical coatings and bulk materials. The integrated scattered light from a test piece is measured in transmission using a HeNe laser as the probe source. When the probe beam is overlapped on a pulsed, high power, ND:YAG laser beam, damage related scatter may be measured. This technique has been used for: (1) mapping of inherent scatter in an optic, (2) on-the-fly damage detection during a high fluence raster scan of an optic, and (3) single site damage evaluation for the determination of a laser damage threshold. Damage thresholds measured with the scatter diagnostic compare within measurement error to those attained using 100 {times} microscopy.

  6. An optical NMR spectrometer for Larmor-beat detection and high-resolution POWER NMR

    NASA Astrophysics Data System (ADS)

    Kempf, J. G.; Marohn, J. A.; Carson, P. J.; Shykind, D. A.; Hwang, J. Y.; Miller, M. A.; Weitekamp, D. P.

    2008-06-01

    Optical nuclear magnetic resonance (ONMR) is a powerful probe of electronic properties in III-V semiconductors. Larmor-beat detection (LBD) is a sensitivity optimized, time-domain NMR version of optical detection based on the Hanle effect. Combining LBD ONMR with the line-narrowing method of POWER (perturbations observed with enhanced resolution) NMR further enables atomically detailed views of local electronic features in III-Vs. POWER NMR spectra display the distribution of resonance shifts or line splittings introduced by a perturbation, such as optical excitation or application of an electric field, that is synchronized with a NMR multiple-pulse time-suspension sequence. Meanwhile, ONMR provides the requisite sensitivity and spatial selectivity to isolate local signals within macroscopic samples. Optical NMR, LBD, and the POWER method each introduce unique demands on instrumentation. Here, we detail the design and implementation of our system, including cryogenic, optical, and radio-frequency components. The result is a flexible, low-cost system with important applications in semiconductor electronics and spin physics. We also demonstrate the performance of our systems with high-resolution ONMR spectra of an epitaxial AlGaAs /GaAs heterojunction. NMR linewidths down to 4.1Hz full width at half maximum were obtained, a 103-fold resolution enhancement relative any previous optically detected NMR experiment.

  7. Optical fiber tip-based quartz-enhanced photoacoustic sensor for trace gas detection

    NASA Astrophysics Data System (ADS)

    Li, Zhili; Wang, Zhen; Wang, Chao; Ren, Wei

    2016-05-01

    We reported the development of an evanescent-wave quartz-enhanced photoacoustic sensor (EW-QEPAS) using a single-mode optical fiber tip for sensitive gas detection in the extended near-infrared region. It is a spectroscopic technique based on the combination of quartz-enhanced photoacoustic spectroscopy with fiber-optic evanescent-wave absorption to achieve low optical noise, easy optical alignment, and high compactness. Carbon monoxide (CO) detection at 2.3 μm using a fiber-coupled, continuous-wave, distributed-feedback laser was selected for the sensor demonstration. By tapering the optical fiber down to 2.5 μm diameter using the flame-brushing technique, an evanescent field of ~0.6 mW around the fiber tip was absorbed by CO molecules. Besides an excellent linear response ( R 2 = 0.9996) to CO concentrations, the EW-QEPAS sensor achieved a normalized noise-equivalent absorption (NNEA) coefficient of 8.6 × 10-8 cm-1W/√Hz for an incident optical power of 1.8 mW and integration time of 1 s. The sensor detection sensitivity can be further improved by enhancing the evanescent-wave power on the fiber tip.

  8. Optimal detection bandwidth for phase-sensitive optical time-domain reflectometry

    NASA Astrophysics Data System (ADS)

    Lu, Xin; Soto, Marcelo A.; Thévenaz, Luc

    2016-05-01

    The spectrum of the temporal traces obtained from a phase-sensitive optical time-domain reflectometer is theoretically and experimentally analysed, demonstrating its dependence on the incident optical pulse shape. Numerical simulations and theoretical results are validated experimentally, showing a good matching for rectangular optical pulses. The influence of the photodetector bandwidth on the temporal trace quality is also investigated by simulation and experiment. Results show that the photodetector bandwidth needs to be ~ 40 % wider than the pulse spectrum to acquire time-domain traces of the Rayleigh backscattered light with direct detection.

  9. Detection of ultrasonic waves in solids by an optical fiber interferometer

    NASA Technical Reports Server (NTRS)

    Claus, R. O.; Cantrell, J. H., Jr.

    1981-01-01

    An optical fiber interferometer was developed for the detection of ultrasonic waves in solids. The optical paths in both the signal and reference arms of the Mach-Zehnder interferometer are through the cores of similar lengths of single mode fiber mode stripped at both input and output. Instantaneous translation of the pattern is proportional to the localized strain produced by ultrasonic bulk waves generated in the disc and integrated along the fiber path. By spatially filtering the moving fringe pattern and synchronously demodulating the filtered optical intensity distirbution, a signal proportional to the integrated strain is obtained.

  10. Three-dimensional representation of late-arriving photons for detecting inhomogeneities in diffuse optical tomography

    SciTech Connect

    Potlov, A Yu; Proskurin, S G; Frolov, S V

    2014-02-28

    A method for rapid detection of absorbing inhomogeneity in a strongly scattering medium having the properties of a biological tissue before the image reconstruction is described based on the principles of diffuse optical tomography. The method is based on preliminary processing of a three-dimensional surface obtained from the set of time-resolved data in the Cartesian coordinate system, followed by its conformal transformation into two surfaces in the cylindrical coordinate system. A specific feature of the method is the use of late-arriving photons, scattered and diffusely transmitted through an optically turbid object. (optical tomography)

  11. Fabrication experiments on supersmooth optics for extrasolar planet detection

    NASA Technical Reports Server (NTRS)

    Ftaclas, C.; Krim, M. H.; Terrile, R. J.

    1989-01-01

    The direct detection of extrasolar planets by imaging will require reductions in scattered and diffracted light by factors in excess of 1000 within one arcsecond of a bright source. While diffraction can be reduced by a number of approaches, small angle scatter can only be reduced by controlling midspatial frequency figure errors. The surface requirements are reviewed and their meaning when compared to the data base of existing mirrors is considered. Experiments are discribed that were successful in reducing midspatial frequency figure so that the scatter level was 500 times less than diffraction for a 25-cm spherical mirror.

  12. Longitudinal Change Detected by Spectral Domain Optical Coherence Tomography in the Optic Nerve Head and Peripapillary Retina in Experimental Glaucoma

    PubMed Central

    Strouthidis, Nicholas G.; Fortune, Brad; Yang, Hongli; Sigal, Ian A.

    2011-01-01

    Purpose. To investigate whether longitudinal changes deep within the optic nerve head (ONH) are detectable by spectral domain optical coherence tomography (SDOCT) in experimental glaucoma (EG) and whether these changes are detectable at the onset of Heidelberg Retina Tomography (HRT; Heidelberg Engineering, Heidelberg, Germany)–defined surface topography depression. Methods. Longitudinal SDOCT imaging (Spectralis; Heidelberg Engineering) was performed in both eyes of nine rhesus macaques every 1 to 3 weeks. One eye of each underwent trabecular laser-induced IOP elevation. Four masked operators delineated internal limiting membrane (ILM), retinal nerve fiber layer (RNFL), Bruch's membrane/retinal pigment epithelium (BM/RPE), neural canal opening (NCO), and anterior lamina cribrosa surface (ALCS) by using custom software. Longitudinal changes were assessed and compared between the EG and control (nonlasered) eyes at the onset of HRT-detected surface depression (follow-up 1; [FU1]) and at the most recent image (follow-up 2; [FU2]). Results. Mean IOP in EG eyes was 7.1 to 24.6 mm Hg at FU1 and 13.5 to 31.9 mm Hg at FU2. In control eyes, the mean IOP was 7.2 to 12.6 mm Hg (FU1) and 8.9 to 16.0 mm Hg (FU2). At FU1, neuroretinal rim decreased and ALCS depth increased significantly (paired t-test, P < 0.01); no change in RNFL thickness was detected. At FU2, however, significant prelaminar tissue thinning, posterior displacement of NCO, and RNFL thinning were observed. Conclusions. Longitudinal SDOCT imaging can detect deep ONH changes in EG eyes, the earliest of which are present at the onset of HRT-detected ONH surface height depression. These parameters represent realistic targets for SDOCT detection of glaucomatous progression in human subjects. PMID:21217108

  13. Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering

    SciTech Connect

    Ott, Dino; Oddershede, Lene B.; Reihani, S. Nader S.

    2014-05-15

    In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Here we present a simple and easy-to-implement method to efficiently eliminate crosstalk. The method is based on spatial filtering by simply inserting a pinhole at the correct position and is highly compatible with standard back focal plane photodiode based detection of position and force. Our spatial filtering method reduces crosstalk up to five times better than polarization filtering alone. The effectiveness is dependent on pinhole size and distance between the traps and is here quantified experimentally and reproduced by theoretical modeling. The method here proposed will improve the accuracy of force-distance measurements, e.g., of single molecules, performed by dual-beam optical traps and hence give much more scientific value for the experimental efforts.

  14. Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering

    NASA Astrophysics Data System (ADS)

    Ott, Dino; Reihani, S. Nader S.; Oddershede, Lene B.

    2014-05-01

    In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Here we present a simple and easy-to-implement method to efficiently eliminate crosstalk. The method is based on spatial filtering by simply inserting a pinhole at the correct position and is highly compatible with standard back focal plane photodiode based detection of position and force. Our spatial filtering method reduces crosstalk up to five times better than polarization filtering alone. The effectiveness is dependent on pinhole size and distance between the traps and is here quantified experimentally and reproduced by theoretical modeling. The method here proposed will improve the accuracy of force-distance measurements, e.g., of single molecules, performed by dual-beam optical traps and hence give much more scientific value for the experimental efforts.

  15. Crosstalk elimination in the detection of dual-beam optical tweezers by spatial filtering.

    PubMed

    Ott, Dino; Reihani, S Nader S; Oddershede, Lene B

    2014-05-01

    In dual-beam optical tweezers, the accuracy of position and force measurements is often compromised by crosstalk between the two detected signals, this crosstalk leading to systematic and significant errors on the measured forces and distances. This is true both for dual-beam optical traps where the splitting of the two traps is done by polarization optics and for dual optical traps constructed by other methods, e.g., holographic tweezers. If the two traps are orthogonally polarized, most often crosstalk is minimized by inserting polarization optics in front of the detector; however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Here we present a simple and easy-to-implement method to efficiently eliminate crosstalk. The method is based on spatial filtering by simply inserting a pinhole at the correct position and is highly compatible with standard back focal plane photodiode based detection of position and force. Our spatial filtering method reduces crosstalk up to five times better than polarization filtering alone. The effectiveness is dependent on pinhole size and distance between the traps and is here quantified experimentally and reproduced by theoretical modeling. The method here proposed will improve the accuracy of force-distance measurements, e.g., of single molecules, performed by dual-beam optical traps and hence give much more scientific value for the experimental efforts. PMID:24880354

  16. Automated detection of kinks from blood vessels for optic cup segmentation in retinal images

    NASA Astrophysics Data System (ADS)

    Wong, D. W. K.; Liu, J.; Lim, J. H.; Li, H.; Wong, T. Y.

    2009-02-01

    The accurate localization of the optic cup in retinal images is important to assess the cup to disc ratio (CDR) for glaucoma screening and management. Glaucoma is physiologically assessed by the increased excavation of the optic cup within the optic nerve head, also known as the optic disc. The CDR is thus an important indicator of risk and severity of glaucoma. In this paper, we propose a method of determining the cup boundary using non-stereographic retinal images by the automatic detection of a morphological feature within the optic disc known as kinks. Kinks are defined as the bendings of small vessels as they traverse from the disc to the cup, providing physiological validation for the cup boundary. To detect kinks, localized patches are first generated from a preliminary cup boundary obtained via level set. Features obtained using edge detection and wavelet transform are combined using a statistical approach rule to identify likely vessel edges. The kinks are then obtained automatically by analyzing the detected vessel edges for angular changes, and these kinks are subsequently used to obtain the cup boundary. A set of retinal images from the Singapore Eye Research Institute was obtained to assess the performance of the method, with each image being clinically graded for the CDR. From experiments, when kinks were used, the error on the CDR was reduced to less than 0.1 CDR units relative to the clinical CDR, which is within the intra-observer variability of 0.2 CDR units.

  17. Stray light suppression of optical and mechanical system for telescope detection

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Ma, Wenli

    2013-09-01

    During telescope detection, there is atmosphere overflow and other stray light affecting the system which leads to background disturbance. Thus reduce the detection capability of the system. So it is very necessary to design mechanical structure to suppress the stray light for the telescope detection system. It can both improve the signal-to-noise and contrast of the object. This paper designs the optical and mechanical structure of the 400mm telescope. And then the main baffle, baffle vane, field stop and coating technology are used to eliminate the effect of stray light on the optical and mechanical system. Finally, software is used to analyze and simulate stray light on the whole optical and mechanical system. Using PST as the evaluating standard, separate and integrated analysis of the suppressing effect of main baffle, baffle vane and field aperture is completed. And also get the results of PST before and after eliminating the stray light. Meanwhile, the results of stray light analysis can be used to guide the design of the optical and mechanical structure. The analysis results demonstrate that reasonable optical and mechanical structure and stray light suppression measure can highly reduce the PST and also improve the detection capability of the telescope system, and the designed outside baffle, inside baffle, vanes and coating technique etc. can decrease the PST approximately 1 to 3 level.

  18. High Speed All Optical Nyquist Signal Generation and Full-band Coherent Detection

    PubMed Central

    Zhang, Junwen; Yu, Jianjun; Fang, Yuan; Chi, Nan

    2014-01-01

    Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems. PMID:25142269

  19. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection.

    PubMed

    Yao, B C; Wu, Y; Yu, C B; He, J R; Rao, Y J; Gong, Y; Fu, F; Chen, Y F; Li, Y R

    2016-01-01

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel 'FRET on Fiber' concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based 'FRET on fiber' configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated 'FRET on Fiber' sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response. PMID:27010752

  20. Drugs of abuse detection in saliva based on actuated optical method

    NASA Astrophysics Data System (ADS)

    Shao, Jie; Li, Zhenyu; Jiang, Hong; Wang, Wenlong; Wu, Yixuan

    2014-12-01

    There has been a considerable increase in the abuse of drugs during the past decade. Combing drug use with driving is very dangerous. More than 11% of drivers in a roadside survey tested positive for drugs, while 18% of drivers killed in accidents tested positive for drugs as reported in USA, 2007. Toward developing a rapid drug screening device, we use saliva as the sample, and combining the traditional immunoassays method with optical magnetic technology. There were several methods for magnetic nanoparticles detection, such as magnetic coils, SQUID, microscopic imaging, and Hall sensors. All of these methods were not suitable for our demands. By developing a novel optical scheme, we demonstrate high-sensitivity detection in saliva. Drugs of abuse are detected at sub-nano gram per milliliter levels in less than 120 seconds. Evanescent wave principle has been applied to sensitively monitor the presence of magnetic nanoparticles on the binding surface. Like the total internal reflection fluorescence microscope (TIRFM), evanescent optical field is generated at the plastic/fluid interface, which decays exponentially and penetrates into the fluid by only a sub-wavelength distance. By disturbance total internal reflection with magnetic nanoparticles, the optical intensity would be influenced. We then detected optical output by imaging the sensor surface onto a CCD camera. We tested four drugs tetrahydrocannabinol (THC), methamphetamine (MAMP), ketamine (KET), morphine (OPI), using this technology. 100 ng mL-1 sensitivity was achieved, and obvious evidence showed that this results could be improved in further researches.

  1. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

    PubMed Central

    Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

    2016-01-01

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response PMID:27010752

  2. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

    NASA Astrophysics Data System (ADS)

    Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

    2016-03-01

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response

  3. Optical sensor for detection of supercavity-body contact location

    NASA Astrophysics Data System (ADS)

    Belden, Jesse; Jandron, Michael; Truscott, Tadd

    2013-11-01

    Supercavitating vehicles have been the subject of intense research due to the potential for drag reduction and/or increased speeds. The control of such vehicles depends on accurate knowledge of planing forces generated by partial, transient wetting of afterbody surfaces. Measurement of the supercavity-body contact location, which determines the planing area, is thus critical for vehicle control. A robust sensor capable of measuring supercavity contact location along the length of a body is presented. The sensor operates on the optical principle of total internal reflection to differentiate between liquid and gas phases in contact with the body. An array of photodetectors is used to sense the presence or absence of light from a laser source to map the contact location. The theoretical operation and limitations of the sensor are discussed and several experiments are presented to validate the theory. Also, we present an elegant signal processing method to compensate for in situ changes in ambient light conditions. This work was funded by the Office of Naval Research.

  4. Radio and optical detection of Martian dust storm discharges.

    NASA Astrophysics Data System (ADS)

    Farrell, W. M.; Desch, M. D.; Kaiser, M. L.; Houser, J.; Landis, G. A.; Wilt, D. M.

    2000-02-01

    Given the known physical attributes of Martian dust storms, we derive their electromagnetic signatures as they would be perceived both remotely and in situ. We also describe a radiowave and optical experiment (REDD), suitable for deployment on the Mars Surveyor 2001 Lander, whose primary scientific objective is to establish the electrical nature of dust storms in the Martian atmosphere. This experiment would be capable of the remote tracking of dust storms across the Martian surface while estimating electrical properties of dust, dust densities, and surface conductivities. The experiment sensors consist of two orthogonal magnetic search coil antennas, an electric field antenna, and a horizon-looking photodetector. The sensors drive a waveform capture system and a set of multichannel analyzers that span the radio spectrum from 1 kHz to 100 MHz. The data sampling strategy incorporates a low-resolution survey mode and a high time-resolution direction-finding mode. Intelligent use of an event-trigger system, circular buffer storage, and data compression minimize the instrument data rate and the impact on spacecraft resources.

  5. Microstructured optical fiber Bragg grating sensor for DNA detection

    NASA Astrophysics Data System (ADS)

    Candiani, A.; Giannetti, S.; Sozzi, M.; Coscelli, E.; Poli, F.; Cucinotta, A.; Bertucci, A.; Corradini, R.; Konstantaki, M.; Margulis, W.; Pissadakis, S.; Selleri, S.

    2013-03-01

    In this work the inner surface of a microstructured optical fiber, where a Bragg grating was previously inscribed, has been functionalized using peptide nucleic acid probe targeting a DNA sequence of the cystic fibrosis disease. The solution of DNA molecules, matched with the PNA probes, has been infiltrated inside the fiber capillaries and hybridization has been realized according to the Watson - Crick Model. In order to achieve signal amplification, oligonucleotide-functionalized gold nanoparticles were then infiltrated and used to form a sandwich-like system. Experimental measurements show a clear wavelength shift of the reflected high order mode for a 100 nM DNA solution. Several experiments have been carried out on the same fiber using the identical concentration, showing the same modulation and proving a good reproducibility of the results, suggesting the possibility of the reuse of the sensor. Measurements have been also made using a 100 nM mis-matched DNA solution, containing a single nucleotide polymorphism, demonstrating the high selectivity of the sensor.

  6. A Rudimentary Optical System in Detecting Ripeness of Red Watermelon

    NASA Astrophysics Data System (ADS)

    Ezan Abdullah, Noor; Hashim, Hadzli; Fathullah Sulaiman, Muhammad; Korlina Madzhi, Nina; Faiz Mohd Sampian, Ahmad; Aima Ismail, Faridatul

    2015-11-01

    The purpose of this project is to detect the ripeness and quality of the watermelon particularly for red watermelon. The ripeness of the watermelon will be evaluated by using near-infrared spectroscopy sensor (NRIS). The color wavelength will classify the ripeness of the watermelon. An infrared light will be used to get the appropriate wavelength from the watermelon either from the rind or inner of it and the signal received will be analyzed. An appropriate algorithm is used to extract the information of the inner of the watermelon. A microcontroller namely Programmable Interface Controller (PIC) will be used to execute the algorithm and the result will be displayed on Liquid Crystal Display (LCD). Based on the result obtain from the device, the data is computed by using Statistical Package for the Social Sciences (SPSS). This approach is vital to verify the relationship between unripe and ripeness of red watermelon. The objective of this project is to produce an efficient system to detect the ripeness of the watermelon.

  7. Refractive index matching improves optical object detection in paper

    NASA Astrophysics Data System (ADS)

    Saarela, J. M. S.; Heikkinen, S. M.; Fabritius, T. E. J.; Haapala, A. T.; Myllylä, R. A.

    2008-05-01

    The demand for high-quality recycled pulp products has increased the need for an efficient deinking process. Assessing process efficiency via residual ink on test sheets has so far been limited to the sheet surface due to the poor transparency of paper. A refractive index matching method was studied to obtain a quantitative measure of particles within the volume of a paper sheet. In actual measurements a glass plate with etched lines from 8.5 µm to 281.1 µm wide was placed beneath the layers of cleared paper, and visible lines were counted with a microscope. Three different paper grades were tested with transparentizing agents. A diffusion theory-based regression model was used to find a correlation between transparency, paper grammage and paper thickness. These equations enable the determination of the size of an object detectable from a paper with a certain transparentizing agent or the parameters of a test sheet needed to detect objects of a known size. Anise oil was found to be the better of the two agents used, and they both had better transparentizing ability than air or water. The transparent paper grammage of the paper grades was determined for all the tested media. Paper's transparency was found to depend more on paper's thickness than grammage.

  8. LED based evanescent wave fiber optic sensor technique to detect Fe+2 concentration

    NASA Astrophysics Data System (ADS)

    Kulkarni, V. K.; Bendigeri, H. H.; Kulkarni, R. M.

    2016-05-01

    In this paper we have reported the development of a very easy and cost effective fiber optic sensor on the basis of evanescent wave absorption technique to detect ferrous Fe+2 using high quality light emitting diode (LED). In this method, unclad portion of the fiber was used as sensing element which is exploited to surrounding media consisting Fe+2 ions. Highly sensitive detector has been used to detect the output power of light guided through unclad optical fiber. Graph revealed that, developed sensor is highly sensitive over the dynamic range of concentration from 0.1ppm to 100ppm

  9. Optical detection of middle ear infection using spectroscopic techniques: phantom experiments

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Huang, Jing; Li, Tianqi; Svanberg, Sune; Svanberg, Katarina

    2015-05-01

    A noninvasive optical technique, which is based on a combination of reflectance spectroscopy and gas in scattering media absorption spectroscopy, is demonstrated. It has the potential to improve diagnostics of middle ear infections. An ear phantom prepared with a tissue cavity, which was covered with scattering material, was used for spectroscopic measurements. Diffuse reflectance spectra of the phantom eardrum were measured with a reflectance probe. The presence of oxygen and water vapor as well as gas exchange in the phantom cavity were studied with a specially designed fiber-optic probe for backscattering detection geometry. The results suggest that this method can be developed for improved clinical detection of middle ear infection.

  10. Optically Based Flame Detection in the NASA Langley 8-ft High- Temperature Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Borg, Stephen E.

    2005-01-01

    Two optically based flame-detection systems have been developed for use in NASA Langley's 8-Foot High-Temperature Tunnel (8-ft HTT). These systems are used to detect the presence and stability of the main-burner and pilot-level flames during facility operation. System design considerations will be discussed, and a detailed description of the system components and circuit diagrams will be provided in the Appendices of this report. A more detailed description of the manufacturing process used in the fabrication of the fiber-optic probes is covered in NASA TM-2001-211233.

  11. Real-time ground-based optical detection system for space debris

    NASA Astrophysics Data System (ADS)

    Marchant, Jonathan; Green, Simon; Dick, James

    1996-10-01

    There are many advantages to supplementing ground based radar debris detection systems with optical systems. For example: objects with a low radar signature can still be optically bright (and vice versa); in the field of space debris optical detection is less sensitive to range; the minimum detectable debris size for a given range is less than that for radar. Destructive debris can be as small as 1 cm, so any improvement in detection sensitivity towards this standard is important. To improve the accuracy of debris orbital elements, a real-time detection system might be preferable in contrast to one in which images are stored for post-observation ('daytime') analysis. This is because more than one telescope is needed to lengthen the observing baseline and so increase the detected fraction of the debris orbit. Therefore, any software based at one telescope that recognizes debris in its field of view, produces a first approximation of its orbit elements and alerts extra telescopes along track, must process its data quickly, and preferably during the same pass. A prototype of such a software system under development for use with a CCD camera at the Royal Greenwich Observatory's satellite laser ranger at Herstmonceux, East Sussex, England, is outlined. The methods which the detection algorithm employs to handle data from the camera system are described, along with the limitations that the hardware and processing time impose on the physical nature of the problem.

  12. Detection of molecular binding via charge-induced mechanical response of optical fibers†

    PubMed Central

    Guan, Yan; Shan, Xiaonan; Wang, Shaopeng; Zhang, Peiming; Tao, Nongjian

    2014-01-01

    We report a charge sensitive optical detection technique for label-free study of molecular interactions. Traditional label-free optical detection techniques largely rely on the detection of the mass of a molecule, which are insensitive to small molecules. In contrast, the present technique detects the charge of a molecule, where the signal does not diminish with the size of the molecule, thus capable for studying small molecules. In addition, the technique is compatible with the standard microplate platform, making it suitable for high-throughput screening of drug candidates. Using the technique, we have detected 0.2 nM anti-BSA and 15 μM anti-cancer drug (imatinib) with an enzyme modified surface. The achieved effective charge detection limit is ~0.25 electron charge/μm2, corresponding to ~0.3 fg/mm2 for imatinib, which is orders of magnitude better than traditional label-free optical detection methods. PMID:25408862

  13. Planar lens integrated capillary action microfluidic immunoassay device for the optical detection of troponin I

    PubMed Central

    Mohammed, Mazher-Iqbal; Desmulliez, Marc P. Y.

    2013-01-01

    Optical based analysis in microfluidic and lab-on-a-chip systems are currently considered the gold standard methodology for the determination of end point reactions for various chemical and biological reaction processes. Typically, assays are performed using bulky ancillary apparatus such as microscopes and complex optical excitation and detection systems. Such instrumentation negates many of the advantages offered by device miniaturisation, particularly with respect to overall portability. In this article, we present a CO2 laser ablation technique for rapidly prototyping on-chip planar lenses, in conjunction with capillary action based autonomous microfluidics, to create a miniaturised and fully integrated optical biosensing platform. The presented self-aligned on-chip optical components offer an efficient means to direct excitation light within microfluidics and to directly couple light from a LED source. The device has been used in conjunction with a miniaturised and bespoke fluorescence detection platform to create a complete, palm sized system (≈60 × 80 × 60 mm) capable of performing fluoro-immunoassays. The system has been applied to the detection of cardiac Troponin I, one of the gold standard biomarkers for the diagnosis of acute myocardial infarction, achieving a lower detection limit of 0.08 ng/ml, which is at the threshold of clinically applicable concentrations. The portable nature of the complete system and the biomarker detection capabilities demonstrate the potential of the devised instrumentation for use as a medical diagnostics device at the point of care. PMID:24396546

  14. Recent Developments in Optical Detection Technologies in Lab-on-a-Chip Devices for Biosensing Applications

    PubMed Central

    Pires, Nuno Miguel Matos; Dong, Tao; Hanke, Ulrik; Hoivik, Nils

    2014-01-01

    The field of microfluidics has yet to develop practical devices that provide real clinical value. One of the main reasons for this is the difficulty in realizing low-cost, sensitive, reproducible, and portable analyte detection microfluidic systems. Previous research has addressed two main approaches for the detection technologies in lab-on-a-chip devices: (a) study of the compatibility of conventional instrumentation with microfluidic structures, and (b) integration of innovative sensors contained within the microfluidic system. Despite the recent advances in electrochemical and mechanical based sensors, their drawbacks pose important challenges to their application in disposable microfluidic devices. Instead, optical detection remains an attractive solution for lab-on-a-chip devices, because of the ubiquity of the optical methods in the laboratory. Besides, robust and cost-effective devices for use in the field can be realized by integrating proper optical detection technologies on chips. This review examines the recent developments in detection technologies applied to microfluidic biosensors, especially addressing several optical methods, including fluorescence, chemiluminescence, absorbance and surface plasmon resonance. PMID:25196161

  15. Detection ability of space-based optical observation system to space debris

    NASA Astrophysics Data System (ADS)

    Zhao, Sisi; Ruan, Ningjuan; Zhuang, Xuxia

    2015-10-01

    For supplying the reference to the spaced-based optical observation system design and performance analysis, the space-based observation mode for space debris is established. Considering the geometry size, the material characteristics, and the distribution region of the debris, the visual magnitude of space debris is calculated in the condition of different detection range and different phase angle. Based on the typical instance, the simulation analysis of the space debris detection ability of space-based optical observation system, which is in LEO orbit and Sub-GEO orbit respectively, is carried out. The results show that the LEO spaced-based optical observation system having an aperture of 25cm can detect the LEO 3cm space debris, which is 100km far away and has the relative velocity of 1km/s, and can also detect the GEO 1m space object, which is 37000km far away and has the relative velocity of 4km/s. The Sub-GEO spaced-based optical observation system having an aperture of 25cm can detect the GEO 1cm space debris, which is 800km far away and has the relative velocity of 15m/s.

  16. Feasibility study of optical boundary layer transition detection method

    NASA Technical Reports Server (NTRS)

    Azzazy, M.; Modarress, D.; Trolinger, J. D.

    1986-01-01

    A high sensitivity differential interferometer was developed to locate the region where the boundary layer flow undergoes transition from laminar to turbulent. Two laboratory experimental configurations were used to evaluate the performance of the interferometer: open shear layer, and low speed wind tunnel turbulent spot configuration. In each experiment, small temperature fluctuations were introduced as the signal source. Simultaneous cold wire measurements were compared with the interferometer data. The comparison shows that the interferometer is sensitive to very weak phase variations in the order of 0.001 the laser wavelength. An attempt to detect boundary layer transition over a flat plate at NASA-Langley Unitary Supersonic Wind Tunnel using the interferometer system was performed. The phase variations during boundary layer transition in the supersonic wind tunnel were beyond the minimum signal-to-noise level of the instrument.

  17. Method for oil pipeline leak detection based on distributed fiber optic technology

    NASA Astrophysics Data System (ADS)

    Chen, Huabo; Tu, Yaqing; Luo, Ting

    1998-08-01

    Pipeline leak detection is a difficult problem to solve up to now. Some traditional leak detection methods have such problems as high rate of false alarm or missing detection, low location estimate capability. For the problems given above, a method for oil pipeline leak detection based on distributed optical fiber sensor with special coating is presented. The fiber's coating interacts with hydrocarbon molecules in oil, which alters the refractive indexed of the coating. Therefore the light-guiding properties of the fiber are modified. Thus pipeline leak location can be determined by OTDR. Oil pipeline lead detection system is designed based on the principle. The system has some features like real time, multi-point detection at the same time and high location accuracy. In the end, some factors that probably influence detection are analyzed and primary improving actions are given.

  18. Automatic intraocular lens segmentation and detection in optical coherence tomography images.

    PubMed

    Gillner, Melanie; Eppig, Timo; Langenbucher, Achim

    2014-05-01

    We present a new algorithm for automatic segmentation and detection of an accommodative intraocular lens implanted in a biomechanical eye model. We extracted lens curvature and position. The algorithm contains denoising and fan correction by a multi-level calibration routine. The segmentation is realized by an adapted canny edge detection algorithm followed by a detection of lens surface with an automatic region of interest search to suppress non-optical surfaces like the lens haptic. The optical distortion of lens back surface is corrected by inverse raytracing. Lens geometry was extracted by a spherical fit. We implemented and demonstrated a powerful algorithm for automatic segmentation, detection and surface analysis of intraocular lenses in vitro. The achieved accuracy is within the expected range determined by previous studies. Future improvements will include the transfer to clinical anterior segment OCT devices. PMID:23928353

  19. Three-gas detection system with IR optical sensor based on NDIR technology

    NASA Astrophysics Data System (ADS)

    Tan, Qiulin; Tang, Licheng; Yang, Mingliang; Xue, Chenyang; Zhang, Wendong; Liu, Jun; Xiong, Jijun

    2015-11-01

    In this paper, a three-gas detection system with a environmental parameter compensation method is proposed based on Non-dispersive infra-red (NDIR) technique, which can be applied to detect multi-gas (methane, carbon dioxide and carbon monoxide). In this system, an IR source and four single-channel pyroelectric sensors are integrated in the miniature optical gas chamber successfully. Inner wall of the chamber coated with Au film is designed as paraboloids. The infrared light is reflected twice before reaching to detectors, thus increasing optical path. Besides, a compensation method is presented to overcome the influence in variation of environment (ambient temperature, humidity and pressure), thus leading to improve the accuracy in gas detection. Experimental results demonstrated that detection ranges are 0-50,000 ppm for CH4, 0-44,500 ppm for CO, 0-48,000 ppm for CO2 and the accuracy is ±0.05%.

  20. Design of oil pipeline leak detection and communication system based on optical fiber technology

    NASA Astrophysics Data System (ADS)

    Tu, Yaqing; Chen, Huabo

    1999-08-01

    The integrity of oil pipeline is always a major concern of operators. Pipeline leak not only leads to loss of oil, but pollutes environment. A new pipeline leak detection and communication system based on optical fiber technology to ensure the pipeline reliability is presented. Combined direct leak detection method with an indirect one, the system will greatly reduce the rate of false alarm. According, to the practical features of oil pipeline,the pipeline communication system is designed employing the state-of-the-art optic fiber communication technology. The system has such feature as high location accuracy of leak detection, good real-time characteristic, etc. which overcomes the disadvantages of traditional leak detection methods and communication system effectively.

  1. A novel data adaptive detection scheme for distributed fiber optic acoustic sensing

    NASA Astrophysics Data System (ADS)

    Ölçer, Íbrahim; Öncü, Ahmet

    2016-05-01

    We introduce a new approach for distributed fiber optic sensing based on adaptive processing of phase sensitive optical time domain reflectometry (Φ-OTDR) signals. Instead of conventional methods which utilizes frame averaging of detected signal traces, our adaptive algorithm senses a set of noise parameters to enhance the signal-to-noise ratio (SNR) for improved detection performance. This data set is called the secondary data set from which a weight vector for the detection of a signal is computed. The signal presence is sought in the primary data set. This adaptive technique can be used for vibration detection of health monitoring of various civil structures as well as any other dynamic monitoring requirements such as pipeline and perimeter security applications.

  2. First detection of optical light from SNR G279.0+1.1

    NASA Astrophysics Data System (ADS)

    Stupar, M.; Parker, Q. A.

    2009-04-01

    This is the initial paper in a series presenting the first optical detections and subsequent follow-up spectroscopy of known southern Galactic supernova remnants (SNRs) previously discovered in the radio. These new detections come from the Anglo-Australian Observatory (AAO)/United Kingdom Schmidt Telescope Hα survey of the southern Galactic plane which has opened up fresh opportunities to study Galactic remnants. Here, we present the first optical imaging and follow-up spectra of Galactic SNR G279.0+1.1 where a series of 14 small-scale fragmented groups of Hα filaments have been discovered in a area centred on G279.0+1.1. Individually they are somewhat inconspicuous but collectively they are completely enclosed within the overall radio contours of this known SNR. Three of these filamentary groupings are particularly prominent and optical spectra have been obtained across two of them. Their morphological structure and spectral characteristics are typical of optically detected SNR filaments. A very strong [SII] emission relative to Hα has been detected with [SII]/Hα > 0.7 and 1.1, confirming strong, shock-heated emission. This is sufficient to classify these filaments in the likely SNR domain and therefore indicating a direct connection with the radio remnant. Other typical SNR emission lines such as [OII] at 3727Å, Hβ, [OIII] at 4959 and 5007Å, Hα and [NII] at 6548 and 6584Å were also detected, lending strong support to an SNR origin of these optical filaments. The value and insights that these optical data can provide for known remnants are discussed along with their relevance to the Galactic nitrogen abundance. A serendipitous discovery of an adjacent HII region is also briefly described.

  3. Optically detected magnetic resonance studies on {pi}-conjugate polymers and novel carbon allotropes

    SciTech Connect

    Partee, J.

    1999-02-12

    This report describes the following: introduction to photoluminescence detected magnetic resonance (PLDMR); introduction to {pi}-conjugated systems; PLDMR measurements on poly(p-phenylene)-type ladder polymers; PLMDR measurements on poly(p-phenylene ethylene); and PLDMR measurements on C{sub 70}, polythiophene, poly(p-phenylene vinylene) and Dan-40. Appendices to this report describe: Operation of ODMR (optically detected magnetic resonance) spectrometer; ODMR system parameters; and Special purpose circuitry.

  4. Development of an optical fiber interferometer for detection of surface flaws in aluminum

    NASA Technical Reports Server (NTRS)

    Gilbert, John A.

    1991-01-01

    The main objective was to demonstrate the potential of using an optical fiber interferometer (OFI) to detect surface flaws in aluminum samples. Standard ultrasonic excitation was used to generate Rayleigh surface waves. After the waves interacted with a defect, the modified responses were detected using the OFI and the results were analyzed for time-of-flight and frequency content to predict the size and location of the flaws.

  5. Fast Optical Hazard Detection for Planetary Rovers Using Multiple Spot Laser Triangulation

    NASA Technical Reports Server (NTRS)

    Matthies, L.; Balch, T.; Wilcox, B.

    1997-01-01

    A new laser-based optical sensor system that provides hazard detection for planetary rovers is presented. It is anticipated that the sensor can support safe travel at speeds up to 6cm/second for large (1m) rovers in full sunlight on Earth or Mars. The system overcomes limitations in an older design that require image differencing ot detect a laser stripe in full sun.

  6. Single Molecule Detection in Living Biological Cells using Carbon Nanotube Optical Probes

    NASA Astrophysics Data System (ADS)

    Strano, Michael

    2009-03-01

    Nanoscale sensing elements offer promise for single molecule analyte detection in physically or biologically constrained environments. Molecular adsorption can be amplified via modulation of sharp singularities in the electronic density of states that arise from 1D quantum confinement [1]. Single-walled carbon nanotubes (SWNT), as single molecule optical sensors [2-3], offer unique advantages such as photostable near-infrared (n-IR) emission for prolonged detection through biological media, single-molecule sensitivity and, nearly orthogonal optical modes for signal transduction that can be used to identify distinct classes of analytes. Selective binding to the SWNT surface is difficult to engineer [4]. In this lecture, we will briefly review the immerging field of fluorescent diagnostics using band gap emission from SWNT. In recent work, we demonstrate that even a single pair of SWNT provides at least four optical modes that can be modulated to uniquely fingerprint chemical agents by the degree to which they alter either the emission band intensity or wavelength. We validate this identification method in vitro by demonstrating detection and identification of six genotoxic analytes, including chemotherapeutic drugs and reactive oxygen species (ROS), which are spectroscopically differentiated into four distinct classes. We also demonstrate single-molecule sensitivity in detecting hydrogen peroxide, one of the most common genotoxins and an important cellular signal. Finally, we employ our sensing and fingerprinting method of these analytes in real time within live 3T3 cells, demonstrating the first multiplexed optical detection from a nanoscale biosensor and the first label-free tool to optically discriminate between genotoxins. We will also discuss our recent efforts to fabricate biomedical sensors for real time detection of glucose and other important physiologically relevant analytes in-vivo. The response of embedded SWNT in a swellable hydrogel construct to

  7. Single living cell detection of telomerase over-expression for cancer detection by an optical fiber nanobiosensor.

    PubMed

    Zheng, Xin Ting; Li, Chang Ming

    2010-02-15

    An optical fiber nanobiosensor was constructed to successfully detect a general cancer biomarker, telomerase at single cell level with its nanoscale tip. The nanotip immobilized with a specific antibody was inserted into a MCF-7 breast cancer cell nucleus to capture telomerases directly, after which an in vitro enzymatic sandwich immunoassay was performed to achieve sensitive single living cell detection. The nanotip inserted into MCF-7 cell nucleus provides significantly higher average (F-F(0))/F(0) ratio than that of human mesenchymal stem cell (hMSC) nucleus, demonstrating the successful detection of the telomerase over-expression in cancer cells as compared to normal cells. The detection in the cytoplasm shows much smaller average ratio than that in the nucleus of MCF-7 cells while clearly verifies the nuclear localization of telomerase. The successful detection of telomerase over-expression in a single living cell for the first time may provide a potential method for cancer detection, and also demonstrate a universal approach that can be used to detect other low expression proteins in a single living cell. PMID:19963365

  8. Optical system of large relative aperture and wide field using aspheric corrector for detecting

    NASA Astrophysics Data System (ADS)

    Ming, Ming; Wang, Jianli; Zhang, Jingxu

    2009-05-01

    The magnitude requirement of space target detecting determines that the image of detecting telescope should have several performances: small spots, small 80% encircled energy diameter and good MTF(Modulation transfer function). So the aperture and field of view of optical system have some demands accordingly. The larger aperture, the more energy that telescope collects and higher magnitude the telescope detects; the wider field of view, the more extensive range which the telescope searches. Now most of ground telescopes whose apertures are from 500mm to 1000mm is on-axis optical system, so wide field of view becomes the most importance problem. To obtain large relative aperture and wide field of view, the paper introduces a catadioptric telescope with small aperture aspheric refractive corrector, whose conic surface will be used to remove the aberrations due to large relative aperture and wide field of view. As to the optical system, there is only one aspheric refractive corrector, and it is relatively easy for manufacturing because of its concave figure and normal material. The paper gives the example, and optimizes this optical system with ZEMAX program. And then the paper provides a specific analysis program for testing the aspheric refractive corrector. The aperture of this optical system is 750mm, and its relative aperture is 0.82, and the field of view is 3.6° diameter(diagonal). Its structure is simple and the image quality is also very good.

  9. Optical coherence tomography of the optic nerve head detects acute changes in intracranial pressure.

    PubMed

    Anand, Aashish; Pass, Anastas; Urfy, Mian Z; Tang, Rosa; Cajavilca, Christian; Calvillo, Eusebia; Suarez, Jose I; Venkatasubba Rao, Chethan P; Bershad, Eric M

    2016-07-01

    We aimed to determine if there are measurable objective changes in the optic nerve head (ONH) immediately after cerebrospinal fluid (CSF) drainage in a prospective case-series of five patients undergoing a clinically indicated lumbar puncture (LP) for diagnosis of idiopathic intracranial hypertension. A Cirrus high-definition optical coherence tomography machine (Carl Zeiss Meditec, Dublin, CA, USA) was used to acquire images in the lateral decubitus position. Optic disc cube and high-definition line raster scans centered on the ONH were obtained immediately before and after draining CSF, while the patient maintained the lateral decubitus position. Measured parameters included retinal nerve fiber layer (RNFL) thickness, peripapillary retinal pigment epithelium/Bruch's membrane (RPE/BM) angulation, transverse neural canal diameter (NCD) and the highest vertical point of the internal limiting membrane from the transverse diameter (papillary height). The mean (±standard deviation) opening and closing CSF pressures were 34.3±11.8 and 11.6±3.3cmH2O, respectively. Mean RNFL thickness (pre LP: 196±105μm; post LP: 164±77μm, p=0.1) and transverse NCD (pre LP: 1985±559μm; post LP: 1590±228μm, p=2.0) decreased in all subjects, but with non-significant trends. The RPE/BM angle (mean change: 5.8±2.0degrees, p=0.003) decreased in all subjects. A decrease in papillary height was seen in three of five subjects (mean: pre LP: 976±275μm; post LP: 938±300μm, p=0.9). Our results show a measurable, objective change in the ONH after acute lowering of the lumbar CSF pressure, suggesting a direct link between the lumbar subarachnoid space and ONH regions, and its potential as a non-invasive method for monitoring intracranial pressures. PMID:26898579

  10. Detection, manipulation and post processing of circulating tumor cells using optical techniques

    NASA Astrophysics Data System (ADS)

    Bakhtiaridoost, Somayyeh; Habibiyan, Hamidreza; Ghafoorifard, Hassan

    2015-12-01

    Circulating tumor cells (CTCs) are malignant cells that are derived from a solid tumor in the metastasis stage and are shed into the blood stream. These cells hold great promise to be used as liquid biopsy that is less aggressive than traditional biopsy. Recently, detection and enumeration of these cells has received ever-increasing attention from researchers as a way of early detection of cancer metastasis, determining the effectiveness of treatment and studying the mechanism of formation of secondary tumors. CTCs are found in blood at low concentration, which is a major limitation of isolation and detection of these cells. Over the last few years, multifarious research studies have been conducted on accurate isolation and detection and post processing of CTCs. Among all the proposed systems, microfluidic systems seem to be more attractive for researchers due to their numerous advantages. On the other hand, recent developments in optical methods have made the possibility of cellular studies at single-cell level. Thus, accuracy and efficiency of separation, detection and manipulation of CTCs can be improved using optical techniques. In this review, we describe optical methods that have been used for CTC detection, manipulation and post processing.

  11. Detection of micro-weld joint by magneto-optical imaging

    NASA Astrophysics Data System (ADS)

    Gao, Xiangdong; Liu, Yonghua; You, Deyong

    2014-10-01

    It is required that the laser beam focus should be controlled to accurately follow the weld joint center during laser butt joint welding; therefore, the weld joint position must be detected automatically in real-time. An approach for detecting the micro-weld joint (weld gap less than 0.1 mm) based on magneto-optical (MO) imaging is investigated during laser butt-joint welding of low carbon steel. Magneto-optical sensor was used to capture the dynamic images of weld joint. Weld MO image gray distribution features were analyzed to extract the transition zone of weld joint. The influences of a different magnetic field intensity and the welding speed on detecting the weld joint position were mainly studied. Under different welding conditions where welding path, weld gap or welding speed varies, it has been found that using magneto-optic imaging technology could effectively detect the position of the micro-weld joint. Different weld joint positions in MO images have been detected with various magnetic field intensities. Experimental results show that the welding speed has little influence on the detection of weld joint position.

  12. Sensitivity Comparison of Vapor Trace Detection of Explosives Based on Chemo-Mechanical Sensing with Optical Detection and Capacitive Sensing with Electronic Detection

    PubMed Central

    Strle, Drago; Štefane, Bogdan; Zupanič, Erik; Trifkovič, Mario; Maček, Marijan; Jakša, Gregor; Kvasič, Ivan; Muševič, Igor

    2014-01-01

    The article offers a comparison of the sensitivities for vapour trace detection of Trinitrotoluene (TNT) explosives of two different sensor systems: a chemo-mechanical sensor based on chemically modified Atomic Force Microscope (AFM) cantilevers based on Micro Electro Mechanical System (MEMS) technology with optical detection (CMO), and a miniature system based on capacitive detection of chemically functionalized planar capacitors with interdigitated electrodes with a comb-like structure with electronic detection (CE). In both cases (either CMO or CE), the sensor surfaces are chemically functionalized with a layer of APhS (trimethoxyphenylsilane) molecules, which give the strongest sensor response for TNT. The construction and calibration of a vapour generator is also presented. The measurements of the sensor response to TNT are performed under equal conditions for both systems, and the results show that CE system with ultrasensitive electronics is far superior to optical detection using MEMS. Using CMO system, we can detect 300 molecules of TNT in 10+12 molecules of N2 carrier gas, whereas the CE system can detect three molecules of TNT in 10+12 molecules of carrier N2. PMID:24977388

  13. Sensitivity comparison of vapor trace detection of explosives based on chemo-mechanical sensing with optical detection and capacitive sensing with electronic detection.

    PubMed

    Strle, Drago; Štefane, Bogdan; Zupanič, Erik; Trifkovič, Mario; Maček, Marijan; Jakša, Gregor; Kvasič, Ivan; Muševič, Igor

    2014-01-01

    The article offers a comparison of the sensitivities for vapour trace detection of Trinitrotoluene (TNT) explosives of two different sensor systems: a chemo-mechanical sensor based on chemically modified Atomic Force Microscope (AFM) cantilevers based on Micro Electro Mechanical System (MEMS) technology with optical detection (CMO), and a miniature system based on capacitive detection of chemically functionalized planar capacitors with interdigitated electrodes with a comb-like structure with electronic detection (CE). In both cases (either CMO or CE), the sensor surfaces are chemically functionalized with a layer of APhS (trimethoxyphenylsilane) molecules, which give the strongest sensor response for TNT. The construction and calibration of a vapour generator is also presented. The measurements of the sensor response to TNT are performed under equal conditions for both systems, and the results show that CE system with ultrasensitive electronics is far superior to optical detection using MEMS. Using CMO system, we can detect 300 molecules of TNT in 10(+12) molecules of N2 carrier gas, whereas the CE system can detect three molecules of TNT in 10(+12) molecules of carrier N2. PMID:24977388

  14. Determination of total metal pollutants in water with optical detection

    NASA Astrophysics Data System (ADS)

    Chudy, Michal; Prokaryn, Piotr; Dybko, Artur; Wroblewski, Wojciech; Brzozka, Zbigniew

    2003-09-01

    The total concentration of heavy metal ions was measured with the use of a highly sensitive reagent (4-(2-pyridylzo)-resorcinol (PAR)). Because of PAR chelates are slightly soluble in water and their forming is not selective, the analytical procedure for Cd, Cu, Hg, Pb, Zn determination was developed to perform the analysis in an aqueous environment without the need of inconvenient and time-consuming extraction. A proposed analysis method is more useful in comparison with classical FIA analysis what is crucial during fast classification of various natural water samples. To minimize the chemicals consumption such a classification can be performed in a specially designed microsystem. The Y- shape microchannel structure with a mixing area was made by fine engraving in PMMA plate and sealed with the PDMS one. The M2+-PAR complex forming conditions were determined for each of the chosen metal ions. The solubility of formed complexes was better when a micellar environment was created by the addition of a non-ionic surfactant (Triton X100). Next the synthetic mixtures of Cd, Cu, Hg, Pb, Zn ions were prepared to obtain total molar metal ions concentration in the range from 10-6 to 10-4 M and measured after on-chip reaction. A tap water and HAC-sample (Highest Allowable Concentration, ΣMe=1,2•10-5 M) were also measured. The detection was performed in a special flow cuvette and spectra measurements were carried out using diode array spectrophotometer and CCD detector.

  15. High Sensitivity Detection of Broadband Acoustic Vibration Using Optical Demodulation Method

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen

    Measuring the high frequency acoustic vibrations represents the fundamental interest in revealing the intrinsic dynamic characteristic of board range of systems, such as the growth of the fetus, blood flow in human palms, and vibrations of carbon nanotube. However, the acoustic wave detection capability is limited by the detection bandwidth and sensitivity of the commonly used piezoelectric based ultrasound detectors. To overcome these limitations, this thesis focuses on exploring the optical demodulation method for highly sensitive detection of broadband acoustic vibration. First, a transparent optical ultrasonic detector has been developed using micro-ring resonator (MRR) made of soft polymeric materials. It outperforms the traditional piezoelectric detectors with broader detection bandwidth, miniaturized size and wide angular sensitivity. Its ease of integration into photoacoustic microscopy system has resulted in the great improvement of the imaging resolution. A theoretic framework has been developed to establish the quantitative understanding of its unique distance and angular dependent detection characteristics and was subsequently validated experimentally. The developed theoretic framework provides a guideline to fully accounts for the trade-offs between axial and lateral resolution, working distance, and the field of view in developing optimal imaging performance for a wide range of biological and clinical applications. MRR-based ultrasonic detector is further integrated into confocal fluorescence microscopy to realize the simultaneous imaging of fluorescence and optical absorption of retinal pigment epithelium, achieving multi-contrast imaging at sub-cellular level. The needs to resolve the fine details of the biological specimen with the resolution beyond the diffraction limit further motivate the development of optical demodulated ultrasonic detection method based on near-field scanning optical microscopy (NSOM). The nano-focusing probe was developed

  16. Multimodal photoacoustic and optical coherence tomography scanner using an all optical detection scheme for 3D morphological skin imaging

    PubMed Central

    Zhang, Edward Z.; Povazay, Boris; Laufer, Jan; Alex, Aneesh; Hofer, Bernd; Pedley, Barbara; Glittenberg, Carl; Treeby, Bradley; Cox, Ben; Beard, Paul; Drexler, Wolfgang

    2011-01-01

    A noninvasive, multimodal photoacoustic and optical coherence tomography (PAT/OCT) scanner for three-dimensional in vivo (3D) skin imaging is described. The system employs an integrated, all optical detection scheme for both modalities in backward mode utilizing a shared 2D optical scanner with a field-of-view of ~13 × 13 mm2. The photoacoustic waves were detected using a Fabry Perot polymer film ultrasound sensor placed on the surface of the skin. The sensor is transparent in the spectral range 590-1200 nm. This permits the photoacoustic excitation beam (670-680 nm) and the OCT probe beam (1050 nm) to be transmitted through the sensor head and into the underlying tissue thus providing a backward mode imaging configuration. The respective OCT and PAT axial resolutions were 8 and 20 µm and the lateral resolutions were 18 and 50-100 µm. The system provides greater penetration depth than previous combined PA/OCT devices due to the longer wavelength of the OCT beam (1050 nm rather than 829-870 nm) and by operating in the tomographic rather than the optical resolution mode of photoacoustic imaging. Three-dimensional in vivo images of the vasculature and the surrounding tissue micro-morphology in murine and human skin were acquired. These studies demonstrated the complementary contrast and tissue information provided by each modality for high-resolution 3D imaging of vascular structures to depths of up to 5 mm. Potential applications include characterizing skin conditions such as tumors, vascular lesions, soft tissue damage such as burns and wounds, inflammatory conditions such as dermatitis and other superficial tissue abnormalities. PMID:21833358

  17. All-optical photoacoustic microscopy based on plasmonic detection of broadband ultrasound

    NASA Astrophysics Data System (ADS)

    Wang, Tianxiong; Cao, Rui; Ning, Bo; Dixon, Adam J.; Hossack, John A.; Klibanov, Alexander L.; Zhou, Qifa; Wang, Anbo; Hu, Song

    2015-10-01

    We report on an implementation of all-optical photoacoustic microscopy (PAM), which capitalizes on the effect of surface plasmon resonance (SPR) for optical detection of ultrasound. The SPR sensor in our all-optical PAM shows, experimentally, a linear response to the acoustic pressure from 5.2 kPa to 2.1 MPa, an ultra-flat frequency response (±0.7 dB) from 680 kHz to 126 MHz, and a noise-equivalent pressure sensitivity of 3.3 kPa. With the broadband ultrasonic detection, our SPR-PAM has achieved high spatial resolution with relatively low anisotropy (i.e., 2.0 μm laterally and 8.4 μm axially). Three-dimensional high-resolution imaging of a single melanoma cell is demonstrated.

  18. Acoustic Longitudinal Field NIF Optic Feature Detection Map Using Time-Reversal & MUSIC

    SciTech Connect

    Lehman, S K

    2006-02-09

    We developed an ultrasonic longitudinal field time-reversal and MUltiple SIgnal Classification (MUSIC) based detection algorithm for identifying and mapping flaws in fused silica NIF optics. The algorithm requires a fully multistatic data set, that is one with multiple, independently operated, spatially diverse transducers, each transmitter of which, in succession, launches a pulse into the optic and the scattered signal measured and recorded at every receiver. We have successfully localized engineered ''defects'' larger than 1 mm in an optic. We confirmed detection and localization of 3 mm and 5 mm features in experimental data, and a 0.5 mm in simulated data with sufficiently high signal-to-noise ratio. We present the theory, experimental results, and simulated results.

  19. Optical hyperpolarization and NMR detection of 129Xe on a microfluidic chip

    NASA Astrophysics Data System (ADS)

    Jiménez-Martínez, Ricardo; Kennedy, Daniel J.; Rosenbluh, Michael; Donley, Elizabeth A.; Knappe, Svenja; Seltzer, Scott J.; Ring, Hattie L.; Bajaj, Vikram S.; Kitching, John

    2014-05-01

    Optically hyperpolarized 129Xe gas has become a powerful contrast agent in nuclear magnetic resonance (NMR) spectroscopy and imaging, with applications ranging from studies of the human lung to the targeted detection of biomolecules. Equally attractive is its potential use to enhance the sensitivity of microfluidic NMR experiments, in which small sample volumes yield poor sensitivity. Unfortunately, most 129Xe polarization systems are large and non-portable. Here we present a microfabricated chip that optically polarizes 129Xe gas. We have achieved 129Xe polarizations >0.5% at flow rates of several microlitres per second, compatible with typical microfluidic applications. We employ in situ optical magnetometry to sensitively detect and characterize the 129Xe polarization at magnetic fields of 1 μT. We construct the device using standard microfabrication techniques, which will facilitate its integration with existing microfluidic platforms. This device may enable the implementation of highly sensitive 129Xe NMR in compact, low-cost, portable devices.

  20. Optical detection of concentrations for mixed acid: HF and HNO3

    NASA Astrophysics Data System (ADS)

    Kang, Gumin; Kim, Kyoungsik

    2009-02-01

    Mixed acid, which consist of HF and HNO3, is used as a good etchant for silicon dioxide in the wet etching and pickling process of stainless steel. The optical detection of concentration for such mixed acids is crucial to optimize and cut costs in the manufacturing process. Optical detection in the IR regime has been utilized to measure the concentration of the mixed acid for HF and HNO3, because that has several strong absorption peaks, which is contributed by vibrational mode of each acid molecular in this spectrum. In this research, we observed the concentrations of mixed acid to consist of HF and HNO3, as we measured the absorption intensity of OH- stretch and NO3 - stretch band by optical spectroscopy. The concentration range of HF over 1.5-3 wt% and that of HNO3 over 2-10 wt% were studied in room temperature.

  1. Mechanism analysis on biofouling detection based on optical fiber sensing technique

    NASA Astrophysics Data System (ADS)

    Ma, Huiping; Yuan, Feng; Liu, Yongmeng; Jiang, Xiuzhen

    2010-08-01

    More attention is paid to on-line monitoring of biofouling in industrial water process systems. Based on optical fiber sensing technology, biofouling detection mechanism is put forward in the paper. With biofouling formation, optical characteristics and the relation between light intensity and refractive index studied, schematic diagram of optical fiber self-referencing detecting system and technological flowchart are presented. Immunity to electromagnetic interference and other influencing factors by which the precision is great improved is also remarkable characteristic. Absorption spectrum of fluid medium molecule is measured by infrared spectrum and impurity is analyzed by character fingerprints of different liquid. Other pollutant source can be identified by means of infrared spectrum and arithmetic research of artificial neural networks (ANN) technology. It can be used in other fields such as mining, environment protection, medical treatment and transportation of oil, gas and water.

  2. Tetrathiafulvalene-capped hybrid materials for the optical detection of explosives.

    PubMed

    Salinas, Yolanda; Martínez-Máñez, Ramón; Jeppesen, Jan O; Petersen, Lars H; Sancenón, Félix; Marcos, María Dolores; Soto, Juan; Guillem, Carmen; Amorós, Pedro

    2013-03-13

    Mesoporous silica microparticles capped with TTF moieties and containing a ruthenium dye in the pores were used for the turn-on optical detection of the nitroaromatic explosives Tetryl and TNT via a selective pore uncapping and release of the entrapped dye. PMID:23373746

  3. A new thermal radiation detector using optical heterodyne detection of absorbed energy

    NASA Technical Reports Server (NTRS)

    Davis, C. C.; Petuchowski, S. J.

    1983-01-01

    The operating principles of a new kind of room-temperature thermal radiation detector are described. In this device modulated light heats a gas, either directly or by conduction from a thin absorbing membrane, and the resultant change in density of the gas is detected by optical heterodyning. The performance of a membrane device of this kind agrees well with the predictions of theory.

  4. Bifunctional electro-optical nanoprobe to real-time detect local biochemical processes in single cells.

    PubMed

    Zheng, Xin Ting; Hu, Weihua; Wang, Houxiao; Yang, Hongbin; Zhou, Wei; Li, Chang Ming

    2011-07-15

    A bifunctional electro-optical nanoprobe with integrated nanoring electrode and optical nanotip was fabricated and investigated to simultaneously detect both electrical and optical signals in real-time with high spatial resolution. Concurrent measurements of the oxidant generation and the intracellular antioxidant levels in single cells correlate the stronger oxidant generation with an altered initial antioxidant response in the breast cancer cells in comparison to the normal ones suggesting that the cell malignancy is associated with the strength of oxidative stress, and the higher antioxidant level may be the cause of the drug resistance. While the optical detection indicates the fluctuation of the intracellular redox homeostasis, the chronoamperometric signals allow quantitative real-time detection of the H₂O₂ release and decay. Furthermore, the nanoscale probe enables localized simultaneous detections thus discovering that activated enzymes responsible for the oxidative stress target at specific membrane regions. This method promises applications in study of the dynamics of important physiological processes, and provides the opportunity to unravel the interplay of various signaling pathways. PMID:21632233

  5. Longitudinal Detection of Optic Nerve Head Changes by Spectral Domain Optical Coherence Tomography in Early Experimental Glaucoma

    PubMed Central

    He, Lin; Yang, Hongli; Gardiner, Stuart K.; Williams, Galen; Hardin, Christy; Strouthidis, Nicholas G.; Fortune, Brad; Burgoyne, Claude F.

    2014-01-01

    Purpose. We determined if the detection of spectral-domain optical coherence tomography (SDOCT) optic nerve head (ONH) change precedes the detection of confocal scanning laser tomography (CSLT) ONH surface, SDOCT retinal nerve fiber layer (RNFL), scanning laser perimetry (SLP), and multifocal electroretinography (mfERG) change in eight experimental glaucoma (EG) eyes. Methods. Both eyes from eight monkeys were tested at least three times at baseline, and then every 2 weeks following laser-induced chronic unilateral IOP elevation. Event and trend-based definitions of onset in the control and EG eyes for 11 SDOCT neural and connective tissue, CSLT surface, SDOCT RNFL, SLP, and mfERG parameters were explored. The frequency and timing of onset for each parameter were compared using a logrank test. Results. Maximum post-laser IOP was 18 to 42 mm Hg in the EG eyes and 12 to 20 mm Hg in the control eyes. For event- and trend-based analyses, onsets were achieved earliest and most frequently within the ONH neural and connective tissues using SDOCT, and at the ONH surface using CSLT. SDOCT ONH neural and connective tissue parameter change preceded or coincided with CSLT ONH surface change in most EG eyes. The SDOCT and SLP measures of RNFL thickness, and mfERG measures of visual function demonstrated similar onset rates, but occurred later than SDOCT ONH and CSLT surface change, and in fewer eyes. Conclusions. SDOCT ONH change detection commonly precedes or coincides with CSLT ONH surface change detection, and consistently precedes RNFLT, SLP, and mfERG change detection in monkey experimental glaucoma. PMID:24255047

  6. Optical observation, image-processing, and detection of space debris in geosynchronous Earth orbit

    NASA Astrophysics Data System (ADS)

    Oda, Hiroshi; Kurosaki, Hirohisa; Yanagisawa, Toshifumi; Tagawa, Makoto

    We report on optical observations and an efficient detection method of space debris in the geosynchronous Earth orbit (GEO). We operate our new Australia Remote Observatory (ARO) where an 18 cm optical telescope with a charged-coupled device (CCD) camera covering a 3.14-degree field of view is used for GEO debris survey, and analyse datasets of successive CCD images using the line detection method (Yanagisawa and Nakajima 2005). In our operation, the exposure time of each CCD image is set to be 3 seconds, and the time interval of each images is about 4.7 seconds. We can detect faint signals (down to about 1.8 sigma of background noise) by applying the line detection method to 18 CCD images. As a result, we detected about 300 GEO objects up to magnitude of 14 among 5 nights data, and found that a certain amount of our detections are new objects that are not contained in the two-line-element (TLE) data provided by the U.S. Strategic Command (USSTRATCOM). We conclude that our ARO posses a high efficiency detection of GEO objects despite the use of comparatively-inexpensive observation and analysis system. We also describe the image-processing method specialised for the detection of GEO objects (not for usual astronomical objects like stars) in this paper.

  7. Optical and mechanical detection of near-field light by atomic force microscopy using a piezoelectric cantilever

    NASA Astrophysics Data System (ADS)

    Satoh, Nobuo; Kobayashi, Kei; Watanabe, Shunji; Fujii, Toru; Matsushige, Kazumi; Yamada, Hirofumi

    2016-08-01

    In this study, we developed an atomic force microscopy (AFM) system with scanning near-field optical microscopy (SNOM) using a microfabricated force-sensing cantilever with a lead zirconate titanate (PZT) thin film. Both optical and mechanical detection techniques were adopted in SNOM to detect scattered light induced by the interaction of the PZT cantilever tip apex and evanescent light, and SNOM images were obtained for each detection scheme. The mechanical detection technique did allow for a clear observation of the light scattered from the PZT cantilever without the interference observed by the optical detection technique, which used an objective lens, a pinhole, and a photomultiplier tube.

  8. Coherent Control of Optically Generated and Detected Picosecond Surface Acoustic Phonons

    SciTech Connect

    David H. Hurley

    2006-11-01

    Coherent control of elementary optical excitations is a key issue in ultrafast materials science. Manipulation of electronic and vibronic excitations in solids as well as chemical and biological systems on ultrafast time scales has attracted a great deal of attention recently. In semiconductors, coherent control of vibronic excitations has been demonstrated for bulk acoustic and optical phonons generated in superlattice structures. The bandwidth of these approaches is typically fully utilized by employing a 1-D geometry where the laser spot size is much larger than the superlattice repeat length. In this presentation we demonstrate coherent control of optically generated picosecond surface acoustic waves using sub-optical wavelength absorption gratings. The generation and detection characteristics of two material systems are investigated (aluminum absorption gratings on Si and GaAs substrates).

  9. Performance analysis of fiber-based free-space optical communications with coherent detection spatial diversity.

    PubMed

    Li, Kangning; Ma, Jing; Tan, Liying; Yu, Siyuan; Zhai, Chao

    2016-06-10

    The performances of fiber-based free-space optical (FSO) communications over gamma-gamma distributed turbulence are studied for multiple aperture receiver systems. The equal gain combining (EGC) technique is considered as a practical scheme to mitigate the atmospheric turbulence. Bit error rate (BER) performances for binary-phase-shift-keying-modulated coherent detection fiber-based free-space optical communications are derived and analyzed for EGC diversity receptions through an approximation method. To show the net diversity gain of a multiple aperture receiver system, BER performances of EGC are compared with a single monolithic aperture receiver system with the same total aperture area (same average total incident optical power on the aperture surface) for fiber-based free-space optical communications. The analytical results are verified by Monte Carlo simulations. System performances are also compared for EGC diversity coherent FSO communications with or without considering fiber-coupling efficiencies. PMID:27409022

  10. Full-field detection of surface defects using real-time holography and optical correlation techniques

    NASA Astrophysics Data System (ADS)

    Blackshire, James L.; Duncan, Bradley D.

    1999-02-01

    Innovative optical NDE techniques are being developed for the full-field detection and evaluation of surface defects and defect precursors in titanium and aluminum based alloys. The techniques are based on frequency-translated holography and optical correlation principles, and use bacteriohodopsin (bR) holographic films and temporal correlation techniques for real-time storage and retrieval of Surface Acoustic Waves (SAW) features and embedded surface defect information. The SAW waves induced on the material surface being studied are made to interfere with optical light waves, and fringes are produced that are a function of optical Doppler shifts induced by phonon-photon interaction on the surface of the materials. Visualization of these SAW patterns allow for NDE characterization of features on and near the surface of the materials, including defect and defect precursor sites. Preliminary results are provided for real-time bR holographic recordings of acoustic patterns induced on Al2024-T3 material surfaces.

  11. High-speed asynchronous optical sampling for high-sensitivity detection of coherent phonons

    NASA Astrophysics Data System (ADS)

    Dekorsy, T.; Taubert, R.; Hudert, F.; Schrenk, G.; Bartels, A.; Cerna, R.; Kotaidis, V.; Plech, A.; Köhler, K.; Schmitz, J.; Wagner, J.

    2007-12-01

    A new optical pump-probe technique is implemented for the investigation of coherent acoustic phonon dynamics in the GHz to THz frequency range which is based on two asynchronously linked femtosecond lasers. Asynchronous optical sampling (ASOPS) provides the performance of on all-optical oscilloscope and allows us to record optically induced lattice dynamics over nanosecond times with femtosecond resolution at scan rates of 10 kHz without any moving part in the set-up. Within 1 minute of data acquisition time signal-to-noise ratios better than 107 are achieved. We present examples of the high-sensitivity detection of coherent phonons in superlattices and of the coherent acoustic vibration of metallic nanoparticles.

  12. A new method of inshore ship detection in high-resolution optical remote sensing images

    NASA Astrophysics Data System (ADS)

    Hu, Qifeng; Du, Yaling; Jiang, Yunqiu; Ming, Delie

    2015-10-01

    Ship as an important military target and water transportation, of which the detection has great significance. In the military field, the automatic detection of ships can be used to monitor ship dynamic in the harbor and maritime of enemy, and then analyze the enemy naval power. In civilian field, the automatic detection of ships can be used in monitoring transportation of harbor and illegal behaviors such as illegal fishing, smuggling and pirates, etc. In recent years, research of ship detection is mainly concentrated in three categories: forward-looking infrared images, downward-looking SAR image, and optical remote sensing images with sea background. Little research has been done into ship detection of optical remote sensing images with harbor background, as the gray-scale and texture features of ships are similar to the coast in high-resolution optical remote sensing images. In this paper, we put forward an effective harbor ship target detection method. First of all, in order to overcome the shortage of the traditional difference method in obtaining histogram valley as the segmentation threshold, we propose an iterative histogram valley segmentation method which separates the harbor and ships from the water quite well. Secondly, as landing ships in optical remote sensing images usually lead to discontinuous harbor edges, we use Hough Transform method to extract harbor edges. First, lines are detected by Hough Transform. Then, lines that have similar slope are connected into a new line, thus we access continuous harbor edges. Secondary segmentation on the result of the land-and-sea separation, we eventually get the ships. At last, we calculate the aspect ratio of the ROIs, thereby remove those targets which are not ship. The experiment results show that our method has good robustness and can tolerate a certain degree of noise and occlusion.

  13. A new approach to optic disc detection in human retinal images using the firefly algorithm.

    PubMed

    Rahebi, Javad; Hardalaç, Fırat

    2016-03-01

    There are various methods and algorithms to detect the optic discs in retinal images. In recent years, much attention has been given to the utilization of the intelligent algorithms. In this paper, we present a new automated method of optic disc detection in human retinal images using the firefly algorithm. The firefly intelligent algorithm is an emerging intelligent algorithm that was inspired by the social behavior of fireflies. The population in this algorithm includes the fireflies, each of which has a specific rate of lighting or fitness. In this method, the insects are compared two by two, and the less attractive insects can be observed to move toward the more attractive insects. Finally, one of the insects is selected as the most attractive, and this insect presents the optimum response to the problem in question. Here, we used the light intensity of the pixels of the retinal image pixels instead of firefly lightings. The movement of these insects due to local fluctuations produces different light intensity values in the images. Because the optic disc is the brightest area in the retinal images, all of the insects move toward brightest area and thus specify the location of the optic disc in the image. The results of implementation show that proposed algorithm could acquire an accuracy rate of 100 % in DRIVE dataset, 95 % in STARE dataset, and 94.38 % in DiaRetDB1 dataset. The results of implementation reveal high capability and accuracy of proposed algorithm in the detection of the optic disc from retinal images. Also, recorded required time for the detection of the optic disc in these images is 2.13 s for DRIVE dataset, 2.81 s for STARE dataset, and 3.52 s for DiaRetDB1 dataset accordingly. These time values are average value. PMID:26093773

  14. A high-resolution measurement device for detecting the positioning accuracy of the optical fiber positioner

    NASA Astrophysics Data System (ADS)

    Gu, Yonggang; Xu, Jianlei; Jin, Yi; Zhai, Chao

    2012-09-01

    The optical fiber positioner with double revolving mechanism is driven by two stepping motors. One stepping motor drives center revolving mechanism and the other drives decentered slewing mechanism. Photogrammetry is currently used to detect the positioning accuracy of the optical fiber positioner, but it cannot achieve high precision because of the small size of the fiber’s diameter. So, a new measurement device, which mainly contained optical microscope, CCD camera and two-dimensional precision mobile platform, was established in this paper. One end of the optical fiber (the other end was lighted by integrating sphere light source) was imaged on the CCD sensor in a magnified way through the optical microscope, and the image was processed to build the position feedback mechanism in real time. Then the two-dimensional mobile platform was controlled by PID control method to track the optical fiber, and the fiber was always kept to locate in center of the CCD image in order to eliminate the aberrations of the optical microscope lens. Finally, the position changes of the moving fiber could be obtained by the coordinates of the two-dimensional precision mobile platform. The experimental results demonstrate that the resolution of this measurement device is 0.1μm and the accuracy of repeat positioning is 1.5μm. The measurement device could satisfy the testing requirement.

  15. Research on small signal detection of optical voltage/current transformer

    NASA Astrophysics Data System (ADS)

    Li, Hongbo; Zhang, Guoqing; Cai, Xingguo; Guo, Zhizhong; Yu, Wenbin; Huo, Guangyu

    2013-08-01

    This paper researches the signal conditioning program of optical voltage/current transformer and the imbalance during the transmission of dual optical path, gives a brief introduction to the basic principle of optical voltage transformer based on electro-optic Pockels effect and optical current transformer based on Faraday Magnetic-optical Effect, and induces a general expression form of output light intensities This paper research on the signal modulation methods for the system: AC and DC modulations. What is more, the advantages and disadvantages of both modulations in the system will be analyzed. Considering the characteristics that the systematic noise and signal have the spectrum overlapping and that when there is any fault, the fact that in the small signal detection system the output SNR of AC modulation is better than that of DC modulation will be proved. For the parameter changes caused by the environment factors, the feedback control linked by the DSP is imported, it automatically adjusts the balance of the two branch parameters, acquires the measured component in the condition of the two branch unbalance parameters. Furthermore, this paper researches on the influence of imbalance of the dual optical path on the signal detection system. It analyzes the error characteristics due to different kinds of losses and to component matching disorders and other intrinsic factors and then put forward the method to calculate balancing factors by means of the RMS of 50Hz signal. The result proves that using this method can improve the output SNR of optical voltage/current transformer to some extent.

  16. High speed low power optical detection of sub-wavelength scatterer.

    PubMed

    Roy, S; Bouwens, Maryse; Wei, Lei; Pereira, S F; Urbach, H P; van der Walle, P

    2015-12-01

    Optical detection of scatterers on a flat substrate, generally done using dark field microscopy technique, is challenging since it requires high power illumination to obtain sufficient SNR (Signal to Noise Ratio) to be able to detect sub-wavelength particles. We developed a bright field technique, based on Fourier scatterometry, with special illumination and detection control to achieve this goal with a power level that can be sustained by most substrates including polymers. The performance of the system in a roll-to-roll line in production environment and strict throughput requirement is shown. PMID:26724010

  17. High speed low power optical detection of sub-wavelength scatterer

    NASA Astrophysics Data System (ADS)

    Roy, S.; Bouwens, Maryse; Wei, Lei; Pereira, S. F.; Urbach, H. P.; van der Walle, P.

    2015-12-01

    Optical detection of scatterers on a flat substrate, generally done using dark field microscopy technique, is challenging since it requires high power illumination to obtain sufficient SNR (Signal to Noise Ratio) to be able to detect sub-wavelength particles. We developed a bright field technique, based on Fourier scatterometry, with special illumination and detection control to achieve this goal with a power level that can be sustained by most substrates including polymers. The performance of the system in a roll-to-roll line in production environment and strict throughput requirement is shown.

  18. Noncontact speckle-based optical sensor for detection of glucose concentration using magneto-optic effect

    NASA Astrophysics Data System (ADS)

    Ozana, Nisan; Beiderman, Yevgeny; Anand, Arun; Javidi, Baharam; Polani, Sagi; Schwarz, Ariel; Shemer, Amir; Garcia, Javier; Zalevsky, Zeev

    2016-06-01

    We experimentally verify a speckle-based technique for noncontact measurement of glucose concentration in the bloodstream. The final device is intended to be a single wristwatch-style device containing a laser, a camera, and an alternating current (ac) electromagnet generated by a solenoid. The experiments presented are performed in vitro as proof of the concept. When a glucose substance is inserted into a solenoid generating an ac magnetic field, it exhibits Faraday rotation, which affects the temporal changes of the secondary speckle pattern distributions. The temporal frequency resulting from the ac magnetic field was found to have a lock-in amplification role, which increased the observability of the relatively small magneto-optic effect. Experimental results to support the proposed concept are presented.

  19. Optical properties of materials at low temperature and their application to optical detection

    NASA Technical Reports Server (NTRS)

    Hartwig, W. H.; Tarchi, A. A.

    1972-01-01

    A lumped model to represent the photodielectric effect is developed. An analog simulation for a sample in a microwave cavity with a static magnetic field is developed. A system to measure continuously the PDE is analyzed. A performance factor to compared PD detectors versus ac photoconductors is computed. The operating conditions are defined for the appropriate noise conditions. The detectivity of the detector is found to be limited by the semiconductor sample noise.

  20. Wavefront detection method of a single-sensor based adaptive optics system.

    PubMed

    Wang, Chongchong; Hu, Lifa; Xu, Huanyu; Wang, Yukun; Li, Dayu; Wang, Shaoxin; Mu, Quanquan; Yang, Chengliang; Cao, Zhaoliang; Lu, Xinghai; Xuan, Li

    2015-08-10

    In adaptive optics system (AOS) for optical telescopes, the reported wavefront sensing strategy consists of two parts: a specific sensor for tip-tilt (TT) detection and another wavefront sensor for other distortions detection. Thus, a part of incident light has to be used for TT detection, which decreases the light energy used by wavefront sensor and eventually reduces the precision of wavefront correction. In this paper, a single Shack-Hartmann wavefront sensor based wavefront measurement method is presented for both large amplitude TT and other distortions' measurement. Experiments were performed for testing the presented wavefront method and validating the wavefront detection and correction ability of the single-sensor based AOS. With adaptive correction, the root-mean-square of residual TT was less than 0.2 λ, and a clear image was obtained in the lab. Equipped on a 1.23-meter optical telescope, the binary stars with angle distance of 0.6″ were clearly resolved using the AOS. This wavefront measurement method removes the separate TT sensor, which not only simplifies the AOS but also saves light energy for subsequent wavefront sensing and imaging, and eventually improves the detection and imaging capability of the AOS. PMID:26367988

  1. Manufacturing and testing flexible microfluidic devices with optical and electrical detection mechanisms

    NASA Astrophysics Data System (ADS)

    Ivan, Marius G.; Vivet, Frédéric; Meinders, Erwin R.

    2010-06-01

    Flexible microfluidic devices made of poly(dimethylsiloxane) (PDMS) were manufactured by soft lithography, and tested in detection of ionic species using optical absorption spectroscopy and electrical measurements. PDMS was chosen due to its flexibility and ease of surface modification by exposure to plasma and UV treatment, its transparency in UV-Vis regions of the light spectrum, and biocompatibility. The dual-detection mechanism allows the user more freedom in choosing the detection tool, and a functional device was successfully tested. Optical lithography was employed for manufacturing templates, which were subsequently used for imprinting liquid PDMS by thermal curing. Gold electrodes having various widths and distances among them were patterned with optical lithography on the top part which sealed the microchannels, and the devices were employed for detection of ionic species in aqueous salt solutions as well as micro-electrolysis cells. Due to the transparency of PDMS in UV-Vis the microfluidics were also used as photoreactors, and the in-situ formed charged species were monitored by applying a voltage between electrodes. Upon addition of a colorimetric pH sensor, acid was detected with absorption spectroscopy.

  2. Optical detection enhancement in porous volumetric microfluidic capture elements using refractive index matching fluids.

    PubMed

    Wiederoder, M S; Peterken, L; Lu, A X; Rahmanian, O D; Raghavan, S R; DeVoe, D L

    2015-08-21

    Porous volumetric capture elements in microfluidic sensors are advantageous compared to planar capture surfaces due to higher reaction site density and decreased diffusion lengths that can reduce detection limits and total assay time. However a mismatch in refractive indices between the capture matrix and fluid within the porous interstices results in scattering of incident, reflected, or emitted light, significantly reducing the signal for optical detection. Here we demonstrate that perfusion of an index-matching fluid within a porous matrix minimizes scattering, thus enhancing optical signal by enabling the entire capture element volume to be probed. Signal enhancement is demonstrated for both fluorescence and absorbance detection, using porous polymer monoliths in a silica capillary and packed beds of glass beads within thermoplastic microchannels, respectively. Fluorescence signal was improved by a factor of 3.5× when measuring emission from a fluorescent compound attached directly to the polymer monolith, and up to 2.6× for a rapid 10 min direct immunoassay. When combining index matching with a silver enhancement step, a detection limit of 0.1 ng mL(-1) human IgG and a 5 log dynamic range was achieved. The demonstrated technique provides a simple method for enhancing optical sensitivity for a wide range of assays, enabling the full benefits of porous detection elements in miniaturized analytical systems to be realized. PMID:26160546

  3. Optic disc detection in color fundus images using ant colony optimization.

    PubMed

    Pereira, Carla; Gonçalves, Luís; Ferreira, Manuel

    2013-03-01

    Diabetic retinopathy has been revealed as the most common cause of blindness among people of working age in developed countries. However, loss of vision could be prevented by an early detection of the disease and, therefore, by a regular screening program to detect retinopathy. Due to its characteristics, the digital color fundus photographs have been the easiest way to analyze the eye fundus. An important prerequisite for automation is the segmentation of the main anatomical features in the image, particularly the optic disc. Currently, there are many works reported in the literature with the purpose of detecting and segmenting this anatomical structure. Though, none of them performs as needed, especially when dealing with images presenting pathologies and a great variability. Ant colony optimization (ACO) is an optimization algorithm inspired by the foraging behavior of some ant species that has been applied in image processing with different purposes. In this paper, this algorithm preceded by anisotropic diffusion is used for optic disc detection in color fundus images. Experimental results demonstrate the good performance of the proposed approach as the optic disc was detected in most of all the images used, even in the images with great variability. PMID:23160896

  4. New optical method for enhanced detection of colon cancer by capsule endoscopy

    NASA Astrophysics Data System (ADS)

    AnkriEqually Contributed, Rinat; Peretz, Dolev; Motiei, Menachem; Sella-Tavor, Osnat; Popovtzer, Rachela

    2013-09-01

    PillCam®COLON capsule endoscopy (CE), a non-invasive diagnostic tool of the digestive tract, has dramatically changed the diagnostic approach and has become an attractive alternative to the conventional colonoscopy for early detection of colorectal cancer. However, despite the significant progress and non-invasive detection capability, studies have shown that its sensitivity and specificity is lower than that of conventional colonoscopy. This work presents a new optical detection method, specifically tailored to colon cancer detection and based on the well-known optical properties of immune-conjugated gold nanorods (GNRs). We show, on a colon cancer model implanted in a chick chorioallantoic membrane (CAM), that this detection method enables conclusive differentiation between cancerous and normal tissues, where neither the distance between the light source and the intestinal wall, nor the background signal, affects the monitored signal. This optical method, which can easily be integrated in CE, is expected to reduce false positive and false negative results and improve identification of tumors and micro metastases.

  5. Optical detection enhancement in porous volumetric microfluidic capture elements using refractive index matching fluids

    PubMed Central

    Wiederoder, M. S.; Peterken, L.; Lu, A. X.; Rahmanian, O. D.; Raghavan, S. R.; DeVoe, D. L.

    2015-01-01

    Porous volumetric capture elements in microfluidic sensors are advantageous compared to planar capture surfaces due to higher reaction site density and decreased diffusion lengths that can reduce detection limits and total assay time. However a mismatch in refractive indices between the capture matrix and fluid within the porous interstices results in scattering of incident, reflected, or emitted light, significantly reducing the signal for optical detection. Here we demonstrate that perfusion of an index-matching fluid within a porous matrix minimizes scattering, thus enhancing optical signal by enabling the entire capture element volume to be probed. Signal enhancement is demonstrated for both fluorescence and absorbance detection, using porous polymer monoliths in a silica capillary and packed beds of glass beads within thermoplastic microchannels, respectively. Fluorescence signal was improved by a factor of 3.5× when measuring emission from a fluorescent compound attached directly to the polymer monolith, and up to 2.6× for a rapid 10 min direct immunoassay. When combining index matching with a silver enhancement step, a detection limit of 0.1 ng/mL human IgG and a 5 log dynamic range was achieved. The demonstrated technique provides a simple method for enhancing optical sensitivity for a wide range of assays, enabling the full benefits of porous detection elements in miniaturized analytical systems to be realized. PMID:26160546

  6. Optical coherence tomography for detection of compound action potential in Xenopus Laevis sciatic nerve

    NASA Astrophysics Data System (ADS)

    Troiani, Francesca; Nikolic, Konstantin; Constandinou, Timothy G.

    2016-03-01

    Due to optical coherence tomography (OCT) high spatial and temporal resolution, this technique could be used to observe the quick changes in the refractive index that accompany action potential. In this study we explore the use of time domain Optical Coherence Tomography (TD-OCT) for real time action potential detection in ex vivo Xenopus Laevis sciatic nerve. TD-OCT is the easiest and less expensive OCT technique and, if successful in detecting real time action potential, it could be used for low cost monitoring devices. A theoretical investigation into the order of magnitude of the signals detected by a TD-OCT setup is provided by this work. A linear dependence between the refractive index and the intensity changes is observed and the minimum SNR for which the setup could work is found to be SNR = 2 x 104.

  7. Towards optical fibre based Raman spectroscopy for the detection of surgical site infection

    NASA Astrophysics Data System (ADS)

    Thompson, Alex J.; Koziej, Lukasz; Williams, Huw D.; Elson, Daniel S.; Yang, Guang-Zhong

    2016-03-01

    Surgical site infections (SSIs) are common post-surgical complications that remain significant clinical problems, as they are associated with substantial mortality and morbidity. As such, there is significant interest in the development of minimally invasive techniques that permit early detection of SSIs. To this end, we are applying a compact, clinically deployable Raman spectrometer coupled to an optical fibre probe to the study of bacteria, with the long term goal of using Raman spectroscopy to detect infection in vivo. Our system comprises a 785 nm laser diode for excitation and a commercial (Ocean Optics, Inc.) Raman spectrometer for detection. Here we discuss the design, optimisation and validation of this system, and describe our first experiences interrogating bacterial cells (Escherichia coli) in vitro.

  8. Optical frequency standards for gravitational wave detection using satellite Doppler velocimetry

    NASA Astrophysics Data System (ADS)

    Vutha, Amar

    2015-06-01

    Gravitational waves (GWs) imprint apparent Doppler shifts on the frequency of photons propagating between an emitter and detector of light. This forms the basis of a method to detect GWs using Doppler velocimetry between pairs of satellites. Operating in the micro-hertz to milli-hertz gravitational frequency band, this method could lead to the direct detection of GWs. The crucial component in such detectors is the frequency standard on board the emitting and receiving satellites. Recent developments in atomic frequency standards have led to devices that are approaching the sensitivity required to detect GWs from astrophysically interesting sources. The sensitivity of satellites equipped with optical frequency standards for Doppler velocimetry is examined, and a design for a robust, space-capable optical frequency standard is presented.

  9. Optical detection of two-color-fluorophore barcode for nanopore DNA sensing

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Sychugov, I.; Schmidt, T.; Linnros, J.

    2015-06-01

    A simple schematic on parallel optical detection of two-fluorophore barcode for single-molecule nanopore sensing is presented. The chosen two fluorophores, ATTO-532 and DY-521-XL, emitting in well-separated spectrum range can be excited at the same wavelength. A beam splitter was employed to separate signals from the two fluorophores and guide them to the same CCD camera. Based on a conventional microscope, sources of background in the nanopore sensing system, including membranes, compounds in buffer solution, and a detection cell was characterized. By photoluminescence excitation measurements, it turned out that silicon membrane has a negligible photoluminescence under the examined excitation from 440 nm to 560 nm, in comparison with a silicon nitrite membrane. Further, background signals from the detection cell were suppressed. Brownian motion of 450 bps DNA labelled with single ATTO-532 or DY-521-XL was successfully recorded by our optical system.

  10. Array sensing using optical methods for detection of chemical and biological hazards.

    PubMed

    Diehl, Katharine L; Anslyn, Eric V

    2013-11-21

    By mimicking the mammalian senses of taste and smell, artificial arrays of cross-reactive receptors have found use in a variety of sensing applications. Pattern recognition algorithms allow these arrays to be used for discriminating analytes and even for predicting the identity of unknown analytes. Furthermore, in selecting a signaling method for these assays, the choice of optical detection is particularly desirable due to its high sensitivity and the associated convenient instrumentation. This tutorial review provides a brief introduction to array sensing using optical detection and chemometrics. While differential sensing approaches have been used for a number of applications, this review focuses on progress towards the detection of chemical and biological hazards. PMID:23999658

  11. Single-molecule detection at high concentrations with optical aperture nanoantennas.

    PubMed

    Alam, Md Shah; Karim, Farzia; Zhao, Chenglong

    2016-05-14

    Single-molecule detection has become an indispensable technology in life science, and medical research. In order to get meaningful information on many biological processes, single-molecule analysis is required in micro-molar concentrations. At such high concentrations, it is very challenging to isolate a single molecule with conventional diffraction-limited optics. Recently, optical aperture nanoantennas (OANs) have emerged as a powerful tool to enhance the single-molecule detection under a physiological environment. The OANs, which consist of nano-scale apertures on a metallic film, have the following unique properties: (1) nanoscale light confinement; (2) enhanced fluorescence emission; (3) tunable radiation pattern; (4) reduced background noise; and (5) massive parallel detection. This review presents the fundamentals, recent developments and future perspectives in this emerging field. PMID:27120086

  12. Optical-digital detection of dents and scratches on specular metal surfaces.

    PubMed

    Lippincott, H W; Stark, H

    1982-08-15

    An optical-digital approach to the problem of automatic detection of dents and scratches on specular or semispecular surfaces is presented. The method uses the optical reflecting properties of dents and scratches to locate and detect them. Dents are found by a grid projection and encoding technique; scratches are found by using the property that diffuse reflectors scatter over a wider angle (Lambert's law) than specular ones and, therefore, seem brighter when viewed at certain angles. The procedure for finding dents and scratches was found to be very robust: dents as small as 1% of the viewed field and 0.0053 cm (0.0021 in.) deep and scratches as small as 0.003 cm (0.001 in.) wide and 0.00064 cm (0.00025 in.) deep and of variable minimum length were easily detected using nonspecially prepared samples. PMID:20396141

  13. Single-molecule detection at high concentrations with optical aperture nanoantennas

    NASA Astrophysics Data System (ADS)

    Alam, Md Shah; Karim, Farzia; Zhao, Chenglong

    2016-05-01

    Single-molecule detection has become an indispensable technology in life science, and medical research. In order to get meaningful information on many biological processes, single-molecule analysis is required in micro-molar concentrations. At such high concentrations, it is very challenging to isolate a single molecule with conventional diffraction-limited optics. Recently, optical aperture nanoantennas (OANs) have emerged as a powerful tool to enhance the single-molecule detection under a physiological environment. The OANs, which consist of nano-scale apertures on a metallic film, have the following unique properties: (1) nanoscale light confinement; (2) enhanced fluorescence emission; (3) tunable radiation pattern; (4) reduced background noise; and (5) massive parallel detection. This review presents the fundamentals, recent developments and future perspectives in this emerging field.

  14. AIRBORNE, OPTICAL REMOTE SENSNG OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION

    SciTech Connect

    Jerry Myers

    2005-04-15

    Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The scope of the work involved designing and developing an airborne, optical remote sensor capable of sensing methane and, if possible, ethane for the detection of natural gas pipeline leaks. Flight testing using a custom dual wavelength, high power fiber amplifier was initiated in February 2005. Ophir successfully demonstrated the airborne system, showing that it was capable of discerning small amounts of methane from a simulated pipeline leak. Leak rates as low as 150 standard cubic feet per hour (scf/h) were detected by the airborne sensor.

  15. Optical Observation, Image-processing, and Detection of Space Debris in Geosynchronous Earth Orbit

    NASA Astrophysics Data System (ADS)

    Oda, H.; Yanagisawa, T.; Kurosaki, H.; Tagawa, M.

    2014-09-01

    We report on optical observations and an efficient detection method of space debris in the geosynchronous Earth orbit (GEO). We operate our new Australia Remote Observatory (ARO) where an 18 cm optical telescope with a charged-coupled device (CCD) camera covering a 3.14-degree field of view is used for GEO debris survey, and analyse datasets of successive CCD images using the line detection method (Yanagisawa and Nakajima 2005). In our operation, the exposure time of each CCD image is set to be 3 seconds (or 5 seconds), and the time interval of CCD shutter open is about 4.7 seconds (or 6.7 seconds). In the line detection method, a sufficient number of sample objects are taken from each image based on their shape and intensity, which includes not only faint signals but also background noise (we take 500 sample objects from each image in this paper). Then we search a sequence of sample objects aligning in a straight line in the successive images to exclude the noise sample. We succeed in detecting faint signals (down to about 1.8 sigma of background noise) by applying the line detection method to 18 CCD images. As a result, we detected about 300 GEO objects up to magnitude of 15.5 among 5 nights data. We also calculate orbits of objects detected using the Simplified General Perturbations Satellite Orbit Model 4(SGP4), and identify the objects listed in the two-line-element (TLE) data catalogue publicly provided by the U.S. Strategic Command (USSTRATCOM). We found that a certain amount of our detections are new objects that are not contained in the catalogue. We conclude that our ARO and detection method posse a high efficiency detection of GEO objects despite the use of comparatively-inexpensive observation and analysis system. We also describe the image-processing specialized for the detection of GEO objects (not for usual astronomical objects like stars) in this paper.

  16. Fiber optic distributed chemical sensor for the real time detection of hydrocarbon fuel leaks

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar; Kempen, C.; Esterkin, Yan; Sun, Sunjian

    2015-09-01

    With the increase worldwide demand for hydrocarbon fuels and the vast development of new fuel production and delivery infrastructure installations around the world, there is a growing need for reliable hydrocarbon fuel leak detection technologies to provide safety and reduce environmental risks. Hydrocarbon leaks (gas or liquid) pose an extreme danger and need to be detected very quickly to avoid potential disasters. Gas leaks have the greatest potential for causing damage due to the explosion risk from the dispersion of gas clouds. This paper describes progress towards the development of a fast response, high sensitivity, distributed fiber optic fuel leak detection (HySense™) system based on the use of an optical fiber that uses a hydrocarbon sensitive fluorescent coating to detect the presence of fuel leaks present in close proximity along the length of the sensor fiber. The HySense™ system operates in two modes, leak detection and leak localization, and will trigger an alarm within seconds of exposure contact. The fast and accurate response of the sensor provides reliable fluid leak detection for pipelines, storage tanks, airports, pumps, and valves to detect and minimize any potential catastrophic damage.

  17. Optical detection of breast cancer: a pilot clinical trial at the Massachusetts General Hospital

    NASA Astrophysics Data System (ADS)

    Cheng, Xuefeng; Mao, Jian M.; Zhu, Wen; Bush, Robin; Kopans, Daniel B.; Moore, Richard H.; Chorlton, Maryann

    2003-06-01

    X-ray mammography has been the major imaging modality in breast cancer detection for years, despite its high false diagnosis rate for malignant tumors and harmful radiation. In the last decade, optical imaging has been emerging as a promising method for breast cancer detection. Using near infrared (NIR) light ranging from 690 nm to 900 nm, an optical device can measure functional properties of breast tissue, such as total hemoglobin concentration (HbT) and oxygen saturation (SO2). Cancers tend to have higher levels of HbT because of their greater vascularization, and lower SO2 because of greater oxygen consumption, than normal tissue. Thus the NIR technology could be useful in breast cancer detection. In addition, optical detection is totally noninvasive and safe, and can be low cost. Photonify Technologies Inc. has developed an optical device for real-time two-dimensional mapping of HbT and SO2 in breast tissue. The device has been tested in a pilot clinical study for a group of 50 patients at the Department of Radiology of the Masachusetts General Hospital at Harvard Medical School. Preliminary results suggest that contrast-normalized standard deviations in HbT and SO2 might be good indicators for breast cancer detection. A patient may have a higher risk to have cancer in a breast portion where the normalized standard deviation in either HbT or SO2 is greater than 0.3. We demonstrate 92% diagnostic sensitivity and 66% specificity in detecting ductal carcinoma, either invasive or in situ. The device may potentially be used as an adjunctive tool with mammography to reduce unnecessary biopsies.

  18. Fiber optic oxygen sensor detection system for harsh environments of aerospace applications

    NASA Astrophysics Data System (ADS)

    Kazemi, Alex A.; Mendoza, Edgar; Goswami, Kish; Kempen, Lothar

    2013-05-01

    This paper describes the first successful fiber optic oxygen detection sensor systems developed for the Boeing Delta IV Launch Vehicle harsh environment of engine section. It illustrates a novel multi-point fiber optic microsensor (optrode) based on dynamic luminescence quenching that was developed for measuring oxygen leak detection for the space applications. The sensor optrodes employ the quenching by oxygen of the fluorescence from a ruthenium complex. These optrodes were fabricated using Ruthenium-based fluorescent indicator immobilized in a porous glass rod placed at the end of multimode fiber. The light from a blue LED is launched into the optrode via a fiber optic bundle and used as the excitation source. The optrode's fluorescent emission intensity in the range of 0% to 10% oxygen is measured as a function of time. The measuring system is based on high reliability and low cost. The system consists of four units: 1) temperature compensated oxygen optrodes combined with an optical setup, 2) multipoint sensor communication fiber optic network cable, 3) digital/analogue optoelectronic signal processing unit with built-in micro controller for control of data acquisition and processing, and 4) a laptop computer for data display and storage. In testing, the sensor exhibited excellent response time and reversibility. To qualify the sensors, performed detail investigation for thermal, humidity, temperature, vibration and accelerate testing for life expectancy of harsh environmental of engine section. Extensive networking using MatLab were carried out for lab and actual field demonstrations.

  19. Detection and diagnosis of oral neoplasia with an optical coherence microscope

    PubMed Central

    Clark, A. L.; Gillenwater, A.; Alizadeh-Naderi, R.; El-Naggar, A. K.; Richards-Kortum, R.

    2009-01-01

    The use of high resolution, in vivo optical imaging may offer a clinically useful adjunct to standard histopathologic techniques. A pilot study was performed to investigate the diagnostic capabilities of optical coherence microscopy (OCM) to discriminate between normal and abnormal oral tissue. Our objective is to determine whether OCM, a technique combining the subcellular resolution of confocal microscopy with the coherence gating and heterodyne detection of optical coherence tomography, has the same ability as confocal microscopy to detect morphological changes present in precancers of the epithelium while providing superior penetration depths. We report our results using OCM to characterize the features of normal and neoplastic oral mucosa excised from 13 subjects. Specifically, we use optical coherence and confocal microscopic images obtained from human oral biopsy specimens at various depths from the mucosal surface to examine the optical properties that distinguish normal and neoplastic oral mucosa. An analysis of penetration depths achieved by the OCM and its associated confocal arm found that the OCM consistently imaged more deeply. Extraction of scattering coefficients from reflected nuclear intensity is successful in nonhyperkeratotic layers and shows differentiation between scattering properties of normal and dysplastic epithelium and invasive cancer. PMID:15568948

  20. Detection of wavelengths in the visible range using fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Díaz, Leonardo; Morales, Yailteh; Mattos, Lorenzo; Torres, Cesar O.

    2013-11-01

    This paper shows the design and implementation of a fiber optic sensor for detecting and identifying wavelengths in the visible range. The system consists of a diffuse optical fiber, a conventional laser diode 650nm, 2.5mW of power, an ambient light sensor LX1972, a PIC 18F2550 and LCD screen for viewing. The principle used in the detection of the lambda is based on specular reflection and absorption. The optoelectronic device designed and built used the absorption and reflection properties of the material under study, having as active optical medium a bifurcated optical fiber, which is optically coupled to an ambient light sensor, which makes the conversion of light signals to electricas, procedure performed by a microcontroller, which acquires and processes the signal. To verify correct operation of the assembly were utilized the color cards of sewing thread and nail polish as samples for analysis. This optoelectronic device can be used in many applications such as quality control of industrial processes, classification of corks or bottle caps, color quality of textiles, sugar solutions, polymers and food among others.

  1. Nanomaterial-based optical sensors for sensitive detection of heavy metal ions

    NASA Astrophysics Data System (ADS)

    Wang, Shasha; Chen, Lingxin

    2015-07-01

    Nanometerial-based optical nanoprobes have been extensively developed because of their high sensitivity, good specificity, and potential for easy quantification of species in chemical and biological analysis. With the development of nanotechnology, various kinds of nanomaterials with novel optical properties have heen generated, laying the foundation of optical nanoprobes. By further integrating receptors (chemical ligand, aptamer, molecular imprinting polymer, etc.), the information of binding specific targets will transform into analytically optical signals by employing different detection techniques including colorimetry/UV-Vis spectra, fluorometry and surface enhanced Raman scattering (SERS). In this presentation, firstly, we introduced a simple, rapid and ultrasensitive SERS nanosensor for mercury ion (Hg2+) detection based on the 4-mercaptopyridine (4-MPY) functionalized silver nanoparticles (AgNPs) in the presence of spermine; then, a novel colorimetric nanosensor for mercury species was developed for the first time due to the analyte-induced aggregation of gold nanoparticles (AuNPs) with the assistance of a thiol-containing ligand of diethyldithiocarbamate (DDTC); finally, the sensitive and selective recognition and detection of trypsin was realized in a SERS strategy by using anti-aggregation of 4-MPY-functionalized AgNPs on the basis of the interaction between protamine and trypsin.

  2. [Optical multi-channel detection and analysis on solar ultra-violet irradiance spectrum].

    PubMed

    Zhao, Xiao-yan; He, Jie; Zuo, Hao-yi; Liang, Hui-min; Yang, Jing-guo

    2007-05-01

    The present paper reports a new type of ultraviolet CCD optical multi-channel analyzer and its application to detecting solar ultraviolet irradiance spectrum. Spectral detecting range of 200-1 100 nm, spectral resolution of 0.1 nm and detecting sensitivity of 0.02 lx were reached in this instrument. The solar spectra of UVB and UVA were measured in real time in Chengdu area. The measurement results have good correlation with the detection using normal solar ultraviolet irradiance detector. Primary analysis on the detection results of solar spectra in UVB and UVA indicated that in the morning and in the afternoon the irradiance of solar ultraviolet is smaller than that at noon, and reverse correlation holds for the change of SZA (Solar Zenith Angle). In different wavelength interval of UVA and UVB, generally, the radiation flux of long wavelength is greater than that of short. Clouds and aerosols in the atmosphere have important influence on ultraviolet irradiance. PMID:17655086

  3. Performance and noise analysis of optical microresonator-based biochemical sensors using intensity detection.

    PubMed

    Zhou, Xiaoyan; Zhang, Lin; Pang, Wei

    2016-08-01

    Optical microcavity sensors using intensity detection open up the possibility to realize fully integrated high-performance sensing devices, which are significant for both fundamental study of molecular interaction and rapid disease diagnosis. Although the performance of microresonator-based sensors has been studied focusing on the resonance-tracking method, the situation can be much different for intensity-detection sensors. Here we conducted a systematically investigation on the noises sources in intensity detection scheme and their influences on key performance parameters, e.g., signal-to-noise ratio (SNR), limit-of-detection (LOD), and detection range, for various sensors configurations. Especially, the trade-off between SNR and LOD is identified and theoretically analyzed. With experiment noises taken into consideration, our work aims to provide design guidelines for integrated microresonator sensors with optimized performance. PMID:27505784

  4. Fiber optic/cone penetrometer system for subsurface heavy metals detection

    SciTech Connect

    Saggese, S.; Greenwell, R.

    1995-10-01

    The objective of this project is to develop an integrated fiber optic sensor/cone penetrometer system to analyze the heavy metals content of the subsurface. This site characterization tool will use an optical fiber cable assembly which delivers high power laser energy to vaporize and excite a sample in-situ and return the emission spectrum from the plasma produced for chemical analysis. The chemical analysis technique, often referred to as laser induced breakdown spectroscopy (LIBS), has recently shown to be an effective method for the quantitative analysis of contaminants soils. By integrating the fiber optic sensor with the cone penetrometer, we anticipate that the resultant system will enable in-situ, low cost, high resolution, real-time subsurface characterization of numerous heavy metal soil contaminants simultaneously. There are several challenges associated with the integration of the LIBS sensor and cone penetrometer. One challenge is to design an effective means of optically accessing the soil via the fiber probe in the penetrometer. A second challenge is to develop the fiber probe system such that the resultant emission signal is adequate for quantitative analysis. Laboratory techniques typically use free space delivery of the laser to the sample. The high laser powers used in the laboratory cannot be used with optical fibers, therefore, the effectiveness of the LIBS system at the laser powers acceptable to fiber delivery must be evaluated. The primary objectives for this project are: (1) Establish that a fiber optic LIBS technique can be used to detect heavy metals to the required concentration levels; (2) Design and fabricate a fiber optic probe for integration with the penetrometer system for the analysis of heavy metals in soil samples; (3) Design, fabricate, and test an integrated fiber/penetrometer system; (4) Fabricate a rugged, field deployable laser source and detection hardware system; and (6) Demonstrate the prototype in field deployments.

  5. Optical digital coherent detection technology enabled flexible and ultra-fast quantitative phase imaging.

    PubMed

    Feng, Yuan-Hua; Lu, Xing; Song, Lu; Guo, Xiaojie; Wang, Yawei; Zhu, Linyan; Sui, Qi; Li, Jianping; Shi, Kebin; Li, Zhaohui

    2016-07-25

    Quantitative phase imaging has been an important labeling-free microscopy modality for many biomedical and material science applications. In which, ultra-fast quantitative phase imaging is indispensable for dynamic or transient characteristics analysis. Conventional wide field optical interferometry is a common scheme for quantitative phase imaging, while its data acquisition rate is usually hindered by the frame rate of arrayed detector. By utilizing novel balanced-photo-detector based digital optics coherent detection techniques, we report on a method of constructing ultra-fast quantitative phase microscopy at the line-scan rate of 100 MHz with ~2 μm spatial resolution. PMID:27464166

  6. Optical Detection of Local Electric Field Dynamics in Solutions by Waveguide-integrated Graphene Device

    NASA Astrophysics Data System (ADS)

    Horng, Jason; Balch, Halleh; Feng Wang Team

    The spatio-temporal dynamics of local electric fields in ionic solutions plays a central role in various chemical and biological processes ranging from batteries technologies to neuron signaling. A non-invasive, precise detection scheme for measuring local electric fields dynamics has long been sought for. Here, we report a sensitive, high-speed, high spatial resolution optical imaging method for local electric fields based on the unique optoelectronic properties of graphene. With enhancement from a waveguide involving critical coupling concept, we show that our graphene optical sensor provides an ideal platform for studying dynamics of local electric field fluctuations in different nonequilibrium solutions.

  7. Fiber-optic thermometer using temperature dependent absorption, broadband detection, and time domain referencing

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory; Piltch, Nancy D.

    1986-01-01

    A fiber-optic thermometer based on temperature dependent absorption in Nd(3+) doped glass is demonstrated over the 298-573 K range. A broadband detection technique allows the use of the complete spectrum of a pulse modulated light emitting diode. A fiber-optic recirculating loop is employed to construct a reference channel in the time domain by generating a train of pulses from one initial pulse. A theoretical model is developed, and experimental data are shown to compare well with the theory. Possible sources of error and instability are identified, and ways to enhance the performance of the system are proposed.

  8. Towards multimodal detection of melanoma thickness based on optical coherence tomography and optoacoustics

    NASA Astrophysics Data System (ADS)

    Rahlves, M.; Varkentin, A.; Stritzel, J.; Blumenröther, E.; Mazurenka, M.; Wollweber, M.; Roth, B.

    2016-03-01

    Melanoma skin cancer has one of the highest mortality rates of all types of cancer if not detected at an early stage. The survival rate is highly dependent on its penetration depth, which is commonly determined by histopathology. In this work, we aim at combining optical coherence tomography and optoacoustic as a non-invasive all-optical method to measure the penetration depth of melanoma. We present our recent achievements to setup a handheld multimodal device and also results from first in vivo measurements on healthy and cancerous skin tissue, which are compared to measurements obtained by ultrasound and histopathology.

  9. Structure detection in a libration vibration spectrum of water molecules by methods of nonlinear optics

    SciTech Connect

    Babenko, V A; Sychev, Andrei A

    2012-09-30

    In exciting water possessing an enhanced optical strength by the radiation of a YAG : Nd{sup 3+} laser with 20-ps pulses, nonlinear scattering of light was detected in the frequency range of the optical second harmonic. A relationship was established of the signal of the nonlinear scattering with a stimulated Raman scattering (SRS) of the laser radiation in water. Near the SRS threshold, the structure was observed in the spectrum of nonlinear scattering, which is related to intermolecular libration vibrations of water molecules. (laser applications and other topics in quantum electronics)

  10. A Multiscale Decomposition Approach to Detect Abnormal Vasculature in the Optic Disc

    PubMed Central

    Agurto, Carla; Yu, Honggang; Murray, Victor; Pattichis, Marios S.; Nemeth, Sheila; Barriga, Simon; Soliz, Peter

    2015-01-01

    This paper presents a multiscale method to detect neovascularization in the optic disc (NVD) using fundus images. Our method is applied to a manually selected region of interest (ROI) containing the optic disc. All the vessels in the ROI are segmented by adaptively combining contrast enhancement methods with a vessel segmentation technique. Textural features extracted using multiscale amplitude-modulation frequency-modulation, morphological granulometry, and fractal dimension are used. A linear SVM is used to perform the classification, which is tested by means of 10-fold cross-validation. The performance is evaluated using 300 images achieving an AUC of 0.93 with maximum accuracy of 88%. PMID:25698545

  11. Coherent fiber optic sensor for early detection of cataractogenesis in a human eye lens

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans S.; Ansari, Rafat R.; Dellavecchia, Michael A.

    1993-01-01

    A lensless backscatter fiber optic probe is used to measure the size distribution of protein molecules inside an excised, but intact, human eye lens. The fiber optic probe, about 5 mm in diameter, can be positioned arbitrarily close to the anterior surface of the eye; it is a trans-receiver, which delivers a Gaussian laser beam into a small region inside the lens and provides a coherent detection of the laser light scattered by the protein molecules in the backward direction. Protein sizes determined from the fast and slow diffusion coefficients show good correlation with the age of the lens and cataractogenesis.

  12. Attonewton force detection using microspheres in a dual-beam optical trap in high vacuum

    NASA Astrophysics Data System (ADS)

    Ranjit, Gambhir; Atherton, David P.; Stutz, Jordan H.; Cunningham, Mark; Geraci, Andrew A.

    2015-05-01

    We describe the implementation of laser-cooled silica microspheres as force sensors in a dual-beam optical dipole trap in high vacuum. Using this system we have demonstrated trap lifetimes exceeding several days, attonewton force detection capability, and wide tunability in trapping and cooling parameters. Measurements have been performed with charged and neutral beads to calibrate the sensitivity of the detector. This work establishes the suitability of dual-beam optical dipole traps for precision force measurement in high vacuum with long averaging times, and enables future applications including the study of gravitational inverse square law violations at short range, Casimir forces, acceleration sensing, and quantum optomechanics.

  13. Lab-on-fiber electrophoretic trace mixture separating and detecting an optofluidic device based on a microstructured optical fiber.

    PubMed

    Yang, Xinghua; Guo, Xiaohui; Li, Song; Kong, Depeng; Liu, Zhihai; Yang, Jun; Yuan, Libo

    2016-04-15

    We report an in-fiber integrated electrophoretic trace mixture separating and detecting an optofluidic optical fiber sensor based on a specially designed optical fiber. In this design, rapid in situ separation and simultaneous detection of mixed analytes can be realized under electro-osmotic flow in the microstructured optical fiber. To visually display the in-fiber separating and detecting process, two common fluorescent indicators are adopted as the optofluidic analytes in the optical fiber. Results show that a trace amount of the mixture (0.15 μL) can be completely separated within 3.5 min under a high voltage of 5 kV. Simultaneously, the distributed information of the separated analytes in the optical fiber can be clearly obtained by scanning along the optical fiber using a 355 nm laser. The emission from the analytes can be efficiently coupled into the inner core and guides to the remote end of the optical fiber. In addition, the thin cladding around the inner core in the optical fiber can prevent the fluorescent cross talk between the analytes in this design. Compared to previous optical fiber optofluidic devices, this device first realizes simultaneously separating treatment and the detection of the mixed samples in an optical fiber. Significantly, such an in-fiber integrated separating and detecting optofluidic device can find wide applications in various analysis fields involves mixed samples, such as biology, chemistry, and environment. PMID:27082367

  14. RadSensor: Xray Detection by Direct Modulation of an Optical Probe Beam

    SciTech Connect

    Lowry, M E; Bennett, C V; Vernon, S P; Bond, T; Welty, R; Behymer, E; Petersen, H; Krey, A; Stewart, R; Kobayashi, N P; Sperry, V; Stephan, P; Reinhardt, C; Simpson, S; Stratton, P; Bionta, R; McKernan, M; Ables, E; Ott, L; Bond, S; Ayers, J.; Landen, O L; Bell, P M

    2003-08-01

    We present a new x-ray detection technique based on optical measurement of the effects of x-ray absorption and electron hole pair creation in a direct band-gap semiconductor. The electron-hole pairs create a frequency dependent shift in optical refractive index and absorption. This is sensed by simultaneously directing an optical carrier beam through the same volume of semiconducting medium that has experienced an xray induced modulation in the electron-hole population. If the operating wavelength of the optical carrier beam is chosen to be close to the semiconductor band-edge, the optical carrier will be modulated significantly in phase and amplitude. This approach should be simultaneously capable of very high sensitivity and excellent temporal response, even in the difficult high-energy xray regime. At xray photon energies near 10 keV and higher, we believe that sub-picosecond temporal responses are possible with near single xray photon sensitivity. The approach also allows for the convenient and EMI robust transport of high-bandwidth information via fiber optics. Furthermore, the technology can be scaled to imaging applications. The basic physics of the detector, implementation considerations, and preliminary experimental data are presented and discussed.

  15. AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION

    SciTech Connect

    Jerry Myers

    2003-11-12

    Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. This second six-month technical report summarizes the progress made towards defining, designing, and developing the hardware and software segments of the airborne, optical remote methane and ethane sensor. The most challenging task to date has been to identify a vendor capable of designing and developing a light source with the appropriate output wavelength and power. This report will document the work that has been done to identify design requirements, and potential vendors for the light source. Significant progress has also been made in characterizing the amount of light return available from a remote target at various distances from the light source. A great deal of time has been spent conducting laboratory and long-optical path target reflectance measurements. This is important since it helps to establish the overall optical output requirements for the sensor. It also reduces the relative uncertainty and risk associated with developing a custom light source. The data gathered from the optical path testing has been translated to the airborne transceiver design in such areas as: fiber coupling, optical detector selection, gas filters, and software analysis. Ophir will next, summarize the design progress of the transceiver hardware and software development. Finally, Ophir will discuss remaining project issues that may impact the success of the project.

  16. Elastomeric optical fiber sensors and method for detecting and measuring events occurring in elastic materials

    DOEpatents

    Muhs, Jeffrey D.; Capps, Gary J.; Smith, David B.; White, Clifford P.

    1994-01-01

    Fiber optic sensing means for the detection and measurement of events such as dynamic loadings imposed upon elastic materials including cementitious materials, elastomers, and animal body components and/or the attrition of such elastic materials are provided. One or more optical fibers each having a deformable core and cladding formed of an elastomeric material such as silicone rubber are embedded in the elastic material. Changes in light transmission through any of the optical fibers due the deformation of the optical fiber by the application of dynamic loads such as compression, tension, or bending loadings imposed on the elastic material or by the attrition of the elastic material such as by cracking, deterioration, aggregate break-up, and muscle, tendon, or organ atrophy provide a measurement of the dynamic loadings and attrition. The fiber optic sensors can be embedded in elastomers subject to dynamic loadings and attrition such as commonly used automobiles and in shoes for determining the amount and frequency of the dynamic loadings and the extent of attrition. The fiber optic sensors are also useable in cementitious material for determining the maturation thereof.

  17. Mobile fiber-optic sensor for detection of oral and cervical cancer in the developing world.

    PubMed

    Yu, Bing; Nagarajan, Vivek Krishna; Ferris, Daron G

    2015-01-01

    Oral and cervical cancers are a growing global health problem that disproportionately impacts women and men living in the developing world. The high death rate in developing countries is largely due to the fact that these countries do not have the appropriate medical infrastructure and resources to support the organized screening and diagnostic programs that are available in the developed world. Diffuse reflectance spectroscopy (DRS) with a fiber-optic probe can noninvasively quantify the optical properties of epithelial tissues and has shown the potential as a cost-effective, easy-to-use, and sensitive tool for diagnosis of early precancerous changes in the cervix and oral cavity. However, current fiber-optic DRS systems have not been designed to be robust and reliable for use in developing countries. They are subject to various sources of systematic or random errors, arising from the uncontrolled probe-tissue interface and lack of real-time calibration, use bulky and expensive optical components, and require extensive training. This chapter describes a portable DRS device that is specifically designed for detection of oral and cervical cancers in resource-poor settings. The device uses an innovative smart fiber-optic probe to eliminate operator bias, state-of-the-art photonics components to reduce size and power consumption, and automated software to reduce the need of operator training. The size and cost of the smart fiber-optic DRS system may be further reduced by incorporating a smartphone based spectrometer. PMID:25626538

  18. Intrinsic Fiber Optic Chemical Sensors for Subsurface Detection of CO2

    SciTech Connect

    Alonso, Jesus

    2016-01-01

    Intelligent Optical Systems, Inc. has developed distributed intrinsic fiber optic sensors to directly quantify the concentration of dissolved or gas-phase CO2 for leak detection or plume migration in carbon capture and sequestration (CCS). The capability of the sensor for highly sensitive detection of CO2 in the pressure and temperature range of 15 to 2,000 psi and 25°C to 175°C was demonstrated, as was the capability of operating in highly corrosive and contaminated environments such as those often found in CO2 injection sites. The novel sensor system was for the first time demonstrated deployed in a deep well, detecting multiple CO2 releases, in real time, at varying depths. Early CO2 release detection, by means of a sensor cable integrating multiple sensor segments, was demonstrated, as was the capability of quantifying the leak. The novel fiber optic sensor system exhibits capabilities not achieved by any other monitoring technology. This project represents a breakthrough in monitoring capabilities for CCS applications.

  19. Breast cancer detection based on time reversal and the optical theorem

    NASA Astrophysics Data System (ADS)

    Marengo, Edwin A.; Tu, Jing

    2015-03-01

    We report a wave physics-based approach to change detection which can be used to detect anomalies in biological tissues such as cancer lesions from active sensing data. Of particular interest are nonionizing radiation methods such as microwave breast imaging, ultrasound imaging, and diffuse optical tomography. The biological medium surrounding the target of interest, e.g., a tumor, is assumed to be highly nonhomogeneous and reverberating. This implies that there are in general multiple paths for the propagation of wave signals from an interior domain where the target of interest is located to the sensing aperture where the scattered fields are measured. Two physical concepts are used to exploit this rich multipath environment so as to enhance change detection performance: wave time reversal, and the optical theorem which describes energy conservation in scattering phenomena. Previous related work has reported the use of time reversal for breast cancer detection. We use not only time reversal, but also the optical theorem, and propose novel algorithms based on both.

  20. Evaluation of optical brightener photodecay characteristics for detection of human fecal contamination.

    PubMed

    Cao, Yiping; Griffith, John F; Weisberg, Stephen B

    2009-05-01

    Detection of optical brighteners by fluorometry combined with ultraviolet light (UV) exposure has been proposed as an inexpensive method for detection of human fecal contamination, but has received limited testing. This study evaluated the approach in southern California by applying it to a variety of detergents, sewage and septage samples from the region, as well as to natural stream water as a negative control. The concept of using UV exposure to differentiate fluorescence from natural organic matter proved valid, as the method produced no false positives. However, the method failed to detect half of the detergents tested in natural stream water at 5 microL/L, due to its conservative thresholds. This study identified a method modification that provides greater sensitivity by taking advantage of differences in the shape of photodecay curves between optical brighteners and natural organic matter. This method modification resulted in detection of all detergents, sewage at 1:10 dilution and septage at 1:100 dilution. Several caveats for its use remain, including our observation that the optical brightener signal degraded rapidly in strong sunlight. Additionally, there was low sensitivity for some environmentally friendly detergents, which does not present a problem on a community basis where a mix of detergents are used, but could be of concern for assessing septic inputs from individual homes. Still, the method is simple to employ in the field, yields rapid results and is useful as a low-cost initial screening tool. PMID:19285334