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Sample records for ftir-fiber optic method

  1. Fourier transform infrared (FTIR) fiber optic monitoring of composites during cure in an autoclave

    NASA Technical Reports Server (NTRS)

    Druy, Mark A.; Elandjian, Lucy; Stevenson, William A.; Driver, Richard D.; Leskowitz, Garett M.

    1990-01-01

    Real-time in situ monitoring of the chemical states of epoxy resins was investigated during cure in an autoclave using infrared evanescent spectroscopy. Fiber evanescent sensors were developed which may be sandwiched between the plies of the prepreg sample. A short length of sapphire fiber was used as the sensor cell portion of the fiber probe. Heavy metal fluoride glass optical fiber cables were designed for connecting the FTIR spectrometer to the sensor fiber within the autoclave. The sapphire fibers have outstanding mechanical thermal properties which should permit their use as an embedded link in all thermoset composites. The system is capable of operation at a temperature of 250 C for periods up to 8 hours without major changes to the fiber transmission. A discussion of the selection of suitable sensor fibers, the construction of a fiber-optic interface, and the interpretation of in situ infrared spectra of the curing process is presented.

  2. Optical switches and switching methods

    DOEpatents

    Doty, Michael

    2008-03-04

    A device and method for collecting subject responses, particularly during magnetic imaging experiments and testing using a method such as functional MRI. The device comprises a non-metallic input device which is coupled via fiber optic cables to a computer or other data collection device. One or more optical switches transmit the subject's responses. The input device keeps the subject's fingers comfortably aligned with the switches by partially immobilizing the forearm, wrist, and/or hand of the subject. Also a robust nonmetallic switch, particularly for use with the input device and methods for optical switching.

  3. Methods for globally treating silica optics to reduce optical damage

    DOEpatents

    Miller, Philip Edward; Suratwala, Tayyab Ishaq; Bude, Jeffrey Devin; Shen, Nan; Steele, William Augustus; Laurence, Ted Alfred; Feit, Michael Dennis; Wong, Lana Louie

    2012-11-20

    A method for preventing damage caused by high intensity light sources to optical components includes annealing the optical component for a predetermined period. Another method includes etching the optical component in an etchant including fluoride and bi-fluoride ions. The method also includes ultrasonically agitating the etching solution during the process followed by rinsing of the optical component in a rinse bath.

  4. Optical measurement methods in thermogasdynamics

    NASA Technical Reports Server (NTRS)

    Stursberg, K.; Erhardt, K.; Krahr, W.; Becker, M.

    1978-01-01

    A review is presented of a number of optical methods of flow measurements. Consideration is given to such spectroscopic methods as emission and absorption techniques, electron beam-stimulated fluorescence, and light scattering - Rayleigh, Raman and Mie - methods. The following visualization methods are also discussed: shadow photography, schlieren photography, interferometry, holographic interferometry, laser anemometry, particle holography, and electron-excitation imaging. A large bibliography is presented and the work is copiously illustrated with figures and photographs.

  5. Method of lightening radiation darkened optical elements

    DOEpatents

    Reich, Frederich R.; Schwankoff, Albert R.

    1980-01-01

    A method of lightening a radiation-darkened optical element in wich visible optical energy or electromagnetic radiation having a wavelength in the range of from about 2000 to about 20,000 angstroms is directed into the radiation-darkened optical element; the method may be used to lighten radiation-darkened optical element in-situ during the use of the optical element to transmit data by electronically separating the optical energy from the optical output by frequency filtering, data cooling, or interlacing the optic energy between data intervals.

  6. Fiber optic sensor and method for making

    DOEpatents

    Vartuli, James Scott; Bousman, Kenneth Sherwood; Deng, Kung-Li; McEvoy, Kevin Paul; Xia, Hua

    2010-05-18

    A fiber optic sensor including a fiber having a modified surface integral with the fiber wherein the modified surface includes an open pore network with optical agents dispersed within the open pores of the open pore network. Methods for preparing the fiber optic sensor are also provided. The fiber optic sensors can withstand high temperatures and harsh environments.

  7. Optical design and active optics methods in astronomy

    NASA Astrophysics Data System (ADS)

    Lemaitre, Gerard R.

    2013-03-01

    Optical designs for astronomy involve implementation of active optics and adaptive optics from X-ray to the infrared. Developments and results of active optics methods for telescopes, spectrographs and coronagraph planet finders are presented. The high accuracy and remarkable smoothness of surfaces generated by active optics methods also allow elaborating new optical design types with high aspheric and/or non-axisymmetric surfaces. Depending on the goal and performance requested for a deformable optical surface analytical investigations are carried out with one of the various facets of elasticity theory: small deformation thin plate theory, large deformation thin plate theory, shallow spherical shell theory, weakly conical shell theory. The resulting thickness distribution and associated bending force boundaries can be refined further with finite element analysis.

  8. Method for optical and mechanically coupling optical fibers

    DOEpatents

    Toeppen, J.S.

    1996-10-01

    A method and apparatus are disclosed for splicing optical fibers. A fluorescing solder glass frit having a melting point lower than the melting point of first and second optical fibers is prepared. The solder glass frit is then attached to the end of the first optical fiber and/or the end of the second optical fiber. The ends of the optical fibers are aligned and placed in close proximity to each other. The solder glass frit is then heated to a temperature which is lower than the melting temperature of the first and second optical fibers, but which is high enough to melt the solder glass frit. A force is applied to the first and second optical fibers pushing the ends of the fibers towards each other. As the solder glass flit becomes molten, the layer of molten solder glass is compressed into a thin layer between the first and second optical fibers. The thin compressed layer of molten solder glass is allowed to cool such that the first and second optical fibers are bonded to each other by the hardened layer of solder glass. 6 figs.

  9. Optical distance measurement device and method thereof

    DOEpatents

    Bowers, Mark W.

    2003-05-27

    A system and method of efficiently obtaining distance measurements of a target. A modulated optical beam may be used to determine the distance to the target. A first beam splitter may be used to split the optical beam and a second beam splitter may be used to recombine a reference beam with a return ranging beam. An optical mixing detector may be used in a receiver to efficiently detect distance measurement information.

  10. Optical Element, Device, Method, and Applications

    DTIC Science & Technology

    2011-04-14

    optical element is a phase-only element; and h) repeating steps ( c -f). 28. The method of claim 26, further comprising: c1) in step (c), setting...jl(l;, 11) to 0, wherein the optical element is an amplitude-only element; and h) repeating steps ( c -f). * * * * *

  11. Optical Distance Measurement Device And Method Thereof

    DOEpatents

    Bowers, Mark W.

    2004-06-15

    A system and method of efficiently obtaining distance measurements of a target by scanning the target. An optical beam is provided by a light source and modulated by a frequency source. The modulated optical beam is transmitted to an acousto-optical deflector capable of changing the angle of the optical beam in a predetermined manner to produce an output for scanning the target. In operation, reflected or diffused light from the target may be received by a detector and transmitted to a controller configured to calculate the distance to the target as well as the measurement uncertainty in calculating the distance to the target.

  12. Package for integrated optic circuit and method

    DOEpatents

    Kravitz, S.H.; Hadley, G.R.; Warren, M.E.; Carson, R.F.; Armendariz, M.G.

    1998-08-04

    A structure and method are disclosed for packaging an integrated optic circuit. The package comprises a first wall having a plurality of microlenses formed therein to establish channels of optical communication with an integrated optic circuit within the package. A first registration pattern is provided on an inside surface of one of the walls of the package for alignment and attachment of the integrated optic circuit. The package in one embodiment may further comprise a fiber holder for aligning and attaching a plurality of optical fibers to the package and extending the channels of optical communication to the fibers outside the package. In another embodiment, a fiber holder may be used to hold the fibers and align the fibers to the package. The fiber holder may be detachably connected to the package. 6 figs.

  13. Package for integrated optic circuit and method

    DOEpatents

    Kravitz, Stanley H.; Hadley, G. Ronald; Warren, Mial E.; Carson, Richard F.; Armendariz, Marcelino G.

    1998-01-01

    A structure and method for packaging an integrated optic circuit. The package comprises a first wall having a plurality of microlenses formed therein to establish channels of optical communication with an integrated optic circuit within the package. A first registration pattern is provided on an inside surface of one of the walls of the package for alignment and attachment of the integrated optic circuit. The package in one embodiment may further comprise a fiber holder for aligning and attaching a plurality of optical fibers to the package and extending the channels of optical communication to the fibers outside the package. In another embodiment, a fiber holder may be used to hold the fibers and align the fibers to the package. The fiber holder may be detachably connected to the package.

  14. Optical switching system and method

    DOEpatents

    Ranganathan, Radha; Gal, Michael; Taylor, P. Craig

    1992-01-01

    An optically bistable device is disclosed. The device includes a uniformly thick layer of amorphous silicon to constitute a Fabry-Perot chamber positioned to provide a target area for a probe beam. The probe beam has a maximum energy less than the energy band gap of the amorphous semiconductor. In a preferred embodiment, a multilayer dielectric mirror is positioned on the Fabry-Perot chamber to increase the finesse of switching of the device. The index of refraction of the amorphous material is thermally altered to alter the transmission of the probe beam.

  15. Method and apparatus for staking optical elements

    DOEpatents

    Woods, Robert O.

    1988-10-04

    A method and apparatus for staking two optical elements together in order to retain their alignment is disclosed. The apparatus includes a removable adaptor made up of first and second adaptor bodies each having a lateral slot in their front and side faces. The adaptor also includes a system for releasably attaching each adaptor body to a respective optical element such that when the two optical elements are positioned relative to one another the adaptor bodies are adjacent and the lateral slots therein are aligned to form key slots. The adaptor includes keys which are adapted to fit into the key slots. A curable filler material is employed to retain the keys in the key slots and thereby join the first and second adaptor bodies to form the adaptor. Also disclosed is a method for staking together two optical elements employing the adaptor of the present invention.

  16. Method and apparatus for staking optical elements

    DOEpatents

    Woods, Robert O.

    1988-01-01

    A method and apparatus for staking two optical elements together in order to retain their alignment is disclosed. The apparatus includes a removable adaptor made up of first and second adaptor bodies each having a lateral slot in their front and side faces. The adaptor also includes a system for releasably attaching each adaptor body to a respective optical element such that when the two optical elements are positioned relative to one another the adaptor bodies are adjacent and the lateral slots therein are aligned to form key slots. The adaptor includes keys which are adapted to fit into the key slots. A curable filler material is employed to retain the keys in the key slots and thereby join the first and second adaptor bodies to form the adaptor. Also disclosed is a method for staking together two optical elements employing the adaptor of the present invention.

  17. Front lighted optical tooling method and apparatus

    DOEpatents

    Stone, William J.

    1985-06-18

    An optical tooling method and apparatus uses a front lighted shadowgraphic technique to enhance visual contrast of reflected light. The apparatus includes an optical assembly including a fiducial mark, such as cross hairs, reflecting polarized light with a first polarization, a polarizing element backing the fiducial mark and a reflective surface backing the polarizing element for reflecting polarized light bypassing the fiducial mark and traveling through the polarizing element. The light reflected by the reflecting surface is directed through a second pass of the polarizing element toward the frontal direction with a polarization differing from the polarization of the light reflected by the fiducial mark. When used as a tooling target, the optical assembly may be mounted directly to a reference surface or may be secured in a mounting, such as a magnetic mounting. The optical assembly may also be mounted in a plane defining structure and used as a spherometer in conjunction with an optical depth measuring instrument. A method of measuring a radius of curvature of an unknown surface includes positioning the spherometer on a surface between the surface and a depth measuring optical instrument. As the spherometer is frontally illuminated, the distance from the depth measuring instrument to the fiducial mark and the underlying surface are alternately measured and the difference in these measurements is used as the sagittal height to calculate a radius of curvature.

  18. Latest optical methods for industrial dimensional metrology

    NASA Astrophysics Data System (ADS)

    Harding, Kevin

    2005-11-01

    Applying optical methods to a simple inspection problem, such as the presence or absence of an assembly component, is likely the least restrictive of any machine vision application. The setup, alignment, and components can be made very simply by using any feature which appears different if the component of interest is present. Gaging to verify proper construction, however, can be a much more complicated task. To take advantage of the capability of machine vision and other optical technologies, some flexibility in part position, orientation, and speed of presentation may be desired. This paper will review the types of methods available from optical methods for industrial dimensional metrology. The emphasis of the discussion will be 2D and 3D gaging applications.

  19. Plasma channel optical pumping device and method

    DOEpatents

    Judd, O.P.

    1983-06-28

    A device and method are disclosed for optically pumping a gaseous laser using blackbody radiation produced by a plasma channel which is formed from an electrical discharge between two electrodes spaced at opposite longitudinal ends of the laser. A preionization device which can comprise a laser or electron beam accelerator produces a preionization beam which is sufficient to cause an electrical discharge between the electrodes to initiate the plasma channel along the preionization path. The optical pumping energy is supplied by a high voltage power supply rather than by the preionization beam. High output optical intensities are produced by the laser due to the high temperature blackbody radiation produced by the plasma channel, in the same manner as an exploding wire type laser. However, unlike the exploding wire type laser, the disclosed invention can be operated in a repetitive manner by utilizing a repetitive pulsed preionization device. 5 figs.

  20. Chip-to-chip optical link by using optical wiring method

    NASA Astrophysics Data System (ADS)

    Cho, In-Kui; Ahn, Seoung Ho; Jeong, Myung-Yung; Rho, Byung Sup; Park, Hyo Hoon

    2008-01-01

    A practical optical link system was prepared with a transmitter (Tx) and receiver (Rx). The optical TRx module consisted of a metal optical bench, a module printed circuit board (PCB), a driver/receiver IC, a VCSEL/PD array, and an optical link block composed of plastic optical fiber (POF). For the optical interconnection between the light-sources and detectors, an optical wiring method has been proposed to enable easy assembly. This paper provides a method for optical interconnection between an optical Tx and an optical Rx, comprising the following steps: (a) forming a light source device, an optical detection device, and an optical transmission unit on a substrate (metal optical bench (MOB)); (b) preparing a flexible optical transmission-connection medium (optical wiring link) to optically connect the light source device formed on the substrate with the optical detection device; and (c) directly connecting one end of the surface-finished optical transmission connection medium with the light source device and the other end with the optical detection device. A chip-to-chip optical link system constructed with TRx modules was fabricated and the optical characteristics were measured. The results clearly demonstrate that the use of an optical wiring method can provide robust and cost-effective assembly for vertical-cavity surface-emitting lasers (VCSELs) and photodiodes (PDs). We successfully achieved a 5 Gb/s data transmission rate with this optical link.

  1. Optical apparatus and method for sensing uranyl

    DOEpatents

    Baylor, L.C.; Buchanan, B.R.

    1994-01-01

    An optical sensing device for uranyl and other substances, a method for making an optical sensing device and a method for chemically binding uranyl and other indicators to glass, quartz, cellulose and similar substrates. The indicator, such as arsenazo III, is immobilized on the substrate using a chemical binding process. The immobilized arsenazo III causes uranyl from a fluid sample to bind irreversibly to the substrate at its active sites, thus causing absorption of a portion of light transmitted through the substrate. Determination of the amount of light absorbed, using conventional means, yields the concentration of uranyl present in the sample fluid. The binding of uranyl on the substrate can be reversed by subsequent exposure of the substrate to a solution of 2,6-pyridinedicarboxylic acid. The chemical binding process is suitable for similarly binding other indicators, such as bromocresol green.

  2. Two optical methods for vehicle tagging

    NASA Astrophysics Data System (ADS)

    Coulter, John K.; Klein, Christopher F.; Jafolla, James C.

    2002-08-01

    Optical tagging methods have the advantage that they cannot be detected by a suspicious criminal or terrorist using a radio frequency (RF) sensitive device to scan his vehicle for the presence of an RF emitting tag. We will describe two optical tagging methods in which the presence of the tagging marks can be visually discovered only by very close observation. On the other hand, the tags can be readily recognized by a surveillance team through the use of infrared imagers, either in the longwave infrared (LWIR) or in the near infrared (NIR). The first approach uses a clear coating that has a higher thermal emissivity than the glass window to which it is applied. This coating can be viewed with a thermal imager that operates in the LWIR, with the tags appearing as bright marks on a dark background. The second method uses an NIR laser illuminator and also quarter-wave thick layers applied to the license plate of a vehicle. When viewed with a polarization-sensitive imager that operates in the NIR, these quarter-wave tags appear as bright marks on a dark background. We will show sample images of both of these optical tags, as viewed in the LWIR and NIR regions, respectively.

  3. Computational methods for optical molecular imaging

    PubMed Central

    Chen, Duan; Wei, Guo-Wei; Cong, Wen-Xiang; Wang, Ge

    2010-01-01

    Summary A new computational technique, the matched interface and boundary (MIB) method, is presented to model the photon propagation in biological tissue for the optical molecular imaging. Optical properties have significant differences in different organs of small animals, resulting in discontinuous coefficients in the diffusion equation model. Complex organ shape of small animal induces singularities of the geometric model as well. The MIB method is designed as a dimension splitting approach to decompose a multidimensional interface problem into one-dimensional ones. The methodology simplifies the topological relation near an interface and is able to handle discontinuous coefficients and complex interfaces with geometric singularities. In the present MIB method, both the interface jump condition and the photon flux jump conditions are rigorously enforced at the interface location by using only the lowest-order jump conditions. This solution near the interface is smoothly extended across the interface so that central finite difference schemes can be employed without the loss of accuracy. A wide range of numerical experiments are carried out to validate the proposed MIB method. The second-order convergence is maintained in all benchmark problems. The fourth-order convergence is also demonstrated for some three-dimensional problems. The robustness of the proposed method over the variable strength of the linear term of the diffusion equation is also examined. The performance of the present approach is compared with that of the standard finite element method. The numerical study indicates that the proposed method is a potentially efficient and robust approach for the optical molecular imaging. PMID:20485461

  4. Optical domain analog to digital conversion methods and apparatus

    SciTech Connect

    Vawter, Gregory A

    2014-05-13

    Methods and apparatus for optical analog to digital conversion are disclosed. An optical signal is converted by mapping the optical analog signal onto a wavelength modulated optical beam, passing the mapped beam through interferometers to generate analog bit representation signals, and converting the analog bit representation signals into an optical digital signal. A photodiode receives an optical analog signal, a wavelength modulated laser coupled to the photodiode maps the optical analog signal to a wavelength modulated optical beam, interferometers produce an analog bit representation signal from the mapped wavelength modulated optical beam, and sample and threshold circuits corresponding to the interferometers produce a digital bit signal from the analog bit representation signal.

  5. Optical method of atomic ordering estimation

    SciTech Connect

    Prutskij, T.; Attolini, G.

    2013-12-04

    It is well known that within metal-organic vapor-phase epitaxy (MOVPE) grown semiconductor III-V ternary alloys atomically ordered regions are spontaneously formed during the epitaxial growth. This ordering leads to bandgap reduction and to valence bands splitting, and therefore to anisotropy of the photoluminescence (PL) emission polarization. The same phenomenon occurs within quaternary semiconductor alloys. While the ordering in ternary alloys is widely studied, for quaternaries there have been only a few detailed experimental studies of it, probably because of the absence of appropriate methods of its detection. Here we propose an optical method to reveal atomic ordering within quaternary alloys by measuring the PL emission polarization.

  6. Method of parallel switching of optical channels

    SciTech Connect

    Kompanets, I N; Neevina, T A; Kompanets, S I

    2012-12-31

    The possibility of creating parallel-type switches for N Multiplication-Sign N optical waveguide channel communication is studied. A method based on bit-by-bit channel addressing is proposed and one of its possible implementations using the photorefractive effect in the waveguide material is considered. The method is modelled by the example of switching of 8 Multiplication-Sign 8 channels, controlled by reconfigurable matrix of light signals. (special issue devoted to the 90th anniversary of n.g. basov)

  7. Electro-Optic Modulator and Method

    DTIC Science & Technology

    An optical intensity modulator which uses a Sagnac interferometer having an electro - optic phase modulator therein. An electric modulation signal is...modulating the optical signals by the electrical signal, the electro - optic effect in the modulator phase shifts the optical signals with respect to one another

  8. Optical methods for measuring DNA folding

    NASA Astrophysics Data System (ADS)

    Smith, Adam D.; Ukogu, Obinna A.; Devenica, Luka M.; White, Elizabeth D.; Carter, Ashley R.

    2017-03-01

    One of the most important biological processes is the dynamic folding and unfolding of deoxyribonucleic acid (DNA). The folding process is crucial for DNA to fit within the boundaries of the cell, while the unfolding process is essential for DNA replication and transcription. To accommodate both processes, the cell employs a highly active folding mechanism that has been the subject of intense study over the last few decades. Still, many open questions remain. What are the pathways for folding or unfolding? How does the folding equilibrium shift? And, what is the energy landscape for a particular process? Here, we review these emerging questions and the in vitro, optical methods that have provided answers, introducing the topic for those physicists seeking to step into biology. Specifically, we discuss two iconic experiments for DNA folding, the tethered particle motion (TPM) experiment and the optical tweezers experiment.

  9. Parametric reconstruction method in optical tomography.

    PubMed

    Gu, Xuejun; Ren, Kui; Masciotti, James; Hielscher, Andreas H

    2006-01-01

    Optical tomography consists of reconstructing the spatial of a medium's optical properties from measurements of transmitted light on the boundary of the medium. Mathematically this problem amounts to parameter identification for the radiative transport equation (ERT) or diffusion approximation (DA). However, this type of boundary-value problem is highly ill-posed and the image reconstruction process is often unstable and non-unique. To overcome this problem, we present a parametric inverse method that considerably reduces the number of variables being reconstructed. In this way the amount of measured data is equal or larger than the number of unknowns. Using synthetic data, we show examples that demonstrate how this approach leads to improvements in imaging quality.

  10. Optical nulling apparatus and method for testing an optical surface

    NASA Technical Reports Server (NTRS)

    Olczak, Eugene (Inventor); Hannon, John J. (Inventor); Dey, Thomas W. (Inventor); Jensen, Arthur E. (Inventor)

    2008-01-01

    An optical nulling apparatus for testing an optical surface includes an aspheric mirror having a reflecting surface for imaging light near or onto the optical surface under test, where the aspheric mirror is configured to reduce spherical aberration of the optical surface under test. The apparatus includes a light source for emitting light toward the aspheric mirror, the light source longitudinally aligned with the aspheric mirror and the optical surface under test. The aspheric mirror is disposed between the light source and the optical surface under test, and the emitted light is reflected off the reflecting surface of the aspheric mirror and imaged near or onto the optical surface under test. An optical measuring device is disposed between the light source and the aspheric mirror, where light reflected from the optical surface under test enters the optical measuring device. An imaging mirror is disposed longitudinally between the light source and the aspheric mirror, and the imaging mirror is configured to again reflect light, which is first reflected from the reflecting surface of the aspheric mirror, onto the optical surface under test.

  11. Method and system for processing optical elements using magnetorheological finishing

    DOEpatents

    Menapace, Joseph Arthur; Schaffers, Kathleen Irene; Bayramian, Andrew James; Molander, William A

    2012-09-18

    A method of finishing an optical element includes mounting the optical element in an optical mount having a plurality of fiducials overlapping with the optical element and obtaining a first metrology map for the optical element and the plurality of fiducials. The method also includes obtaining a second metrology map for the optical element without the plurality of fiducials, forming a difference map between the first metrology map and the second metrology map, and aligning the first metrology map and the second metrology map. The method further includes placing mathematical fiducials onto the second metrology map using the difference map to form a third metrology map and associating the third metrology map to the optical element. Moreover, the method includes mounting the optical element in the fixture in an MRF tool, positioning the optical element in the fixture; removing the plurality of fiducials, and finishing the optical element.

  12. Method and apparatus for optical temperature measurement

    DOEpatents

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

    1994-01-01

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

  13. Method and apparatus for optical temperature measurement

    DOEpatents

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

    1994-09-20

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

  14. Optical feedback structures and methods of making

    DOEpatents

    Snee, Preston T; Chan, Yin Thai; Nocera, Daniel G; Bawendi, Moungi G

    2014-11-18

    An optical resonator can include an optical feedback structure disposed on a substrate, and a composite including a matrix including a chromophore. The composite disposed on the substrate and in optical communication with the optical feedback structure. The chromophore can be a semiconductor nanocrystal. The resonator can provide laser emission when excited.

  15. Method for Implementing Optical Phase Adjustment

    NASA Technical Reports Server (NTRS)

    Hovde, David C.; Corsini, Eric

    2011-01-01

    A method has been developed to mechanically implement the optical phase shift by adjusting the polarization of the pump and probe beams in an NMOR (nonlinear magneto-optical rotation) magnetometer as the proper phase shift is necessary to induce self-oscillation. This innovation consists of mounting the pump beam on a ring that surrounds the atomic vapor sample. The propagation of the probe beam is perpendicular to that of the pump beam. The probe beam can be considered as defining the axis of a cylinder, while the pump beam is directed radially. The magnetic field to be measured defines a third vector, but it is also taken to lie along the cylinder axis. Both the pump and probe beams are polarized such that their electric field vectors are substantially perpendicular to the magnet field. By rotation of the ring supporting the pump beam, its direction can be varied relative to the plane defined by the probe electric field and the magnetic field to be measured.

  16. System and method for attitude determination based on optical imaging

    NASA Technical Reports Server (NTRS)

    Junkins, John L. (Inventor); Pollock, Thomas C. (Inventor); Mortari, Daniele (Inventor)

    2003-01-01

    A method and apparatus is provide for receiving a first set of optical data from a first field of view and receiving a second set of optical data from a second field of view. A portion of the first set of optical data is communicated and a portion of the second set of optical data is reflected, both toward an optical combiner. The optical combiner then focuses the portions onto the image plane such that information at the image plane that is associated with the first and second fields of view is received by an optical detector and used to determine an attitude characteristic.

  17. Systems and methods for free space optical communication

    DOEpatents

    Harper, Warren W [Benton City, WA; Aker, Pamela M [Richland, WA; Pratt, Richard M [Richland, WA

    2011-05-10

    Free space optical communication methods and systems, according to various aspects are described. The methods and systems are characterized by transmission of data through free space with a digitized optical signal acquired using wavelength modulation, and by discrimination between bit states in the digitized optical signal using a spectroscopic absorption feature of a chemical substance.

  18. Smart Optical Material Characterization System and Method

    NASA Technical Reports Server (NTRS)

    Choi, Sang Hyouk (Inventor); Park, Yeonjoon (Inventor)

    2015-01-01

    Disclosed is a system and method for characterizing optical materials, using steps and equipment for generating a coherent laser light, filtering the light to remove high order spatial components, collecting the filtered light and forming a parallel light beam, splitting the parallel beam into a first direction and a second direction wherein the parallel beam travelling in the second direction travels toward the material sample so that the parallel beam passes through the sample, applying various physical quantities to the sample, reflecting the beam travelling in the first direction to produce a first reflected beam, reflecting the beam that passes through the sample to produce a second reflected beam that travels back through the sample, combining the second reflected beam after it travels back though the sample with the first reflected beam, sensing the light beam produced by combining the first and second reflected beams, and processing the sensed beam to determine sample characteristics and properties.

  19. Method for producing damage resistant optics

    DOEpatents

    Hackel, Lloyd A.; Burnham, Alan K.; Penetrante, Bernardino M.; Brusasco, Raymond M.; Wegner, Paul J.; Hrubesh, Lawrence W.; Kozlowski, Mark R.; Feit, Michael D.

    2003-01-01

    The present invention provides a system that mitigates the growth of surface damage in an optic. Damage to the optic is minimally initiated. In an embodiment of the invention, damage sites in the optic are initiated, located, and then treated to stop the growth of the damage sites. The step of initiating damage sites in the optic includes a scan of the optic using a laser to initiate defects. The exact positions of the initiated sites are identified. A mitigation process is performed that locally or globally removes the cause of subsequent growth of the damaged sites.

  20. Acousto-Optics as an Efficient Method for Physical Measurements

    NASA Astrophysics Data System (ADS)

    Kulakov, Sergei V.; Balysheva, Olga L.; Zhdanov, Arcenii Yu.; Kludzin, Victor V.; Shakin, Oleg V.

    In addition to acousto-optic information processing and manufacturing of such devices, the interaction between optical and acoustic waves are an efficient method for physical measurements. The paper analyses the potential of the acousto-optic method for measurement and investigation of crystal properties. It also presents some examples of this method applied to such measurements and investigations. The acousto-optic implementation of the pulse-phase method is used for acoustic velocity measurements. Velocities in an arbitrary directions can be measured using the Shaefer-Bergman method (the visualization of the angular distribution of the inverse phase velocities) together with the pulse-phase method. The matrices of crystal elastic coefficients can be evaluated using the Shaefer-Bergman patterns, using the minimum number of tested samples. The Schlieren (shadow) image method can give information both on the characteristics of acoustic and optical fields. The acousto-optic interaction is Efficient Method for determination of elastic material nonlinearity parameters.

  1. Apparatus and method for optical pulse measurement

    DOEpatents

    Trebino, Rick P.; Tsang, Thomas; Fittinghoff, David N.; Sweetser, John N.; Krumbuegel, Marco A.

    1999-12-28

    Practical third-order frequency-resolved optical grating (FROG) techniques for characterization of ultrashort optical pulses are disclosed. The techniques are particularly suited to the measurement of single and/or weak optical pulses having pulse durations in the picosecond and subpicosecond regime. The relative quantum inefficiency of third-order nonlinear optical effects is compensated for through i) use of phase-matched transient grating beam geometry to maximize interaction length, and ii) use of interface-enhanced third-harmonic generation.

  2. Optical conversion method. [for spacecraft television

    NASA Technical Reports Server (NTRS)

    Perry, W. E. (Inventor)

    1978-01-01

    An optical pickup comprising an electrooptical device located between two crossed polarizing devices all positioned along a common optical axis is described for switching a TV system between a color mode and a black and white mode. Embodiments in which the electrooptical system is used as a neutral density filter, a selective color filter, or a light shutter as applied to a television camera are described. Where the optical system is used as a selective color filter to produce light beams of alternating color in a field sequential color television system, deactivation of the optical system renders the television a black and white system.

  3. Optical caliper with compensation for specimen deflection and method

    DOEpatents

    Bernacki, B.E.

    1997-12-09

    An optical non-contact profilometry system and method provided by an optical caliper with matched optical sensors that are arranged conjugate to each other so that the surface profile and thickness of an article can be measured without using a fixed reference surface and while permitting the article to deflect in space within the acquisition range of the optical sensors. The output signals from the two optical sensors are algebraically added to compensate for any such deflection of the article and provide a so compensated signal, the balance and sign of which provides a measurement of the actual thickness of the article at the optical sensors. 2 figs.

  4. Optical caliper with compensation for specimen deflection and method

    DOEpatents

    Bernacki, Bruce E.

    1997-01-01

    An optical non-contact profilometry system and method provided by an optical caliper with matched optical sensors that are arranged conjugate to each other so that the surface profile and thickness of an article can be measured without using a fixed reference surface and while permitting the article to deflect in space within the acquisition range of the optical sensors. The output signals from the two optical sensors are algebraically added to compensate for any such deflection of the article and provide a so compensated signal, the balance and sign of which provides a measurement of the actual thickness of the article at the optical sensors.

  5. Optical seismic sensor systems and methods

    SciTech Connect

    Beal, A. Craig; Cummings, Malcolm E.; Zavriyev, Anton; Christensen, Caleb A.; Lee, Keun

    2015-12-08

    Disclosed is an optical seismic sensor system for measuring seismic events in a geological formation, including a surface unit for generating and processing an optical signal, and a sensor device optically connected to the surface unit for receiving the optical signal over an optical conduit. The sensor device includes at least one sensor head for sensing a seismic disturbance from at least one direction during a deployment of the sensor device within a borehole of the geological formation. The sensor head includes a frame and a reference mass attached to the frame via at least one flexure, such that movement of the reference mass relative to the frame is constrained to a single predetermined path.

  6. Method and apparatus for bistable optical information storage for erasable optical disks

    DOEpatents

    Land, Cecil E.; McKinney, Ira D.

    1990-01-01

    A method and an optical device for bistable storage of optical information, together with reading and erasure of the optical information, using a photoactivated shift in a field dependent phase transition between a metastable or a bias-stabilized ferroelectric (FE) phase and a stable antiferroelectric (AFE) phase in an lead lanthanum zirconate titanate (PLZT). An optical disk contains the PLZT. Writing and erasing of optical information can be accomplished by a light beam normal to the disk. Reading of optical information can be accomplished by a light beam at an incidence angle of 15 to 60 degrees to the normal of the disk.

  7. Method and apparatus for bistable optical information storage for erasable optical disks

    DOEpatents

    Land, C.E.; McKinney, I.D.

    1988-05-31

    A method and an optical device for bistable storage of optical information, together with reading and erasure of the optical information, using a photoactivated shift in a field dependent phase transition between a metastable or a bias-stabilized ferroelectric (FE) phase and a stable antiferroelectric (AFE) phase in a lead lanthanum zirconate titanate (PLZT). An optical disk contains the PLZT. Writing and erasing of optical information can be accomplished by a light beam normal to the disk. Reading of optical information can be accomplished by a light beam at an incidence angle of 15 to 60 degrees to the normal of the disk. 10 figs.

  8. All-optical relative intensity noise suppression method for the high precision fiber optic gyroscope

    NASA Astrophysics Data System (ADS)

    Zheng, Yue; Zhang, Chunxi; Li, Lijing; Song, Lailiang; Zhang, Yuhui

    2016-10-01

    The relative intensity noise (RIN) is a main factor that limits the detection accuracy of the high precision fiber optic gyroscope (FOG). The RIN spectrum is determined by the normalized autocorrelation of the optical spectrum of the broadband source and is intrinsically different from other fundamental noises. In this paper, we propose an all-optical technique to suppress the RIN. With the power addition of the optical waves from the signal optical path and the reference optical path, the RIN is effectively eliminated at the eigen frequency of the FOG, which is also the demodulation window for the rotation rate signal. Compared with the traditional optical configuration of the FOG, there is only one additional optical component. Experimental results show that, with this method, we can achieve a nearly 3-fold improvement in the angular random walk coefficient. The improved optical configuration for RIN suppression is simple to realize and suitable for engineering application.

  9. Method of making a small inlet optical panel

    DOEpatents

    Veligdan, James T.; Slobodin, David E.

    2004-02-03

    An optical panel having a small inlet, and a method of making a small inlet optical panel, are disclosed, which optical panel includes a individually coating, stacking, and cutting a first plurality of stacked optical waveguides to form an outlet face body with an outlet face, individually coating, stacking, and cutting a second plurality of stacked optical waveguides to form an inlet face body with an inlet face, and connecting an optical coupling element to the first plurality and second plurality of stacked optical waveguides, wherein the optical coupling element redirects light along a parallel axis of the inlet face to a parallel axis of the outlet face. In the preferred embodiment of the present invention, the inlet face is disposed obliquely with and askew from the outlet face.

  10. Laser Safety Method For Duplex Open Loop Parallel Optical Link

    DOEpatents

    Baumgartner, Steven John; Hedin, Daniel Scott; Paschal, Matthew James

    2003-12-02

    A method and apparatus are provided to ensure that laser optical power does not exceed a "safe" level in an open loop parallel optical link in the event that a fiber optic ribbon cable is broken or otherwise severed. A duplex parallel optical link includes a transmitter and receiver pair and a fiber optic ribbon that includes a designated number of channels that cannot be split. The duplex transceiver includes a corresponding transmitter and receiver that are physically attached to each other and cannot be detached therefrom, so as to ensure safe, laser optical power in the event that the fiber optic ribbon cable is broken or severed. Safe optical power is ensured by redundant current and voltage safety checks.

  11. Methods of formation and nonlinear conversion of Bessel optical vortices

    NASA Astrophysics Data System (ADS)

    Belyi, V. N.; King, Terence A.; Kazak, Nikolai S.; Khilo, Nikolay A.; Katranji, Evgeni G.; Ryzhevich, Anatol A.

    2001-05-01

    Linear and nonlinear processes of generation and transformation of optical vortices in crystals were investigated. New universal methods for production of Bessel light beams with optical vortices of the first, second and higher order by means of uniaxial and biaxial crystals were proposed. Light beams with optical vortices of topological charge +/- 1 and +/- 2 are experimentally obtained using KTP and HIO3 (iodic acid) biaxial crystals. We studied type II second harmonic generation by Bessel beams with optical vortices in nonlinear crystals. Results of investigation of the processes of Bessel light vortex order doubling, transfer of vortex to the second harmonic radiation, and annihilation of optical vortices with the opposite signa are presented.

  12. Method of holding optical elements without deformation during their fabrication

    DOEpatents

    Hed, P. Paul

    1997-01-01

    An improved method for securing and removing an optical element to and from a blocking tool without causing deformation of the optical element. A lens tissue is placed on the top surface of the blocking tool. Dots of UV cement are applied to the lens tissue without any of the dots contacting each other. An optical element is placed on top of the blocking tool with the lens tissue sandwiched therebetween. The UV cement is then cured. After subsequent fabrication steps, the bonded blocking tool, lens tissue, and optical element are placed in a debonding solution to soften the UV cement. The optical element is then removed from the blocking tool.

  13. A Method of Assembling Compact Coherent Fiber-Optic Bundles

    NASA Technical Reports Server (NTRS)

    Martin, Stefan; Liu, Duncan; Levine, Bruce Martin; Shao, Michael; Wallace, James

    2007-01-01

    A method of assembling coherent fiber-optic bundles in which all the fibers are packed together as closely as possible is undergoing development. The method is based, straightforwardly, on the established concept of hexagonal close packing; hence, the development efforts are focused on fixtures and techniques for practical implementation of hexagonal close packing of parallel optical fibers.

  14. Inorganic optical taggant and method of making

    DOEpatents

    Lauf, Robert J.; Anderson, Kimberly K.; Montgomery, Frederick C.

    2005-05-31

    Sintered, translucent ceramic microbeads, preferably alumina, titania, zirconia, yttria, zirconium phosphate, or yttrium aluminum garnet (YAG) are doped with one or more optically active species. The beads may be added to substances such as explosives in order to create a distinctive optical signature that identifies a manufacturer, lot number, etc. in the event of the need for forensic analysis. Because the beads have a generally spherical surface, the radius of curvature provides an additional distinguishing characteristic by which a particular sample may be identified. The beads could also be formulated into paints if needed to create distinctive optical signatures for camouflage, decoys, or other countermeasures and could also be applied as a dust to track the movement of personnel, vehicles, etc.

  15. Fiber-optic backreflectance method for determining the effective focal lengths of optical elements.

    PubMed

    Ilev, I; Uttamchandani, D; Culshaw, B

    1996-02-01

    An alternative and simple fiber-optic backreflectance method for indirectly determining the effective focal lengths of optical elements by the spatial location of three specific points (the focal point and two object points) is presented. The basic optical element of the method is the single-mode optical fiber. It serves simultaneously as a point light source, an object for projecting, and a point receiver that is highly sensitive to spatial displacements for focused backreflectance laser emission. The method provides high accuracy for both locating the spatial points (1 µm) and determining the effective focal length (less than 0.5%).

  16. New optical frequency domain differential mode delay measurement method for a multimode optical fiber.

    PubMed

    Ahn, T; Moon, S; Youk, Y; Jung, Y; Oh, K; Kim, D

    2005-05-30

    A novel mode analysis method and differential mode delay (DMD) measurement technique for a multimode optical fiber based on optical frequency domain reflectometry has been proposed for the first time. We have used a conventional OFDR with a tunable external cavity laser and a Michelson interferometer. A few-mode optical multimode fiber was prepared to test our proposed measurement technique. We have also compared the OFDR measurement results with those obtained using a traditional time-domain measurement method.

  17. ANALYSIS OF CARBONACEOUS AEROSOLS USING THE THERMAL OPTICAL TRANSMITTANCE AND THERMAL OPTICAL REFLECTANCE METHODS

    EPA Science Inventory

    Carbonaceous particulate typically represents a large fraction of PM2.5 (20 - 40%). Two primary techniques presently used for the analysis of particulate carbon are Thermal Optical Transmission (TOT - NIOSH Method 5040) and Thermal Optical Reflectance (TOR). These two methods b...

  18. REVIEW OF METHODS OF OPTICAL GAS Detection by Direct Optical Spectroscopy, with Emphasis on Correlation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dakin, John P.; Chambers, Paul

    This chapter reviews the development of optical gas sensors, starting with an initial emphasis on optical-fibre remoted techniques and finishing with a particular focus on our own group's work on highly selective methods using correlation spectroscopy. This latter section includes extensive theoretical modelling of a correlation spectroscopy method, and compares theory with practice for a CO2 sensor.

  19. A method of developing frequency encoded multi-bit optical data comparator using semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Garai, Sisir Kumar

    2011-02-01

    Optical data comparator is the part and parcel of arithmetic and logical unit of any optical data processor and it is working as a building block in a larger optical circuit, as an optical switch in all optical header processing and optical packet switching based all optical telecommunications system. In this article the author proposes a method of developing an all optical single bit comparator unit and subsequently extending the proposal to develop a n-bit comparator exploiting the nonlinear rotation of the state of polarization of the probe beam in semiconductor optical amplifier (SOA). Here the dataset to be compared are taken in frequency encoded/decoded form throughout the communication. The major advantages of frequency encoding over all other conventional techniques are that as the frequency of any signal is fundamental one so it can preserve its identity throughout the communication of optical signal and minimizes the probability of bit error problem. For frequency routing purpose optical add/drop multiplexer (ADM) is used which not only route the pump beams properly but also to amplify the pump beams efficiently. Switching speed of 'MZI-SOA switch' as well as SOA based switches are very fast with good on-off contrast ratio and as a result it is possible to obtain very fast action of optical data comparator.

  20. Optical method for the determination of stress in thin films

    DOEpatents

    Maris, Humphrey J.

    1999-01-01

    A method and optical system is disclosed for measuring an amount of stress in a film layer disposed over a substrate. The method includes steps of: (A) applying a sequence of optical pump pulses to the film layer, individual ones of said optical pump pulses inducing a propagating strain pulse in the film layer, and for each of the optical pump pulses, applying at least one optical probe pulse, the optical probe pulses being applied with different time delays after the application of the corresponding optical probe pulses; (B) detecting variations in an intensity of a reflection of portions of the optical probe pulses, the variations being due at least in part to the propagation of the strain pulse in the film layer; (C) determining, from the detected intensity variations, a sound velocity in the film layer; and (D) calculating, using the determined sound velocity, the amount of stress in the film layer. In one embodiment of this invention the step of detecting measures a period of an oscillation in the intensity of the reflection of portions of the optical probe pulses, while in another embodiment the step of detecting measures a change in intensity of the reflection of portions of the optical probe pulses and determines a time at which the propagating strain pulse reflects from a boundary of the film layer.

  1. Optical method for the determination of stress in thin films

    DOEpatents

    Maris, H.J.

    1999-01-26

    A method and optical system is disclosed for measuring an amount of stress in a film layer disposed over a substrate. The method includes steps of: (A) applying a sequence of optical pump pulses to the film layer, individual ones of said optical pump pulses inducing a propagating strain pulse in the film layer, and for each of the optical pump pulses, applying at least one optical probe pulse, the optical probe pulses being applied with different time delays after the application of the corresponding optical probe pulses; (B) detecting variations in an intensity of a reflection of portions of the optical probe pulses, the variations being due at least in part to the propagation of the strain pulse in the film layer; (C) determining, from the detected intensity variations, a sound velocity in the film layer; and (D) calculating, using the determined sound velocity, the amount of stress in the film layer. In one embodiment of this invention the step of detecting measures a period of an oscillation in the intensity of the reflection of portions of the optical probe pulses, while in another embodiment the step of detecting measures a change in intensity of the reflection of portions of the optical probe pulses and determines a time at which the propagating strain pulse reflects from a boundary of the film layer. 16 figs.

  2. HOMES Holographic Optical Method for Exoplanet Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ditto, Thomas D.; McGrew, Stephen P.

    2013-09-01

    A novel telescope architecture is proposed specifically for the purpose of taking spectra of exoplanets orbiting stars within 10 pc ("the neighborhood"). The primary objective and the secondary spectrograph are holographic optical elements (HOEs) formed on flat membrane substrates of low areal mass that can be transported on cylinder rolls that are compatible with the payload geometry of delivery vehicles. Ribbon-shaped HOEs of up to 100 x 10 meters are contemplated. Computer models are presented with these dimensions. The models predict resolving power better than 10 mas. Because the primary separates wavelengths, we consider coronagraphs that use the divide and conquer strategy of one wavelength at a time. After delivery at the second Lagrange point, the stowed membranes are unfurled into flat holographic optics positioned in a four part formation spanning 1 km of open space.

  3. Optical steam quality measurement system and method

    DOEpatents

    Davidson, James R.; Partin, Judy K.

    2006-04-25

    An optical measurement system is presented that offers precision on-line monitoring of the quality of steam. Multiple wavelengths of radiant energy are passed through the steam from an emitter to a detector. By comparing the amount of radiant energy absorbed by the flow of steam for each wavelength, a highly accurate measurement of the steam quality can be determined on a continuous basis in real-time. In an embodiment of the present invention, the emitter, comprises three separate radiant energy sources for transmitting specific wavelengths of radiant energy through the steam. In a further embodiment, the wavelengths of radiant energy are combined into a single beam of radiant energy for transmission through the steam using time or wavelength division multiplexing. In yet a further embodiment, the single beam of radiant energy is transmitted using specialized optical elements.

  4. Small inlet optical panel and a method of making a small inlet optical panel

    DOEpatents

    Veligdan, James T.; Slobodin, David

    2001-01-01

    An optical panel having a small inlet, and a method of making a small inlet optical panel, are disclosed, which optical panel includes a individually coating, stacking, and cutting a first plurality of stacked optical waveguides to form an outlet face body with an outlet face, individually coating, stacking, and cutting a second plurality of stacked optical waveguides to form an inlet face body with an inlet face, and connecting an optical coupling element to the first plurality and to the second plurality, wherein the optical coupling element redirects light along a parallel axis of the inlet face to a parallel axis of the outlet face. In the preferred embodiment of the present invention, the inlet face is disposed obliquely with and askew from the outlet face.

  5. Simple fiber-optic autocollimation method for determining the focal lengths of optical elements.

    PubMed

    Ilev, I K

    1995-03-15

    A novel simple fiber-optic autocollimation method for determining the focal lengths of lenses and objectives is presented. This method is based on the intensity sensing of reflected light, photoelectric measurement, and the use of single-mode optical fiber. This fiber serves simultaneously as a point light source for the formation of a collimated input laser beam and as a receiver that is highly sensitive to spatial displacements for the autocollimation backreflectance. The method permits us to locate the focal point spatially and to determine the back focal length of a focusing optical element with accuracies exceeding 1 and 2 microm, respectively, which are confirmed by both experimental and analytical investigations.

  6. Theoretical research and comparison of forces in optical tweezers based on ray optics method and T matrix method

    NASA Astrophysics Data System (ADS)

    Li, Zhenggang; Hu, Huizhu; Fu, ZhenHai; Zhu, Qi; Shen, Yu

    2016-10-01

    Based on ray tracing method of ray optics (RO) theory and T-matrix method of electromagnetic scattering theory, we establish optical trap force model and calculate the optical trap force of trapped microspheres whose size is in the beam wavelength scale. Calculation results of axial and transverse trapping efficiency based on the two models agree qualitatively, but differ quantitatively. Then we introduce a trapping efficiency calculation deviation parameter to characterize the difference between these two methods, and analyze how the deviation parameter is influenced by trapped microsphere radius and trapping beam waist radius. Simulation result shows that best agreement between RO model and T matrix calculation method is met when a strongly focused laser beam traps a large microsphere in near the beam waist plane area. In such cases both ray optics approximation conditions and T matrix method approximate conditions are satisfied. Numerical results coincide well with theoretical expectations.

  7. Preform For Producing An Optical Fiber And Method Therefor

    DOEpatents

    Kliner, Dahv A. V.; Koplow, Jeffery P.

    2004-08-10

    The present invention provides a simple method for fabricating fiber-optic glass preforms having complex refractive index configurations and/or dopant distributions in a radial direction with a high degree of accuracy and precision. The method teaches bundling together a plurality of glass rods of specific physical, chemical, or optical properties and wherein the rod bundle is fused in a manner that maintains the cross-sectional composition and refractive-index profiles established by the position of the rods.

  8. Preform For Producing An Optical Fiber And Method Therefor

    DOEpatents

    Kliner, Dahv A. V.; Koplow, Jeffery P.

    2005-04-19

    The present invention provides a simple method for fabricating fiber-optic glass preforms having complex refractive index configurations and/or dopant distributions in a radial direction with a high degree of accuracy and precision. The method teaches bundling together a plurality of glass rods of specific physical, chemical, or optical properties and wherein the rod bundle is fused in a manner that maintains the cross-sectional composition and refractive-index profiles established by the position of the rods.

  9. Optical limiting device and method of preparation thereof

    DOEpatents

    Wang, Hsing-Lin; Xu, Su; McBranch, Duncan W.

    2003-01-01

    Optical limiting device and method of preparation thereof. The optical limiting device includes a transparent substrate and at least one homogeneous layer of an RSA material in polyvinylbutyral attached to the substrate. The device may be produced by preparing a solution of an RSA material, preferably a metallophthalocyanine complex, and a solution of polyvinylbutyral, and then mixing the two solutions together to remove air bubbles. The resulting solution is layered onto the substrate and the solvent is evaporated. The method can be used to produce a dual tandem optical limiting device.

  10. Living Brain Optical Imaging: Technology, Methods and Applications

    PubMed Central

    Tsytsarev, Vassiliy; Bernardelli, Chad; Maslov, Konstantin I.

    2017-01-01

    Within the last few decades, optical imaging methods have yielded revolutionary results when applied to all parts of the central nervous system. The purpose of this review is to analyze research possibilities and limitations of several novel imaging techniques and show some of the most interesting achievements obtained by these methods. Here we covered intrinsic optical imaging, voltage-sensitive dye, photoacoustic, optical coherence tomography, near-infrared spectroscopy and some other techniques. All of them are mainly applicable for experimental neuroscience but some of them also suitable for the clinical studies. PMID:28251038

  11. Simple method for measuring reflectance of optical coatings

    SciTech Connect

    Wen Gui Wang; Yi Sheng Chen

    1995-12-31

    The quality of optical coatings has an important effect on the performance of optical instrument. The last few years, the requirements for super low loss dielectric mirror coatings used in low gain laser systems such as free electron laser and the ring laser etc., have given an impetus to the development of the technology of precise reflectance measurement of optical coatings. A reliable and workable technique is to measure the light intensity decay time of optical resonant cavity. This paper describes a measuring method which is dependent on direct measurement of the light intensity decay time of a resonant cavity comprised of low loss optical components. According to the evolution of a luminous flux stored inside the cavity, this method guarantees not only a quick and precise reflectance measurements of low loss highly reflecting mirror coatings but also transmittance measurements of low loss antireflection coatings and is especially effective with super los loss highly reflecting mirror. From the round-trip path length of the cavity and the speed of light, the light intensity exponential decay time of an optical cavity is easy to obtain and the cavity losses can be deduced. An optical reflectance of low loss highly mirror coatings and antireflection coatings is precisely measured as well. This is highly significant for the discrimination of the coating surface characteristics, the improvement of the performance of optical instrument and the development of high technology.

  12. 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.

  13. Electro-optical method for polarimetric measurement

    NASA Astrophysics Data System (ADS)

    Díaz, Lázaro J. M.

    2011-05-01

    When passing a pulsing beam of polarize light of a light emitter d iode (LED) or a semiconductor laser thru an optical system and two photodiodes spatially arranged at 900 to each other and both with their detection surfaces parallel to the transmission shaft of light, and polarization axis oriented at 450 of the vertices of the edges where the photodiodes join, in the outputs of two operational amplifiers, e have two signals with the same shape in time, i.e. a pulse train with the same phase, but when you turn the polarization plane, change the radiance of the light projected onto the photodiodes, being out of phase signals to the outputs of the amplifiers, where the d ifference between the fronts of the pulses is proportional to the angle of rotation of the plane of polarization of polarization light. In a digital circuit phase discriminator, a puls e is obtained equal to the time d ifference between two sides of the rise time in the output of two amplifiers. The width of this is directly proportional to the value of rotation the plane of polarization of light, that is, the greater the rotation, the greater the width of this.

  14. Method of holding optical elements without deformation during their fabrication

    DOEpatents

    Hed, P.P.

    1997-04-29

    An improved method for securing and removing an optical element to and from a blocking tool without causing deformation of the optical element is disclosed. A lens tissue is placed on the top surface of the blocking tool. Dots of UV cement are applied to the lens tissue without any of the dots contacting each other. An optical element is placed on top of the blocking tool with the lens tissue sandwiched therebetween. The UV cement is then cured. After subsequent fabrication steps, the bonded blocking tool, lens tissue, and optical element are placed in a debonding solution to soften the UV cement. The optical element is then removed from the blocking tool. 16 figs.

  15. Optical trapping apparatus, methods and applications using photonic crystal resonators

    SciTech Connect

    Erickson, David; Chen, Yih-Fan

    2015-06-16

    A plurality of photonic crystal resonator optical trapping apparatuses and a plurality optical trapping methods using the plurality of photonic crystal resonator optical trapping apparatuses include located and formed over a substrate a photonic waveguide that is coupled (i.e., either separately coupled or integrally coupled) with a photonic crystal resonator. In a particular embodiment, the photonic waveguide and the photonic crystal resonator comprise a monocrystalline silicon (or other) photonic material absent any chemical functionalization. In another particular embodiment, the photonic waveguide and the photonic crystal resonator comprise a silicon nitride material which when actuating the photonic crystal resonator optical trapping apparatus with a 1064 nanometer resonant photonic radiation wavelength (or other resonant photonic radiation wavelength in a range from about 700 to about 1200 nanometers) provides no appreciable heating of an aqueous sample fluid that is analyzed by the photonic crystal resonator optical trapping apparatus.

  16. Method to improve optical parametric oscillator beam quality

    DOEpatents

    Smith, Arlee V.; Alford, William J.; Bowers, Mark S.

    2003-11-11

    A method to improving optical parametric oscillator (OPO) beam quality having an optical pump, which generates a pump beam at a pump frequency greater than a desired signal frequency, a nonlinear optical medium oriented so that a signal wave at the desired signal frequency and a corresponding idler wave are produced when the pump beam (wave) propagates through the nonlinear optical medium, resulting in beam walk off of the signal and idler waves, and an optical cavity which directs the signal wave to repeatedly pass through the nonlinear optical medium, said optical cavity comprising an equivalently even number of non-planar mirrors that produce image rotation on each pass through the nonlinear optical medium. Utilizing beam walk off where the signal wave and said idler wave have nonparallel Poynting vectors in the nonlinear medium and image rotation, a correlation zone of distance equal to approximately .rho.L.sub.crystal is created which, through multiple passes through the nonlinear medium, improves the beam quality of the OPO output.

  17. Calibration method of absolute orientation of camera optical axis

    NASA Astrophysics Data System (ADS)

    Xu, Yong; Guo, Pengyu; Zhang, Xiaohu; Ding, Shaowen; Su, Ang; Li, Lichun

    2013-08-01

    Camera calibration is one of the most basic and important processes in optical measuring field. Generally, the objective of camera calibration is to estimate the internal and external parameters of object cameras, while the orientation error of optical axis is not included yet. Orientation error of optical axis is a important factor, which seriously affects measuring precision in high-precision measurement field, especially for those distant aerospace measurement in which object distance is much longer than focal length, that lead to magnifying the orientation errors to thousands times. In order to eliminate the influence of orientation error of camera optical axis, the imaging model of camera is analysed and established in this paper, and the calibration method is also introduced: Firstly, we analyse the reasons that cause optical axis error and its influence. Then, we find the model of optical axis orientation error and imaging model of camera basing on it's practical physical meaning. Furthermore, we derive the bundle adjustment algorithm which could compute the internal and external camera parameters and absolute orientation of camera optical axis simultaneously at high precision. In numeric simulation, we solve the camera parameters by using bundle adjustment optimization algorithm, then we correct the image points by calibration results according to the model of optical axis error, and the simulation result shows that our calibration model is reliable, effective and precise.

  18. Optical methods for the analysis of dermatopharmacokinetics

    NASA Astrophysics Data System (ADS)

    Lademann, Juergen; Weigmann, Hans-Juergen; von Pelchrzim, R.; Sterry, Wolfram

    2002-07-01

    The method of tape stripping in combination with spectroscopic measurements is a simple and noninvasive method for the analysis of dermatopharmacokinetics of cosmetic products and topically applied drugs. The absorbance at 430 nm was used for the characterization of the amount of corneocytes on the tape strips. It was compared to the increase of weight of the tapes after removing them from the skin surface. The penetration profiles of two UV filter substances used in sunscreens were determined. The combined method of tape stripping and spectroscopic measurements can be also used for the investigation of the dermatopharmacokinetics of topically applied drugs passing through the skin. Differences in the penetration profiles of the steroid compound clobetasol, applied in the same concentration in different formulations on the skin are presented.

  19. Method and apparatus for optical temperature measurements

    DOEpatents

    Angel, S.M.; Hirschfeld, T.B.

    1986-04-22

    A method and apparatus are provided for remotely monitoring temperature. Both method and apparatus employ a temperature probe material having an excitation-dependent emission line whose fluorescence intensity varies directly with temperature whenever excited by light having a first wavelength and whose fluorescence intensity varies inversely with temperature whenever excited by light having a second wavelength. Temperature is measured by alternatively illiminating the temperature probe material with light having the first wavelength and light having the second wavelength, monitoring the intensity of the successive emissions of the excitation-dependent emission line, and relating the intensity ratio of successive emissions to temperature. 3 figs.

  20. Method and apparatus for optical temperature measurements

    DOEpatents

    Angel, S. Michael; Hirschfeld, Tomas B.

    1988-01-01

    A method and apparatus are provided for remotely monitoring temperature. Both method and apparatus employ a temperature probe material having an excitation-dependent emission line whose fluorescence intensity varies directly with temperature whenever excited by light having a first wavelength and whose fluorescence intensity varies inversely with temperature whenever excited by light having a second wavelength. Temperature is measured by alternatively illuminating the temperature probe material with light having the first wavelength and light having the second wavelength, monitoring the intensity of the successive emissions of the excitation-dependent emission line, and relating the intensity ratio of successive emissions to temperature.

  1. Optical tissue phantoms based on spin coating method

    NASA Astrophysics Data System (ADS)

    Park, Jihoon; Ha, Myungjin; Yu, Sung Kon; Radfar, Edalat; Jun, Eunkwon; Lee, Nara; Jung, Byungjo

    2015-03-01

    Fabrication of optical tissue phantom (OTP) simulating whole skin structure has been regarded as laborious and time consuming work. This study fabricated multilayer OTP optically and structurally simulating epidermis-dermis structure including blood vessel. Spin coating method was used to produce thin layer mimicking epidermal layer, then optimized for reference epoxy and silicone matrix. Adequacy of both materials in phantom fabrication was considered by comparison the fabrication results. In addition similarities between OTP and biological tissue in optical property and thickness was measured to evaluate this fabrication process.

  2. Data Optical Networking Architecture Using Wavelength-Division Multiplexing Method for Optical Sensors

    NASA Technical Reports Server (NTRS)

    Nguyen, Hung D.

    2008-01-01

    Recently there has been a growth in the number of fiber optical sensors used for health monitoring in the hostile environment of commercial aircraft. Health monitoring to detect the onset of failure in structural systems from such causes as corrosion, stress corrosion cracking, and fatigue is a critical factor in safety as well in aircraft maintenance costs. This report presents an assessment of an analysis model of optical data networking architectures used for monitoring data signals among these optical sensors. Our model is focused on the design concept of the wavelength-division multiplexing (WDM) method since most of the optical sensors deployed in the aircraft for health monitoring typically operate in a wide spectrum of optical wavelengths from 710 to 1550 nm.

  3. Whispering Gallery Optical Resonator Spectroscopic Probe and Method

    NASA Technical Reports Server (NTRS)

    Anderson, Mark S. (Inventor)

    2014-01-01

    Disclosed herein is a spectroscopic probe comprising at least one whispering gallery mode optical resonator disposed on a support, the whispering gallery mode optical resonator comprising a continuous outer surface having a cross section comprising a first diameter and a second diameter, wherein the first diameter is greater than the second diameter. A method of measuring a Raman spectrum and an Infra-red spectrum of an analyte using the spectroscopic probe is also disclosed.

  4. Optical methods in nano-biotechnology

    NASA Astrophysics Data System (ADS)

    Bruno, Luigi; Gentile, Francesco

    2016-01-01

    A scientific theory is not a mathematical paradigm. It is a framework that explains natural facts and may predict future observations. A scientific theory may be modified, improved, or rejected. Science is less a collection of theories and more the process that brings either to deny some hypothesis, maintain or accept somehow universal beliefs (or disbeliefs), and create new models that may improve or replace precedent theories. This process cannot be entrusted to common sense, personal experiences or anecdotes (many precepts in physics are indeed counterintuitive), but on a rigorous design, observation and rational to statistical analysis of new experiments. Scientific results are always provisional: scientists rarely proclaim an absolute truth or absolute certainty. Uncertainty is inevitable at the frontiers of knowledge. Notably, this is the definition of the scientific method and what we have written in the above echoes the opinion Marcia McNutt who is the Editor of Science 'Science is a method for deciding whether what we choose to believe has a basis in the laws of nature or not'. A new discovery, a new theory that explains that discovery and the scientific method itself need observations, verifications and are susceptible of falsification.

  5. Method to render second order beam optics programs symplectic

    SciTech Connect

    Douglas, D.; Servranckx, R.V.

    1984-10-01

    We present evidence that second order matrix-based beam optics programs violate the symplectic condition. A simple method to avoid this difficulty, based on a generating function approach to evaluating transfer maps, is described. A simple example illustrating the non-symplectricity of second order matrix methods, and the effectiveness of our solution to the problem, is provided. We conclude that it is in fact possible to bring second order matrix optics methods to a canonical form. The procedure for doing so has been implemented in the program DIMAT, and could be implemented in programs such as TRANSPORT and TURTLE, making them useful in multiturn applications. 15 refs.

  6. Optical air data systems and methods

    NASA Technical Reports Server (NTRS)

    Caldwell, Loren M. (Inventor); O'Brien, Martin J. (Inventor); Weimer, Carl S. (Inventor); Nelson, Loren D. (Inventor)

    2005-01-01

    Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip.

  7. Optical air data systems and methods

    NASA Technical Reports Server (NTRS)

    Caldwell, Loren M. (Inventor); Tang, Shoou-yu (Inventor); Acott, Phillip E. (Inventor); Spaeth, Lisa G. (Inventor); O'Brien, Martin (Inventor)

    2011-01-01

    Systems and methods for sensing air includes at least one, and in some embodiments three, transceivers for projecting the laser energy as laser radiation to the air. The transceivers are scanned or aligned along several different axes. Each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines air temperatures, wind speeds, and wind directions based on the scattered laser radiation. Applications of the system to wind power site evaluation, wind turbine control, traffic safety, general meteorological monitoring and airport safety are presented.

  8. Optical air data systems and methods

    NASA Technical Reports Server (NTRS)

    Caldwell, Loren M. (Inventor); Tang, Shoou-yu (Inventor); O'Brien, Martin (Inventor)

    2010-01-01

    Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip.

  9. Optical air data systems and methods

    NASA Technical Reports Server (NTRS)

    Caldwell, Loren M. (Inventor); Tang, Shoou-Yu (Inventor); O'Brien, Martin J. (Inventor)

    2011-01-01

    A method for remotely sensing air outside a moving aircraft includes generating laser radiation within a swept frequency range. A portion of the laser radiation is projected from the aircraft into the air to induce scattered laser radiation. Filtered scattered laser radiation, filtered laser radiation, and unfiltered laser radiation are detected. At least one actual ratio is determined from data corresponding to the filtered scattered laser radiation and the unfiltered laser radiation. One or more air parameters are determined by correlating the actual ratio to at least one reference ratio.

  10. Optical air data systems and methods

    NASA Technical Reports Server (NTRS)

    Caldwell, Loren M. (Inventor); Tang, Shoou-Yu (Inventor); O'Brien, Martin J. (Inventor)

    2009-01-01

    A method for remotely sensing air outside a moving aircraft includes generating laser radiation within a swept frequency range. A portion of the laser radiation is projected from the aircraft into the air to induce scattered laser radiation. Filtered scattered laser radiation, filtered laser radiation, and unfiltered laser radiation are detected. At least one actual ratio is determined from data corresponding to the filtered scattered laser radiation and the unfiltered laser radiation. One or more air parameters are determined by correlating the actual ratio to at least one reference ratio.

  11. Optical methods for measurements of skin penetration.

    PubMed

    Gotter, B; Faubel, W; Neubert, R H H

    2008-01-01

    Fourier transform infrared photoacoustic (PAS), photothermal deflection (PDS) and Raman spectroscopy belong to the modern innovative noninvasive analytical tools that are beginning to be recognized as highly potential techniques for the noninvasive study of biological tissues and human skin under in vivo conditions. They can be applied to obtain information regarding the molecular composition of the skin down to several hundred micrometers below the skin surface. All three methods allow depth-resolved investigations. While PAS and PDS use a frequency modulation of the excitation beam to reach deeper regions in the sample, the principle of confocal Raman microspectroscopy (CRM) is a movement of the specimen in the focal plane. In consideration of depth measurements PAS and PDS complete the applicable spectrum of CRM, since Raman microscopy requires particular transparent materials.

  12. Method for producing angled optical fiber tips in the laboratory

    NASA Astrophysics Data System (ADS)

    Davenport, John J.; Hickey, Michelle; Phillips, Justin P.; Kyriacou, Panicos A.

    2016-02-01

    A simple laboratory method is presented for producing optical fibers with tips polished at various angles. Angled optical fiber tips are used in applications such as optical sensing and remote laser surgery, where they can be used to control the angle of light leaving the fiber or direct it to the side. This allows for greater control and allows areas to be reached that otherwise could not. Optical fibers were produced with tip angles of 45 deg using a Perspex mounting block with an aluminum base plate. The dispersion of light leaving the tip was tested using a blue (470 nm) LED. The angle imposed an angular shift on the light diffracting out of the tip of approximately 30 deg. Additionally, some light reflected from the tip surface to diffract at 90 deg through the side of the fiber. These observations are consistent with theory and those seen by other studies, validating the method. The method was simple to perform and does not require advanced manufacturing tools. The method is suitable for producing small quantities of angle-tipped optical fibers for research applications.

  13. Application of optical diffraction method in designing phase plates

    NASA Astrophysics Data System (ADS)

    Lei, Ze-Min; Sun, Xiao-Yan; Lv, Feng-Nian; Zhang, Zhen; Lu, Xing-Qiang

    2016-11-01

    Continuous phase plate (CPP), which has a function of beam shaping in laser systems, is one kind of important diffractive optics. Based on the Fourier transform of the Gerchberg-Saxton (G-S) algorithm for designing CPP, we proposed an optical diffraction method according to the real system conditions. A thin lens can complete the Fourier transform of the input signal and the inverse propagation of light can be implemented in a program. Using both of the two functions can realize the iteration process to calculate the near-field distribution of light and the far-field repeatedly, which is similar to the G-S algorithm. The results show that using the optical diffraction method can design a CPP for a complicated laser system, and make the CPP have abilities of beam shaping and phase compensation for the phase aberration of the system. The method can improve the adaptation of the phase plate in systems with phase aberrations.

  14. Initial alignment method for free space optics laser beam

    NASA Astrophysics Data System (ADS)

    Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

    2016-08-01

    The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

  15. Phased-array optical whispering gallery mode modulation and method

    NASA Technical Reports Server (NTRS)

    Strekalov, Dmitry V. (Inventor)

    2009-01-01

    A whispering gallery mode (WGM) resonator device and method capable of filtering sidebands of optical modulators are provided. The method includes providing an optical resonator adapted to support whispering gallery modes and forming a first field and a second field from a first location and a second location, respectively, at the circumference of the optical resonator and being separated by an arc angle, .alpha.. The method includes adjusting relative phase between the first field and the second field in accordance to a differential phase, .beta., and combining the first and the second fields into an output. Particular selection of the arc angle, .alpha., and the differential phase, .beta., can determine the function of the output.

  16. Relaxation method of compensation in an optical correlator

    NASA Technical Reports Server (NTRS)

    Juday, Richard D.; Daiuto, Brian J.

    1987-01-01

    An iterative method is proposed for the sharpening of programmable filters in a 4-f optical correlator. Continuously variable spatial light modulators (SLMs) permit the fine adjustment of optical processing filters so as to compensate for the departures from ideal behavior of a real optical system. Although motivated by the development of continuously variable phase-only SLMs, the proposed sharpening method is also applicable to amplitude modulators and, with appropriate adjustments, to binary modulators as well. A computer simulation is presented that illustrates the potential effectiveness of the method: an image is placed on the input to the correlator, and its corresponding phase-only filter is adjusted (allowed to relax) so as to produce a progressively brighter and more centralized peak in the correlation plane. The technique is highly robust against the form of the system's departure from ideal behavior.

  17. Optic disk localization by a robust fusion method

    NASA Astrophysics Data System (ADS)

    Zhang, Jielin; Yin, Fengshou; Wong, Damon W. K.; Liu, Jiang; Baskaran, Mani; Cheng, Ching-Yu; Wong, Tien Yin

    2013-02-01

    The optic disk localization plays an important role in developing computer-aided diagnosis (CAD) systems for ocular diseases such as glaucoma, diabetic retinopathy and age-related macula degeneration. In this paper, we propose an intelligent fusion of methods for the localization of the optic disk in retinal fundus images. Three different approaches are developed to detect the location of the optic disk separately. The first method is the maximum vessel crossing method, which finds the region with the most number of blood vessel crossing points. The second one is the multichannel thresholding method, targeting the area with the highest intensity. The final method searches the vertical and horizontal region-of-interest separately on the basis of blood vessel structure and neighborhood entropy profile. Finally, these three methods are combined using an intelligent fusion method to improve the overall accuracy. The proposed algorithm was tested on the STARE database and the ORIGAlight database, each consisting of images with various pathologies. The preliminary result on the STARE database can achieve 81.5%, while a higher result of 99% can be obtained for the ORIGAlight database. The proposed method outperforms each individual approach and state-of-the-art method which utilizes an intensity-based approach. The result demonstrates a high potential for this method to be used in retinal CAD systems.

  18. Frequency domain optical tomography using a Monte Carlo perturbation method

    NASA Astrophysics Data System (ADS)

    Yamamoto, Toshihiro; Sakamoto, Hiroki

    2016-04-01

    A frequency domain Monte Carlo method is applied to near-infrared optical tomography, where an intensity-modulated light source with a given modulation frequency is used to reconstruct optical properties. The frequency domain reconstruction technique allows for better separation between the scattering and absorption properties of inclusions, even for ill-posed inverse problems, due to cross-talk between the scattering and absorption reconstructions. The frequency domain Monte Carlo calculation for light transport in an absorbing and scattering medium has thus far been analyzed mostly for the reconstruction of optical properties in simple layered tissues. This study applies a Monte Carlo calculation algorithm, which can handle complex-valued particle weights for solving a frequency domain transport equation, to optical tomography in two-dimensional heterogeneous tissues. The Jacobian matrix that is needed to reconstruct the optical properties is obtained by a first-order "differential operator" technique, which involves less variance than the conventional "correlated sampling" technique. The numerical examples in this paper indicate that the newly proposed Monte Carlo method provides reconstructed results for the scattering and absorption coefficients that compare favorably with the results obtained from conventional deterministic or Monte Carlo methods.

  19. Simple method for manufacturing and optical characterization of tapered optical fibres

    NASA Astrophysics Data System (ADS)

    Zakrzewski, A.; Pięta, A.; Patela, S.

    2016-12-01

    Photonic devices often use light delivered by a single-mode telecommunication fibre. However, as the diameter of the core of the optical fibre is of 10 microns, and the transverse dimensions of the photonic waveguides are usually micrometer or less, there is an issue of incompatibility. The problem may be solved by application of tapered optical fibres. For efficient light coupling, the taper should be prepared so as to create a beam of long focal length and small spot diameter in the focus. The article describes the design, fabrication and characterization of tapered optical fibres prepared with a fibre-optic fusion splicer. We modelled the tapers with FDTD method, for estimation of the influence of the tapered length and angle on the spot diameter and the focal length of an outgoing beam. We fabricated tapers from a standard single mode fibre by the Ericsson 995 PMfi- bre-optic fusion splicer. We planned the splicing technology so as to get the needed features of the beam. We planned a multistep fusion process, with optimized fusion current and fusion time. The experimental measurements of best tapered optical fibres were carried out by the knife-edge method.

  20. Method for quantifying optical properties of the human lens

    DOEpatents

    Loree, T.R.; Bigio, I.J.; Zuclich, J.A.; Shimada, Tsutomu; Strobl, K.

    1999-04-13

    A method is disclosed for quantifying optical properties of the human lens. The present invention includes the application of fiberoptic, OMA-based instrumentation as an in vivo diagnostic tool for the human ocular lens. Rapid, noninvasive and comprehensive assessment of the optical characteristics of a lens using very modest levels of exciting light are described. Typically, the backscatter and fluorescence spectra (from about 300- to 900-nm) elicited by each of several exciting wavelengths (from about 300- to 600-nm) are collected within a few seconds. The resulting optical signature of individual lenses is then used to assess the overall optical quality of the lens by comparing the results with a database of similar measurements obtained from a reference set of normal human lenses having various ages. Several metrics have been identified which gauge the optical quality of a given lens relative to the norm for the subject`s chronological age. These metrics may also serve to document accelerated optical aging and/or as early indicators of cataract or other disease processes. 8 figs.

  1. Method for quantifying optical properties of the human lens

    DOEpatents

    Loree, deceased, Thomas R.; Bigio, Irving J.; Zuclich, Joseph A.; Shimada, Tsutomu; Strobl, Karlheinz

    1999-01-01

    Method for quantifying optical properties of the human lens. The present invention includes the application of fiberoptic, OMA-based instrumentation as an in vivo diagnostic tool for the human ocular lens. Rapid, noninvasive and comprehensive assessment of the optical characteristics of a lens using very modest levels of exciting light are described. Typically, the backscatter and fluorescence spectra (from about 300- to 900-nm) elicited by each of several exciting wavelengths (from about 300- to 600-nm) are collected within a few seconds. The resulting optical signature of individual lenses is then used to assess the overall optical quality of the lens by comparing the results with a database of similar measurements obtained from a reference set of normal human lenses having various ages. Several metrics have been identified which gauge the optical quality of a given lens relative to the norm for the subject's chronological age. These metrics may also serve to document accelerated optical aging and/or as early indicators of cataract or other disease processes.

  2. Imaging Methods in the Diagnosis of Optic Disc Drusen

    PubMed Central

    Tuğcu, Betül; Özdemir, Hakan

    2016-01-01

    Optic disc drusen (ODD) are benign congenital anomalies of the optic nerve characterized by calcified hyaline bodies. While superficial drusen can be diagnosed easily during fundus examination, detecting buried drusen requires the use of additional imaging methods such as B-scan ultrasonography (USG), fundus fluorescein angiography (FFA), computed tomography (CT) and fundus autofluorescence (FAF). ODD can be detected by USG with the presentation of highly reflective round structures. ODD appear as hyperautofluorescent areas on FAF and bright spots on CT scans. FFA can be helpful in differentiating ODD from true optic disc edema. Optic disc edema shows early hyperfluorescence due to diffuse leakage whereas ODD presents as well-defined hyperfluorescence in the late phase. In recent years, it has been reported that optical coherence tomography (OCT) examination has allowed more detailed evaluation of ODD and yielded useful findings for the differentiation of optic disc edema from ODD. In this review, the role of OCT in the diagnosis of ODD is discussed. PMID:28058166

  3. Wavelet methods in multi-conjugate adaptive optics

    NASA Astrophysics Data System (ADS)

    Helin, T.; Yudytskiy, M.

    2013-08-01

    The next generation ground-based telescopes rely heavily on adaptive optics for overcoming the limitation of atmospheric turbulence. In the future adaptive optics modalities, like multi-conjugate adaptive optics (MCAO), atmospheric tomography is the major mathematical and computational challenge. In this severely ill-posed problem, a fast and stable reconstruction algorithm is needed that can take into account many real-life phenomena of telescope imaging. We introduce a novel reconstruction method for the atmospheric tomography problem and demonstrate its performance and flexibility in the context of MCAO. Our method is based on using locality properties of compactly supported wavelets, both in the spatial and frequency domains. The reconstruction in the atmospheric tomography problem is obtained by solving the Bayesian MAP estimator with a conjugate-gradient-based algorithm. An accelerated algorithm with preconditioning is also introduced. Numerical performance is demonstrated on the official end-to-end simulation tool OCTOPUS of European Southern Observatory.

  4. Optically Stimulated Electron Emission Contamination Monitor and Method

    NASA Technical Reports Server (NTRS)

    Welch, Christopher S. (Inventor); Perey, Daniel F. (Inventor)

    2005-01-01

    An apparatus and method for performing quality inspections on a test surface based on optically stimulated emission of electrons. In one embodiment, the apparatus comprises a device for producing optical radiation having a plurality of different spectrum lines, selecting at least one of the spectrum lines, and directing the selected spectrum line to the test surface, and circuitry for detecting a current of photoelectrons emitted from the test surface, generating a signal indicative of photoelectron current, and for indicating a condition of quality based on the generated signal indicative of the photoelectron current. In one embodiment, the method comprises producing optical radiation having a plurality of different spectrum lines, selecting at least one of the spectrum lines and directing the selected spectrum line to the test surface, detecting a current of photoelectrons emitted from the test surface and generating a signal indicative of photoelectron current, and indicating a condition of quality based on the generated signal indicative of the photoelectron current.

  5. Comparative study of optical fiber cure-monitoring methods

    NASA Astrophysics Data System (ADS)

    Crosby, Peter A.; Powell, Graham R.; Fernando, Gerard F.; Waters, David N.; France, Chris M.; Spooncer, Ronald C.

    1997-06-01

    This paper reports on a comparative study undertaken for different types of optical fiber sensor developed to monitor the cure of an epoxy resin system. The optical fiber sensors used to monitor the cure process were based on transmission spectroscopy, evanescent wave spectroscopy and refractive index monitoring. The transmission sensor was prepared by aligning two optical fibers within a specially prepared sleeve with a gap between the optical fiber end-faces. During cure, resin from the specimen flowed into the gap between the optical fibers allowing transmission spectra of the resin to be obtained. The evanescent wave sensor was prepared by stripping the cladding from a high refractive index core optical fiber. The prepared sensor was embedded in the sample and attenuated total reflectance spectra recorded from the resin/core boundary. Refractive index monitoring was undertaken using a high refractive index core optical fiber which had a small portion of its cladding removed. The prepared sensor was embedded in the resin specimen and light from a single wavelength source was launched into the fiber. Changes in the guiding characteristics of the sensor due to refractive index changes at the resin/core boundary were used to monitor the progress of the cure reaction. The transmission and evanescent wave spectroscopy sensors were used to follow changes in characteristic near-infrared absorption bands of the resin over the range 1450 - 1700 nm during the cure reaction. Consequently these techniques required tunable wavelength sources covering specific wavelength ranges. However, the refractive index based sensor used a single wavelength source. Therefore the equipment costs for this type of sensor were considerably less. Additionally, the refractive index sensor did not require a single wavelength source at any particular wavelength and could be applied to any spectral region in which the optical fiber would transmit light. The advantages and disadvantages of these

  6. Role of Optical Spectroscopic Methods in Neuro-Oncological Sciences

    PubMed Central

    Bahreini, Maryam

    2015-01-01

    In the surgical treatment of malignant tumors, it is crucial to characterize the tumor as precisely as possible. The determination of the exact tumor location as well as the analysis of its properties is very important in order to obtain an accurate diagnosis as early as possible. In neurosurgical applications, the optical, non-invasive and in situ techniques allow for the label-free analysis of tissue, which is helpful in neuropathology. In the past decades, optical spectroscopic methods have been investigated drastically in the management of cancer. In the optical spectroscopic techniques, tissue interrogate with sources of light which are ranged from the ultraviolet to the infrared wavelength in the spectrum. The information accumulation of light can be in a reflection which is named reflectance spectroscopy; or interactions with tissue at different wavelengths which are called fluorescence and Raman spectroscopy. This review paper introduces the optical spectroscopic methods which are used to characterize brain tumors (neuro-oncology). Based on biochemical information obtained from these spectroscopic methods, it is possible to identify tumor from normal brain tissues, to indicate tumor margins, the borders towards normal brain tissue and infiltrating gliomas, to distinguish radiation damage of tissues, to detect particular central nervous system (CNS) structures to identify cell types using particular neurotransmitters, to detect cells or drugs which are optically labeled within therapeutic intermediations and to estimate the viability of tissue and the prediction of apoptosis beginning in vitro and in vivo. The label-free, optical biochemical spectroscopic methods can provide clinically relevant information and need to be further exploited to develop a safe and easy-to-use technology for in situ diagnosis of malignant tumors. PMID:25987969

  7. Protocol independent transmission method in software defined optical network

    NASA Astrophysics Data System (ADS)

    Liu, Yuze; Li, Hui; Hou, Yanfang; Qiu, Yajun; Ji, Yuefeng

    2016-10-01

    With the development of big data and cloud computing technology, the traditional software-defined network is facing new challenges (e.i., ubiquitous accessibility, higher bandwidth, more flexible management and greater security). Using a proprietary protocol or encoding format is a way to improve information security. However, the flow, which carried by proprietary protocol or code, cannot go through the traditional IP network. In addition, ultra- high-definition video transmission service once again become a hot spot. Traditionally, in the IP network, the Serial Digital Interface (SDI) signal must be compressed. This approach offers additional advantages but also bring some disadvantages such as signal degradation and high latency. To some extent, HD-SDI can also be regard as a proprietary protocol, which need transparent transmission such as optical channel. However, traditional optical networks cannot support flexible traffics . In response to aforementioned challenges for future network, one immediate solution would be to use NFV technology to abstract the network infrastructure and provide an all-optical switching topology graph for the SDN control plane. This paper proposes a new service-based software defined optical network architecture, including an infrastructure layer, a virtualization layer, a service abstract layer and an application layer. We then dwell on the corresponding service providing method in order to implement the protocol-independent transport. Finally, we experimentally evaluate that proposed service providing method can be applied to transmit the HD-SDI signal in the software-defined optical network.

  8. Novel method for high accuracy figure measurement of optical flat

    NASA Astrophysics Data System (ADS)

    E, Kewei; Li, Dahai; Yang, Lijie; Guo, Guangrao; Li, Mengyang; Wang, Xuemin; Zhang, Tao; Xiong, Zhao

    2017-01-01

    Phase Measuring Deflectometry (PMD) is a non-contact, high dynamic-range and full-field metrology which becomes a serious competitor to interferometry. However, the accuracy of deflectometry metrology is strongly influenced by the level of the calibrations, including test geometry, imaging pin-hole camera and digital display. In this paper, we propose a novel method that can measure optical flat surface figure to a high accuracy. We first calibrate the camera using a checker pattern shown on a LCD display at six different orientations, and the last orientation is aligned at the same position as the test optical flat. By using this method, lens distortions and the mapping relationship between the CCD pixels and the subaperture coordinates on the test optical flat can be determined at the same time. To further reduce the influence of the calibration errors on measurements, a reference optical flat with a high quality surface is measured, and then the system errors in our PMD setup can be eliminated by subtracting the figure of the reference flat from the figure of the test flat. Although any expensive coordinates measuring machine, such as laser tracker and coordinates measuring machine are not applied in our measurement, our experimental results of optical flat figure from low to high order aberrations still show a good agreement with that from the Fizeau interferometer.

  9. Optical method for the determination of grain orientation in films

    DOEpatents

    Maris, Humphrey J.

    2003-05-13

    A method for the determination of grain orientation in a film sample is provided comprising the steps of measuring a first transient optical response of the film and determining the contribution to the transient optical response arising from a change in the energy distribution of the electrons in the sample, determining the contribution to the transient optical response arising from a propagating strain pulse within the sample, and determining the contribution to the transient optical response arising from a change in sample temperature of the sample. The grain orientation of the sample may be determined using the contributions to the transient optical response arising from the change in the energy distribution of the electrons, the propagating strain pulse, and the change in sample temperature. Additionally, a method for determination of the thickness of a film sample is provided. The grain orientation of the sample is first determined. The grain orientation, together with the velocity of sound and a propagation time of a strain pulse through the sample are then used to determine the thickness of the film sample.

  10. Optical method for the determination of grain orientation in films

    DOEpatents

    Maris, Humphrey J.

    2001-01-01

    A method for the determination of grain orientation in a film sample is provided comprising the steps of measuring a first transient optical response of the film and determining the contribution to the transient optical response arising from a change in the energy distribution of the electrons in the sample, determining the contribution to the transient optical response arising from a propagating strain pulse within the sample, and determining the contribution to the transient optical response arising from a change in sample temperature of the sample. The grain orientation of the sample may be determined using the contributions to the transient optical response arising from the change in the energy distribution of the electrons, the propagating strain pulse, and the change in sample temperature. Additionally, a method for determination of the thickness of a film sample is provided. The grain orientation of the sample is first determined. The grain orientation, together with the velocity of sound and a propagation time of a strain pulse through the sample are then used to determine the thickness of the film sample.

  11. Optical methods for diagnostic of cell-tissue grafts

    NASA Astrophysics Data System (ADS)

    Timchenko, P. E.; Timchenko, E. V.; Volova, L. T.; Boltovskaya, V. V.; Zherdeva, L. A.; Belousov, N. V.; Pershutkina, S. V.

    2015-08-01

    In this work the results of cell-tissue grafts research with a complex of optical methods - confocal fluorescent microscopy and Raman spectroscopy are presented. It was established that coefficient M scatter is related to irregularity of demineralization process. It was microscopically shown that the quantity of integrated cells into these types of transplants amounts to 20% of its surface.

  12. Method for forming hermetic coatings for optical fibers

    DOEpatents

    Michalske, Terry A.; Rye, Robert R.; Smith, William L.

    1993-01-01

    A method for forming hermetic coatings on optical fibers by hot filament assisted chemical vapor deposition advantageously produces a desirable coating while maintaining the pristine strength of the pristine fiber. The hermetic coatings may be formed from a variety of substances, such as, for example, boron nitride and carbon.

  13. Apparatus and method for determining the optical power passing through an optical fiber

    DOEpatents

    Toeppen, John S.

    1995-04-04

    An apparatus and method for determining the optical power transmitted through an optical fiber. The invention is based on measuring the intensity of the fluorescence produced by a doped segment of an optical fiber. The dopant is selected so that it emits light at a different wavelength than that responsible for producing the fluorescence. The doped segment is of sufficient length and dopant concentration to provide a detectable signal, but short enough to prevent the doped segment from serving as a gain medium, resulting in amplified spontaneous emission and excess fluorescence traveling along the optical fiber. The dopant material is excited by the optical signal carried by the fiber, causing a fluorescence. In the preferred embodiment the intensity of the fluorescence is proportional to the intensity of the propagating light. The signal power is then determined from the intensity of the fluorescence. The intensity of the fluorescent signal is measured by a photodetector placed so as to detect the light emitted through the side of the doped segment. The detector may wrap around the circumference of the fiber, or be placed to one side and used in conjunction with a reflector placed on the opposing side of the fiber. Filters may be used to shield the detector from other light sources and assist with accurately determining the optical power of the signal propagating within the fiber.

  14. Apparatus and method for determining the optical power passing through an optical fiber

    DOEpatents

    Toeppen, John S.

    1995-01-01

    An apparatus and method for determining the optical power transmitted through an optical fiber. The invention is based on measuring the intensity of the fluorescence produced by a doped segment of an optical fiber. The dopant is selected so that it emits light at a different wavelength than that responsible for producing the fluorescence. The doped segment is of sufficient length and dopant concentration to provide a detectable signal, but short enough to prevent the doped segment from serving as a gain medium, resulting in amplified spontaneous emission and excess fluorescence traveling along the optical fiber. The dopant material is excited by the optical signal carried by the fiber, causing a fluorescence. In the preferred embodiment the intensity of the fluorescence is proportional to the intensity of the propagating light. The signal power is then determined from the intensity of the fluorescence. The intensity of the fluorescent signal is measured by a photodetector placed so as to detect the light emitted through the side of the doped segment. The detector may wrap around the circumference of the fiber, or be placed to one side and used in conjunction with a reflector placed on the opposing side of the fiber. Filters may be used to shield the detector from other light sources and assist with accurately determining the optical power of the signal propagating within the fiber.

  15. Dynamic Optical Grating Device and Associated Method for Modulating Light

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor); Chu, Sang-Hyon (Inventor)

    2012-01-01

    A dynamic optical grating device and associated method for modulating light is provided that is capable of controlling the spectral properties and propagation of light without moving mechanical components by the use of a dynamic electric and/or magnetic field. By changing the electric field and/or magnetic field, the index of refraction, the extinction coefficient, the transmittivity, and the reflectivity fo the optical grating device may be controlled in order to control the spectral properties of the light reflected or transmitted by the device.

  16. Rays inserting method (RIM) to design dielectric optical devices

    NASA Astrophysics Data System (ADS)

    Taskhiri, Mohammad Mahdi; Khalaj Amirhosseini, Mohammad

    2017-01-01

    In this article, a novel approach, called Rays Inserted Method (RIM), is introduced to design dielectric optical devices. In this approach, some rays are inserted between two ends of desired device and then the refractive index of the points along the route of rays are obtained. The validity of the introduced approach is verified by designing three types of optical devices, i.e. power splitter, bend, and flat lens. The results are confirmed with numerical simulations by the means of FDTD scheme at the frequency of 100 GHz.

  17. Method for enhancing signals transmitted over optical fibers

    DOEpatents

    Ogle, James W.; Lyons, Peter B.

    1983-01-01

    A method for spectral equalization of high frequency spectrally broadband signals transmitted through an optical fiber. The broadband signal input is first dispersed by a grating. Narrow spectral components are collected into an array of equalizing fibers. The fibers serve as optical delay lines compensating for material dispersion of each spectral component during transmission. The relative lengths of the individual equalizing fibers are selected to compensate for such prior dispersion. The output of the equalizing fibers couple the spectrally equalized light onto a suitable detector for subsequent electronic processing of the enhanced broadband signal.

  18. Method for enhancing signals transmitted over optical fibers

    DOEpatents

    Ogle, J.W.; Lyons, P.B.

    1981-02-11

    A method for spectral equalization of high frequency spectrally broadband signals transmitted through an optical fiber is disclosed. The broadband signal input is first dispersed by a grating. Narrow spectral components are collected into an array of equalizing fibers. The fibers serve as optical delay lines compensating for material dispersion of each spectral component during transmission. The relative lengths of the individual equalizing fibers are selected to compensate for such prior dispersion. The output of the equalizing fibers couple the spectrally equalized light onto a suitable detector for subsequent electronic processing of the enhanced broadband signal.

  19. Water jet: a promising method for cutting optical glass.

    PubMed

    Salinas-Luna, Javier; Machorro, Roberto; Camacho, Javier; Luna, Esteban; Nunez, Juan

    2006-05-20

    We present an alternative method for cutting optical glass. It works with a high-pressure fluid, carring abrasive powder. This technique offers some advantages over conventional methods that use diamond abrasive covered wires or disks. We make a critical comparison between those two techniques, characterizing cuts with interferometric, polarimetric, and Ronchi testing. The main feature of the water-jet technique is that it allows surface of any shape, already polished, to be cut safely.

  20. Water jet: a promising method for cutting optical glass

    NASA Astrophysics Data System (ADS)

    Salinas-Luna, Javier; Machorro, Roberto; Camacho, Javier; Luna, Esteban; Nunez, Juan

    2006-05-01

    We present an alternative method for cutting optical glass. It works with a high-pressure fluid, carring abrasive powder. This technique offers some advantages over conventional methods that use diamond abrasive covered wires or disks. We make a critical comparison between those two techniques, characterizing cuts with interferometric, polarimetric, and Ronchi testing. The main feature of the water-jet technique is that it allows surface of any shape, already polished, to be cut safely.

  1. Method of Bonding Optical Elements with Near-Zero Displacement

    NASA Technical Reports Server (NTRS)

    Robinson, David; McClelland, Ryan; Byron, Glenn; Evans, Tyler

    2012-01-01

    The International X-ray Project seeks to build an x-ray telescope using thousands of pieces of thin and flexible glass mirror segments. Each mirror segment must be bonded into a housing in nearly perfect optical alignment without distortion. Forces greater than 0.001 Newton, or displacements greater than 0.5 m of the glass, cause unacceptable optical distortion. All known epoxies shrink as they cure. Even the epoxies with the least amount of shrinkage (<0.01%) cause unacceptable optical distortion and misalignment by pulling the mirror segments towards the housing as it cures. A related problem is that the shrinkage is not consistent or predictable so that it cannot be accounted for in the setup (i.e., if all of the bonds shrunk an equal amount, there would be no problem). A method has been developed that allows two components to be joined with epoxy in such a way that reduces the displacement caused by epoxy shrinking as it cures to less than 200 nm. The method involves using ultraviolet-cured epoxy with a displacement sensor and a nanoactuator in a control loop. The epoxy is cured by short-duration exposures to UV light. In between each exposure, the nano-actuator zeroes out the displacement caused by epoxy shrinkage and thermal expansion. After a few exposures, the epoxy has cured sufficiently to prevent further displacement of the two components. Bonding of optical elements has been done for many years, but most optics are thick and rigid elements that resist micro-Newton-level forces without causing distortion. When bonding thin glass optics such as the 0.40-mm thick IXO X-ray mirrors, forces in the micro- and milli-Newton levels cause unacceptable optical figure error. This innovation can now repeatedly and reliably bond a thin glass mirror to a metal housing with less than 0.2 m of displacement (<200 nm). This is an enabling technology that allows the installation of virtually stress-free, undistorted thin optics onto structures. This innovation is

  2. The optical density of erythrolabe determined by a new method

    PubMed Central

    King-Smith, P. E.

    1973-01-01

    1. A new method is described for the determination of optical density by retinal densitometry based on an analysis of stray light. 2. The basic assumption used is that the stray light present in retinal densitometry is independent of wave-length. The justification for this assumption is considered. 3. The stray light and hence the optical density was determined by a method of successive approximations using a Linc 8 computer. 4. The optical density of erythrolabe for the direction of maximum Stiles—Crawford efficiency was determined for five subjects, two deuteranopes, two deuteranomalous and one red-rich normal subject. The mean values for three of the subjects were close to the grand mean value of 0·42, but the other two subjects had considerably higher and lower values respectively. 5. The results are in satisfactory agreement with optical density values determined by the self-screening method using retinal densitometry, and also with determinations using microspectrophotometry and psychophysics. 6. The relevance of dielectric wave-guide modes in the outer segments is considered. PMID:4541512

  3. Application of optical controlling methods for plants under external influence

    NASA Astrophysics Data System (ADS)

    Timchenko, E. V.; Taskina, L. A.

    2012-10-01

    The experimental study results of spectral characteristic change of different types of plants influenced by external factors (synthetic superficially active substances, salts of heavy metals and nitrate fertilizers) are presented. Differential optical factor was used as the monitored optical parameter that characterizes the chlorophyll concentration change. The differential backscatter method which has high test-sensitivity and provides with the most complete information on the plant condition was the main optical monitoring method. For understanding the mechanisms of external factor accumulation and influence on plants the confocal fluorescent microscopy method providing contrast micrographs of high resolution was used for microscopic analysis in the study. It was revealed that synthetic superficially active substances and heavy metal presence lead to quasilinear decrease of differential backscatter factor with time. It was shown that the presence of salts of heavy metals in a water solution leads to chlorophyll "binding" which is microscopically shown as their «adhesion» near the cell membranes. On the contrary, the presence of synthetic superficially active substances maintains the uniformity of chlorophyll distribution in a cell, but its concentration falls with increasing the concentration in a major emission. The latter depends on the fact that synthetic superficially active substances solubilize the cell membrane proteins, increasing its penetrability. It causes pigment release ("washing away") from a plant, thereby leading to differential optical factor change. It was shown that nitrate fertilizer presence leads to increase of differential backscatter factor with time which is microscopically connected to increase in chlorophyll concentration.

  4. Optical methods for monitoring harmful gas in animal facilities

    NASA Astrophysics Data System (ADS)

    Zhang, Shirui; Dong, Daming; Zheng, Wengang; Wang, Jihua

    2014-06-01

    Animal facilities produce large amounts of harmful gases such as ammonia, hydrogen sulfide, and methane, many of which have a pungent odor. The harmful gases produced by animal housing not only affect the health of people and livestock but also pollute the air. The detection of the harmful gases can effectively improve efficiency of livestock production and reduce environmental pollution. More and more optical detection methods are applied to the detection of the harmful gases produced by animal housing. This summarizes optical detection methods for monitoring the harmful gases in animal housing recently, including nondispersive infrared gas analyzer, ultraviolet differential optical absorption spectroscopy, Fourier transform infrared spectroscopy, and tunable diode laser absorption spectroscopy. The basic principle and the characteristics of these methods are illustrated and the applications on the detection of harmful gases in animal housing are described. Meanwhile, the research of harmful gases monitoring for livestock production based on these methods were listed. The current situation and future development of the detection methods for harmful gases generated by animal housing were summarized by comparing the advantages and disadvantages of each method.

  5. Nodal line-scanning method for maskless optical lithography.

    PubMed

    Johnson, Kenneth C

    2014-12-01

    Maskless optical lithography can improve the economics and performance of multi-patterning by eliminating photomasks and by simplifying the lithography exposure technology. It could also potentially eliminate the need for multi-patterning by enabling dual-wavelength, nonlinear optical recording methods. High-resolution, maskless patterning can be achieved with a scanned-spot-array system in which modulated, diffraction-limited focus spots write the exposure pattern. Each spot has a central zero-intensity interference null along a line parallel to the scan direction for printing sub-resolution line patterns. High throughput can be achieved at the comparatively low repetition rate of excimer lasers (e.g., 6 kHz). The low repetition rate simplifies the optical modulation technology, enabling the use of supplemental modulation controls including dynamic gray-level and beam-centration controls for resolution enhancement.

  6. Plasma channel optical-pumping device and method

    SciTech Connect

    Judd, O.P.

    1981-07-17

    A device and method are described for optically pumping a gaseous laser using blackbody radiation produced by a plasma channel which is formed from an electrical discharge between two electrodes spaced at opposite longitudinal ends of the laser. A preionization device which can comprise a laser or electron beam accelerator produces a preionization beam which is sufficient to cause an elctrical discharge between the electrodes to initiate the plasma channel along the preionization path. The optical pumping energy is supplied by a high voltage power supply rather than by the preionization beam. High output optical intensities are produced by the laser due to the high temperature black-body radiation produced by the plasma channel, in the same manner as an exploding wire type laser. However, unlike the exploding wire type laser, the disclosed invention can be operated in a repetitive manner by utilizing a repetitive pulsed preionization device.

  7. Ultrafast optical imaging technology: principles and applications of emerging methods

    NASA Astrophysics Data System (ADS)

    Mikami, Hideharu; Gao, Liang; Goda, Keisuke

    2016-09-01

    High-speed optical imaging is an indispensable technology for blur-free observation of fast transient dynamics in virtually all areas including science, industry, defense, energy, and medicine. High temporal resolution is particularly important for microscopy as even a slow event appears to occur "fast" in a small field of view. Unfortunately, the shutter speed and frame rate of conventional cameras based on electronic image sensors are significantly constrained by their electrical operation and limited storage. Over the recent years, several unique and unconventional approaches to high-speed optical imaging have been reported to circumvent these technical challenges and achieve a frame rate and shutter speed far beyond what can be reached with the conventional image sensors. In this article, we review the concepts and principles of such ultrafast optical imaging methods, compare their advantages and disadvantages, and discuss an entirely new class of applications that are possible using them.

  8. In vivo imaging methods to assess glaucomatous optic neuropathy

    PubMed Central

    Fortune, Brad

    2015-01-01

    The goal of this review is to summarize the most common imaging methods currently applied for in vivo assessment of ocular structure in animal models of experimental glaucoma with an emphasis on translational relevance to clinical studies of the human disease. The most common techniques in current use include optical coherence tomography and scanning laser ophthalmoscopy. In reviewing the application of these and other imaging modalities to study glaucomatous optic neuropathy, this article is organized into three major sections: 1) imaging the optic nerve head, 2) imaging the retinal nerve fiber layer and 3) imaging retinal ganglion cell soma and dendrites. The article concludes with a brief section on possible future directions. PMID:26048475

  9. Method of fabricating optical waveguides by ion implantation doping

    DOEpatents

    Appleton, Bill R.; Ashley, Paul R.; Buchal, Christopher J.

    1989-01-01

    A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO.sub.3 crystals are implanted with high concentrations of Ti dopant at ion energies of about 350 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000.degree. C. produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality single crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguides properties.

  10. Method of fabricating optical waveguides by ion implantation doping

    DOEpatents

    Appleton, B.R.; Ashley, P.R.; Buchal, C.J.

    1987-03-24

    A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO/sub 3/ crystals are implanted with high concentrations of Ti dopant at ion energies of about 360 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000/degree/C produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguiding properties.

  11. Design method for automotive high-beam LED optics

    NASA Astrophysics Data System (ADS)

    Byzov, Egor V.; Moiseev, Mikhail A.; Doskolovich, Leonid L.; Kazanskiy, Nikolay L.

    2015-09-01

    New analytical method for the calculation of the LED secondary optics for automotive high-beam lamps is presented. Automotive headlamps should illuminate the road and the curb at the distance of 100-150 meters and create a bright, flat, relatively powerful light beam. To generate intensity distribution of this kind we propose to use TIR optical element (collimator working on the total internal reflection principle) with array of microlenses (optical corrector) on the upper surface. TIR part of the optical element enables reflection of the side rays to the front direction and provides a collimated beam which incidents on the microrelief. Microrelief, in its turn, dissipates the light flux in horizontal direction to meet the requirements of the Regulations 112, 113 and to provide well-illuminated area across the road in the far field. As an example, we computed and simulated the optical element with the diameter of 33 millimeters and the height of 22 millimeters. Simulation data shows that three illuminating modules including Cree XP-G2 LED and lens allow generating an appropriate intensity distribution for the class D of UNECE Regulations.

  12. A source number estimation method for single optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Hu, Junpeng; Huang, Zhiping; Su, Shaojing; Zhang, Yimeng; Liu, Chunwu

    2015-10-01

    The single-channel blind source separation (SCBSS) technique makes great significance in many fields, such as optical fiber communication, sensor detection, image processing and so on. It is a wide range application to realize blind source separation (BSS) from a single optical fiber sensor received data. The performance of many BSS algorithms and signal process methods will be worsened with inaccurate source number estimation. Many excellent algorithms have been proposed to deal with the source number estimation in array signal process which consists of multiple sensors, but they can not be applied directly to the single sensor condition. This paper presents a source number estimation method dealing with the single optical fiber sensor received data. By delay process, this paper converts the single sensor received data to multi-dimension form. And the data covariance matrix is constructed. Then the estimation algorithms used in array signal processing can be utilized. The information theoretic criteria (ITC) based methods, presented by AIC and MDL, Gerschgorin's disk estimation (GDE) are introduced to estimate the source number of the single optical fiber sensor's received signal. To improve the performance of these estimation methods at low signal noise ratio (SNR), this paper make a smooth process to the data covariance matrix. By the smooth process, the fluctuation and uncertainty of the eigenvalues of the covariance matrix are reduced. Simulation results prove that ITC base methods can not estimate the source number effectively under colored noise. The GDE method, although gets a poor performance at low SNR, but it is able to accurately estimate the number of sources with colored noise. The experiments also show that the proposed method can be applied to estimate the source number of single sensor received data.

  13. Optical methods for measurements of surface shape in optical components for high power laser beam forming

    NASA Astrophysics Data System (ADS)

    Józwik, Michał; Trusiak, Maciej; LiŻewski, Kamil; Martínez-Carranza, Juan; Voznesenskiy, Nikolay; Kujawińska, Małgorzata

    2016-12-01

    The paper presents modifications of full-field optical methods commonly used to test the surface quality of optical components used for forming a high power laser beam and tests of a final wavefront. The modifications in reference to surface measurements rely on implementation of the novel fringe pattern processing methods including the quality improvement of initial interferogram and analysis of a reconstructed phase based on Hilbert-Huang transform aided by the principal component analysis. Also the Point Diffraction Interferometer as the efficient tool for high quality measurements of elements with high NA is introduced. In reference to a wavefront quality measurements two solutions are discussed: the use of a lateral shear interferometer and the system employing Transport of Intensity Equation method. The pros and cons for both methods are discussed.

  14. Study of methods for direct optical address of integrated optical circuits

    NASA Technical Reports Server (NTRS)

    Wood, V. E.; Verber, C. M.

    1979-01-01

    Methods for introducing optical information directly, without intervening recording and storage steps, into integrated optical data-processing devices are surveyed. The information is taken to be in the form of a one-dimensional variation of intensity across the beam. Physical phenomena that may be utilized are evaluated, and the most suitable presently known classes of materials for exploitation of each type of interaction are discussed. A variety of possible device configurations are suggested and general principles are outlined whereby many more device types can be generated. A simple experimental device was demonstrated and its operation was analyzed.

  15. The optical nonlinearity of gold nanoparticles prepared by bioreduction method

    NASA Astrophysics Data System (ADS)

    Balbuena Ortega, A.; Arroyo Carrasco, M. L.; Gayou, V. L.; Orduña Díaz, A.; Delgado Macuil, R.; Rojas López, Marlon

    2013-11-01

    Nonlinear optical and electronic properties of nanosized metal particles have drawn considerable attention because of their strong and size-dependent plasmon resonance absorption. In a metal nanoparticle system such as gold dispersed in a transparent matrix, an absorption peak due to surface plasmon resonance is usually observed in the visible spectral region. Metal nanoparticles are of special interest as nonlinear materials for optical switching and computing because of their relatively large third-order nonlinearity (χ3) and ultrafast response time. The purpose of this study was to analyze the nonlinear optical properties of biosynthesized gold nanoparticles. The samples were prepared by biosynthesis method using yeast extract as reducing agent and the nonlinear optical properties of the nanoparticles were investigated using a single beam Z-scan technique with a beam power of 20 mW and operated at wavelength of 514 nm. The reaction between metal ions and yeast extracts were monitored by UV-visible spectra of Au nanoparticles in aqueous solution with different pH (3-6). The surface plasmon peak position was shifted from 528 nm to 573 nm, according to of pH variation 4 to 6. The average particle size was calculated by the absorption peak position using the Fernig method, from 42 to 103 nm. The z-scan curves showed a negative nonlocal nonlinear refractive index with a magnitude dependent on the nanoparticle size.

  16. Ultrathin optical panel and a method of making an ultrathin optical panel

    DOEpatents

    Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

    2001-10-09

    An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated with a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

  17. Ultrathin Optical Panel And A Method Of Making An Ultrathin Optical Panel.

    DOEpatents

    Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

    2005-02-15

    An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated with a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

  18. Ultrathin optical panel and a method of making an ultrathin optical panel

    DOEpatents

    Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

    2003-02-11

    An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated with a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

  19. Ultrathin optical panel and a method of making an ultrathin optical panel

    DOEpatents

    Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

    2002-01-01

    An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated With a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

  20. Ultrathin Optical Panel And A Method Of Making An Ultrathin Optical Panel.

    DOEpatents

    Biscardi, Cyrus; Brewster, Calvin; DeSanto, Leonard; Veligdan, James T.

    2005-05-17

    An ultrathin optical panel, and a method of producing an ultrathin optical panel, are disclosed, including stacking a plurality of glass sheets, which sheets may be coated with a transparent cladding substance or may be uncoated, fastening together the plurality of stacked coated glass sheets using an epoxy or ultraviolet adhesive, applying uniform pressure to the stack, curing the stack, sawing the stack to form an inlet face on a side of the stack and an outlet face on an opposed side of the stack, bonding a coupler to the inlet face of the stack, and fastening the stack, having the coupler bonded thereto, within a rectangular housing having an open front which is aligned with the outlet face, the rectangular housing having therein a light generator which is optically aligned with the coupler. The light generator is preferably placed parallel to and proximate with the inlet face, thereby allowing for a reduction in the depth of the housing.

  1. Emerging optical methods for surveillance of Barrett’s oesophagus

    PubMed Central

    Sturm, Matthew B; Wang, Thomas D

    2016-01-01

    The rapid rise in incidence of oesophageal adenocarcinoma has motivated the need for improved methods for surveillance of Barrett’s oesophagus. Early neoplasia is flat in morphology and patchy in distribution and is difficult to detect with conventional white light endoscopy (WLE). Light offers numerous advantages for rapidly visualising the oesophagus, and advanced optical methods are being developed for wide-field and cross-sectional imaging to guide tissue biopsy and stage early neoplasia, respectively. We review key features of these promising methods and address their potential to improve detection of Barrett’s neoplasia. The clinical performance of key advanced imaging technologies is reviewed, including (1) wide-field methods, such as high-definition WLE, chromoendoscopy, narrow-band imaging, autofluorescence and trimodal imaging and (2) cross-sectional techniques, such as optical coherence tomography, optical frequency domain imaging and confocal laser endomicroscopy. Some of these instruments are being adapted for molecular imaging to detect specific biological targets that are overexpressed in Barrett’s neoplasia. Gene expression profiles are being used to identify early targets that appear before morphological changes can be visualised with white light. These targets are detected in vivo using exogenous probes, such as lectins, peptides, antibodies, affibodies and activatable enzymes that are labelled with fluorescence dyes to produce high contrast images. This emerging approach has potential to provide a ‘red flag’ to identify regions of premalignant mucosa, outline disease margins and guide therapy based on the underlying molecular mechanisms of cancer progression. PMID:25975605

  2. Underwater Optical Wireless Channel Modeling Using Monte-Carlo Method

    NASA Astrophysics Data System (ADS)

    Saini, P. Sri; Prince, Shanthi

    2011-10-01

    At present, there is a lot of interest in the functioning of the marine environment. Unmanned or Autonomous Underwater Vehicles (UUVs or AUVs) are used in the exploration of the underwater resources, pollution monitoring, disaster prevention etc. Underwater, where radio waves do not propagate, acoustic communication is being used. But, underwater communication is moving towards Optical Communication which has higher bandwidth when compared to Acoustic Communication but has shorter range comparatively. Underwater Optical Wireless Communication (OWC) is mainly affected by the absorption and scattering of the optical signal. In coastal waters, both inherent and apparent optical properties (IOPs and AOPs) are influenced by a wide array of physical, biological and chemical processes leading to optical variability. The scattering effect has two effects: the attenuation of the signal and the Inter-Symbol Interference (ISI) of the signal. However, the Inter-Symbol Interference is ignored in the present paper. Therefore, in order to have an efficient underwater OWC link it is necessary to model the channel efficiently. In this paper, the underwater optical channel is modeled using Monte-Carlo method. The Monte Carlo approach provides the most general and most flexible technique for numerically solving the equations of Radiative transfer. The attenuation co-efficient of the light signal is studied as a function of the absorption (a) and scattering (b) coefficients. It has been observed that for pure sea water and for less chlorophyll conditions blue wavelength is less absorbed whereas for chlorophyll rich environment red wavelength signal is absorbed less comparative to blue and green wavelength.

  3. Three optical methods for remotely measuring aerosol size distributions.

    NASA Technical Reports Server (NTRS)

    Reagan, J. A.; Herman, B. M.

    1971-01-01

    Three optical probing methods for remotely measuring atmospheric aerosol size distributions are discussed and contrasted. The particular detection methods which are considered make use of monostatic lidar (laser radar), bistatic lidar, and solar radiometer sensing techniques. The theory of each of these measurement techniques is discussed briefly, and the necessary constraints which must be applied to obtain aerosol size distribution information from such measurements are pointed out. Theoretical and/or experimental results are also presented which demonstrate the utility of the three proposed probing methods.

  4. Methods to assess sensitivity of optical coherence tomography systems

    PubMed Central

    Agrawal, Anant; Pfefer, T. Joshua; Woolliams, Peter D.; Tomlins, Peter H.; Nehmetallah, George

    2017-01-01

    Measuring the sensitivity of an optical coherence tomography (OCT) system determines the minimum sample reflectivity it can detect and provides a figure of merit for system optimization and comparison. The published literature lacks a detailed description of OCT sensitivity measurement procedures. Here we describe a commonly-used measurement method and introduce two new phantom-based methods, which also offer a means to directly visualize low reflectivity conditions relevant to biological tissue. We provide quantitative results for the three methods from different OCT system configurations and discuss the methods’ advantages and disadvantages. PMID:28270992

  5. Expected Energy Method for Electro-Optical SNR Calculations.

    DTIC Science & Technology

    1984-02-02

    r’AD-Ri39 984 EXPECTED ENERGY METHOD FOR ELECTPO-OPTICRL SNR i/i CALCULRTIONS(U) MASSRCHUSETTS INST OF TECH LEXINGTON LINCOLN LAB G J MAYER 82 FEB 84...ENERGY METHOD FOR ELECTRO-OPTICAL SNR CALCULATIONS * Ci. MA YER Group 9 TECHNICAL REPORT 634 2 FEBRUARY 1984 Approved for public release; distribution...analysis of image and sensor element configuration. This method allows the optimal pixel size to be selected to maximize the expected SNR for any point

  6. Beam propagation method analysis of optical waveguide lenses.

    PubMed

    Ishikawa, A; Izutsu, M; Sueta, T

    1990-12-01

    Focusing characteristics of optical waveguide lenses are analyzed by the beam propagation method (BPM) instead of the ray tracing method. By use of the BPM, we can observe field distributions of a converging or diverging light beam after it passes through a waveguide lens. Variations of the spot width and magnitude of diffraction can immediately be evaluated with this calculation. The BPM calculations are used for a mode-index, Luneburg, and geodesic lenses. For the application of the method to the geodesic lens, the surface deformation is converted into an equivalent index.

  7. Method for polishing the end of an optical fiber

    NASA Technical Reports Server (NTRS)

    Dholakia, Anil R. (Inventor)

    1988-01-01

    A method of polishing a roof-shaped, or bevelled, tip having a predetermined angle on the end of an optical fiber is disclosed. The method comprises placing an optical fiber in contact with an abrasive tape at an angle corresponding to the desired predetermined angle. The fiber is moved towards the tape beyond the point of contact so as to cause a bend in the fiber. Upon moving the abrasive tape, the compliance of the fiber, by virtue of the bend, provides a pressure of the fiber against the tape to enable polishing to occur. As polishing continues the pressure decreases until enough material is removed so as to eliminate the bend and impart the predetermined angle to the fiber tip. The fiber may be rotated to polish the other side in a similar manner, if so desired.

  8. New compensation method for bulk optical sensors with multiple birefringences.

    PubMed

    Lee, K S

    1989-06-01

    The dielectric tensor of an anisotropic crystal with multiple perturbations is presented to include the effects of multiple perturbations. To study electromagnetic wave propagation in anisotropic crystals subject to various influences the perturbed dielectric tensor is substituted into Maxwell's equation. Then, a 2 x 2 transmission matrix formalism, based on a normal-mode approach, is extended to anisotropic crystals possessing multiple birefringences to develop compensation schemes for ac optical sensors employing the crystal. It is shown that a new compensation method utilizing two analyzers can eliminate the effects of both unwanted linear birefringences and unwanted circular birefringences on the stability of the ac bulk polarimetric optical sensor. The conditions (here referred to as the quenching condition) in which the compensation method becomes important are also derived for both the voltage (or electric field) and current (or magnetic field) sensors.

  9. 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

  10. Fast calculation method of complex space targets' optical cross section.

    PubMed

    Han, Yi; Sun, Huayan; Li, Yingchun; Guo, Huichao

    2013-06-10

    This paper utilizes the optical cross section (OCS) to characterize the optical scattering characteristics of a space target under the conditions of Sun lighting. We derive the mathematical expression of OCS according to the radiometric theory, and put forward a fast visualization calculation method of complex space targets' OCS based on an OpenGL and 3D model. Through the OCS simulation of Lambert bodies (cylinder and sphere), the computational accuracy and speed of the algorithm were verified. By using this method, the relative error for OCS will not exceed 0.1%, and it only takes 0.05 s to complete a complex calculation. Additionally, we calculated the OCS of three actual satellites with bidirectional reflectance distribution function model parameters in visible bands, and results indicate that it is easy to distinguish the three targets by comparing their OCS curves. This work is helpful for the identification and classification of unresolved space target based on photometric characteristics.

  11. Anisotropy minimization via least squares method for transformation optics.

    PubMed

    Junqueira, Mateus A F C; Gabrielli, Lucas H; Spadoti, Danilo H

    2014-07-28

    In this work the least squares method is used to reduce anisotropy in transformation optics technique. To apply the least squares method a power series is added on the coordinate transformation functions. The series coefficients were calculated to reduce the deviations in Cauchy-Riemann equations, which, when satisfied, result in both conformal transformations and isotropic media. We also present a mathematical treatment for the special case of transformation optics to design waveguides. To demonstrate the proposed technique a waveguide with a 30° of bend and with a 50% of increase in its output width was designed. The results show that our technique is simultaneously straightforward to be implement and effective in reducing the anisotropy of the transformation for an extremely low value close to zero.

  12. Transformation-optics simulation method for stimulated Brillouin scattering

    NASA Astrophysics Data System (ADS)

    Zecca, Roberto; Bowen, Patrick T.; Smith, David R.; Larouche, Stéphane

    2016-12-01

    We develop an approach to enable the full-wave simulation of stimulated Brillouin scattering and related phenomena in a frequency-domain, finite-element environment. The method uses transformation-optics techniques to implement a time-harmonic coordinate transform that reconciles the different frames of reference used by electromagnetic and mechanical finite-element solvers. We show how this strategy can be successfully applied to bulk and guided systems, comparing the results with the predictions of established theory.

  13. Aircraft Transparency Optical Quality: New Methods of Measurement

    DTIC Science & Technology

    1981-02-01

    AFAMRL.TR-1-21 X AIRCRAFT TRANSPARENCY OPTICAL QUALITY: NEW METHODS OF MEASUREMENT LOUIS V. GENCO , O.D., Lt. Colonel HARRY L. TASK, Ph.D. FEBRUARY...aircraft transparency with simple modifications of a positioning fixture ( Genco , 1979). DESIRABLE CHARACTERISTICS The ideal field evaluation unit for...34Windscreen Angular Deviation Measurement Device," U.S. Air Force Invention No. 13647, Patent Pending. Task, Harry L., Louis V. Genco , and Kenneth L. Smith

  14. Optical Sensors and Methods for Underwater 3D Reconstruction

    PubMed Central

    Massot-Campos, Miquel; Oliver-Codina, Gabriel

    2015-01-01

    This paper presents a survey on optical sensors and methods for 3D reconstruction in underwater environments. The techniques to obtain range data have been listed and explained, together with the different sensor hardware that makes them possible. The literature has been reviewed, and a classification has been proposed for the existing solutions. New developments, commercial solutions and previous reviews in this topic have also been gathered and considered. PMID:26694389

  15. Optical methods for the detection of heavy metal ions

    NASA Astrophysics Data System (ADS)

    Uglov, A. N.; Bessmertnykh-Lemeune, A.; Guilard, R.; Averin, A. D.; Beletskaya, I. P.

    2014-03-01

    The review covers an important area of the modern chemistry, namely, the detection of heavy metal ions using optical molecular detectors. The role of this method in metal ion detection and the physicochemical grounds of operation of chemosensors are discussed, and examples of detection of most abundant heavy metal ions and synthetic approaches to molecular detectors are presented. The immobilization of molecular detectors on solid substrates for the design of analytical sensor devices is described. The bibliography includes 178 references.

  16. Testing of flat optical surfaces by the quantitative Foucault method.

    PubMed

    Simon, M C; Simon, J M

    1978-01-01

    The complete theory of measurement of optical flat mirrors of circular or elliptical shape using the quantitative Foucault method is described here. It has been used in Córdoba since 1939 in a partially intuitive but correct form. The surface, not yet flat and, at times, astigmatic, is assimilated to the sum of a spherical plus a cylindrical dome. The errors of the three possible ways of reckoning are calculated.

  17. An image reconstruction method (IRBis) for optical/infrared interferometry

    NASA Astrophysics Data System (ADS)

    Hofmann, K.-H.; Weigelt, G.; Schertl, D.

    2014-05-01

    Aims: We present an image reconstruction method for optical/infrared long-baseline interferometry called IRBis (image reconstruction software using the bispectrum). We describe the theory and present applications to computer-simulated interferograms. Methods: The IRBis method can reconstruct an image from measured visibilities and closure phases. The applied optimization routine ASA_CG is based on conjugate gradients. The method allows the user to implement different regularizers, apply residual ratios as an additional metric for goodness-of-fit, and use previous iteration results as a prior to force convergence. Results: We present the theory of the IRBis method and several applications of the method to computer-simulated interferograms. The image reconstruction results show the dependence of the reconstructed image on the noise in the interferograms (e.g., for ten electron read-out noise and 139 to 1219 detected photons per interferogram), the regularization method, the angular resolution, and the reconstruction parameters applied. Furthermore, we present the IRBis reconstructions submitted to the interferometric imaging beauty contest 2012 initiated by the IAU Working Group on Optical/IR Interferometry and describe the performed data processing steps.

  18. Image Retrieval Method for Multiscale Objects from Optical Colonoscopy Images

    PubMed Central

    Sakanashi, Hidenori; Takahashi, Eiichi; Murakawa, Masahiro; Aoki, Hiroshi; Takeuchi, Ken; Suzuki, Yasuo

    2017-01-01

    Optical colonoscopy is the most common approach to diagnosing bowel diseases through direct colon and rectum inspections. Periodic optical colonoscopy examinations are particularly important for detecting cancers at early stages while still treatable. However, diagnostic accuracy is highly dependent on both the experience and knowledge of the medical doctor. Moreover, it is extremely difficult, even for specialist doctors, to detect the early stages of cancer when obscured by inflammations of the colonic mucosa due to intractable inflammatory bowel diseases, such as ulcerative colitis. Thus, to assist the UC diagnosis, it is necessary to develop a new technology that can retrieve similar cases of diagnostic target image from cases in the past that stored the diagnosed images with various symptoms of colonic mucosa. In order to assist diagnoses with optical colonoscopy, this paper proposes a retrieval method for colonoscopy images that can cope with multiscale objects. The proposed method can retrieve similar colonoscopy images despite varying visible sizes of the target objects. Through three experiments conducted with real clinical colonoscopy images, we demonstrate that the method is able to retrieve objects of any visible size and any location at a high level of accuracy. PMID:28255295

  19. Neurophotonics: optical methods to study and control the brain

    NASA Astrophysics Data System (ADS)

    Doronina-Amitonova, L. V.; Fedotov, I. V.; Fedotov, A. B.; Anokhin, K. V.; Zheltikov, A. M.

    2015-04-01

    Methods of optical physics offer unique opportunities for the investigation of brain and higher nervous activity. The integration of cutting-edge laser technologies and advanced neurobiology opens a new cross-disciplinary area of natural sciences - neurophotonics - focusing on the development of a vast arsenal of tools for functional brain diagnostics, stimulation of individual neurons and neural networks, and the molecular engineering of brain cells aimed at the diagnosis and therapy of neurodegenerative and psychic diseases. Optical fibers help to confront the most challenging problems in brain research, including the analysis of molecular-cellular mechanisms of the formation of memory and behavior. New generation optical fibers provide new solutions for the development of fundamentally new, unique tools for neurophotonics and laser neuroengineering - fiber-optic neuroendoscopes and neurointerfaces. These instruments broaden research horizons when investigating the most complex brain functions, enabling a long-term multiplex detection of fluorescent protein markers, as well as photostimulation of neuronal activity in deep brain areas in living, freely moving animals with an unprecedented spatial resolution and minimal invasiveness. This emerging technology opens new horizons for understanding learning and long-term memory through experiments with living, freely moving mammals. Here, we present a brief review of this rapidly growing field of research.

  20. Alignment method of off-axis RC reflective optical system

    NASA Astrophysics Data System (ADS)

    Xue-min, Zhang; Xing, Song; Zhi-jun, Zhang; Hou, Xiao-hua

    2016-10-01

    Off-axis optical system has a wide application in space optics and remote detective area. The high surface shape accuracy can be ensured with the development of advanced manufacture technique. So the only condition which limits the wide application of off-axis optical system is how to realize the precise alignment of it. Based on a RC reflective optical system whose diameter is 400mm, the alignment method which combines the high resolution initial placement and computer-aided alignment is introduced. By designing a system which can measure the off-axis fabrication and off-axis angle precisely, the high resolution initial placement of off-axis mirror can be ensured with a measurement accuracy of +/-0.05mm and +/-10". The good initial placement can give a good initial state, so the computer-aided model can be converged well. The experiment shows that a system which has a good initial placement could have a good wave aberration of 0.04λ after three times iteration adjustment.

  1. 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.

  2. Method for the continuous processing of hermetic fiber optic components and the resultant fiber optic-to-metal components

    DOEpatents

    Kramer, Daniel P.

    1994-08-09

    Hermetic fiber optic-to-metal components and method for making hermetic fiber optic-to-metal components by assembling and fixturing elements comprising a metal shell, a glass preform, and a metal-coated fiber optic into desired relative positions and then sealing said fixtured elements preferably using a continuous heating process. The resultant hermetic fiber optic-to-metal components exhibit high hermeticity and durability despite the large differences in thermal coefficients of expansion among the various elements.

  3. Fabrication Method for LOBSTER-Eye Optics in <110> Silicon

    NASA Technical Reports Server (NTRS)

    Chervenak, James; Collier, Michael; Mateo, Jennette

    2013-01-01

    Soft x-ray optics can use narrow slots to direct x-rays into a desirable pattern on a focal plane. While square-pack, square-pore, slumped optics exist for this purpose, they are costly. Silicon (Si) is being examined as a possible low-cost replacement. A fabrication method was developed for narrow slots in <110> Si demonstrating the feasibility of stacked slot optics to replace micropores. Current micropore optics exist that have 20-micron-square pores on 26-micron pitch in glass with a depth of 1 mm and an extent of several square centimeters. Among several proposals to emulate the square pore optics are stacked slot chips with etched vertical slots. When the slots in the stack are positioned orthogonally to each other, the component will approach the soft x-ray focusing observed in the micropore optics. A specific improvement Si provides is that it can have narrower sidewalls between slots to permit greater throughput of x-rays through the optics. In general, Si can have more variation in slot geometry (width, length). Further, the sidewalls can be coated with high-Z materials to enhance reflection and potentially reduce the surface roughness of the reflecting surface. Narrow, close-packed deep slots in <110> Si have been produced using potassium hydroxide (KOH) etching and a patterned silicon nitride (SiN) mask. The achieved slot geometries have sufficient wall smoothness, as observed through scanning electron microscope (SEM) imaging, to enable evaluation of these slot plates as an optical element for soft x-rays. Etches of different angles to the crystal plane of Si were evaluated to identify a specific range of etch angles that will enable low undercut slots in the Si <110> material. These slots with the narrow sidewalls are demonstrated to several hundred microns in depth, and a technical path to 500-micron deep slots in a precision geometry of narrow, closepacked slots is feasible. Although intrinsic stress in ultrathin wall Si is observed, slots with

  4. New method for lightning location using optical ground wire

    NASA Astrophysics Data System (ADS)

    Qin, Zhaoyu; Cheng, Zhaogu; Zhang, Zhiping; Zhu, Jianqiang; Li, Feng

    2006-12-01

    A new technology of lightning location is described, which is based on detecting the state of polarization (SOP) fluctuation of the laser light in the optic ground wire (OPGW). Compared with the conventional lightning location method, the new method is more accurate, more stable, and cheaper. Theories of Stokes parameters and Poincare sphere are introduced to analyze the SOP at the lightning strike point. It can be concluded that although the initial points of SOP on the Poincare sphere are random, the SOP fluctuation generated by lightning strike can still be accurately identified by detecting the velocity of polarization motion. A new algorithm to quantify the velocity is also introduced.

  5. Innovative methods to promote optics at school level

    NASA Astrophysics Data System (ADS)

    Garg, Amit; Bharadwaj, Sadashiv Raj; Kachru, Priyanka; Dutta, Subhajit Kumar; Singh, Shatakshi

    2016-09-01

    The conventional pedagogical techniques in Indian schools are predominantly limited to coursework and involve just necessary laboratory work. It lacks in inculcating the aptitude for practical applications relevant to the coursework amongst the students. This results in a major setback for the students as their mental approach remains constrained to books, where on the contrary, the future depends only on technologies and applications. Considering this, under Optics Outreach Education Program 2014, University of Delhi at Acharya Narendra Dev College SPIE Student Chapter conducted workshops in 22 schools of Delhi including various Government schools as well. The workshop zeroed into the concepts of optics and various innovative techniques developed by our Student chapter members to embark a new method of teaching.

  6. Optical methods for hydrogen degassing monitoring in urban conditions

    NASA Astrophysics Data System (ADS)

    Timchenko, E. V.; Timchenko, P. E.; Zherdeva, L. A.; Tregub, N. V.; Selezneva, E. A.; Yakovlev, V. N.

    2015-12-01

    Results of a study of variations in optical parameters of bioindicators that grow in the regions of hydrogen degassing in Samara are presented. Raman spectroscopy and confocal fluorescence microscopy were used as the main methods of the study. Features of Raman spectra of plants that grow in zones with presence/ absence of deep hydrogen emissions have been ascertained. The main variations have been recorded at wavenumbers of 1380, 1522, 1547, and 1600 cm-1, which are responsible for stretching vibrations in lignin and β-carotene and chlorophyll a and cellulose in plant leaves. Confocal fluorescence microscopy showed an increase in the chloroplasts in leaves of plants which grow at hydrogen degassing territories. An optical coefficient was introduced, on the basis of which the Samara region was monitored.

  7. Optical center alignment technique based on inner profile measurement method

    NASA Astrophysics Data System (ADS)

    Wakayama, Toshitaka; Yoshizawa, Toru

    2014-05-01

    Center alignment is important technique to tune up the spindle of various precision machines in manufacturing industry. Conventionally such a tool as a dial indicator has been used to adjust and to position the axis by manual operations of a technical worker. However, it is not easy to precisely control its axis. In this paper, we developed the optical center alignment technique based on inner profile measurement using a ring beam device. In this case, the center position of the cylinder hole can be determined from circular profile detected by optical sectioning method using a ring beam device. In our trials, the resolution of the center position is proved less than 10 micrometers in extreme cases. This technique is available for practical applications in machine tool industry.

  8. Comparison of three optical methods to study erythrocyte aggregation.

    PubMed

    Zhao, H; Wang, X; Stoltz, J F

    1999-01-01

    The aim of this work was to evaluate three optical methods designed to determine erythrocyte aggregation: Erythroaggregometer (EA; Regulest, France), Laser-assisted Optical Rotational Cell Analyzer (LORCA; Mechatronics, Netherlands) and Fully Automatic Erythrocyte Aggregometer (FAEA; Myrenne, GmbH, Germany). Blood samples were taken from fifty donors (26 males and 24 females). The aggregation of normal red blood cell (RBC) and RBCs suspended in three normo- and hyperaggregating suspending media was studied. The results revealed some significant correlations between parameters measured by these instruments, in particular, between the indexes of aggregation of EA and LORCA. Further, RBC aggregation of multiple myeloma patients was also studied and a hyper erythrocyte aggregation state was found by EA and LORCA.

  9. Method and apparatus of highly linear optical modulation

    DOEpatents

    DeRose, Christopher; Watts, Michael R.

    2016-05-03

    In a new optical intensity modulator, a nonlinear change in refractive index is used to balance the nonlinearities in the optical transfer function in a way that leads to highly linear optical intensity modulation.

  10. Application of optical non-invasive methods in skin physiology

    NASA Astrophysics Data System (ADS)

    Lademann, J.; Patzelt, A.; Darvin, M.; Richter, H.; Antoniou, C.; Sterry, W.; Koch, S.

    2008-05-01

    In the present paper the application of optical non-invasive methods in dermatology and cosmetology is discussed. Laser scanning microscopy (LSM) and optical coherent tomography (OCT) are the most promising methods for this application. Using these methods, the analysis of different skin parameters like dryness and oiliness of the skin, the barrier function and the structure of furrows and wrinkles are discussed. Additionally the homogeneity of distribution of topically applied creams, as well as their penetration into the skin were investigated. It is shown that these methods are highly valuable in dermatology for diagnostic and therapy control and for basic research, for instance in the field of structure analysis of hair follicles and sweat glands. The vertical images of the tissue produced by OCT can be easily compared with histological sections. Unfortunately, the resolution of the OCT technique is not high enough to carry out measurements on a cellular level, as is possible by LSM. LSM has the advantage that it can be used for the investigation of penetration and storage processes of topically applied substances, if these substances have fluorescent properties or if they are fluorescent-labelled.

  11. Test methods for optical disk media characteristics (for 356 mm ruggedized magneto-optic media)

    NASA Technical Reports Server (NTRS)

    Podio, Fernando L.

    1991-01-01

    Standard test methods for computer storage media characteristics are essential and allow for conformance to media interchange standards. The test methods were developed for 356 mm two-sided laminated glass substrate with a magneto-optic active layer media technology. These test methods may be used for testing other media types, but in each case their applicability must be evaluated. Test methods are included for a series of different media characteristics, including operational, nonoperational, and storage environments; mechanical and physical characteristics; and substrate, recording layer, and preformat characteristics. Tests for environmental qualification and media lifetimes are also included. The best methods include testing conditions, testing procedures, a description of the testing setup, and the required calibration procedures.

  12. Optical methods for determining the shock Hugoniot of Solids

    NASA Astrophysics Data System (ADS)

    Svingala, Forrest; Hargather, Michael; Settles, Gary

    2013-06-01

    Traditionally, the shock Hugoniot is measured on a point-bypoint basis by a series of high-velocity impact experiments. Observations are typically confined to pointwise pressure or velocity measurements at the free-surfaces of the sample. In this work, shock waves are initiated in transparent polyurethane and opaque polyurea samples using exploding bridgewires, aluminum ballistic projectiles, and gram-scale explosive charges. Shock waves and material motion are observed optically by shadowgraphy using a high-speed-digital camera recording at up to 106 frames/s. Ballistic impact, producing a constant-strength shock wave, is combined with these optical techniques to obtain a single shock Hugoniot point per test. A gram-scale explosive charge produces a shock wave in the material sample that is initially strong, but attenuates as it transits the polymer sample. With optical access to the entire sample, multiple shock and particle velocity combinations may be observed in a single test, allowing the measurement of a shock Hugoniot curve in fewer experiments than by traditional methods. These techniques produce data in general agreement with an extrapolation of published Hugoniot data for polyurethane and polyurea. Work funded by the Office of Naval Research.

  13. Method for optical coherence elastography of the cornea

    NASA Astrophysics Data System (ADS)

    Ford, Matthew R.; Dupps, William J.; Rollins, Andrew M.; Roy, Abhijit Sinha; Hu, Zhilin

    2011-01-01

    The material properties of the cornea are important determinants of corneal shape and refractive power. Corneal ectatic diseases, such as keratoconus, are characterized by material property abnormalities, are associated with progressive thinning and distortion of the cornea, and represent a leading indication for corneal transplantation. We describe a corneal elastography technique based on optical coherence tomography (OCT) imaging, in which displacement of intracorneal optical features is tracked with a 2-D cross-correlation algorithm as a step toward nondestructive estimation of local and directional corneal material properties. Phantom experiments are performed to measure the effects of image noise and out-of-plane displacement on effectiveness of displacement tracking and demonstrated accuracy within the tolerance of a micromechanical translation stage. Tissue experiments demonstrate the ability to produce 2-D maps of heterogeneous intracorneal displacement with OCT. The ability of a nondestructive optical method to assess tissue under in situ mechanical conditions with physiologic-range stress levels provides a framework for in vivo quantification of 3-D corneal elastic and viscoelastic resistance, including analogs of shear deformation and Poisson's ratio that may be relevant in the early diagnosis of corneal ectatic disease.

  14. Method for optical coherence elastography of the cornea

    PubMed Central

    Ford, Matthew R.; Dupps, William J.; Rollins, Andrew M.; Roy, Abhijit Sinha; Hu, Zhilin

    2011-01-01

    The material properties of the cornea are important determinants of corneal shape and refractive power. Corneal ectatic diseases, such as keratoconus, are characterized by material property abnormalities, are associated with progressive thinning and distortion of the cornea, and represent a leading indication for corneal transplantation. We describe a corneal elastography technique based on optical coherence tomography (OCT) imaging, in which displacement of intracorneal optical features is tracked with a 2-D cross-correlation algorithm as a step toward nondestructive estimation of local and directional corneal material properties. Phantom experiments are performed to measure the effects of image noise and out-of-plane displacement on effectiveness of displacement tracking and demonstrated accuracy within the tolerance of a micromechanical translation stage. Tissue experiments demonstrate the ability to produce 2-D maps of heterogeneous intracorneal displacement with OCT. The ability of a nondestructive optical method to assess tissue under in situ mechanical conditions with physiologic-range stress levels provides a framework for in vivo quantification of 3-D corneal elastic and viscoelastic resistance, including analogs of shear deformation and Poisson’s ratio that may be relevant in the early diagnosis of corneal ectatic disease. PMID:21280911

  15. New optical method for noninvasive blood glucose measurement by optical ultrasonic modulation

    NASA Astrophysics Data System (ADS)

    Zhu, Lili; Lin, Jieqing; Xie, Wenming; Li, Hui

    2010-11-01

    A new optical technique for continuous, noninvasive monitoring of blood glucose levels based on ultrasonic modulation of scattering light is proposed. The ultrasound-modulated scattered light has an accurate separation of scattering and absorption changes in tissue. And the optical scattering and absorbing coefficient of tissue depend on the concentration of glucose in the extracellular fluid. As the glucose induced to scattering and absorption changes, the ultrasoundmodulated light also changes. In this paper, a correlation is observed between ultrasound-modulated light intensity as well as its modulation depth and blood glucose concentration in phantom experiments. In addition, some researches about ultrasound-modulated signal affected by the temperature of glucose aqueous solution are done. Preliminary experiments find that this method is a promising noninvasive blood glucose measurement.

  16. Fiber optic liquid mass flow sensor and method

    NASA Technical Reports Server (NTRS)

    Korman, Valentin (Inventor); Gregory, Don Allen (Inventor); Wiley, John T. (Inventor); Pedersen, Kevin W. (Inventor)

    2010-01-01

    A method and apparatus are provided for sensing the mass flow rate of a fluid flowing through a pipe. A light beam containing plural individual wavelengths is projected from one side of the pipe across the width of the pipe so as to pass through the fluid under test. Fiber optic couplers located at least two positions on the opposite side of the pipe are used to detect the light beam. A determination is then made of the relative strengths of the light beam for each wavelength at the at least two positions and based at least in part on these relative strengths, the mass flow rate of the fluid is determined.

  17. Optical model methods of predicting nuclide production from spallation reactions.

    PubMed

    Ramsey, C R; Townsend, L W; Tripathi, R K; Cucinotta, F A

    1998-02-01

    Quantum mechanical optical model methods for calculating isotope production cross sections from the spallation of heavy nuclei by high-energy protons are developed from a modified abrasion-ablation collision formalism. The abrasion step is treated quantum-mechanically as a knockout process which leaves the residual prefragment nucleus in an excited state. In ablation the prefragment deexcites to produce the final fragment. The excitation energies of the prefragments are estimated from a combination of liquid drop and frictional-spectator interaction considerations. Estimates of elemental and isotopic production cross sections are in good agreement with recently published cross section measurements.

  18. Experimental methods of molecular matter-wave optics.

    PubMed

    Juffmann, Thomas; Ulbricht, Hendrik; Arndt, Markus

    2013-08-01

    We describe the state of the art in preparing, manipulating and detecting coherent molecular matter. We focus on experimental methods for handling the quantum motion of compound systems from diatomic molecules to clusters or biomolecules.Molecular quantum optics offers many challenges and innovative prospects: already the combination of two atoms into one molecule takes several well-established methods from atomic physics, such as for instance laser cooling, to their limits. The enormous internal complexity that arises when hundreds or thousands of atoms are bound in a single organic molecule, cluster or nanocrystal provides a richness that can only be tackled by combining methods from atomic physics, chemistry, cluster physics, nanotechnology and the life sciences.We review various molecular beam sources and their suitability for matter-wave experiments. We discuss numerous molecular detection schemes and give an overview over diffraction and interference experiments that have already been performed with molecules or clusters.Applications of de Broglie studies with composite systems range from fundamental tests of physics up to quantum-enhanced metrology in physical chemistry, biophysics and the surface sciences.Nanoparticle quantum optics is a growing field, which will intrigue researchers still for many years to come. This review can, therefore, only be a snapshot of a very dynamical process.

  19. Method for quick thermal tolerancing of optical systems

    NASA Astrophysics Data System (ADS)

    Werschnik, J.; Uhlendorf, K.

    2016-09-01

    Optical systems for lithography (projection lens), inspection (micro-objectives) or laser material processing usually have tight specifications regarding focus and wave-front stability. The same is true regarding the field dependent properties. Especially projection lenses have tight specifications on field curvature, magnification and distortion. Unwanted heating either from internal or external sources lead to undesired changes of the above properties. In this work we show an elegant and fast method to analyze the thermal sensitivity using ZEMAX. The key point of this method is using the thermal changes of the lens data from the multi-configuration editor as starting point for a (standard) tolerance analysis. Knowing the sensitivity we can either define requirements on the environment or use it to systematically improve the thermal behavior of the lens. We demonstrate this method for a typical projection lens for which we optimized the thermal field curvature to a minimum.

  20. Diffuse optical methods for assessing breast cancer chemotherapy

    NASA Astrophysics Data System (ADS)

    Tromberg, Bruce J.

    2014-03-01

    In his talk, "Diffuse Optical Methods for Assessing Breast Cancer Chemotherapy," SPIE Fellow Bruce Tromberg (Beckman Laser Institute and Medical Clinic) describes a method combining frequency domain photon migration, essentially a method of tracking photon motion in tissue, with a NIR spectroscopy technique using 850nm LEDs. The result is a scatter corrected absorption spectra. The technique takes advantage of elevated blood and water levels and decreased lipid levels in the presence of tumors to provide a more accurate mapping of the breast, allowing more effective treatment. Tromberg's team recently completed their first full mapping of the breast and have taken the instrument from a standalone unit to a portable one suitable for travel. In addition to providing feedback to enhance breast cancer treatment, Tromberg expects that this technique will be applicable in treating other forms of cancer as well.

  1. Recurrent methods of the minimization of optical multilayer structures for fiber-optic communication facilities

    NASA Astrophysics Data System (ADS)

    Bagmanov, Valeriy H.; Kostrov, Sergey V.; Sultanov, Albert H.

    2008-12-01

    Optical multilayer selective mirror (OMSM) are widely used in different applications of fiber optic telecommunications. In this paper we represent the solution for synthesis of OMSM for constructing wavelength division multiplexing (WDM) optical filter used in add/drop multiplexers.

  2. Fast integral methods for integrated optical systems simulations: a review

    NASA Astrophysics Data System (ADS)

    Kleemann, Bernd H.

    2015-09-01

    Boundary integral equation methods (BIM) or simply integral methods (IM) in the context of optical design and simulation are rigorous electromagnetic methods solving Helmholtz or Maxwell equations on the boundary (surface or interface of the structures between two materials) for scattering or/and diffraction purposes. This work is mainly restricted to integral methods for diffracting structures such as gratings, kinoforms, diffractive optical elements (DOEs), micro Fresnel lenses, computer generated holograms (CGHs), holographic or digital phase holograms, periodic lithographic structures, and the like. In most cases all of the mentioned structures have dimensions of thousands of wavelengths in diameter. Therefore, the basic methods necessary for the numerical treatment are locally applied electromagnetic grating diffraction algorithms. Interestingly, integral methods belong to the first electromagnetic methods investigated for grating diffraction. The development started in the mid 1960ies for gratings with infinite conductivity and it was mainly due to the good convergence of the integral methods especially for TM polarization. The first integral equation methods (IEM) for finite conductivity were the methods by D. Maystre at Fresnel Institute in Marseille: in 1972/74 for dielectric, and metallic gratings, and later for multiprofile, and other types of gratings and for photonic crystals. Other methods such as differential and modal methods suffered from unstable behaviour and slow convergence compared to BIMs for metallic gratings in TM polarization from the beginning to the mid 1990ies. The first BIM for gratings using a parametrization of the profile was developed at Karl-Weierstrass Institute in Berlin under a contract with Carl Zeiss Jena works in 1984-1986 by A. Pomp, J. Creutziger, and the author. Due to the parametrization, this method was able to deal with any kind of surface grating from the beginning: whether profiles with edges, overhanging non

  3. Turbulence profiling methods applied to ESO's adaptive optics facility

    NASA Astrophysics Data System (ADS)

    Valenzuela, Javier; Béchet, Clémentine; Garcia-Rissmann, Aurea; Gonté, Frédéric; Kolb, Johann; Le Louarn, Miska; Neichel, Benoît; Madec, Pierre-Yves; Guesalaga, Andrés.

    2014-07-01

    Two algorithms were recently studied for C2n profiling from wide-field Adaptive Optics (AO) measurements on GeMS (Gemini Multi-Conjugate AO system). They both rely on the Slope Detection and Ranging (SLODAR) approach, using spatial covariances of the measurements issued from various wavefront sensors. The first algorithm estimates the C2n profile by applying the truncated least-squares inverse of a matrix modeling the response of slopes covariances to various turbulent layer heights. In the second method, the profile is estimated by deconvolution of these spatial cross-covariances of slopes. We compare these methods in the new configuration of ESO Adaptive Optics Facility (AOF), a high-order multiple laser system under integration. For this, we use measurements simulated by the AO cluster of ESO. The impact of the measurement noise and of the outer scale of the atmospheric turbulence is analyzed. The important influence of the outer scale on the results leads to the development of a new step for outer scale fitting included in each algorithm. This increases the reliability and robustness of the turbulence strength and profile estimations.

  4. Recent developments in optical detection methods for microchip separations.

    PubMed

    Götz, Sebastian; Karst, Uwe

    2007-01-01

    This paper summarizes the features and performances of optical detection systems currently applied in order to monitor separations on microchip devices. Fluorescence detection, which delivers very high sensitivity and selectivity, is still the most widely applied method of detection. Instruments utilizing laser-induced fluorescence (LIF) and lamp-based fluorescence along with recent applications of light-emitting diodes (LED) as excitation sources are also covered in this paper. Since chemiluminescence detection can be achieved using extremely simple devices which no longer require light sources and optical components for focusing and collimation, interesting approaches based on this technique are presented, too. Although UV/vis absorbance is a detection method that is commonly used in standard desktop electrophoresis and liquid chromatography instruments, it has not yet reached the same level of popularity for microchip applications. Current applications of UV/vis absorbance detection to microchip separations and innovative approaches that increase sensitivity are described. This article, which contains 85 references, focuses on developments and applications published within the last three years, points out exciting new approaches, and provides future perspectives on this field.

  5. Reliable chromatic dispersion measurement method for installed optical fibers.

    PubMed

    Zong, Liangjia

    2015-09-10

    We propose and experimentally demonstrate a reliable chromatic dispersion measurement method for installed optical fibers. This technique is based on a modified Sagnac interferometer which is polarization-independent, hence no polarization controller device is needed to control the polarization state of the light entering into the interferometer during measurement. In our proposed system, the polarization mode dispersion (PMD) of the test fiber is compensated by employing a Faraday rotator mirror at one end of the fiber, so that the measured dispersion results will not be affected by any external perturbations on the test fiber. In addition, our method is single-ended, rapid (<1  s), and accurate. Experimental results show the differences for dispersion and dispersion slope of only 0.17% and 1.24%, respectively, compared with that of a commercial instrument. All characteristics indicate that our approach is indeed suitable for in-field dispersion measurement of installed fibers.

  6. System and method for optically locating microchannel positions

    SciTech Connect

    Brewer, Laurence R.; Kimbrough, Joseph; Balch, Joseph; Davidson, J. Courtney

    2001-01-01

    A system and method is disclosed for optically locating a microchannel position. A laser source generates a primary laser beam which is directed at a microchannel plate. The microchannel plates include microchannels at various locations. A back-reflectance beam detector receives a back-reflected beam from the plate. The back-reflected beam is generated when the primary beam reflects off of the plate. A photodiode circuit generates a trigger signal when the back-reflected beam exceeds a predetermined threshold, indicating a presence of the microchannel. The method of the present invention includes the steps of generating a primary beam, directing the primary beam to a plate containing a microchannel, receiving from the plate a back-reflected beam generated in response to the primary beam, and generating a trigger signal when the back-reflected beam exceeds a predetermined threshold which corresponds to a presence of the microchannel.

  7. Spectroscopic Methods for Label-Free Optical Nanoscopy

    NASA Astrophysics Data System (ADS)

    Chandler, John E.

    It is becoming increasingly evident that the nanoscale organization and structure of macromolecules play a significant role in determining the function and properties of biological systems. To understand the relationships between biological structure and function at nanometer length scales, there is a need for methods which enable imaging of intact nanoscale biological structure. An ideal technique for these applications is sensitive to nanoscale structure below the resolution limit of conventional optical microscopy ( 200 nm), achieves label-free contrast, is non-perturbing to biological samples, is quantitative, is capable of molecular specificity, is high-throughput, and finally is simple, enabling widespread utilization. Existing techniques meet some of these criteria, but all have limitations. For example, super-resolution optical microscopy methods achieve molecular-specific nanoscale resolution well below the resolution limit of conventional optical microscopes, however, they rely on fluorescent labels often at high densities that can be toxic and can often require potentially damaging illumination intensities for imaging. As a result, there remains a need for label-free optical techniques to study the nanoscale structural properties of cells. To address this need, the development of instrumentation and algorithms for Partial Wave Spectroscopic (PWS) microscopy will be described. PWS is a spectroscopic, label-free, nanoscale sensitive microscope which, senses rather than resolves structure below the resolution limit of conventional microscopes ( 200nm). First, PWS has shown utility as a diagnostic screening tool for cancer due to nanoscale structural alterations that occur in cells as part of the earliest stages of carcinogenesis. Instrumentation and algorithms developed to enable high-throughput cancer screening applications will be described. Further enhancement of data acquisition and analysis speed will then be described through the development of new

  8. Method and apparatus for optical phase error correction

    DOEpatents

    DeRose, Christopher; Bender, Daniel A.

    2014-09-02

    The phase value of a phase-sensitive optical device, which includes an optical transport region, is modified by laser processing. At least a portion of the optical transport region is exposed to a laser beam such that the phase value is changed from a first phase value to a second phase value, where the second phase value is different from the first phase value. The portion of the optical transport region that is exposed to the laser beam can be a surface of the optical transport region or a portion of the volume of the optical transport region. In an embodiment of the invention, the phase value of the optical device is corrected by laser processing. At least a portion of the optical transport region is exposed to a laser beam until the phase value of the optical device is within a specified tolerance of a target phase value.

  9. Human psychophysiological activity monitoring methods using fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Zyczkowski, M.; Uzieblo-Zyczkowska, B.

    2010-10-01

    The paper presents the concept of fiber optic sensor system for human psycho-physical activity detection. A fiber optic sensor that utilizes optical phase interferometry or intensity in modalmetric to monitor a patient's vital signs such as respiration cardiac activity, blood pressure and body's physical movements. The sensor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that time varying acusto-mechanical signals from the patient are coupled into the optical fiber. The system can be implemented in embodiments ranging form a low cost in-home to a high end product for in hospital use.

  10. Analysis of a digital microstrip optical switch: a novel method.

    PubMed

    Al-Ruwaihi, K M; Hindy, M A

    1997-02-20

    A time domain analysis of an optically controlled digital microstrip switch for microwave integrated circuits on Si substrates is studied. A new model for high-frequency pulse propagation on a microstrip optical switch for different optical parameters is presented. A frequency-dependent macromodel for a microstrip line with a gap is implemented in Spice 3, taking into consideration high-frequency pulse dispersion, conductor and dielectric losses, metallization thickness, gap length, and different optical parameters such as optical energy, surface recombination velocities, and diffusion of generated carriers. In addition, the developed model has been used to optimize the switching frequency, gap length, level of optical power, and suitable substrate material parameters.

  11. Method of making and structure for monolithic optical circuits

    NASA Technical Reports Server (NTRS)

    Evanchuk, Vincent L. (Inventor)

    1983-01-01

    A method for making monolithic optical circuits, with related optical devices as required or desired, on a supporting surface (10) consists of coating the supporting surface with reflecting metal or cladding resin, spreading a layer of liquid radiation senstivie plastic (12) on the surface, exposing the liquid plastic with a mask (14) to cure it in a desired pattern of light conductors (16, 18, 20), washing away the unexposed liquid plastic, and coating the conductors thus formed with reflective metal or cladding resin. The index of refraction for the cladding (22) is selected to be lower than for the conductors so that light in the conductors will be reflected by the interface with the cladding. For multiple level conductors, as where one conductor must cross over another, the process may be repeated to fabricate a bridge with columns (24, 26) of conductors to the next level, and conductor (28) between the columns. For more efficient transfer of energy over the bridge, faces at 45.degree. may be formed to reflect light up and across the bridge.

  12. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOEpatents

    Smirl, Arthur; Trebino, Rick P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques.

  13. Method of forming a sharp edge on an optical device

    NASA Technical Reports Server (NTRS)

    Fleetwood, C. M.; Rice, S. H.

    1980-01-01

    A sharp edge is formed on an optical device by placing the optical device in a holding mechanism; grinding one surface so that it and a surface of the holding mechanism are co-planar; and polishing both the surface of the optical device and the surface of the holding mechanism with felt until an edge on the surface of the optical device adjacent to the surface of the holding mechanism obtains a desired sharpness.

  14. Optical Spatial integration methods for ambiguity function generation

    NASA Technical Reports Server (NTRS)

    Tamura, P. N.; Rebholz, J. J.; Daehlin, O. T.; Lee, T. C.

    1981-01-01

    A coherent optical spatial integration approach to ambiguity function generation is described. It uses one dimensional acousto-optic Bragg cells as input tranducers in conjunction with a space variant linear phase shifter, a passive optical element, to generate the two dimensional ambiguity function in one exposure. Results of a real time implementation of this system are shown.

  15. Method for the continuous processing of hermetic fiber optic components and the resultant fiber optic-to-metal components

    DOEpatents

    Kramer, D.P.

    1994-08-09

    Hermetic fiber optic-to-metal components and method for making hermetic fiber optic-to-metal components by assembling and fixturing elements comprising a metal shell, a glass preform, and a metal-coated fiber optic into desired relative positions and then sealing said fixtured elements preferably using a continuous heating process is disclosed. The resultant hermetic fiber optic-to-metal components exhibit high hermeticity and durability despite the large differences in thermal coefficients of expansion among the various elements. 3 figs.

  16. Method and apparatus for two-dimensional absolute optical encoding

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B. (Inventor)

    2004-01-01

    This invention presents a two-dimensional absolute optical encoder and a method for determining position of an object in accordance with information from the encoder. The encoder of the present invention comprises a scale having a pattern being predetermined to indicate an absolute location on the scale, means for illuminating the scale, means for forming an image of the pattern; and detector means for outputting signals derived from the portion of the image of the pattern which lies within a field of view of the detector means, the field of view defining an image reference coordinate system, and analyzing means, receiving the signals from the detector means, for determining the absolute location of the object. There are two types of scale patterns presented in this invention: grid type and starfield type.

  17. Kyropoulos method for growth of nonlinear optical organic crystal ABP (4-aminobenzophenone) from the melt

    NASA Astrophysics Data System (ADS)

    Pan, Shoukui; Okano, Y.; Tsunekawa, S.; Fukuda, T.

    1993-03-01

    The Kyropoulus method was used to grow nonlinear optical organic crystals ABP (4-aminobenzophenone). The crystals were characterized by nonlinear optical measurements and had a large effect of frequency doubling.

  18. Optical geometry calibration method for free-form digital tomosynthesis

    NASA Astrophysics Data System (ADS)

    Chtcheprov, Pavel; Hartman, Allison; Shan, Jing; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

    2016-03-01

    Digital tomosynthesis is a type of limited angle tomography that allows 3D information to be reconstructed from a set of x-ray projection images taken at various angles using an x-ray tube, a mechanical arm to rotate the tube about the object, and a digital detector. Tomosynthesis reconstruction requires the precise location of the detector with respect to each x-ray source, forcing all current clinical tomosynthesis systems to use a physically coupled source and detector so the geometry is always known and is always the same. This limits the imaging geometries and its large size is impractical for mobile or field operations. To counter this, we have developed a free form tomosynthesis with a decoupled, free-moving source and detector that uses a novel optical method for accurate and real-time geometry calibration to allow for manual, hand-held tomosynthesis and even CT imaging. We accomplish this by using a camera, attached to the source, to track the motion of the source relative to the detector. Attached to the detector is an optical pattern and the image captured by the camera is then used to determine the relative camera/pattern position and orientation by analyzing the pattern distortion and calculating the source positions for each projection, necessary for 3D reconstruction. This allows for portable imaging in the field and also as an inexpensive upgrade to existing 2D systems, such as in developing countries, to provide 3D image data. Here we report the first feasibility demonstrations of free form digital tomosynthesis systems using the method.

  19. Methods of making composite optical devices employing polymer liquid crystal

    DOEpatents

    Jacobs, S.D.; Marshall, K.L.; Cerqua, K.A.

    1991-10-08

    Composite optical devices are disclosed using polymer liquid crystal materials both as optical and adhesive elements. The devices are made by assembling a heated polymer liquid crystal compound, while in a low viscosity form between optically transparent substrates. The molecules of the polymer are oriented, while in the liquid crystalline state and while above the glass transition temperature (T[sub g]) of the polymer, to provide the desired optical effects, such as polarization, and selective reflection. The liquid crystal polymer cements the substrates together to form an assembly providing the composite optical device. 7 figures.

  20. Methods of making composite optical devices employing polymer liquid crystal

    DOEpatents

    Jacobs, Stephen D.; Marshall, Kenneth L.; Cerqua, Kathleen A.

    1991-01-01

    Composite optical devices using polymer liquid crystal materials both as optical and adhesive elements. The devices are made by assembling a heated polymer liquid crystal compound, while in a low viscosity form between optically transparent substrates. The molecules of the polymer are oriented, while in the liquid crystalline state and while above the glass transition temperature (T.sub.g) of the polymer, to provide the desired optical effects, such as polarization, and selective reflection. The liquid crystal polymer cements the substrates together to form an assembly providing the composite optical device.

  1. Method And Apparatus For Coupling Optical Elements To Optoelectronic Devices For Manufacturing Optical Transceiver Modules

    DOEpatents

    Anderson, Gene R.; Armendariz, Marcelino G.; Bryan, Robert P.; Carson, Richard F.; Chu, Dahwey; Duckett, III, Edwin B.; Giunta, Rachel Knudsen; Mitchell, Robert T.; McCormick, Frederick B.; Peterson, David W.; Rising, Merideth A.; Reber, Cathleen A.; Reysen, Bill H.

    2005-06-14

    A process is provided for aligning and connecting at least one optical fiber to at least one optoelectronic device so as to couple light between at least one optical fiber and at least one optoelectronic device. One embodiment of this process comprises the following steps: (1) holding at least one optical element close to at least one optoelectronic device, at least one optical element having at least a first end; (2) aligning at least one optical element with at least one optoelectronic device; (3) depositing a first non-opaque material on a first end of at least one optoelectronic device; and (4) bringing the first end of at least one optical element proximate to the first end of at least one optoelectronic device in such a manner that the first non-opaque material contacts the first end of at least one optoelectronic device and the first end of at least one optical element. The optical element may be an optical fiber, and the optoelectronic device may be a vertical cavity surface emitting laser. The first non-opaque material may be a UV optical adhesive that provides an optical path and mechanical stability. In another embodiment of the alignment process, the first end of at least one optical element is brought proximate to the first end of at least one optoelectronic device in such a manner that an interstitial space exists between the first end of at least one optoelectronic device and the first end of at least one optical element.

  2. Integrated resonant micro-optical gyroscope and method of fabrication

    DOEpatents

    Vawter, G. Allen; Zubrzycki, Walter J.; Guo, Junpeng; Sullivan, Charles T.

    2006-09-12

    An integrated optic gyroscope is disclosed which is based on a photonic integrated circuit (PIC) having a bidirectional laser source, a pair of optical waveguide phase modulators and a pair of waveguide photodetectors. The PIC can be connected to a passive ring resonator formed either as a coil of optical fiber or as a coiled optical waveguide. The lasing output from each end of the bidirectional laser source is phase modulated and directed around the passive ring resonator in two counterpropagating directions, with a portion of the lasing output then being detected to determine a rotation rate for the integrated optical gyroscope. The coiled optical waveguide can be formed on a silicon, glass or quartz substrate with a silicon nitride core and a silica cladding, while the PIC includes a plurality of III V compound semiconductor layers including one or more quantum well layers which are disordered in the phase modulators and to form passive optical waveguides.

  3. Study on manufacturing method of optical surface with high precision in angle and surface

    NASA Astrophysics Data System (ADS)

    Yu, Xin; Li, Xin; Yu, Ze; Zhao, Bin; Zhang, Xuebin; Sun, Lipeng; Tong, Yi

    2016-10-01

    This paper studied a manufacturing processing of optical surface with high precision in angel and surface. By theoretical analysis of the relationships between the angel precision and surface, the measurement conversion of the technical indicators, optical-cement method application, the optical-cement tooling design, the experiment has been finished successfully, the processing method has been verified, which can be also used in the manufacturing of the optical surface with similar high precision in angle and surface.

  4. Response Surface Methods for Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatial ly-re solved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/-30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-light, inflatable space antenna at NASA Langley Research Center.

  5. Accurate optical CD profiler based on specialized finite element method

    NASA Astrophysics Data System (ADS)

    Carrero, Jesus; Perçin, Gökhan

    2012-03-01

    As the semiconductor industry is moving to very low-k1 patterning solutions, the metrology problems facing process engineers are becoming much more complex. Choosing the right optical critical dimension (OCD) metrology technique is essential for bridging the metrology gap and achieving the required manufacturing volume throughput. The critical dimension scanning electron microscope (CD-SEM) measurement is usually distorted by the high aspect ratio of the photoresist and hard mask layers. CD-SEM measurements cease to correlate with complex three-dimensional profiles, such as the cases for double patterning and FinFETs, thus necessitating sophisticated, accurate and fast computational methods to bridge the gap. In this work, a suite of computational methods that complement advanced OCD equipment, and enabling them to operate at higher accuracies, are developed. In this article, a novel method for accurately modeling OCD profiles is presented. A finite element formulation in primal form is used to discretize the equations. The implementation uses specialized finite element spaces to solve Maxwell equations in two dimensions.

  6. Optical Calibration Process Developed for Neural-Network-Based Optical Nondestructive Evaluation Method

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2004-01-01

    A completely optical calibration process has been developed at Glenn for calibrating a neural-network-based nondestructive evaluation (NDE) method. The NDE method itself detects very small changes in the characteristic patterns or vibration mode shapes of vibrating structures as discussed in many references. The mode shapes or characteristic patterns are recorded using television or electronic holography and change when a structure experiences, for example, cracking, debonds, or variations in fastener properties. An artificial neural network can be trained to be very sensitive to changes in the mode shapes, but quantifying or calibrating that sensitivity in a consistent, meaningful, and deliverable manner has been challenging. The standard calibration approach has been difficult to implement, where the response to damage of the trained neural network is compared with the responses of vibration-measurement sensors. In particular, the vibration-measurement sensors are intrusive, insufficiently sensitive, and not numerous enough. In response to these difficulties, a completely optical alternative to the standard calibration approach was proposed and tested successfully. Specifically, the vibration mode to be monitored for structural damage was intentionally contaminated with known amounts of another mode, and the response of the trained neural network was measured as a function of the peak-to-peak amplitude of the contaminating mode. The neural network calibration technique essentially uses the vibration mode shapes of the undamaged structure as standards against which the changed mode shapes are compared. The published response of the network can be made nearly independent of the contaminating mode, if enough vibration modes are used to train the net. The sensitivity of the neural network can be adjusted for the environment in which the test is to be conducted. The response of a neural network trained with measured vibration patterns for use on a vibration isolation

  7. Electro-optical and Magneto-optical Sensing Apparatus and Method for Characterizing Free-space Electromagnetic Radiation

    DOEpatents

    Zhang, Xi-Cheng; Riordan, Jenifer Ann; Sun, Feng-Guo

    2000-08-29

    Apparatus and methods for characterizing free-space electromagnetic energy, and in particular, apparatus/method suitable for real-time two-dimensional far-infrared imaging applications are presented. The sensing technique is based on a non-linear coupling between a low-frequency electric (or magnetic) field and a laser beam in an electro-optic (or magnetic-optic) crystal. In addition to a practical counter-propagating sensing technique, a co-linear approach is described which provides longer radiated field-optical beam interaction length, thereby making imaging applications practical.

  8. Method for removing tilt control in adaptive optics systems

    DOEpatents

    Salmon, Joseph Thaddeus

    1998-01-01

    A new adaptive optics system and method of operation, whereby the method removes tilt control, and includes the steps of using a steering mirror to steer a wavefront in the desired direction, for aiming an impinging aberrated light beam in the direction of a deformable mirror. The deformable mirror has its surface deformed selectively by means of a plurality of actuators, and compensates, at least partially, for existing aberrations in the light beam. The light beam is split into an output beam and a sample beam, and the sample beam is sampled using a wavefront sensor. The sampled signals are converted into corresponding electrical signals for driving a controller, which, in turn, drives the deformable mirror in a feedback loop in response to the sampled signals, for compensating for aberrations in the wavefront. To this purpose, a displacement error (gradient) of the wavefront is measured, and adjusted by a modified gain matrix, which satisfies the following equation: G'=(I-X(X.sup.T X).sup.-1 X.sup.T)G(I-A)

  9. Method for removing tilt control in adaptive optics systems

    DOEpatents

    Salmon, J.T.

    1998-04-28

    A new adaptive optics system and method of operation are disclosed, whereby the method removes tilt control, and includes the steps of using a steering mirror to steer a wavefront in the desired direction, for aiming an impinging aberrated light beam in the direction of a deformable mirror. The deformable mirror has its surface deformed selectively by means of a plurality of actuators, and compensates, at least partially, for existing aberrations in the light beam. The light beam is split into an output beam and a sample beam, and the sample beam is sampled using a wavefront sensor. The sampled signals are converted into corresponding electrical signals for driving a controller, which, in turn, drives the deformable mirror in a feedback loop in response to the sampled signals, for compensating for aberrations in the wavefront. To this purpose, a displacement error (gradient) of the wavefront is measured, and adjusted by a modified gain matrix, which satisfies the following equation: G{prime} = (I{minus}X(X{sup T} X){sup {minus}1}X{sup T})G(I{minus}A). 3 figs.

  10. Generalized spectral method for near-field optical microscopy

    SciTech Connect

    Jiang, B.-Y.; Zhang, L. M.; Basov, D. N.; Fogler, M. M.; Castro Neto, A. H.

    2016-02-07

    Electromagnetic interaction between a sub-wavelength particle (the “probe”) and a material surface (the “sample”) is studied theoretically. The interaction is shown to be governed by a series of resonances corresponding to surface polariton modes localized near the probe. The resonance parameters depend on the dielectric function and geometry of the probe as well as on the surface reflectivity of the material. Calculation of such resonances is carried out for several types of axisymmetric probes: spherical, spheroidal, and pear-shaped. For spheroids, an efficient numerical method is developed, capable of handling cases of large or strongly momentum-dependent surface reflectivity. Application of the method to highly resonant materials, such as aluminum oxide (by itself or covered with graphene), reveals a rich structure of multi-peak spectra and nonmonotonic approach curves, i.e., the probe-sample distance dependence. These features also strongly depend on the probe shape and optical constants of the model. For less resonant materials such as silicon oxide, the dependence is weak, so that the spheroidal model is reliable. The calculations are done within the quasistatic approximation with radiative damping included perturbatively.

  11. Generalized spectral method for near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Jiang, B.-Y.; Zhang, L. M.; Castro Neto, A. H.; Basov, D. N.; Fogler, M. M.

    2016-02-01

    Electromagnetic interaction between a sub-wavelength particle (the "probe") and a material surface (the "sample") is studied theoretically. The interaction is shown to be governed by a series of resonances corresponding to surface polariton modes localized near the probe. The resonance parameters depend on the dielectric function and geometry of the probe as well as on the surface reflectivity of the material. Calculation of such resonances is carried out for several types of axisymmetric probes: spherical, spheroidal, and pear-shaped. For spheroids, an efficient numerical method is developed, capable of handling cases of large or strongly momentum-dependent surface reflectivity. Application of the method to highly resonant materials, such as aluminum oxide (by itself or covered with graphene), reveals a rich structure of multi-peak spectra and nonmonotonic approach curves, i.e., the probe-sample distance dependence. These features also strongly depend on the probe shape and optical constants of the model. For less resonant materials such as silicon oxide, the dependence is weak, so that the spheroidal model is reliable. The calculations are done within the quasistatic approximation with radiative damping included perturbatively.

  12. Fiber optics interface for a dye laser oscillator and method

    DOEpatents

    Johnson, S.A.; Seppala, L.G.

    1984-06-13

    A dye laser oscillator in which one light beam is used to pump a continuous stream of dye within a cooperating dye chamber for producing a second, different beam is generally disclosed herein along with a specific arrangement including an optical fiber and a fiber optics interface for directing the pumping beam into the dye chamber. The specific fiber optics interface illustrated includes three cooperating lenses which together image one particular dimension of the pumping beam into the dye chamber from the output end of the optical fiber in order to insure that the dye chamber is properly illuminated by the pumping beam.

  13. Fiber optics interface for a dye laser oscillator and method

    DOEpatents

    Johnson, Steve A.; Seppala, Lynn G.

    1986-01-01

    A dye laser oscillator in which one light beam is used to pump a continuous tream of dye within a cooperating dye chamber for producing a second, different beam is generally disclosed herein along with a specific arrangement including an optical fiber and a fiber optics interface for directing the pumping beam into the dye chamber. The specific fiber optics interface illustrated includes three cooperating lenses which together image one particular dimension of the pumping beam into the dye chamber from the output end of the optical fiber in order to insure that the dye chamber is properly illuminated by the pumping beam.

  14. Method and device for remotely monitoring an area using a low peak power optical pump

    DOEpatents

    Woodruff, Steven D.; Mcintyre, Dustin L.; Jain, Jinesh C.

    2014-07-22

    A method and device for remotely monitoring an area using a low peak power optical pump comprising one or more pumping sources, one or more lasers; and an optical response analyzer. Each pumping source creates a pumping energy. The lasers each comprise a high reflectivity mirror, a laser media, an output coupler, and an output lens. Each laser media is made of a material that emits a lasing power when exposed to pumping energy. Each laser media is optically connected to and positioned between a corresponding high reflectivity mirror and output coupler along a pumping axis. Each output coupler is optically connected to a corresponding output lens along the pumping axis. The high reflectivity mirror of each laser is optically connected to an optical pumping source from the one or more optical pumping sources via an optical connection comprising one or more first optical fibers.

  15. Simple in-line method to measure the dispersion of an optical system

    NASA Technical Reports Server (NTRS)

    Yao, X. S.; Feinberg, Jack

    1993-01-01

    We describe a simple in-line method to measure the dispersion of an optical system. The light beam passing through the optical system interferes with a reference beam in a spectrometer, and the resulting spectrum yields the quadratic and cubic dispersion terms of the system. We demonstrate this technique on an optical system made of grating pairs.

  16. Methods of biomedical optical imaging: from subcellular structures to tissues and organs

    NASA Astrophysics Data System (ADS)

    Turchin, I. V.

    2016-05-01

    Optical bioimaging methods have a wide range of applications in the life sciences, most notably including the molecular resolution study of subcellular structures, small animal molecular imaging, and structural and functional clinical diagnostics of tissue layers and organs. We review fluorescent microscopy, fluorescent macroscopy, optical coherence tomography, optoacoustic tomography, and optical diffuse spectroscopy and tomography from the standpoint of physical fundamentals, applications, and progress.

  17. Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

  18. A Simple Optical Coherence Tomography Quantification Method for Choroidal Neovascularization

    PubMed Central

    Sulaiman, Rania S.; Quigley, Judith; Qi, Xiaoping; O'Hare, Michael N.; Grant, Maria B.; Boulton, Michael E.

    2015-01-01

    Abstract Purpose: Therapeutic efficacy is routinely assessed by measurement of lesion size using flatmounted choroids and confocal microscopy in the laser-induced choroidal neovascularization (L-CNV) rodent model. We investigated whether optical coherence tomography (OCT) quantification, using an ellipsoid volume measurement, was comparable to standard ex vivo evaluation methods for this model and whether this approach could be used to monitor treatment-related lesion changes. Methods: Bruch's membrane was ruptured by argon laser in the dilated eyes of C57BL/6J mice, followed by intravitreal injections of anti-VEGF164 or vehicle, or no injection. In vivo OCT images were acquired using Micron III or InVivoVue systems at 7, 10, and/or 14 days post-laser and neovascular lesion volume was calculated as an ellipsoid. Subsequently, lesion volume was compared to that calculated from confocal Z-stack images of agglutinin-stained choroidal flatmounts. Results: Ellipsoid volume measurement of orthogonal 2-dimensional OCT images obtained from different imaging systems correlated with ex vivo lesion volumes for L-CNV (Spearman's ρ=0.82, 0.75, and 0.82 at days 7, 10, and 14, respectively). Ellipsoid volume calculation allowed temporal monitoring and evaluation of CNV lesions in response to antivascular endothelial growth factor treatment. Conclusions: Ellipsoid volume measurements allow rapid, quantitative use of OCT for the assessment of CNV lesions in vivo. This novel method can be used with different OCT imaging systems with sensitivity to distinguish between treatment conditions. It may serve as a useful adjunct to the standard ex vivo confocal quantification, to assess therapeutic efficacy in preclinical models of CNV, and in models of other ocular diseases. PMID:26060878

  19. Universal method for constructing N-port non-blocking optical router based on 2 × 2 optical switch for photonic networks-on-chip.

    PubMed

    Chen, Qiaoshan; Zhang, Fanfan; Ji, Ruiqiang; Zhang, Lei; Yang, Lin

    2014-05-19

    We propose a universal method for constructing N-port non-blocking optical router for photonic networks-on-chip, in which all microring (MR) optical switches or Mach-Zehnder (M-Z) optical switches behave as 2 × 2 optical switches. The optical router constructed by the proposed method has minimum optical switches, in which the number of the optical switches is reduced about 50% compared to the reported optical routers based on MR optical switches and more than 30% compared to the reported optical routers based on M-Z optical switches, and therefore is more compact in footprint and more power-efficient. We also present a strict mathematical proof of the non-blocking routing of the proposed N-port optical router.

  20. 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...

  1. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    DOEpatents

    Smirl, A.; Trebino, R.P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques. 2 figs.

  2. Analytical theory and method for longitudinal magneto-optical Kerr effect of optically anisotropic magnetic film

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Lian, Jie; Li, Ping; Xu, XiJin; Li, MengMeng

    2017-01-01

    The Fresnel equations are solved to analyze the reflection and propagation properties of the ordinary and extraordinary light of the optically anisotropic magnetic film. Using the boundary and propagation matrix, the longitudinal magneto-optical Kerr rotation expression is derived. After that, simulations are performed on optically anisotropic and isotropic Co/SiO2 film. Results show that for Co material in the thin-film limit, the anisotropic Co can provide larger max rotations than the isotropic Co in the visible region. This is because that the refractive index discrepancy of optically anisotropic Co film reduces the Fresnel reflective coefficient rpp, which improves the Kerr rotation. This makes the optically anisotropic Co film more effective in magneto optical sensor design and device fabrication.

  3. Evaluating optical aberrations using fluorescent microspheres: methods, analysis, and corrective actions.

    PubMed

    Goodwin, Paul C

    2013-01-01

    Obtaining optimal performance from a microscopy system requires careful evaluation of the entire optics train of the imaging system. This evaluation starts with a fundamental evaluation of the optical components in the microscope. Concise and visual methods are provided for understanding the optical performance of the microscope as a system using subdiffraction fluorescent microspheres to evaluate both monochromatic and polychromatic aberrations. Further practical guides are given to troubleshooting optical problems and final comments are made on optimizing sample preparation.

  4. Modern methods of production of large-sized multicomponent optical systems

    NASA Astrophysics Data System (ADS)

    Galyavov, Igor R.; Belousov, Sergey P.; Ignatov, Aleksandr N.; Ponin, Oleg V.; Sharov, Aleksandr A.; Domnin, Aleksandr V.

    2016-10-01

    The article describes the technology of production of large-sized multicomponent optical systems of different function. All stages of a production cycle are considered: assembly of separate units of optical components, including aspherical and off-axis mirrors; preliminary assembly and adjustment of all system; final adjustment of optical system. Modern computer-controlled methods of testings and adjustment of multicomponent optical systems, using the examples of production of such systems at JSC LZOS, are described.

  5. Optical method for determining the mechanical properties of a material

    DOEpatents

    Maris, H.J.; Stoner, R.J.

    1998-12-01

    Disclosed is a method for characterizing a sample, comprising the steps of: (a) acquiring data from the sample using at least one probe beam wavelength to measure, for times less than a few nanoseconds, a change in the reflectivity of the sample induced by a pump beam; (b) analyzing the data to determine at least one material property by comparing a background signal component of the data with data obtained for a similar delay time range from one or more samples prepared under conditions known to give rise to certain physical and chemical material properties; and (c) analyzing a component of the measured time dependent reflectivity caused by ultrasonic waves generated by the pump beam using the at least one determined material property. The first step of analyzing may include a step of interpolating between reference samples to obtain an intermediate set of material properties. The material properties may include sound velocity, density, and optical constants. In one embodiment, only a correlation is made with the background signal, and at least one of the structural phase, grain orientation, and stoichiometry is determined. 14 figs.

  6. Fiber optic assembly and method of making same

    DOEpatents

    Kramer, Daniel P.; Beckman, Thomas M.

    1997-09-02

    There is provided an assembly having a light guiding medium sealed to a her. Preferably the holder is a metal shell and a light guiding medium is an optical fiber of glass or sapphire whisker. The assembly includes a sealing medium which sealingly engages the metal holder to the fiber. In the formation of the assembly, the seal is essentially hermetic having a capability of minimizing leakage having a helium leak rate of less than 1.times.10.sup.-8 cubic centimeters per second and high strength having a capability of withstanding pressures of 100,000 psi or greater. The features of the assembly are obtained by a specific preparation method and by selection of specific starting materials. The fiber is selected to have a sufficiently high coefficient of thermal expansion which minimizes strains in the component during fabrication, as a result of fabrication, and during use. The other components are selected to be of a material having compatible coefficients of thermal expansion (TEC) where the TEC of the holder is greater than or equal to the TEC of the sealing material. The TEC of the sealing material is in turn greater than or equal to the TEC of the fiber. It is preferred that the materials be selected so that their respective coefficients of thermal expansion are as close as possible to one another and they may all be equal.

  7. Determination of petrophysical properties of sedimentary rocks by optical methods

    NASA Astrophysics Data System (ADS)

    Korte, D.; Kaukler, D.; Fanetti, M.; Cabrera, H.; Daubront, E.; Franko, M.

    2017-04-01

    Petrophysical properties of rocks (thermal diffusivity and conductivity, porosity and density) as well as the correlation between them are of great importance for many geoscientific applications. The porosity of the reservoir rocks and their permeability are the most fundamental physical properties with respect to the storage and transmission of fluids, mainly oil characterization. Accurate knowledge of these parameters for any hydrocarbon reservoir is required for efficient development, management, and prediction of future performance of the oilfield. Thus, the porosity and permeability, as well as the chemical composition must be quantified as precisely as possible. This should be done along with the thermal properties, density, conductivity, diffusivity and effusivity that are intimately related with them. For this reason, photothermal Beam Deflection Spectrometry (BDS) technique for determination of materials' thermal properties together with other methods such as Energy Dispersive X-ray Scanning Electron Microscopy (SEM-EDX) for determining the chemical composition and sample structure, as well as optical microscopy to determine the particles size, were applied for characterization of sedimentary rocks. The rocks were obtained from the Andes south flank in the Venezuela's western basin. The validation of BDS applicability for determination of petrophysical properties of three sedimentary rocks of different texture and composition (all from Late Cretaceous associated with the Luna, Capacho and Colón-Mito Juan geological formations) was performed. The rocks' thermal properties were correlated to the microstructures and chemical composition of the examined samples.

  8. Flexible multi-dimensional modulation method for elastic optical networks

    NASA Astrophysics Data System (ADS)

    He, Zilong; Liu, Wentao; Shi, Sheping; Shen, Bailin; Chen, Xue; Gao, Xiqing; Zhang, Qi; Shang, Dongdong; Ji, Yongning; Liu, Yingfeng

    2016-01-01

    We demonstrate a flexible multi-dimensional modulation method for elastic optical networks. We compare the flexible multi-dimensional modulation formats PM-kSC-mQAM with traditional modulation formats PM-mQAM using numerical simulations in back-to-back and wavelength division multiplexed (WDM) transmission (50 GHz-spaced) scenarios at the same symbol rate of 32 Gbaud. The simulation results show that PM-kSC-QPSK and PM-kSC-16QAM can achieve obvious back-to-back sensitivity gain with respect to PM-QPSK and PM-16QAM at the expense of spectral efficiency reduction. And the WDM transmission simulation results show that PM-2SC-QPSK can achieve 57.5% increase in transmission reach compared to PM-QPSK, and 48.5% increase for PM-2SC-16QAM over PM-16QAM. Furthermore, we also experimentally investigate the back to back performance of PM-2SC-QPSK, PM-4SC-QPSK, PM-2SC-16QAM and PM-3SC-16QAM, and the experimental results agree well with the numerical simulations.

  9. Optical method for determining the mechanical properties of a material

    DOEpatents

    Maris, Humphrey J.; Stoner, Robert J.

    1998-01-01

    Disclosed is a method for characterizing a sample, comprising the steps of: (a) acquiring data from the sample using at least one probe beam wavelength to measure, for times less than a few nanoseconds, a change in the reflectivity of the sample induced by a pump beam; (b) analyzing the data to determine at least one material property by comparing a background signal component of the data with data obtained for a similar delay time range from one or more samples prepared under conditions known to give rise to certain physical and chemical material properties; and (c) analyzing a component of the measured time dependent reflectivity caused by ultrasonic waves generated by the pump beam using the at least one determined material property. The first step of analyzing may include a step of interpolating between reference samples to obtain an intermediate set of material properties. The material properties may include sound velocity, density, and optical constants. In one embodiment, only a correlation is made with the background signal, and at least one of the structural phase, grain orientation, and stoichiometry is determined.

  10. Fiber optic assembly and method of making same

    DOEpatents

    Kramer, D.P.; Beckman, T.M.

    1997-09-02

    There is provided an assembly having a light guiding medium sealed to a holder. Preferably the holder is a metal shell and a light guiding medium is an optical fiber of glass or sapphire whisker. The assembly includes a sealing medium which sealingly engages the metal holder to the fiber. In the formation of the assembly, the seal is essentially hermetic having a capability of minimizing leakage having a helium leak rate of less than 1{times}10{sup {minus}8} cubic centimeters per second and high strength having a capability of withstanding pressures of 100,000 psi or greater. The features of the assembly are obtained by a specific preparation method and by selection of specific starting materials. The fiber is selected to have a sufficiently high coefficient of thermal expansion which minimizes strains in the component during fabrication, as a result of fabrication, and during use. The other components are selected to be of a material having compatible coefficients of thermal expansion (TEC) where the TEC of the holder is greater than or equal to the TEC of the sealing material. The TEC of the sealing material is in turn greater than or equal to the TEC of the fiber. It is preferred that the materials be selected so that their respective coefficients of thermal expansion are as close as possible to one another and they may all be equal. 4 figs.

  11. An Optical Streaking Method for Measuring Femtosecond Electron Bunches

    SciTech Connect

    Ding, Yuantao; Bane, Karl L.F.; Huang, Zhirong; /SLAC

    2011-12-14

    The measurement of the ultra-short electron bunch length on the femtosecond time scale constitutes a very challenging problem. In the x-ray free electron laser facilities such as the Linac Coherent Light Source, generation of a sub-ten femtoseconds electron beam with 20pC charge is possible, but direct measurements are very difficult due to the resolution limit of the present diagnostics. We propose a new method here based on the measurement of the electron beam energy modulation induced from laser-electron interaction in a short wiggler. A typical optical streaking method requires a laser wavelength much longer than the electron bunch length. In this paper a laser with its wavelength shorter than the electron bunch length has been adopted, while the slope on the laser intensity envelope is used to distinguish the different periods. With this technique it is possible to reconstruct the bunch longitudinal profile from a single shot measurement. Generation of ultrashort x-ray pulses at femtoseconds (fs) scale is of great interest within synchrotron radiation and free electron laser (FEL) user community. One of the simple methods is to operate the FEL facility at low charge. At the Linac Coherent Light Source (LCLS), we have demonstrated the capability of generating ultrashort electron-beam (e-beam) with a duration of less than 10 fs fwhm using 20 pC charge. The x-ray pulses have been delivered to the x-ray users with a similar or even shorter pulse duration. However, The measurement of such short electron or x-ray pulse length at the fs time-scale constitutes a challenging problem. A standard method using an S-band radio-frequency (rf) transverse deflector has been established at LCLS, which works like a streak camera for electrons and is capable of resolving bunch lengths as short as 25 fs fwhm. With this device, the electrons are transversely deflected by the high-frequency time-variation of the deflecting fields. Increasing the deflecting voltage and rf frequency

  12. A method to determine the number of nanoparticles in a cluster using conventional optical microscopes

    SciTech Connect

    Kang, Hyeonggon; Attota, Ravikiran Tondare, Vipin; Vladár, András E.; Kavuri, Premsagar

    2015-09-07

    We present a method that uses conventional optical microscopes to determine the number of nanoparticles in a cluster, which is typically not possible using traditional image-based optical methods due to the diffraction limit. The method, called through-focus scanning optical microscopy (TSOM), uses a series of optical images taken at varying focus levels to achieve this. The optical images cannot directly resolve the individual nanoparticles, but contain information related to the number of particles. The TSOM method makes use of this information to determine the number of nanoparticles in a cluster. Initial good agreement between the simulations and the measurements is also presented. The TSOM method can be applied to fluorescent and non-fluorescent as well as metallic and non-metallic nano-scale materials, including soft materials, making it attractive for tag-less, high-speed, optical analysis of nanoparticles down to 45 nm diameter.

  13. A novel method of developing all-optical frequency encoded memory unit exploiting nonlinear switching character of semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Kumar Garai, Sisir; Mukhopadhyay, Sourangshu

    2010-10-01

    The very fast running optical memory and optical logic gates are the basic building blocks for any optical computing data processing system. Realization of a very fast memory-cell in the optical domain is very challenging. In the last two decades many methods of implementing all-optical flip-flops have been proposed. Most of these suffer from speed limitation because of low switching response of the active devices. In our present communication the authors propose a method of developing a frequency encoded memory unit based on the switching action of semiconductor optical amplifier (SOA). Nonlinear polarization rotation characters of SOA and 'SOA based Mach-Zehnder Interferometer' switch, i.e. 'SOA-MZI' switch, are exploited for the purpose of some switching action with least switching power (<-3 dB m) and high switching contrast ratio (20 dB). Here two logic states ('0' state and '1' state) of the memory is encoded by two different frequencies, which will remain unchanged throughout the data communication irrespective of loss of light energy due to reflection, refraction, attenuation, etc. Though the SOA based switch runs with the operational speed 100 Gb/s, still due to the presence of the other optical components in the memory unit, the overall speed of the proposed system will come down to 10 Gb/s.

  14. System and method for reproducibly mounting an optical element

    DOEpatents

    Eisenbies, Stephen; Haney, Steven

    2005-05-31

    The present invention provides a two-piece apparatus for holding and aligning the MEMS deformable mirror. The two-piece apparatus comprises a holding plate for fixedly holding an adaptive optics element in an overall optical system and a base spatially fixed with respect to the optical system and adapted for mounting and containing the holding plate. The invention further relates to a means for configuring the holding plate through adjustments to each of a number of off-set pads touching each of three orthogonal plane surfaces on the base, wherein through the adjustments the orientation of the holding plate, and the adaptive optics element attached thereto, can be aligned with respect to the optical system with six degrees of freedom when aligning the plane surface of the optical element. The mounting system thus described also enables an operator to repeatedly remove and restore the adaptive element in the optical system without the need to realign the system once that element has been aligned.

  15. Combined application of optical methods to increase the information content of optical coherent tomography in diagnostics of neoplastic processes

    SciTech Connect

    Kuranov, R V; Sapozhnikova, V V; Shakhova, N M; Gelikonov, V M; Zagainova, E V; Petrova, S A

    2002-11-30

    A combined application of optical methods [optical coherent tomography (OCT), cross-polarisation optical coherent tomography, and fluorescence spectroscopy] is proposed for obtaining information on morphological and biochemical changes occurring in tissues in norm and pathology. It is shown that neoplastic and scar changes in esophagus can be distinguished using a combination of polarisation and standard OCT due to the difference between the depolarising properties of the tissues caused by the structural properties of collagenic fibres in stroma. It is shown that OCT combined with fluorescence spectroscopy with the use of 5-aminolevulinic acid is promising for determining the boundaries of carcinoma of the uterine cervix and vulva. It is found that the tumour boundary detected by optical methods coincides with the morphological boundary and extends beyond colposcopically determined boundary by about 2 mm. (laser biology and medicine)

  16. All-optical flip-flop and control methods thereof

    DOEpatents

    Maywar, Drew; Agrawal, Govind P.

    2010-03-23

    Embodiments of the invention pertain to remote optical control of holding beam-type, optical flip-flop devices, as well as to the devices themselves. All-optical SET and RE-SET control signals operate on a cw holding beam in a remote manner to vary the power of the holding beam between threshold switching values to enable flip-flop operation. Cross-gain modulation and cross-polarization modulation processes can be used to change the power of the holding beam.

  17. Probing high quality pentacene monolayers by optical methods

    NASA Astrophysics Data System (ADS)

    He, Rui; Tassi, Nancy G.; Blanchet, Graciela B.; Pinczuk, Aron

    2006-05-01

    We report optical studies of pentacene monolayers grown on poly-alpha-methyl-styrene (PAMS) substrates of high uniformity that reaches into the micron length-scale in the lateral dimension. Raman scattering intensities from a two-monolayer pentacene film exhibit large resonance enhancements when incoming and outgoing photon energies overlap the free exciton measured in optical emission. The incoming and outgoing resonance enhancements are of about the same strength. The free exciton optical emission band is sharp and intense, and it blue-shifts by about 85 meV from that of the pentacene single crystal.

  18. Analytical study of acousto/optical holography-interfacing methods for acoustical and optical holography NDT research

    NASA Technical Reports Server (NTRS)

    El-Sum, H. M. A.

    1976-01-01

    The international status of the art of acousto optical imaging techniques adaptable to nondestructive testing and, interfacing methods for acoustical and optical holography in nondestructive testing research are studied. Evaluation of 20 different techniques encompassed investigation of varieties of detectors and detection schemes, all of which are described and summarized. Related investigation is reported in an Appendix. Important remarks on image quality, factors to be considered in designing a particular system, and conclusions and recommendations are presented. Three bibliographies are included.

  19. Method and apparatus for optical communication by frequency modulation

    DOEpatents

    Priatko, Gordon J.

    1988-01-01

    Laser optical communication according to this invention is carried out by producing multi-frequency laser beams having different frequencies, splitting one or more of these constituent beams into reference and signal beams, encoding information on the signal beams by frequency modulation and detecting the encoded information by heterodyne techniques. Much more information can be transmitted over optical paths according to the present invention than with the use of only one path as done previously.

  20. Adhesive Bubble Removal Method and Apparatus for Fiber Optic Applications

    NASA Technical Reports Server (NTRS)

    Kolasinski, John R. (Inventor)

    2001-01-01

    An assembly for supporting a fiber optic termination or connector in a centrifuge and comprising a cylindrical body member having a top portion adapted to receive the ferrule body portion of a fiber optic termination or connector and a bottom portion for receiving a cylindrical piston/sealing unit is presented. The piston portion of the piston/sealing unit includes a compressible tip which is adapted to a butt up against the outer end of the ferrule body portion of the fiber optic termination or connector. A cylindrical end cap fits over the upper end of the body member for holding the fiber optic termination in place on the body member and causing a seal to be formed between the termination or connector and the upper portion of the body member adjacent the compressible tip of the plunger. The parts, when fitted together, are placed in a centrifuge which is operated for a predetermined spin cycle, so as to cause any bubbles in the uncured liquid adhesive to be vented outwardly from the termination through the end cap. Subsequent removal of the fiber optic termination or connector from the centrifuge and assembly is "bubble free" and ready to be joined with an optical fiber which is inserted in the ferrule end of the termination or connector.

  1. Fiber optic transmission line stabilization apparatus and method

    NASA Technical Reports Server (NTRS)

    Lutes, G. F., Jr.; Lau, K. Y. (Inventor)

    1981-01-01

    A reference signal of RF frequency modulates a 0.85 micrometer wavelength optical transmitter. The output of which passes through a first optical filter and a voltage-controller phase shifter. The output of the phase shifter is provided to the fiber optic transmission line. At the receiving end of the transmission line, the signal is demodulated and used to modulate a 1.06 micrometer optical transmitter. The signal from the transmitter is provided to the fiber optic transmission line and passes through the voltage-controlled phase shifter to a phase error detector. The phase of the modulation of the 1.06 micrometer wavelength signal is compared to the phase of the reference signal by the phase error detector. A phase control signal related to the phase difference is provided to the voltage controlled phase shifter which alters the phase of both optical signals until a predetermined phase relationship between modulation on the 1.06 micrometer signal and the reference signal is obtained.

  2. Nonlinear optical methods for cellular imaging and localization.

    PubMed

    McVey, A; Crain, J

    2014-07-01

    Of all the ways in which complex materials (including many biological systems) can be explored, imaging is perhaps the most powerful because delivering high information content directly. This is particular relevant in aspects of cellular localization where the physical proximity of molecules is crucial in biochemical processes. A great deal of effort in imaging has been spent on enabling chemically selective imaging so that only specific features are revealed. This is almost always achieved by adding fluorescent chemical labels to specific molecules. Under appropriate illumination conditions only the molecules (via their labels) will be visible. The technique is simple and elegant but does suffer from fundamental limitations: (1) the fluorescent labels may fade when illuminated (a phenomenon called photobleaching) thereby constantly decreasing signal contrast over the course of image acquisition. To combat photobleaching one must reduce observation times or apply unfavourably low excitation levels all of which reduce the information content of images; (2) the fluorescent species may be deactivated by various environmental factors (the general term is fluorescence quenching); (3) the presence of fluorescent labels may introduce unexpected complications or may interfere with processes of interest (4) Some molecules of interest cannot be labelled. In these circumstances we require a fundamentally different strategy. One of the most promising alternative is based on a technique called Coherent Anti-Stokes Raman scattering (CARS). CARS is a fundamentally more complex process than is fluorescence and the experimental procedures and optical systems required to deliver high quality CARS images are intricate. However, the rewards are correspondingly very high: CARS probes the chemically distinct vibrations of the constituent molecules in a complex system and is therefore also chemically selective as are fluorescence-based methods. Moreover,the potentially severe problems of

  3. Study of 3D printing method for GRIN micro-optics devices

    NASA Astrophysics Data System (ADS)

    Wang, P. J.; Yeh, J. A.; Hsu, W. Y.; Cheng, Y. C.; Lee, W.; Wu, N. H.; Wu, C. Y.

    2016-03-01

    Conventional optical elements are based on either refractive or reflective optics theory to fulfill the design specifications via optics performance data. In refractive optical lenses, the refractive index of materials and radius of curvature of element surfaces determine the optical power and wavefront aberrations so that optical performance can be further optimized iteratively. Although gradient index (GRIN) phenomenon in optical materials is well studied for more than a half century, the optics theory in lens design via GRIN materials is still yet to be comprehensively investigated before realistic GRIN lenses are manufactured. In this paper, 3D printing method for manufacture of micro-optics devices with special features has been studied based on methods reported in the literatures. Due to the additive nature of the method, GRIN lenses in micro-optics devices seem to be readily achievable if a design methodology is available. First, derivation of ray-tracing formulae is introduced for all possible structures in GRIN lenses. Optics simulation program is employed for characterization of GRIN lenses with performance data given by aberration coefficients in Zernike polynomial. Finally, a proposed structure of 3D printing machine is described with conceptual illustration.

  4. PMD test method in the fiber link with optical amplifier

    NASA Astrophysics Data System (ADS)

    Li, Tangjun; Wang, Muguang; Gong, Xiangfeng; Diao, Cao; Tong, Zhi; Wei, Hui; Jian, Shuisheng

    2005-02-01

    To learn the surrounding conditions in the fiber link and its effect on PMD, and to provide the first-hand design basis, we have carried out the data observation of PMD in a fiber link for a long time. We have tested the first-order and second-order PMD. The fiber tested is the G652 fiber produced by Corning Co. of USA, and the testing distance is 1000km; n segments of same fibers are linked into one, and n equals to 40, that is to say, the length of every segment is 25km; for the requirement of dispersion compensation in the high-speed and long distance fiber optical communication system, one fiber grating dispersion compensator is added in the place of every 200km, and there are five compensators; one EDFA is added in the place of every 100km, and there are eleven EDFA. The result suggests that, with the increase of length of fiber link, the distribution of PMD intends to be stable, that is, with the number n increasing, the relative error of PMD becomes less. The testing methods are the Jones matrix eigenanalysis technique and interference technique. HP8509B fiber polarization analyzer of Agilent in USA is used for measuring instrument of the Jones matrix eigenanalysis technique; FPMD-5600 Femtosecond PMD Analyzer of EXFO in Canada is used for measuring instrument of interference technique. The difference between these two testing methods is analyzed. With the Jones matrix eigenanalysis technique, fibers of 1000km are inspected through 48 hours, and the result suggests that, at nine o'clock in the morning, PMD reaches the maximum, at nine o'clock in the evening, it reaches the minimum, during other time, its change is very little. So it can be concluded that, PMD in the long distance fiber link is affected by temperature of the lab. Stress testing is carried in the ultra-short fiber (less than one meter). PMD has no obvious change in the range of stress which can be endured by the fiber.

  5. Computer-aided alignment method of optical lens with high accuracy

    NASA Astrophysics Data System (ADS)

    Xing, Song; Hou, Xiao-hua; Zhang, Xue-min; Ji, Bin-dong

    2016-09-01

    With the development of space and aviation industry, the optical systems with high resolution and better imaging quality are required. According to the alignment technical process, the factors of every step which have big influence to the imaging quality are analyzed. It is detected that the micro-stress assembly of the optical unit and the high co-axial precision of the entire optical system are the two important factors which are supposed to determine how well the imaging quality of the optical system is; also the technical methods are discussed to ensure these two factors from the engineering view. The reflective interference testing method to measure the surface figure and the transitive interference testing method to measure the wave aberration of the optical unit are combined to ensure the micro-stress assembly of the optical unit, so it will not bring astigmatism to the whole system imaging quality. Optical alignment machining and precision alignment are combined to ensure the high co-axial precision of the optical system. An optical lens of high accuracy is assembled by using these methods; the final wave aberration of optical lens is 0.022λ.

  6. Study of GaInNAs Epilayers Using Optical Methods

    NASA Astrophysics Data System (ADS)

    Tsai, Yutsung

    Photovoltaic devices that convert sun's energy into electricity have the potential to influence energy needs on a global scale. A major limitation of single junction solar cells is that only photons with energy slightly above the bandgap are absorbed efficiently. One of the methods is to split the energy of the incoming spectrum into multiple bands each of which is absorbed separately for more efficient collection. That is why multijunction solar cells formed from III-V compound semiconductors are the highest efficiency photovoltaic devices today. To achieve this goal, researchers stack a number of junctions made of different materials with the highest gap material at the top and the lowest at the bottom since each material is transparent to photons with energy smaller than its bandgap. Kurtz [1] predicted an improvement in the performance of multijunction solar cells if a fourth material with bandgap in the 1.0eV-1.05eV range is included between the GaAs (bandgap = 1.42 eV) and Ge (bandgap = 0.67 eV) in the solar cell. In order for this fourth material to be easily incorporated into the GaInP/ GaAs/Ge triple junction device, it must also be lattice matched to germanium. Since it is preferred to grow multijunction solar cells monolithically lattice matching is required making the options for the 1 eV material rather limited. The most promising material for the fourth junction is currently GaInNAs. This is the reason why this thesis concentrates on the study of this material. In this thesis, we have conducted PL, optical pumping, magneto-PL, reflectance and transmission spectroscopic studies of undoped and p-type doped GaInNAs epilayers. The objective of these studies is to investigate the following phenomena in our samples: (a) Localized excitons and free excitons at low temperatures in GaInNAs epilayers: The exciton localization at low temperatures in undoped GaInNAs epilayers results in the S-shape of the PL peaks versus temperature plot. On the other hand, the

  7. Method and system for processing optical materials for high power laser systems

    SciTech Connect

    Demos, Stavros G; Raman, Rajesh; Negres, Raluca A

    2015-02-03

    A method of determining conditioning pulse parameters for an optical element includes directing a pump pulse to impinge on the optical element and directing a probe pulse to impinge on the optical element. The method also includes determining a first time associated with an onset of electronic excitation leading to formation of an absorbing region of the optical element and determining a second time associated with expansion of the absorbing region of the optical element. The method further includes defining a turn-off time for a conditioning pulse between the first time and the second time. According to embodiments of the present invention, pulse shaping of the conditioning pulse enables laser conditioning of optical elements to achieve improvements in their laser induced damage threshold.

  8. High efficiency replicated x-ray optics and fabrication method

    DOEpatents

    Barbee, Jr., Troy W.; Lane, Stephen M.; Hoffman, Donald E.

    2001-01-01

    Replicated x-ray optics are fabricated by sputter deposition of reflecting layers on a super-polished reusable mandrel. The reflecting layers are strengthened by a supporting multilayer that results in stronger stress-relieved reflecting surfaces that do not deform during separation from the mandrel. The supporting multilayer enhances the ability to part the replica from the mandrel without degradation in surface roughness. The reflecting surfaces are comparable in smoothness to the mandrel surface. An outer layer is electrodeposited on the supporting multilayer. A parting layer may be deposited directly on the mandrel before the reflecting surface to facilitate removal of the layered, tubular optic device from the mandrel without deformation. The inner reflecting surface of the shell can be a single layer grazing reflection mirror or a resonant multilayer mirror. The resulting optics can be used in a wide variety of applications, including lithography, microscopy, radiography, tomography, and crystallography.

  9. Method and apparatus for efficient operation of optically pumped laser

    NASA Technical Reports Server (NTRS)

    Sipes, Jr., Donald L. (Inventor)

    1987-01-01

    An optically pumped single mode laser, e.g., Nd:YAG crystal (20) with planoconcave mirrors is increased in efficiency by an order of magnitude to about 8% by optics (25, 27) for focusing the high power multimode output of laser diode arrays (21, 22) into the mode volume (20') of the laser medium (20). A plurality of these optically pumped single mode lasers (1-4) may be cascaded in a ring with dichroic mirrors (M.sub.1 -M.sub.4) at the corners for coupling in the laser diode arrays, each having its own means for spatially tailoring its beam to concentrate pump distribution inside the lasing mode volume of the medium. An InGaAlAs pump diode (30) with its wavelength the same as the lasing medium makes the ring unidirectional.

  10. Low-cost method for producing extreme ultraviolet lithography optics

    DOEpatents

    Folta, James A.; Montcalm, Claude; Taylor, John S.; Spiller, Eberhard A.

    2003-11-21

    Spherical and non-spherical optical elements produced by standard optical figuring and polishing techniques are extremely expensive. Such surfaces can be cheaply produced by diamond turning; however, the roughness in the diamond turned surface prevent their use for EUV lithography. These ripples are smoothed with a coating of polyimide before applying a 60 period Mo/Si multilayer to reflect a wavelength of 134 .ANG. and have obtained peak reflectivities close to 63%. The savings in cost are about a factor of 100.

  11. Fibre Optic Connections And Method For Using Same

    DOEpatents

    Chan, Benson; Cohen, Mitchell S.; Fortier, Paul F.; Freitag, Ladd W.; Hall, Richard R.; Johnson, Glen W.; Lin, How Tzu; Sherman, John H.

    2004-03-30

    A package is described that couples a twelve channel wide fiber optic cable to a twelve channel Vertical Cavity Surface Emitting Laser (VCSEL) transmitter and a multiple channel Perpendicularly Aligned Integrated Die (PAID) receiver. The package allows for reduction in the height of the assembly package by vertically orienting certain dies parallel to the fiber optic cable and horizontally orienting certain other dies. The assembly allows the vertically oriented optoelectronic dies to be perpendicularly attached to the horizontally oriented laminate via a flexible circuit.

  12. Shapes, spectra and new methods in nonlinear spatial optics

    NASA Astrophysics Data System (ADS)

    Sun, Can

    For a myriad of optical applications, the quality of the light source is poor and the beam is inherently spatially partially-coherent. For this broad class of systems, wave dynamics depends not only on the wave intensity, but also on its distribution of spatial frequencies. Unfortunately, this entire spectrum of problems has often been overlooked - for reasons of theoretical ease or experimental difficulties. Here, we remedy this by demonstrating a novel experimental setup which, for the first time, allows arbitrarily modulation of the spatial spectra of light to obtain any distribution of interest. Using modulation instability as an example, we isolate the effect of different spectral shapes and observe distinct beam dynamics. Next, we turn to a thermodynamic description of the long-term evolution of statistical fields. For quantum systems, a major consequence is Bose-Einstein Condensation. However, recent theoretical studies have suggested that quantum mechanics is not necessary for the condensation process: classical waves with random phases can also self-organize into a coherent state. Starting from a random ensemble, nonlinear interactions can lead to a turbulent energy cascade towards longer spatial scales. In complete analogy with the kinetics of a gas system, there is a statistical dynamics of waves in which particle velocities map to wavepacket k-vectors while collisions are mimicked by four-wave mixing. As with collisions, each wave interaction is formally reversible, yet entropy principles mandate that the ensemble evolves towards an equilibrium state of maximum disorder. The result is an equipartition of energy, in the form of a Rayleigh-Jeans spectrum, with information about the condensation process recorded in small-scale fluctuations. Here, we give the first experimental observation of the condensation of classical waves in any media. Using classical light in a self-defocusing photorefractive, we observe all aspects of the condensation process

  13. Optics Demonstration with Student Eyeglasses Using the Inquiry Method

    ERIC Educational Resources Information Center

    James, Mark C.

    2011-01-01

    A favorite qualitative optics demonstration I perform in introductory physics classes makes use of students' eyeglasses to introduce converging and diverging lenses. Taking on the persona of a magician, I walk to the back of the classroom and approach a student wearing glasses. The top part of Fig. 1 shows a glasses-wearing student who is…

  14. A New Method for Determining the Optical Constants of Highly Transparent Solids.

    PubMed

    Li, Xingcan; Wang, Chengchao; Zhao, Junming; Liu, Linhua

    2017-01-01

    Highly transparent substrates are of interest for a variety of applications, but it is difficult to measure their optical constants precisely, especially the absorption index in the transparent spectral region. In this paper, a combination technique (DOPTM-EM) using both the double optical pathlength transmission method (DOPTM) and the ellipsometry method (EM) is presented to obtain the optical constants of highly transparent substrates, which overcomes the deficiencies of both the two methods. The EM cannot give accurate result of optical constants when the absorption index is very weak. The DOPTM is suitable to retrieve the weak absorption index; however, two sets of solutions exist for the retrieved refractive index and absorption index, and only one is the true value that needs to be identified. In the DOPTM-EM, the optical constants are measured first by using the EM and set as the initial value in the gradient-based inverse method used in the DOPTM, which ensures only the true optical constants are retrieved. The new method simultaneously obtains the refractive index and the absorption index of highly transparent substrate without relying on the Kramers-Kronig relation. The optical constants of three highly transparent substrates (polycrystalline BaF2, CaF2, and MgF2) were experimentally determined within wavelength range from ultraviolet to infrared regions (0.2-14 µm). The presented method will facilitate the measurement of optical constants for highly transparent materials.

  15. THUNDER Piezoelectric Actuators as a Method of Stretch-Tuning an Optical Fiber Grating

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G.; Fox, Robert L.; Froggatt, Mark E.; Childers, Brooks A.

    2000-01-01

    A method of stretching optical fiber holds interest for measuring strain in smart structures where the physical displacement may be used to tune optical fiber lasers. A small, light weight, low power tunable fiber laser is ideal for demodulating strain in optical fiber Bragg gratings attached to smart structures such as the re-usable launch vehicle that is being developed by NASA. A method is presented for stretching optical fibers using the THUNDER piezoelectric actuators invented at NASA Langley Research Center. THUNDER actuators use a piezoelectric layer bonded to a metal backing to enable the actuators to produce displacements larger than the unbonded piezoelectric material. The shift in reflected optical wavelength resulting from stretching the fiber Bragg grating is presented. Means of adapting THUNDER actuators for stretching optical fibers is discussed, including ferrules, ferrule clamp blocks, and plastic hinges made with stereo lithography.

  16. "METHOD": A tool for mechanical, electrical, thermal, and optical characterization of single lens module design

    NASA Astrophysics Data System (ADS)

    Besson, Pierre; Dominguez, Cesar; Voarino, Philippe; Garcia-Linares, Pablo; Weick, Clement; Lemiti, Mustapha; Baudrit, Mathieu

    2015-09-01

    The optical characterization and electrical performance evaluation are essential in the design and optimization of a concentrator photovoltaic system. The geometry, materials, and size of concentrator optics are diverse and different environmental conditions impact their performance. CEA has developed a new concentrator photovoltaic system characterization bench, METHOD, which enables multi-physics optimization studies. The lens and cell temperatures are controlled independently with the METHOD to study their isolated effects on the electrical and optical performance of the system. These influences can be studied in terms of their effect on optical efficiency, focal distance, spectral sensitivity, electrical efficiency, or cell current matching. Furthermore, the irradiance map of a concentrator optic can be mapped to study its variations versus the focal length or the lens temperature. The present work shows this application to analyze the performance of a Fresnel lens linking temperature to optical and electrical performance.

  17. Method of glass selection for color correction in optical system design.

    PubMed

    de Albuquerque, Bráulio Fonseca Carneiro; Sasian, Jose; de Sousa, Fabiano Luis; Montes, Amauri Silva

    2012-06-18

    A method of glass selection for the design of optical systems with reduced chromatic aberration is presented. This method is based on the unification of two previously published methods adding new contributions and using a multi-objective approach. This new method makes it possible to select sets of compatible glasses suitable for the design of super-apochromatic optical systems. As an example, we present the selection of compatible glasses and the effective designs for all-refractive optical systems corrected in five spectral bands, with central wavelengths going from 485 nm to 1600 nm.

  18. Spatial-light-modulator-based adaptive optical system for the use of multiple phase retrieval methods.

    PubMed

    Lingel, Christian; Haist, Tobias; Osten, Wolfgang

    2016-12-20

    We propose an adaptive optical setup using a spatial light modulator (SLM), which is suitable to perform different phase retrieval methods with varying optical features and without mechanical movement. By this approach, it is possible to test many different phase retrieval methods and their parameters (optical and algorithmic) using one stable setup and without hardware adaption. We show exemplary results for the well-known transport of intensity equation (TIE) method and a new iterative adaptive phase retrieval method, where the object phase is canceled by an inverse phase written into part of the SLM. The measurement results are compared to white light interferometric measurements.

  19. Multiscale optical simulation settings: challenging applications handled with an iterative ray-tracing FDTD interface method.

    PubMed

    Leiner, Claude; Nemitz, Wolfgang; Schweitzer, Susanne; Kuna, Ladislav; Wenzl, Franz P; Hartmann, Paul; Satzinger, Valentin; Sommer, Christian

    2016-03-20

    We show that with an appropriate combination of two optical simulation techniques-classical ray-tracing and the finite difference time domain method-an optical device containing multiple diffractive and refractive optical elements can be accurately simulated in an iterative simulation approach. We compare the simulation results with experimental measurements of the device to discuss the applicability and accuracy of our iterative simulation procedure.

  20. Method for path imbalance measurement of the two-arm fiber-optic interferometer.

    PubMed

    Huang, Shih-Chu; Lin, Hermann

    2008-10-01

    The path imbalance (PI) of the two-arm fiber-optic interferometric sensor is a substantial parameter; a precise value of millimeters is required. Currently the precision reflectometry and the millimeter optical time-domain reflectometry are used to measure the tiny optical path difference, but the performances of these measurements are limited from the length and the resolution of the PI. We propose a new method accomplished by interferometer to accurately measure millimeters to within a few decimeters of the PI.

  1. Apparatus and Method for Elimination of Polarization-Induced Fading in Fiber-optic Sensor System

    NASA Technical Reports Server (NTRS)

    Chan, Hon Man (Inventor); Parker, Jr., Allen R. (Inventor)

    2015-01-01

    The invention is an apparatus and method of eliminating polarization-induced fading in interferometric fiber-optic sensor system having a wavelength-swept laser optical signal. The interferometric return signal from the sensor arms are combined and provided to a multi-optical path detector assembly and ultimately to a data acquisition and processing unit by way of a switch that is time synchronized with the laser scan sweep cycle.

  2. Optical caries diagnostics: comparison of laser spectroscopic PNC method with method of laser integral fluorescence

    NASA Astrophysics Data System (ADS)

    Masychev, Victor I.

    2000-11-01

    In this research we present the results of approbation of two methods of optical caries diagnostics: PNC-spectral diagnostics and caries detection by laser integral fluorescence. The research was conducted in a dental clinic. PNC-method analyses parameters of probing laser radiation and PNC-spectrums of stimulated secondary radiations: backscattering and endogenous fluorescence of caries-involved bacterias. He-Ne-laser ((lambda) =632,8 nm, 1-2mW) was used as a source of probing (stimulated) radiation. For registration of signals, received from intact and pathological teeth PDA-detector was applied. PNC-spectrums were processed by special algorithms, and were displayed on PC monitor. The method of laser integral fluorescence was used for comparison. In this case integral power of fluorescence of human teeth was measured. As a source of probing (stimulated) radiation diode lasers ((lambda) =655 nm, 0.1 mW and 630nm, 1mW) and He-Ne laser were applied. For registration of signals Si-photodetector was used. Integral power was shown in a digital indicator. Advantages and disadvantages of these methods are described in this research. It is disclosed that the method of laser integral power of fluorescence has the following characteristics: simplicity of construction and schema-technical decisions. However the method of PNC-spectral diagnostics are characterized by considerably more sensitivity in diagnostics of initial caries and capability to differentiate pathologies of various stages (for example, calculus/initial caries). Estimation of spectral characteristics of PNC-signals allows eliminating a number of drawbacks, which are character for detection by method of laser integral fluorescence (for instance, detection of fluorescent fillings, plagues, calculus, discolorations generally, amalgam, gold fillings as if it were caries.

  3. Photogrammetry and optical methods in structural dynamics - A review

    NASA Astrophysics Data System (ADS)

    Baqersad, Javad; Poozesh, Peyman; Niezrecki, Christopher; Avitabile, Peter

    2017-03-01

    In the last few decades, there has been a surge of research in the area of non-contact measurement techniques. Photogrammetry has received considerable attention due to its ability to achieve full-field measurement and its robustness to work in testing environments and on testing articles in which using other measurement techniques may not be practical. More recently, researchers have used this technique to study transient phenomena and to perform measurements on vibrating structures. The current paper reviews the most current trends in the photogrammetry technique (point tracking, digital image correlation, and target-less approaches) and compares the applications of photogrammetry to other measurement techniques used in structural dynamics (e.g. laser Doppler vibrometry and interferometry techniques). The paper does not present the theoretical background of the optical techniques, but instead presents the general principles of each approach and highlights the novel structural dynamic measurement concepts and applications that are enhanced by utilizing optical techniques.

  4. Method for the protection of extreme ultraviolet lithography optics

    DOEpatents

    Grunow, Philip A.; Clift, Wayne M.; Klebanoff, Leonard E.

    2010-06-22

    A coating for the protection of optical surfaces exposed to a high energy erosive plasma. A gas that can be decomposed by the high energy plasma, such as the xenon plasma used for extreme ultraviolet lithography (EUVL), is injected into the EUVL machine. The decomposition products coat the optical surfaces with a protective coating maintained at less than about 100 .ANG. thick by periodic injections of the gas. Gases that can be used include hydrocarbon gases, particularly methane, PH.sub.3 and H.sub.2S. The use of PH.sub.3 and H.sub.2S is particularly advantageous since films of the plasma-induced decomposition products S and P cannot grow to greater than 10 .ANG. thick in a vacuum atmosphere such as found in an EUVL machine.

  5. Optical efficiency enhancement methods for terahertz receiving photoconductive switches

    NASA Astrophysics Data System (ADS)

    Heshmat, Barmak; Pahlevaninezhad, Hamid; Darcie, Thomas Edward

    2013-12-01

    We improve the efficiency of THz receiving photoconductive switches by improving the conversion of the optical pump to signal current. This is achieved by both optimizing the incident excitation beam polarization and spatial profile of excitation. Due to boundary conditions of the electric field at the electrode edge, a nanometer-sized polarization-dependent shadow is created in the substrate at the electrode edge where most picosecond lifetime photocarriers are collected. This edge effect is further harnessed by elongating the excitation beam next to the stripline electrode. The effects of excitation beam polarization and spatial profile were experimented with InGaAs/InAlAs quantum-well-based photoconductive switch. In both cases notable enhancement in the signal is observed-30% with polarization optimization and up to 100% with beam elongation. Both techniques preserve the pulse quality and are applicable with readily available optical elements.

  6. The study of plant tissue by optical coherent microscopy method

    NASA Astrophysics Data System (ADS)

    Chirskaya, V. V.; Margaryants, N. B.; Zhukova, E. V.

    2016-08-01

    The article presents the results of application of the optical coherent microscopy technique using a high-resolution automatic Linnik interference microscope to study the structure of plant tissues exemplified by surface periderm layers of a tuberous nightshade (solánum tuberosum) bulb. The results of 3D visualization of the structure of the sample under examination are provided. Scanning depth was 32 µm, with axial and lateral resolution of the device 1 µm.

  7. New Methods for Design and Computation of Freeform Optics

    DTIC Science & Technology

    2015-07-09

    as a partial differential equation(PDE) of second order with nonstandard boundary conditions. The solution to this PDE problem is a scalar function...the exact solution with any a priori given accuracy. By contrast with other approaches the solution obtained with our approach does not depend on ad hoc...strategy for constructing weak solutions to nonlinear partial differential equations arising in design problems involving freeform optical surfaces[10

  8. Optics Demonstration with Student Eyeglasses Using the Inquiry Method

    NASA Astrophysics Data System (ADS)

    James, Mark C.

    2011-09-01

    A favorite qualitative optics demonstration I perform in introductory physics classes makes use of students' eyeglasses to introduce converging and diverging lenses. Taking on the persona of a magician, I walk to the back of the classroom and approach a student wearing glasses. The top part of Fig. 1 shows a glasses-wearing student who is farsighted in her left eye and has a slight astigmatism in her right eye.

  9. Effects of fiber manipulation methods on optical fiber properties

    NASA Astrophysics Data System (ADS)

    Reynolds, Robert O.; Bechter, Andrew; Crass, Jonathan

    2016-07-01

    Optical fibers are routinely used to couple high-resolution spectrographs to modern telescopes, enabling important advantages in areas such as the search for extrasolar planets using spectroscopic radial velocity measurements of candidate stars. Optical fibers partially scramble the input illumination, and this feature enables a fiber feed to provide more uniform illumination to the spectrograph optics, thereby reducing systematic errors in radial velocity measurements. However fibers suffer from focal ratio degradation (FRD), a spreading of the beam at the output of the fiber with respect to that at the fiber input, which results in losses in throughput and resolution. Modal noise, a measurement uncertainty caused by inherent fiber properties and evident as a varying spatial intensity at the fiber exit plane, reduces the signal to noise ratio in the data. Devices such as double scramblers are often used to improve scrambling, and better fiber end preparation can mitigate FRD. Many instruments agitate the fiber during an observation to reduce modal noise, and stretching the fiber during use has been shown to offer a greater reduction in that noise. But effects of agitation and stretching on fiber parameters such as total transmission and focal ratio degradation have not been adequately studied. In this paper we present measurements of transmission loss and focal ratio degradation for both agitated and stretched fibers.

  10. Detection and laser ranging of orbital objects using optical methods

    NASA Astrophysics Data System (ADS)

    Wagner, P.; Hampf, D.; Sproll, F.; Hasenohr, T.; Humbert, L.; Rodmann, J.; Riede, W.

    2016-09-01

    Laser ranging to satellites (SLR) in earth orbit is an established technology used for geodesy, fundamental science and precise orbit determination. A combined active and passive optical measurement system using a single telescope mount is presented which performs precise ranging measurements of retro reflector equipped objects in low earth orbit (LEO). The German Aerospace Center (DLR) runs an observatory in Stuttgart where a system has been assembled completely from commercial off-the-shelf (COTS) components. The visible light directed to the tracking camera is used to perform angular measurements of objects under investigation. This is done astrometrically by comparing the apparent target position with cataloged star positions. First successful satellite laser ranging was demonstrated recently using an optical fiber directing laser pulses onto the astronomical mount. The transmitter operates at a wavelength of 1064 nm with a repetition rate of 3 kHz and pulse energy of 25 μJ. A motorized tip/tilt mount allows beam steering of the collimated beam with μrad accuracy. The returning photons reflected from the object in space are captured with the tracking telescope. A special low aberration beam splitter unit was designed to separate the infrared from visible light. This allows passive optical closed loop tracking and operation of a single photon detector for time of flight measurements at a single telescope simultaneously. The presented innovative design yields to a compact and cost effective but very precise ranging system which allows orbit determination.

  11. Applying fiber optical methods for toxicological testing in vitro

    NASA Astrophysics Data System (ADS)

    Maerz, Holger K.; Buchholz, Rainer; Emmrich, Frank; Fink, Frank; Geddes, Clive L.; Pfeifer, Lutz; Raabe, Ferdinand; Scheper, Thomas-Helmut; Ulrich, Elizabeth; Marx, Uwe

    1999-04-01

    The new medical developments, e.g. immune therapy, patient oriented chemotherapy or even gene therapy, create a questionable doubt to the further requirement of animal test. Instead the call for humanitarian reproductive in vitro models becomes increasingly louder. Pharmaceutical usage of in vitro has a long proven history. In cancer research and therapy, the effect of chemostatica in vitro in the so-called oncobiogram is being tested; but the assays do not always correlate with in vivo-like drug resistance and sensitivity. We developed a drug test system in vitro, feasible for therapeutic drug monitoring by the combination of tissue cultivation in hollow fiber bioreactors and fiber optic sensors for monitoring the pharmaceutical effect. Using two fiber optic sensors - an optical oxygen sensor and a metabolism detecting Laserfluoroscope, we were able to successfully monitor the biological status of tissue culture and the drug or toxic effects of in vitro pharmaceutical testing. Furthermore, we developed and patented a system for monitoring the effect of minor toxic compounds which can induce Sick Building Syndrome.

  12. Advanced scanning methods with tracking optical coherence tomography

    PubMed Central

    Ferguson, R. Daniel; Iftimia, Nicusor V.; Ustun, Teoman; Wollstein, Gadi; Ishikawa, Hiroshi; Gabriele, Michelle L.; Dilworth, William D.; Kagemann, Larry; Schuman, Joel S.

    2013-01-01

    An upgraded optical coherence tomography system with integrated retinal tracker (TOCT) was developed. The upgraded system uses improved components to extend the tracking bandwidth, fully integrates the tracking hardware into the optical head of the clinical OCT system, and operates from a single software platform. The system was able to achieve transverse scan registration with sub-pixel accuracy (~10 μm). We demonstrate several advanced scan sequences with the TOCT, including composite scans averaged (co-added) from multiple B-scans taken consecutively and several hours apart, en face images collected by summing the A-scans of circular, line, and raster scans, and three-dimensional (3D) retinal maps of the fovea and optic disc. The new system achieves highly accurate OCT scan registration yielding composite images with significantly improved spatial resolution, increased signal-to-noise ratio, and reduced speckle while maintaining well-defined boundaries and sharp fine structure compared to single scans. Precise re-registration of multiple scans over separate imaging sessions demonstrates TOCT utility for longitudinal studies. En face images and 3D data cubes generated from these data reveal high fidelity image registration with tracking, despite scan durations of more than one minute. PMID:19498823

  13. Improved retrievals of the optical properties of cirrus clouds by a combination of lidar methods.

    PubMed

    Cadet, Bertrand; Giraud, Vincent; Haeffelin, Martial; Keckhut, Philippe; Rechou, Anne; Baldy, Serge

    2005-03-20

    We focus on improvement of the retrieval of optical properties of cirrus clouds by combining two lidar methods. We retrieve the cloud's optical depth by using independently the molecular backscattering profile below and above the cloud [molecular integration (MI) method] and the backscattering profile inside the cloud with an a priori effective lidar ratio [particle integration (PI) method]. When the MI method is reliable, the combined MI-PI method allows us to retrieve the optimal effective lidar ratio. We compare these results with Raman lidar retrievals. We then use the derived optimal effective lidar ratio for retrieval with the PI method for situations in which the MI method cannot be applied.

  14. Electro-optical deflectors as a method of beam smoothing for Inertial Confinement Fusion

    SciTech Connect

    Rothenberg, J.E.

    1997-01-01

    The electro-optic deflector is analyzed and compared to smoothing by spectral dispersion for efficacy as a beam smoothing method for ICF. It is found that the electro-optic deflector is inherently somewhat less efficient when compared either on the basis of equal peak phase modulation or equal generated bandwidth.

  15. An Auto-Focusing Method in a Microscopic Testbed for Optical Discs.

    PubMed

    Tang, X; L'Hostis, P; Xiao, Y

    2000-01-01

    An auto-focusing method in a digital image system is demonstrated that uses a standard deviation of pixel gray levels as a feedback signal. In this system, an optical microscope and a charge coupled device (CCD) camera are used to create clear pit images of optical discs. A dynamic focusing scheme is designed in the system-control software, which is able to eliminate environmental disturbances and other noises so that a fast and stable focus can be achieved. The method shows an excellent focusing accuracy. The performance and possible applications of this method are discussed. The test results for optical discs are given in this paper.

  16. Optical Device, System, and Method of Generating High Angular Momentum Beams

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy A. (Inventor); Matsko, Andrey B. (Inventor); Strekalov, Dmitry V. (Inventor); Grudinin, Ivan S. (Inventor); Maleki, Lute (Inventor)

    2009-01-01

    An optical device, optical system, and method of generating optical beams having high angular momenta are provided. The optical device includes a whispering gallery mode resonator defining a resonator radius and an elongated wavegWde having a length defined between a first end and a second end of the waveguide. The waveguide defines a waveguide radius which increases at least along a portion of the length of the waveguide in a direction from the first end to the second end. The waveguide radius at the first end of the waveguide is smaller than the resonator radius and the resonator is integrally formed with the first end of the waveguide.

  17. Cryogenic fiber optic temperature sensor and method of manufacturing the same

    NASA Technical Reports Server (NTRS)

    Kochergin, Vladimir (Inventor)

    2012-01-01

    This invention teaches the fiber optic sensors temperature sensors for cryogenic temperature range with improved sensitivity and resolution, and method of making said sensors. In more detail, the present invention is related to enhancement of temperature sensitivity of fiber optic temperature sensors at cryogenic temperatures by utilizing nanomaterials with a thermal expansion coefficient that is smaller than the thermal expansion coefficient of the optical fiber but larger in absolute value than the thermal expansion coefficient of the optical fiber at least over a range of temperatures.

  18. Method to adjust multilayer film stress induced deformation of optics

    DOEpatents

    Spiller, Eberhard A.; Mirkarimi, Paul B.; Montcalm, Claude; Bajt, Sasa; Folta, James A.

    2000-01-01

    Stress compensating systems that reduces/compensates stress in a multilayer without loss in reflectivity, while reducing total film thickness compared to the earlier buffer-layer approach. The stress free multilayer systems contain multilayer systems with two different material combinations of opposite stress, where both systems give good reflectivity at the design wavelengths. The main advantage of the multilayer system design is that stress reduction does not require the deposition of any additional layers, as in the buffer layer approach. If the optical performance of the two systems at the design wavelength differ, the system with the poorer performance is deposited first, and then the system with better performance last, thus forming the top of the multilayer system. The components for the stress reducing layer are chosen among materials that have opposite stress to that of the preferred multilayer reflecting stack and simultaneously have optical constants that allow one to get good reflectivity at the design wavelength. For a wavelength of 13.4 nm, the wavelength presently used for extreme ultraviolet (EUV) lithography, Si and Be have practically the same optical constants, but the Mo/Si multilayer has opposite stress than the Mo/Be multilayer. Multilayer systems of these materials have practically identical reflectivity curves. For example, stress free multilayers can be formed on a substrate using Mo/Be multilayers in the bottom of the stack and Mo/Si multilayers at the top of the stack, with the switch-over point selected to obtain zero stress. In this multilayer system, the switch-over point is at about the half point of the total thickness of the stack, and for the Mo/Be--Mo/Si system, there may be 25 deposition periods Mo/Be to 20 deposition periods Mo/Si.

  19. Fiber-optic delay-line stabilization of heterodyne optical signal generator and method using same

    NASA Technical Reports Server (NTRS)

    Logan, Ronald T. (Inventor)

    1997-01-01

    The present invention is a laser heterodyne frequency generator system with a stabilizer for use in the microwave and millimeter-wave frequency ranges utilizing a photonic mixer as a photonic phase detector in a stable optical fiber delay-line. Phase and frequency fluctuations of the heterodyne laser signal generators are stabilized at microwave and millimeter wave frequencies by a delay line system operating as a frequency discriminator. The present invention is free from amplifier and mixer 1/.function. noise at microwave and millimeter-wave frequencies that typically limit phase noise performance in electronic cavity stabilized electronic oscillators. Thus, 1/.function. noise due to conventional mixers is eliminated and stable optical heterodyne generation of electrical signals is achieved.

  20. Optical-diffraction method for determining crystal orientation

    DOEpatents

    Sopori, B.L.

    1982-05-07

    Disclosed is an optical diffraction technique for characterizing the three-dimensional orientation of a crystal sample. An arbitrary surface of the crystal sample is texture etched so as to generate a pseudo-periodic diffraction grating on the surface. A laser light beam is then directed onto the etched surface, and the reflected light forms a farfield diffraction pattern in reflection. Parameters of the diffraction pattern, such as the geometry and angular dispersion of the diffracted beam are then related to grating shape of the etched surface which is in turn related to crystal orientation. This technique may be used for examining polycrystalline silicon for use in solar cells.

  1. System and method for optical monitoring of a combustion flame

    DOEpatents

    Brown, Dale M; Sandvik, Peter M; Fedison, Jeffrey B; Matocha, Kevin S; Johnson, Thomas E

    2006-09-26

    An optical spectrometer for combustion flame temperature determination includes at least two photodetectors positioned for receiving light from a combustion flame, each of the at least two photodetectors having a different, overlapping bandwidth for detecting a respective output signal in an ultraviolet emission band; and a computer for subtracting a respective output signal of a first one of the at least two photodetectors from a respective output signal of a second one of the at least two photodetectors to obtain a segment signal, and using the segment signal to determine the combustion flame temperature.

  2. One step geometrical calibration method for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Díaz Díaz, Jesús; Stritzel, Jenny; Rahlves, Maik; Majdani, Omid; Reithmeier, Eduard; Ortmaier, Tobias; Roth, Bernhard

    2016-01-01

    We present a novel one-step calibration methodology for geometrical distortion correction for optical coherence tomography (OCT). A calibration standard especially designed for OCT is introduced, which consists of an array of inverse pyramidal structures. The use of multiple landmarks situated on four different height levels on the pyramids allow performing a 3D geometrical calibration. The calibration procedure itself is based on a parametric model of the OCT beam propagation. It is validated by experimental results and enables the reduction of systematic errors by more than one order of magnitude. In future, our results can improve OCT image reconstruction and interpretation for medical applications such as real time monitoring of surgery.

  3. Method of forming silicon structures with selectable optical characteristics

    NASA Technical Reports Server (NTRS)

    Fathauer, Robert W. (Inventor); Schowalter, Leo (Inventor)

    1993-01-01

    Silicon and metal are coevaporated onto a silicon substrate in a molecular beam epitaxy system with a larger than stoichiometric amount of silicon so as to epitaxially grow particles of metal silicide embedded in a matrix of single crystal epitaxially grown silicon. The particles interact with incident photons by resonant optical absorption at the surface plasmon resonance frequency. Controlling the substrate temperature and deposition rate and time allows the aspect ratio of the particles to be tailored to desired wavelength photons and polarizations. The plasmon energy may decay as excited charge carriers or phonons, either of which can be monitored to indicate the amount of incident radiation at the selected frequency and polarization.

  4. Comparison of Three Optical Methods for Measuring Model Deformation

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Fleming, G. A.; Hoppe, J. C.

    2000-01-01

    The objective of this paper is to compare the current state-of-the-art of the following three optical techniques under study by NASA for measuring model deformation in wind tunnels: (1) video photogrammetry, (2) projection moire interferometry, and (3) the commercially available Optotrak system. An objective comparison of these three techniques should enable the selection of the best technique for a particular test undertaken at various NASA facilities. As might be expected, no one technique is best for all applications. The techniques are also not necessarily mutually exclusive and in some cases can be complementary to one another.

  5. Method and apparatus for optical encoding with compressible imaging

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B. (Inventor)

    2006-01-01

    The present invention presents an optical encoder with increased conversion rates. Improvement in the conversion rate is a result of combining changes in the pattern recognition encoder's scale pattern with an image sensor readout technique which takes full advantage of those changes, and lends itself to operation by modern, high-speed, ultra-compact microprocessors and digital signal processors (DSP) or field programmable gate array (FPGA) logic elements which can process encoder scale images at the highest speeds. Through these improvements, all three components of conversion time (reciprocal conversion rate)--namely exposure time, image readout time, and image processing time--are minimized.

  6. Optics-Only Calibration of a Neural-Net Based Optical NDE Method for Structural Health Monitoring

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2004-01-01

    A calibration process is presented that uses optical measurements alone to calibrate a neural-net based NDE method. The method itself detects small changes in the vibration mode shapes of structures. The optics-only calibration process confirms previous work that the sensitivity to vibration-amplitude changes can be as small as 10 nanometers. A more practical value in an NDE service laboratory is shown to be 50 nanometers. Both model-generated and experimental calibrations are demonstrated using two implementations of the calibration technique. The implementations are based on previously published demonstrations of the NDE method and an alternative calibration procedure that depends on comparing neural-net and point sensor measurements. The optics-only calibration method, unlike the alternative method, does not require modifications of the structure being tested or the creation of calibration objects. The calibration process can be used to test improvements in the NDE process and to develop a vibration-mode-independence of damagedetection sensitivity. The calibration effort was intended to support NASA s objective to promote safety in the operations of ground test facilities or aviation safety, in general, by allowing the detection of the gradual onset of structural changes and damage.

  7. Optical near-field analysis of spherical metals: Application of the FDTD method combined with the ADE method.

    PubMed

    Yamaguchi, Takashi; Hinata, Takashi

    2007-09-03

    The time-average energy density of the optical near-field generated around a metallic sphere is computed using the finite-difference time-domain method. To check the accuracy, the numerical results are compared with the rigorous solutions by Mie theory. The Lorentz-Drude model, which is coupled with Maxwell's equation via motion equations of an electron, is applied to simulate the dispersion relation of metallic materials. The distributions of the optical near-filed generated around a metallic hemisphere and a metallic spheroid are also computed, and strong optical near-fields are obtained at the rim of them.

  8. Evaluation of a time-resolved stress detection method to determine tissue optical properties

    NASA Astrophysics Data System (ADS)

    Vijverberg, Helene; Thomsen, Sharon L.; Jacques, Steven L.; Oraevsky, Alexander A.

    1995-01-01

    A new method to determine optical properties of biological tissue, time-resolved stress detection (TRSD), was tested on albino rat skin, heated in vitro. The TRSD method is based on the detection of pressure waves that are generated by short laser pulses. The pressure waves carry information about the optical properties (absorption and effective attenuation coefficients) of the medium. The evaluation was done in a systematic way by comparing the results of the TRSD method with results obtained using an integrating sphere. Measurements for both methods were performed on the same skin samples to minimize biological variations. The TRSD method proved to be reasonably successful to determine optical properties of tissue for the used wavelength of 355 nm: (1) The effective attenuation coefficients of both methods agreed very well; (2) The TRSD method gave absorption coefficients of a factor 2 + 0.5 times higher than the integrating sphere method; and (3) The reduced scattering coefficients were sensitive to error.

  9. Cell death monitoring using quantitative optical coherence tomography methods

    NASA Astrophysics Data System (ADS)

    Farhat, Golnaz; Yang, Victor X. D.; Kolios, Michael C.; Czarnota, Gregory J.

    2011-03-01

    Cell death is characterized by a series of predictable morphological changes, which modify the light scattering properties of cells. We present a multi-parametric approach to detecting changes in subcellular morphology related to cell death using optical coherence tomography (OCT). Optical coherence tomography data were acquired from acute myeloid leukemia (AML) cells undergoing apoptosis over a period of 48 hours. Integrated backscatter (IB) and spectral slope (SS) were computed from OCT backscatter spectra and statistical parameters were extracted from a generalized gamma (GG) distribution fit to OCT signal intensity histograms. The IB increased by 2-fold over 48 hours with significant increases observed as early as 4 hours. The SS increased in steepness by 2.5-fold with significant changes at 12 hours, while the GG parameters were sensitive to apoptotic changes at 24 to 48 hours. Histology slides indicated nuclear condensation and fragmentation at 24 hours, suggesting the late scattering changes could be related to nuclear structure. A second series of measurements from AML cells treated with cisplatin, colchicine or ionizing radiation suggested that the GG parameters could potentially differentiate between modes of cell death. Distinct cellular morphology was observed in histology slides obtained from cells treated under each condition.

  10. Methods for Manipulating CaF Using Optical Polychromatic Forces

    NASA Astrophysics Data System (ADS)

    Eyler, Edward E.; Galica, Scott E.; Aldridge, Leland M.

    2013-06-01

    We are undertaking theoretical and experimental studies of laser deceleration and cooling of molecules using coherent multi-frequency optical forces. A primary objective is to reduce radiative loss into dark states when a pure two-level cycling transition is unavailable. The optical bichromatic force (BCF) can multiply the available velocity change for a given number of radiative cycles, by employing alternating cycles of excitation and stimulated emission from opposing directions. Tests in atomic helium show that when the BCF is combined with frequency chirping, very large decelerations are achieved. We report numerical studies of variations intended to further optimize deceleration, including a 4-color version. We describe progress on experimental tests using the 531 nm B ^2Σ^+leftrightarrow X ^2Σ^+ transition in CaF. We also describe low-cost lasers and electronics developed for these experiments. Several versatile new instruments are based on 32-bit microcontrollers, interfaced to an Android tablet that provides a touch-screen graphical interface. These include a timing/ramp generator, a PZT driver, a temperature controller, and even a phase-synchronized dual 35-4000 MHz rf synthesizer that fits on a 2 1/4" × 4 3/4" board. This research is supported by the National Science Foundation. M.A. Chieda and E.E. Eyler, Phys. Rev. A 86, 053415 (2012); also Phys. Rev. A 84, 063401 (2011).

  11. The optical method for investigation of the peritonitis progressing process

    NASA Astrophysics Data System (ADS)

    Guminetskiy, S. H.; Ushenko, O. G.; Polyanskiy, I. P.; Motrych, A. V.; Grynchuk, F. V.

    2008-05-01

    There have been given the results of the spectrophotometric examination of the dogs' and rats' venous and whole blood plasma taken in the process of the peritonitis progressing within the spectral interval λ = 220 - 320 nm (for plasma) and λ = 350 - 610 nm (for the whole blood). It has been defined that D-optical density values in the field of the long-waved maximum of plasma absorption intensity of the venous blood at λ = 280 nm depend upon the intensity of the inflammatory process and also upon the circumstances against the background of which it started to progress. It was found out that the dynamics of D= values changes for λ = 540 (or 570) nm in the process of the peritonitis progressing in case of the whole blood taken from a portal vein is a mirror symmetrical if to compare to the same dynamics for the blood from cava inferior. The defined conformities with regularities may have a diagnostic meaning. It was also found out that the biggest influence upon the dynamics of D-values at λ = 280nm of the venous blood plasma has the content of the circulating immune complexes, necrosis factor of α-tumors and interleukin - 2, the changes of which explain for almost on 100% the distribution of the optical density parameters and what proves a possible immunologic explanation of its changes.

  12. Research on the Calculation Method of Optical Path Difference of the Shanghai Tian Ma Telescope

    NASA Astrophysics Data System (ADS)

    Dong, J.; Fu, L.; Jiang, Y. B.; Liu, Q. H.; Gou, W.; Yan, F.

    2016-03-01

    Based on the Shanghai Tian Ma Telescope (TM), an optical path difference calculation method of the shaped Cassegrain antenna is presented in the paper. Firstly, the mathematical model of the TM optics is established based on the antenna reciprocity theorem. Secondly, the TM sub-reflector and main reflector are fitted by the Non-Uniform Rational B-Splines (NURBS). Finally, the method of optical path difference calculation is implemented, and the expanding application of the Ruze optical path difference formulas in the TM is researched. The method can be used to calculate the optical path difference distributions across the aperture field of the TM due to misalignment like the axial and lateral displacements of the feed and sub-reflector, or the tilt of the sub-reflector. When the misalignment quantity is small, the expanding Ruze optical path difference formulas can be used to calculate the optical path difference quickly. The paper supports the real-time measurement and adjustment of the TM structure. The research has universality, and can provide reference for the optical path difference calculation of other radio telescopes with shaped surfaces.

  13. Multispeed rewritable optical-recording method with an initialization-free phase-change disk.

    PubMed

    Miao, Xiang Shui; Shi, Lu Ping; Tan, Pik Kee; Li, Jian Ming; Lim, Kian Guan; Hu, Xiang; Chong, Tow Chong

    2004-02-10

    A new method of multispeed rewritable optical recording is presented. An initialization-free phase-change optical disk is proposed as a candidate for multispeed rewritable optical recording. The simulated results of the initialization-free disk at different linear velocities show that the cooling rate increases from approximately 18.69% to 37.96%. A model that combines the crystallization acceleration effect due to the additional layers and the rapid cooling rate due to the initialization-free disk structure is proposed as the physical mechanism of the multispeed recording method with an initialization-free disk. The dynamic optical-recording properties of the initialization-free DVD-RAM disk at different recording speeds shows that the initialization-free phase-change optical-recording disk is compatible with a broad range of recording speeds from 3.49 to 12.21 m/s.

  14. An Optical Fiber Lateral Displacement Measurement Method and Experiments Based on Reflective Grating Panel

    PubMed Central

    Li, Yuhe; Guan, Kaisen; Hu, Zhaohui; Chen, Yanxiang

    2016-01-01

    An optical fiber sensing method based on a reflective grating panel is demonstrated for lateral displacement measurement. The reflective panel is a homemade grating with a periodic variation of its refractive index, which is used to modulate the reflected light intensity. The system structure and operation principle are illustrated in detail. The intensity calculation and simulation of the optical path are carried out to theoretically analyze the measurement performance. A distinctive fiber optic grating ruler with a special fiber optic measuring probe and reflective grating panel is set up. Experiments with different grating pitches are conducted, and long-distance measurements are executed to accomplish the functions of counting optical signals, subdivision, and discerning direction. Experimental results show that the proposed measurement method can be used to detect lateral displacement, especially for applications in working environments with high temperatures. PMID:27271624

  15. An Optical Fiber Lateral Displacement Measurement Method and Experiments Based on Reflective Grating Panel.

    PubMed

    Li, Yuhe; Guan, Kaisen; Hu, Zhaohui; Chen, Yanxiang

    2016-06-02

    An optical fiber sensing method based on a reflective grating panel is demonstrated for lateral displacement measurement. The reflective panel is a homemade grating with a periodic variation of its refractive index, which is used to modulate the reflected light intensity. The system structure and operation principle are illustrated in detail. The intensity calculation and simulation of the optical path are carried out to theoretically analyze the measurement performance. A distinctive fiber optic grating ruler with a special fiber optic measuring probe and reflective grating panel is set up. Experiments with different grating pitches are conducted, and long-distance measurements are executed to accomplish the functions of counting optical signals, subdivision, and discerning direction. Experimental results show that the proposed measurement method can be used to detect lateral displacement, especially for applications in working environments with high temperatures.

  16. All-optical beam deflection method for simultaneous thermal conductivity and thermo-optic coefficient ( d n / d T ) measurements

    NASA Astrophysics Data System (ADS)

    Putnam, Shawn A.; Fairchild, Steven B.; Arends, Armando A.; Urbas, Augustine M.

    2016-05-01

    This work describes an all-optical beam deflection method to simultaneously measure the thermal conductivity ( Λ) and thermo-optic coefficient ( d n / d T ) of materials that are absorbing at λ = 10.6 μm and are transparent to semi-transparent at λ = 632.8 nm. The technique is based on the principle of measuring the beam deflection of a probe beam (632.8 nm) in the frequency-domain due to a spatially and temporally varying index gradient that is thermally induced by 50:50 split pump beam from a CO2 laser (10.6 μm). The technique and analysis methods are validated with measurements of 10 different optical materials having Λ and d n / d T properties ranging between 0.7 W/m K ≲ Λ ≲ 33.5 W/m K and -12 × 10-6 K-1 ≲ d n / d T ≲ 14 × 10-6 K-1, respectively. The described beam deflection technique is highly related to other well-established, all-optical materials characterization methods, namely, thermal lensing and photothermal deflection spectroscopy. Likewise, due to its all-optical, pump-probe nature, it is applicable to materials characterization in extreme environments with minimal errors due to black-body radiation. In addition, the measurement principle can be extended over a broad range of electromagnetic wavelengths (e.g., ultraviolet to THz) provided the required sources, detectors, and focusing elements are available.

  17. Method of optical coherence tomography with parallel depth-resolved signal reception and fibre-optic phase modulators

    SciTech Connect

    Morozov, A N; Turchin, I V

    2013-12-31

    The method of optical coherence tomography with the scheme of parallel reception of the interference signal (P-OCT) is developed on the basis of spatial paralleling of the reference wave by means of a phase diffraction grating producing the appropriate time delay in the Mach–Zehnder interferometer. The absence of mechanical variation of the optical path difference in the interferometer essentially reduces the time required for 2D imaging of the object internal structure, as compared to the classical OCT that uses the time-domain method of the image construction, the sensitivity and the dynamic range being comparable in both approaches. For the resulting field of the interfering object and reference waves an analytical expression is derived that allows the calculation of the autocorrelation function in the plane of photodetectors. For the first time a method of linear phase modulation by 2π is proposed for P-OCT systems, which allows the use of compact high-frequency (a few hundred kHz) piezoelectric cell-based modulators. For the demonstration of the P-OCT method an experimental setup was created, using which the images of the inner structure of biological objects at the depth up to 1 mm with the axial spatial resolution of 12 μm were obtained. (optical coherence tomography)

  18. [A reflection interference method for determining optical constants and thickness of a thin solid film].

    PubMed

    Yang, P; Xu, Z; Xu, L

    2000-06-01

    In this paper we report a simple method for deducing optical constants and thickness from the reflection interference spectrum of a thin transparent film which is on a substrate of high reflection coefficient. When a light beam is incident on the surface of the film, the reflection light beams at the front and rear faces are coherent. We calculated the optical constants and thickness of the film from the reflection spectrum. This simple method makes a directly programmable calculation possible.

  19. Practical Methods for Molecular In Vivo Optical Imaging.

    PubMed

    Chen, Hannah; Thorne, Stephen H

    2012-01-01

    Traditional approaches for translating observations of molecular events into the context of a living organism have suffered from the requirements for either sacrificing animals at multiple time points prior to labor-intensive analyses of multiple tissues, or have relied on subjective observations or measurements of the animals over time. Recently an explosion of dedicated animal imaging modalities and the release of modified clinical imaging devices dedicated for animal imaging have allowed for the design of quantitative real time experiments incorporating fewer animals and providing whole animal analyses. Of these modalities, optical imaging (bioluminescence and fluorescence) has emerged as a powerful research tool, allowing investigators with limited whole animal imaging expertise to rapidly and inexpensively translate models produced in cellular assays into the context of a living animal. Here we will outline the steps necessary for translation of models established in culture systems into rodents.

  20. 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.

  1. Non-Intrusive Optical Diagnostic Methods for Flowfield Characterization

    NASA Technical Reports Server (NTRS)

    Tabibi, Bagher M.; Terrell, Charles A.; Spraggins, Darrell; Lee, Ja. H.; Weinstein, Leonard M.

    1997-01-01

    Non-intrusive optical diagnostic techniques such as Electron Beam Fluorescence (EBF), Laser-Induced Fluorescence (LIF), and Focusing Schlieren (FS) have been setup for high-speed flow characterization and large flowfield visualization, respectively. Fluorescence emission from the First Negative band of N2(+) with the (0,0) vibration transition (at lambda =391.44 nm) was obtained using the EBF technique and a quenching rate of N2(+)* molecules by argon gas was reported. A very high sensitivity FS system was built and applied in the High-Speed Flow Generator (HFG) at NASA LaRC. A LIF system is available at the Advanced Propulsion Laboratory (APL) on campus and a plume exhaust velocity measurement, measuring the Doppler shift from lambda = 728.7 nm of argon gas, is under way.

  2. Optical measurement methods to study dynamic behavior in MEMS

    NASA Astrophysics Data System (ADS)

    Rembe, Christian; Kant, Rishi; Muller, Richard S.

    2001-10-01

    The maturing designs of moving microelectromechanical systems (MEMS) make it more-and-more important to have precise measurements and visual means to characterize dynamic microstructures. The Berkeley Sensor&Actuator Center (BSAC) has a forefront project aimed at developing these capabilities and at providing high-speed Internet (Supernet) access for remote use of its facilities. Already in operation are three optical-characterization tools: a stroboscopic-interferometer system, a computer-microvision system, and a laser-Doppler vibrometer. This paper describes precision and limitations of these systems and discusses their further development. In addition, we describe the results of experimental studies on the different MEMS devices, and give an overview about high-speed visualization of rapidly moving MEMS structures.

  3. Method of making an integral window hermetic fiber optic component

    DOEpatents

    Dalton, R.D.; Kramer, D.P.; Massey, R.T.; Waker, D.A.

    1996-11-12

    In the fabrication of igniters, actuators, detonators, and other pyrotechnic devices to be activated by a laser beam, an integral optical glass window is formed by placing a preform in the structural member of the device and then melting the glass and sealing it in place by heating at a temperature between the ceramming temperature of the glass and the melting point of the metal, followed by rapid furnace cooling to avoid devitrification. No other sealing material is needed to achieve hermeticity. A preferred embodiment of this type of device is fabricated by allowing the molten glass to flow further and form a plano-convex lens integral with and at the bottom of the window. The lens functions to decrease the beam divergence caused by refraction of the laser light passing through the window when the device is fired by means of a laser beam. 9 figs.

  4. Method of making an integral window hermetic fiber optic component

    DOEpatents

    Dalton, Rick D.; Kramer, Daniel P.; Massey, Richard T.; Waker, Damon A.

    1996-11-12

    In the fabrication of igniters, actuators, detonators, and other pyrotechnic devices to be activated by a laser beam, an integral optical glass window is formed by placing a preform in the structural member of the device and then melting the glass and sealing it in place by heating at a temperature between the ceramming temperature of the glass and the melting point of the metal, followed by rapid furnace cooling to avoid devitrification. No other sealing material is needed to achieve hermeticity. A preferred embodiment of this type of device is fabricated by allowing the molten glass to flow further and form a plano-convex lens integral with and at the bottom of the window. The lens functions to decrease the beam divergence caused by refraction of the laser light passing through the window when the device is fired by means of a laser beam.

  5. Optical method for the screening of doping substances

    NASA Astrophysics Data System (ADS)

    Lademann, J.; Shevtsova, J.; Patzelt, A.; Richter, H.; Gladkowa, N. D.; Gelikonov, V. M.; Gonchukov, S. A.; Sterry, W.; Blume-Peytavi, U.

    2008-12-01

    During the last years, an increased misuse of doping substances in sport has been observed. The action of doping substances characterized by the stimulation of blood flow and metabolic processes is also reflected in the hair structure. In the present study it was demonstrated that optical coherent tomography is well suited for the analysis of hair parameters influenced by doping. Analyzing 20 patients, systemically treated with steroids which also represent doping substances, it was found that in all cases a significant increase in the cross-section of the hairs could be detected. The results obtained in the study are not only important for the screening of doping substances but also for medical diagnostics and control of compliance of patients.

  6. Anti-aliasing optical method for Shack Hartmann WFSs

    NASA Astrophysics Data System (ADS)

    Herriot, Glen; Véran, Jean-Pierre

    2016-07-01

    Measurement errors due to aliasing in a Shack-Hartmann WFS are typically 40% larger in variance than the fitting error of an AO system. On bright stars, aliasing is the dominant error within the control radius of the deformable mirror. Wavefront spatial frequencies beyond the WFS' Nyquist frequency corrupt measurements below this frequency. A common misconception is to think that aliasing primarily affects the higher spatial frequency measurements. But in fact aliasing propagates to the lowest order modes, and corrupts even tip/tilt. There are many examples including the observation that the temporal power spectrum of measured tip/tilt from a WFS does not correspond to Kolmogorov theory. We propose a simple optical modification to a SH WFS (borrowed from the digital video camera industry), and present simulation results showing that the aliasing errors are reduced.

  7. Practical Methods for Molecular In Vivo Optical Imaging

    PubMed Central

    Chen, Hannah; Thorne, Stephen H

    2011-01-01

    Traditional approaches for translating observations of molecular events into the context of a living organism have suffered from the requirements for either sacrificing animals at multiple time points prior to labor-intensive analyses of multiple tissues, or have relied on subjective observations or measurements of the animals over time. Recently an explosion of dedicated animal imaging modalities and the release of modified clinical imaging devices dedicated for animal imaging have allowed for the design of quantitative real time experiments incorporating fewer animals and providing whole animal analyses. Of these modalities, optical imaging (bioluminescence and fluorescence) has emerged as a powerful research tool, allowing investigators with limited whole animal imaging expertise to rapidly and inexpensively translate models produced in cellular assays into the context of a living animal. Here we will outline the steps necessary for translation of models established in culture systems into rodents. PMID:25419262

  8. Methods and optical fibers that decrease pulse degradation resulting from random chromatic dispersion

    DOEpatents

    Chertkov, Michael; Gabitov, Ildar

    2004-03-02

    The present invention provides methods and optical fibers for periodically pinning an actual (random) accumulated chromatic dispersion of an optical fiber to a predicted accumulated dispersion of the fiber through relatively simple modifications of fiber-optic manufacturing methods or retrofitting of existing fibers. If the pinning occurs with sufficient frequency (at a distance less than or are equal to a correlation scale), pulse degradation resulting from random chromatic dispersion is minimized. Alternatively, pinning may occur quasi-periodically, i.e., the pinning distance is distributed between approximately zero and approximately two to three times the correlation scale.

  9. CHRONICLE: Fourth Scientific and Technical Conference on Optical Methods for Flow Diagnostics

    NASA Astrophysics Data System (ADS)

    Zubov, Vladimir A.; Rinkevichius, Bronyus S.

    1997-12-01

    A review is given of the papers presented at the Fourth Scientific and Technical Conference on Optical Methods for Flow Diagnostics. This conference was concerned with research and applications in the field of flow diagnostics and with related physical and technical topics, such as determination and visualisation of optical and dynamic characteristics of media, creation and monitoring of local directional precision displacements, local measurements and determination of the spatial distribution of optical inhomogeneities in transparent media, as well as a number of practical applications of new methods and techniques.

  10. Simple wide-range method for angle measurement with a point fiber-optic output.

    PubMed

    Ilev, I; Kumagai, H; Toyoda, K

    1997-01-01

    We propose a simple optical method for precise, wide-range angle measurement based on the use of a single-mode optical fiber as a registration scheme output. Because of its micrometric core dimensions, the fiber serves as a point receiver that is highly sensitive to angular displacements of focused laser emission. The method allows the independent photoelectric measurement of both rotation and spatial angles of various optical elements, combining a wide angular dynamic range (from 0 degrees to 360 degrees ) with high accuracy (exceeding 3 arcsec).

  11. A review on self-reference wavefront methods in optical testing

    NASA Astrophysics Data System (ADS)

    Cornejo-Rodríguez, Alejandro; Granados-Agustín, Fermín. S.

    2013-11-01

    For the testing of components and optical systems, there are diverse methods with different characteristics each one; in the presentation will be done a review of some of them, that can be classified as optical testing techniques, using a self-reference wavefront. Some examples are the lateral shearing interferometers (Bates, Ronchi, Murty), point diffraction interferometer (Linnik), Burch's scattering interferometer, and the knife edge interferometer. Some advantages of such self-reference methods is the fact that are not necessary optical reference surfaces; and usually the light interfering beams have common paths, that implies that the set up is not affected by environment vibrations and other effects.

  12. Power-efficient method for IM-DD optical transmission of multiple OFDM signals.

    PubMed

    Effenberger, Frank; Liu, Xiang

    2015-05-18

    We propose a power-efficient method for transmitting multiple frequency-division multiplexed (FDM) orthogonal frequency-division multiplexing (OFDM) signals in intensity-modulation direct-detection (IM-DD) optical systems. This method is based on quadratic soft clipping in combination with odd-only channel mapping. We show, both analytically and experimentally, that the proposed approach is capable of improving the power efficiency by about 3 dB as compared to conventional FDM OFDM signals under practical bias conditions, making it a viable solution in applications such as optical fiber-wireless integrated systems where both IM-DD optical transmission and OFDM signaling are important.

  13. Optical Method for Detecting Displacements and Strains at Ultra-High Temperatures During Thermo-Mechanical Testing

    NASA Technical Reports Server (NTRS)

    Smith, Russell W. (Inventor); Rivers, H. Kevin (Inventor); Sikora, Joseph G. (Inventor); Roth, Mark C. (Inventor); Johnston, William M. (Inventor)

    2016-01-01

    An ultra-high temperature optical method incorporates speckle optics for sensing displacement and strain measurements well above conventional measurement techniques. High temperature pattern materials are used which can endure experimental high temperature environments while simultaneously having a minimum optical aberration. A purge medium is used to reduce or eliminate optical distortions and to reduce, and/or eliminate oxidation of the target specimen.

  14. Application of optical methods in the monitoring of traumatic brain injury: A review

    PubMed Central

    Milej, Daniel; Janusek, Dariusz; Wojtkiewicz, Stanisław; Sawosz, Piotr; Kacprzak, Michał; Gerega, Anna; Maniewski, Roman; Liebert, Adam

    2016-01-01

    We present an overview of the wide range of potential applications of optical methods for monitoring traumatic brain injury. The MEDLINE database was electronically searched with the following search terms: “traumatic brain injury,” “head injury,” or “head trauma,” and “optical methods,” “NIRS,” “near-infrared spectroscopy,” “cerebral oxygenation,” or “cerebral oximetry.” Original reports concerning human subjects published from January 1980 to June 2015 in English were analyzed. Fifty-four studies met our inclusion criteria. Optical methods have been tested for detection of intracranial lesions, monitoring brain oxygenation, assessment of brain perfusion, and evaluation of cerebral autoregulation or intracellular metabolic processes in the brain. Some studies have also examined the applicability of optical methods during the recovery phase of traumatic brain injury . The limitations of currently available optical methods and promising directions of future development are described in this review. Considering the outstanding technical challenges, the limited number of patients studied, and the mixed results and opinions gathered from other reviews on this subject, we believe that optical methods must remain primarily research tools for the present. More studies are needed to gain confidence in the use of these techniques for neuromonitoring of traumatic brain injury patients. PMID:27604312

  15. A polarization measurement method for the quantification of retardation in optic nerve fiber layer

    NASA Astrophysics Data System (ADS)

    Fukuma, Yasufumi; Okazaki, Yoshio; Shioiri, Takashi; Iida, Yukio; Kikuta, Hisao; Ohnuma, Kazuhiko

    2008-02-01

    The thickness measurement of the optic nerve fiber layer is one of the most important evaluations for carrying out glaucoma diagnosis. Because the optic nerve fiber layer has birefringence, the thickness can be measured by illuminating eye optics with circular polarized light and analyzing the elliptical rate of the detected polarized light reflected from the optic nerve fiber layer. In this method, the scattering light from the background and the retardation caused by the cornea disturbs the precise measurement. If the Stokes vector expressing the whole state of polarization can be detected, we can eliminate numerically the influence of the background scattering and of the retardation caused by the cornea. Because the retardation process of the eye optics can be represented by a numerical equation using the retardation matrix of each component and also the nonpolarized background scattering light, it can be calculated by using the Stokes vector. We applied a polarization analysis system that can detect the Stokes vector onto the fundus camera. The polarization analysis system is constructed with a CCD area image sensor, a linear polarizing plate, a micro phase plate array, and a circularly polarized light illumination unit. With this simply constructed system, we can calculate the retardation caused only by the optic nerve fiber layer and it can predict the thickness of the optic nerve fiber layer. We report the method and the results graphically showing the retardation of the optic nerve fiber layer without the retardation of the cornea.

  16. A FrFT based method for measuring chromatic dispersion and SPM in optical fibers

    NASA Astrophysics Data System (ADS)

    Yang, Aiying; Liu, Xiang; Chen, Xiaoyu

    2017-03-01

    A fractional Fourier transformation based method is proposed to blindly estimate the chromatic dispersion and self phase modulation in optical fibers. The experimental results demonstrate that up to 20,000 ps/nm accumulative chromatic dispersion of a fiber link is measured with the error less than 0.8%. If the chromatic dispersion is compensated by multiplying an opposite chromatic dispersion function in frequency domain, the 1st order chirp parameter caused by SPM in an optical fiber communication system can be measured by fractional Fourier transformation based method, i.e. the accumulative SPM of a fiber link can be quantitatively measured. The results of equalizing chromatic dispersion and self phase modulation in an optical fiber communication system demonstrated that the FrFT based method is promising to blindly monitor and equalize the chromatic dispersion and SPM of the fiber link in an optical network with dynamical routing function.

  17. Weak scratch detection and defect classification methods for a large-aperture optical element

    NASA Astrophysics Data System (ADS)

    Tao, Xian; Xu, De; Zhang, Zheng-Tao; Zhang, Feng; Liu, Xi-Long; Zhang, Da-Peng

    2017-03-01

    Surface defects on optics cause optic failure and heavy loss to the optical system. Therefore, surface defects on optics must be carefully inspected. This paper proposes a coarse-to-fine detection strategy of weak scratches in complicated dark-field images. First, all possible scratches are detected based on bionic vision. Then, each possible scratch is precisely positioned and connected to a complete scratch by the LSD and a priori knowledge. Finally, multiple scratches with various types can be detected in dark-field images. To classify defects and pollutants, a classification method based on GIST features is proposed. This paper uses many real dark-field images as experimental images. The results show that this method can detect multiple types of weak scratches in complex images and that the defects can be correctly distinguished with interference. This method satisfies the real-time and accurate detection requirements of surface defects.

  18. Novel optical interconnect devices applying mask-transfer self-written method

    NASA Astrophysics Data System (ADS)

    Ishizawa, Nobuhiko; Matsuzawa, Yusuke; Tokiwa, Yu; Nakama, Kenichi; Mikami, Osamu

    2012-01-01

    The introduction of optical interconnect technology is expected to solve problems of conventional electric wiring. One of the promising technologies realizing optical interconnect is the self-written waveguide (SWW) technology with lightcurable resin. We have developed a new technology of the "Mask-Transfer Self-Written (MTSW)" method. This new method enables fabrication of arrayed M x N optical channels at one shot of UV-light. Using this technology, several new optical interconnect devices and connection technologies have been proposed and investigated. In this paper, first, we introduce MTSW method briefly. Next, we show plug-in alignment approach using optical waveguide plugs (OWP) and a micro-hole array (MHA) which are made of the light-curable resin. Easy and high efficiency plug-in alignment between fibers and an optoelectronic-printed wiring board (OE-PWB), between a fiber and a VCSEL, so on will be feasible. Then, we propose a new three-dimensional (3D) branch waveguide. By controlling the irradiating angle through the photomask aperture, it will be possible to fabricate 2-branch and 4-branch waveguides with a certain branch angle. The 3D branch waveguide will be very promising in the future optical interconnects and coupler devices of the multicore optical fiber.

  19. Optical inspection methods and their applications in the manufactured industrial sector: knowledge transfer to Panamanian industry

    NASA Astrophysics Data System (ADS)

    Pino, Abdiel O.; Pladellorens, Josep

    2014-07-01

    A means of facilitating the transfer of Optical inspection methods knowledge and skills from academic institutions and their research partners into Panama optics and optical research groups is described. The process involves the creation of an Integrated Knowledge Group Research (IKGR), a partnership led by Polytechnic University of Panama with the support of the SENACYT and Optics and Optometry Department, Polytechnic University of Catalonia. This paper describes the development of the Project for knowledge transfer "Implementation of a method of optical inspection of low cost for improving the surface quality of rolled material of metallic and nonmetallic industrial use", this project will develop a method for measuring the surface quality using texture analysis speckle pattern formed on the surface to be characterized. The project is designed to address the shortage of key skills in the field of precision engineering for optical applications. The main issues encountered during the development of the knowledge transfer teaching and learning are discussed, and the outcomes from the first four months of knowledge transfer activities are described. In overall summary, the results demonstrate how the Integrated Knowledge Group Research and new approach to knowledge transfer has been effective in addressing the engineering skills gap in precision optics for manufactured industrial sector.

  20. Atmospheric pollution measurement by optical cross correlation methods - A concept

    NASA Technical Reports Server (NTRS)

    Fisher, M. J.; Krause, F. R.

    1971-01-01

    Method combines standard spectroscopy with statistical cross correlation analysis of two narrow light beams for remote sensing to detect foreign matter of given particulate size and consistency. Method is applicable in studies of generation and motion of clouds, nuclear debris, ozone, and radiation belts.

  1. Efficient numerical method for analyzing optical bistability in photonic crystal microcavities.

    PubMed

    Yuan, Lijun; Lu, Ya Yan

    2013-05-20

    Nonlinear optical effects can be enhanced by photonic crystal microcavities and be used to develop practical ultra-compact optical devices with low power requirements. The finite-difference time-domain method is the standard numerical method for simulating nonlinear optical devices, but it has limitations in terms of accuracy and efficiency. In this paper, a rigorous and efficient frequency-domain numerical method is developed for analyzing nonlinear optical devices where the nonlinear effect is concentrated in the microcavities. The method replaces the linear problem outside the microcavities by a rigorous and numerically computed boundary condition, then solves the nonlinear problem iteratively in a small region around the microcavities. Convergence of the iterative method is much easier to achieve since the size of the problem is significantly reduced. The method is presented for a specific two-dimensional photonic crystal waveguide-cavity system with a Kerr nonlinearity, using numerical methods that can take advantage of the geometric features of the structure. The method is able to calculate multiple solutions exhibiting the optical bistability phenomenon in the strongly nonlinear regime.

  2. An improved image reconstruction method for optical intensity correlation Imaging

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Feng, Lingjie; Li, Xiyu

    2016-12-01

    The intensity correlation imaging method is a novel kind of interference imaging and it has favorable prospects in deep space recognition. However, restricted by the low detecting signal-to-noise ratio (SNR), it's usually very difficult to obtain high-quality image of deep space object like high-Earth-orbit (HEO) satellite with existing phase retrieval methods. In this paper, based on the priori intensity statistical distribution model of the object and characteristics of measurement noise distribution, an improved method of Prior Information Optimization (PIO) is proposed to reduce the ambiguous images and accelerate the phase retrieval procedure thus realizing fine image reconstruction. As the simulations and experiments show, compared to previous methods, our method could acquire higher-resolution images with less error in low SNR condition.

  3. Method to adjust multilayer film stress induced deformation of optics

    DOEpatents

    Mirkarimi, Paul B.; Montcalm, Claude

    2000-01-01

    A buffer-layer located between a substrate and a multilayer for counteracting stress in the multilayer. Depositing a buffer-layer having a stress of sufficient magnitude and opposite in sign reduces or cancels out deformation in the substrate due to the stress in the multilayer. By providing a buffer-layer between the substrate and the multilayer, a tunable, near-zero net stress results, and hence results in little or no deformation of the substrate, such as an optic for an extreme ultraviolet (EUV) lithography tool. Buffer-layers have been deposited, for example, between Mo/Si and Mo/Be multilayer films and their associated substrate reducing significantly the stress, wherein the magnitude of the stress is less than 100 MPa and respectively near-normal incidence (5.degree.) reflectance of over 60% is obtained at 13.4 nm and 11.4 nm. The present invention is applicable to crystalline and non-crystalline materials, and can be used at ambient temperatures.

  4. Using DFT Methods to Study Activators in Optical Materials

    DOE PAGES

    Du, Mao-Hua

    2015-08-17

    Density functional theory (DFT) calculations of various activators (ranging from transition metal ions, rare-earth ions, ns2 ions, to self-trapped and dopant-bound excitons) in phosphors and scintillators are reviewed. As a single-particle ground-state theory, DFT calculations cannot reproduce the experimentally observed optical spectra, which involve transitions between multi-electronic states. However, DFT calculations can generally provide sufficiently accurate structural relaxation and distinguish different hybridization strengths between an activator and its ligands in different host compounds. This is important because the activator-ligand interaction often governs the trends in luminescence properties in phosphors and scintillators, and can be used to search for new materials.more » DFT calculations of the electronic structure of the host compound and the positions of the activator levels relative to the host band edges in scintillators are also important for finding optimal host-activator combinations for high light yields and fast scintillation response. Mn4+ activated red phosphors, scintillators activated by Ce3+, Eu2+, Tl+, and excitons are shown as examples of using DFT calculations in phosphor and scintillator research.« less

  5. Using DFT Methods to Study Activators in Optical Materials

    SciTech Connect

    Du, Mao-Hua

    2015-08-17

    Density functional theory (DFT) calculations of various activators (ranging from transition metal ions, rare-earth ions, ns2 ions, to self-trapped and dopant-bound excitons) in phosphors and scintillators are reviewed. As a single-particle ground-state theory, DFT calculations cannot reproduce the experimentally observed optical spectra, which involve transitions between multi-electronic states. However, DFT calculations can generally provide sufficiently accurate structural relaxation and distinguish different hybridization strengths between an activator and its ligands in different host compounds. This is important because the activator-ligand interaction often governs the trends in luminescence properties in phosphors and scintillators, and can be used to search for new materials. DFT calculations of the electronic structure of the host compound and the positions of the activator levels relative to the host band edges in scintillators are also important for finding optimal host-activator combinations for high light yields and fast scintillation response. Mn4+ activated red phosphors, scintillators activated by Ce3+, Eu2+, Tl+, and excitons are shown as examples of using DFT calculations in phosphor and scintillator research.

  6. Signal digitizing system and method based on amplitude-to-time optical mapping

    DOEpatents

    Chou, Jason; Bennett, Corey V; Hernandez, Vince

    2015-01-13

    A signal digitizing system and method based on analog-to-time optical mapping, optically maps amplitude information of an analog signal of interest first into wavelength information using an amplitude tunable filter (ATF) to impress spectral changes induced by the amplitude of the analog signal onto a carrier signal, i.e. a train of optical pulses, and next from wavelength information to temporal information using a dispersive element so that temporal information representing the amplitude information is encoded in the time domain in the carrier signal. Optical-to-electrical conversion of the optical pulses into voltage waveforms and subsequently digitizing the voltage waveforms into a digital image enables the temporal information to be resolved and quantized in the time domain. The digital image may them be digital signal processed to digitally reconstruct the analog signal based on the temporal information with high fidelity.

  7. PREFACE: I International Scientific School Methods of Digital Image Processing in Optics and Photonics

    NASA Astrophysics Data System (ADS)

    Gurov, I. P.; Kozlov, S. A.

    2014-09-01

    The first international scientific school "Methods of Digital Image Processing in Optics and Photonics" was held with a view to develop cooperation between world-class experts, young scientists, students and post-graduate students, and to exchange information on the current status and directions of research in the field of digital image processing in optics and photonics. The International Scientific School was managed by: Saint Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University) - Saint Petersburg (Russia) Chernyshevsky Saratov State University - Saratov (Russia) National research nuclear University "MEPHI" (NRNU MEPhI) - Moscow (Russia) The school was held with the participation of the local chapters of Optical Society of America (OSA), the Society of Photo-Optical Instrumentation Engineers (SPIE) and IEEE Photonics Society. Further details, including topics, committees and conference photos are available in the PDF

  8. Comparing optical test methods for a lightweight primary mirror of a space-borne Cassegrain telescope

    NASA Astrophysics Data System (ADS)

    Lin, Wei-Cheng; Chang, Shenq-Tsong; Yu, Zong-Ru; Lin, Yu-Chuan; Ho, Cheng-Fong; Huang, Ting-Ming; Chen, Cheng-Huan

    2014-09-01

    A Cassegrain telescope with a 450 mm clear aperture was developed for use in a spaceborne optical remote-sensing instrument. Self-weight deformation and thermal distortion were considered: to this end, Zerodur was used to manufacture the primary mirror. The lightweight scheme adopted a hexagonal cell structure yielding a lightweight ratio of 50%. In general, optical testing on a lightweight mirror is a critical technique during both the manufacturing and assembly processes. To prevent unexpected measurement errors that cause erroneous judgment, this paper proposes a novel and reliable analytical method for optical testing, called the bench test. The proposed algorithm was used to distinguish the manufacturing form error from surface deformation caused by the mounting, supporter and gravity effects for the optical testing. The performance of the proposed bench test was compared with a conventional vertical setup for optical testing during the manufacturing process of the lightweight mirror.

  9. White-Light Whispering Gallery Mode Optical Resonator System and Method

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey B. (Inventor); Savchenkov, Anatoliy A. (Inventor); Maleki, Lute (Inventor)

    2009-01-01

    An optical resonator system and method that includes a whispering-gallery mode (WGM) optical resonator that is capable of resonating across a broad, continuous swath of frequencies is provided. The optical resonator of the system is shaped to support at least one whispering gallery mode and includes a top surface, a bottom surface, a side wall, and a first curved transition region extending between the side wall and the top surface. The system further includes a coupler having a coupling surface which is arranged to face the transition region of the optical resonator and in the vicinity thereof such that an evanescent field emitted from the coupler is capable of being coupled into the optical resonator through the first curved transition region

  10. Cleaning Verification Monitor Technique Based on Infrared Optical Methods

    DTIC Science & Technology

    2004-10-01

    Cleaning Verification Techniques.” Real-time methods to provide both qualitative and quantitative assessments of surface cleanliness are needed for a...detection VCPI method offer a wide range of complementary capabilities in real-time surface cleanliness verification. Introduction Currently...also has great potential to reduce or eliminate premature failures of surface coatings caused by a lack of surface cleanliness . Additional

  11. Fired Cartridge Case Identification Using Optical Images and the Congruent Matching Cells (CMC) Method

    PubMed Central

    Tong, Mingsi; Song, John; Chu, Wei; Thompson, Robert M

    2014-01-01

    The Congruent Matching Cells (CMC) method for ballistics identification was invented at the National Institute of Standards and Technology (NIST). The CMC method is based on the correlation of pairs of small correlation cells instead of the correlation of entire images. Four identification parameters – TCCF, Tθ, Tx and Ty are proposed for identifying correlated cell pairs originating from the same firearm. The correlation conclusion (matching or non-matching) is determined by whether the number of CMC is ≥ 6. This method has been previously validated using a set of 780 pair-wise 3D topography images. However, most ballistic images stored in current local and national databases are in an optical intensity (grayscale) format. As a result, the reliability of applying the CMC method on optical intensity images is an important issue. In this paper, optical intensity images of breech face impressions captured on the same set of 40 cartridge cases are correlated and analyzed for the validation test of CMC method using optical images. This includes correlations of 63 pairs of matching images and 717 pairs of non-matching images under top ring lighting. Tests of the method do not produce any false identification (false positive) or false exclusion (false negative) results, which support the CMC method and the proposed identification criterion, C = 6, for firearm breech face identifications using optical intensity images. PMID:26601045

  12. Structural Properties of Potexvirus Coat Proteins Detected by Optical Methods.

    PubMed

    Semenyuk, P I; Karpova, O V; Ksenofontov, A L; Kalinina, N O; Dobrov, E N; Makarov, V V

    2016-12-01

    It has been shown by X-ray analysis that cores of coat proteins (CPs) from three potexviruses, flexible helical RNA-containing plant viruses, have similar α-helical structure. However, this similarity cannot explain structural lability of potexvirus virions, which is believed to determine their biological activity. Here, we used circular dichroism (CD) spectroscopy in the far UV region to compare optical properties of CPs from three potexviruses with the same morphology and similar structure. CPs from Alternanthera mosaic virus (AltMV), potato aucuba mosaic virus (PAMV), and potato virus X (PVX) have been studied in a free state and in virions. The CD spectrum of AltMV virions was similar to the previously obtained CD spectrum of papaya mosaic virus (PapMV) virions, but differed significantly from the CD spectrum of PAMV virions. The CD spectrum of PAMV virions resembled in its basic characteristics the CD spectrum of PVX virions characterized by molar ellipticity that is abnormally low for α-helical proteins. Homology modeling of the CP structures in AltMV, PAMV, and PVX virions was based on the known high-resolution structures of CPs from papaya mosaic virus and bamboo mosaic virus and confirmed that the structures of the CP cores in all three viruses were nearly identical. Comparison of amino acid sequences of different potexvirus CPs and prediction of unstructured regions in these proteins revealed a possible correlation between specific features in the virion CD spectra and the presence of disordered N-terminal segments in the CPs.

  13. A new method for acquiring the complex hologram in optical scanning holography

    NASA Astrophysics Data System (ADS)

    Zhu, Meijuan; Dai, Enwen; Liu, Liren; Sun, Jianfeng; Wu, Yapeng; Zhou, Yu; Yan, Aimin; Zhi, Yanan

    2011-09-01

    In this paper, we propose a new method that can acquire the complex hologram of a 3D object for optical scanning holography (OSH) by using polarized optical elements and a 90 degrees 2×4 optical hybrid. The 3D object is scanned by a wave front combined by a plane and spherical wave with orthogonal polarization. The transmitted/reflected signal light is divided into two beams by a polarized beamsplitter (PBS). Then after the polarization control, the two separated beams are heterodyne detected by a 90 degrees 2×4 optical hybrid with two balanced detectors. The 3D object can be reconstructed from the complex hologram acquired from the balanced detectors. Compared with the conventional OSH, the acousto-optic modulator and complex electronic system are not needed in this method. Another advantage of this method lies in its high efficiency since there is almost no energy loss in the generation of the scanning beam by using the polarized optical elements. This method should be used for 3D holographic microscopy and 3D holographic television.

  14. Comprehensive validation scheme for in situ fiber optics dissolution method for pharmaceutical drug product testing.

    PubMed

    Mirza, Tahseen; Liu, Qian Julie; Vivilecchia, Richard; Joshi, Yatindra

    2009-03-01

    There has been a growing interest during the past decade in the use of fiber optics dissolution testing. Use of this novel technology is mainly confined to research and development laboratories. It has not yet emerged as a tool for end product release testing despite its ability to generate in situ results and efficiency improvement. One potential reason may be the lack of clear validation guidelines that can be applied for the assessment of suitability of fiber optics. This article describes a comprehensive validation scheme and development of a reliable, robust, reproducible and cost-effective dissolution test using fiber optics technology. The test was successfully applied for characterizing the dissolution behavior of a 40-mg immediate-release tablet dosage form that is under development at Novartis Pharmaceuticals, East Hanover, New Jersey. The method was validated for the following parameters: linearity, precision, accuracy, specificity, and robustness. In particular, robustness was evaluated in terms of probe sampling depth and probe orientation. The in situ fiber optic method was found to be comparable to the existing manual sampling dissolution method. Finally, the fiber optic dissolution test was successfully performed by different operators on different days, to further enhance the validity of the method. The results demonstrate that the fiber optics technology can be successfully validated for end product dissolution/release testing.

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

    DOEpatents

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

    1994-01-01

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

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

    DOEpatents

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

    1997-01-01

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

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

    DOEpatents

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

    1994-11-01

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

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

    DOEpatents

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

    1997-05-06

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

  19. Novel methods for measuring modulation transfer function for fiber optic taper

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wang, Yaoxiang; Tian, Weijian; Ma, Weihong; Zhang, Hongjian; Sun, Aijuan

    2006-01-01

    As a relay optical component, fiber optic taper has become more important and more widely used in the integrated taper assembly image intensified sensors for military and medical imaging application. However, the method for evaluating the quality of output images from the fiber optic taper is few. In this article, the Modulation Transfer Function (MTF) is introduced and measured to evaluate the image quality of fiber optic taper. Because fiber optic taper is of a mosaic array architecture, there are some new problems need to be resolved in defining MTF of it. And there also should be some special requirements in MTF measurement. Two methods including edge scanning and point imaging analyzing are introduced in measuring MTF of fiber optic taper, in which the incident light, scanning step and scanning range are specially limited. Experiments show that the results of the measurements consist with the theoretical analysis simulated by computer. And the spatial averaged MTF of fiber optic taper has been gotten by two means. It is concluded that the MTF value measured by point imaging is always some higher than measured by edge scanning, because the point imaging is more weakly effected by the fiber arrangement in taper.

  20. INSTRUMENTS AND METHODS OF INVESTIGATION: Cladding modes of optical fibers: properties and applications

    NASA Astrophysics Data System (ADS)

    Ivanov, Oleg V.; Nikitov, Sergei A.; Gulyaev, Yurii V.

    2006-02-01

    One of the new methods of fiber optics uses cladding modes for controlling propagation of radiation in optical fibers. This paper reviews the results of studies on the propagation, excitation, and interaction of cladding modes in optical fibers. The resonance between core and cladding modes excited by means of fiber Bragg gratings, including tilted ones, is analyzed. Propagation of cladding modes in microstructured fibers is considered. The most frequently used method of exciting cladding modes is described, based on the application of long-period fiber gratings. Examples are presented of long-period gratings used as sensors and gain equalizers for fiber amplifiers, as well as devices for coupling light into and out of optical fibers.

  1. A method for calculating phase-space densities in ion-optical systems

    NASA Astrophysics Data System (ADS)

    Hanelt, E.; Schmidt, K.-H.

    1992-10-01

    A method for calculating the motion of an ensemble of beam particles through an ion-optical system is presented. The collective motion of the ensemble which covers a finite phase-space volume is described by an analytical transformation of the corresponding particle density distribution in phase space. This density distribution is represented by a convolution of generating functions. It is transformed by applying the ion-optical matrix formalism tto the generating functions. Physical effects acting on the particle ensemble on its way through the ion-optical system are taken into account by additional generating functions. This method allows to calculate rare processes in ion-optical systems with low computational effort.

  2. Laser optical method of visualizing cutaneous blood vessels and its applications in biometry and photomedicine

    NASA Astrophysics Data System (ADS)

    Asimov, M. M.; Asimov, R. M.; Rubinov, A. N.

    2011-05-01

    We propose and examine a new approach to visualizing a local network of cutaneous blood vessels using laser optical methods for applications in biometry and photomedicine. Various optical schemes of the formation of biometrical information on the architecture of blood vessels of skin tissue are analyzed. We developed an optical model of the interaction of the laser radiation with the biological tissue and a mathematical algorithm of processing of measurement results. We show that, in medicine, the visualization of blood vessels makes it possible to calculate and determine regions of disturbance of blood microcirculation and to control tissue hypoxia, as well as to maintain the local concentration of oxygen at a level necessary for the normal cellular metabolism. We propose noninvasive optical methods for modern photomedicine and biometry for diagnostics and elimination of tissue hypoxia and for personality identification and verification via the pattern of cutaneous blood vessels.

  3. Stability Characterization of Quinazoline Derivative BG1188 by Optical Methods

    NASA Astrophysics Data System (ADS)

    Militaru, Andra; Smarandache, Adriana; Mahamoud, Abdallah; Damian, Victor; Ganea, Paul; Alibert, Sandrine; Pagès, Jean-Marie; Pascu, Mihail-Lucian

    2011-08-01

    3-[2-(dimethylamino)ethyl]-6-nitroquinazolin-4(3H)-one, labeled BG1188, is a new synthesized compound, out of a series of quinazoline derivatives developed to fight the multidrug resistance of antibiotics acquired by bacteria. A characterization of the BG1188 powder was made using FTIR spectra in order to evidence the functional groups in the medicine's molecule. The ultraviolet-visible (UV-Vis) absorption spectra were used to study the stability of the BG1188 solutions in two solvents and at different temperatures. BG1188 concentration in ultrapure water was varied between 2×10-3 M (stock solution) and 10-6 M. The concentration recommended by higher activity on bacteria was 10-3 M. For the same reason, this was the utilized concentration of BG1188 in dimethyl sulfoxide (DMSO). Time stability was characterized by comparing the time evolution of the UV-Vis absorption spectra of the BG1188 solutions in ultrapure de-ionized water or in DMSO. The spectra were recorded daily for about 4 months after the preparation for the BG1188 solutions in ultrapure water. Generally, samples are stable within the experimental errors at concentrations higher than 10-5 M, but the stability time interval may vary from 119 days at 10-4 M to 34 days at 10-5 M. Time evolution of the absorption spectra at 10-3 M in ultrapure water shows reproducibility within the measuring errors (±1.045%) for time intervals up to 1032 hours (more than 40 days) after preparation. On the other hand, BG1188 solutions in DMSO may be considered unstable because the absorption spectra modify in terms of peak shapes and intensities, indicating that the samples exhibit modifications immediately after preparation. Regardless the solvent used, some aggregation phenomena took place and wire-like aggregates were observed in all the solutions with the naked eye. These aggregates were analyzed, tentatively, using optical microscopy and FTIR.

  4. Imaging photorefractive optical vibration measurement method and device

    DOEpatents

    Telschow, Kenneth L.; Deason, Vance A.; Hale, Thomas C.

    2000-01-01

    A method and apparatus are disclosed for characterizing a vibrating image of an object of interest. The method includes providing a sensing media having a detection resolution within a limited bandwidth and providing an object of interest having a vibrating medium. Two or more wavefronts are provided, with at least one of the wavefronts being modulated by interacting the one wavefront with the vibrating medium of the object of interest. The another wavefront is modulated such that the difference frequency between the one wavefront and the another wavefront is within a response range of the sensing media. The modulated one wavefront and another wavefront are combined in association with the sensing media to interfere and produce simultaneous vibration measurements that are distributed over the object so as to provide an image of the vibrating medium. The image has an output intensity that is substantially linear with small physical variations within the vibrating medium. Furthermore, the method includes detecting the image. In one implementation, the apparatus comprises a vibration spectrum analyzer having an emitter, a modulator, sensing media and a detector configured so as to realize such method. According to another implementation, the apparatus comprises a vibration imaging device.

  5. Applicability of optical scanner method for fine root dynamics

    NASA Astrophysics Data System (ADS)

    Kume, Tomonori; Ohashi, Mizue; Makita, Naoki; Khoon Kho, Lip; Katayama, Ayumi; Matsumoto, Kazuho; Ikeno, Hidetoshi

    2016-04-01

    Fine root dynamics is one of the important components in forest carbon cycling, as ~60 % of tree photosynthetic production can be allocated to root growth and metabolic activities. Various techniques have been developed for monitoring fine root biomass, production, mortality in order to understand carbon pools and fluxes resulting from fine roots dynamics. The minirhizotron method is now a widely used technique, in which a transparent tube is inserted into the soil and researchers count an increase and decrease of roots along the tube using images taken by a minirhizotron camera or minirhizotron video camera inside the tube. This method allows us to observe root behavior directly without destruction, but has several weaknesses; e.g., the difficulty of scaling up the results to stand level because of the small observation windows. Also, most of the image analysis are performed manually, which may yield insufficient quantitative and objective data. Recently, scanner method has been proposed, which can produce much bigger-size images (A4-size) with lower cost than those of the minirhizotron methods. However, laborious and time-consuming image analysis still limits the applicability of this method. In this study, therefore, we aimed to develop a new protocol for scanner image analysis to extract root behavior in soil. We evaluated applicability of this method in two ways; 1) the impact of different observers including root-study professionals, semi- and non-professionals on the detected results of root dynamics such as abundance, growth, and decomposition, and 2) the impact of window size on the results using a random sampling basis exercise. We applied our new protocol to analyze temporal changes of root behavior from sequential scanner images derived from a Bornean tropical forests. The results detected by the six observers showed considerable concordance in temporal changes in the abundance and the growth of fine roots but less in the decomposition. We also examined

  6. Organic crystalline films for optical applications and related methods of fabrication

    NASA Technical Reports Server (NTRS)

    Leyderman, Alexander (Inventor); Cui, Yunlong (Inventor)

    2003-01-01

    The present invention provides organic single crystal films of less than 20 .mu.m, and devices and methods of making such films. The crystal films are useful in electro-optical applications and can be provided as part of an electro-optical device which provides strength, durability, and relative ease of manipulation of the mono-crystalline films during and after crystal growth.

  7. A new method for determining the plasma electron density using optical frequency comb interferometer

    SciTech Connect

    Arakawa, Hiroyuki Tojo, Hiroshi; Sasao, Hajime; Kawano, Yasunori; Itami, Kiyoshi

    2014-04-15

    A new method of plasma electron density measurement using interferometric phases (fractional fringes) of an optical frequency comb interferometer is proposed. Using the characteristics of the optical frequency comb laser, high density measurement can be achieved without fringe counting errors. Simulations show that the short wavelength and wide wavelength range of the laser source and low noise in interferometric phases measurements are effective to reduce ambiguity of measured density.

  8. Apparatus and Method for Measuring Strain in Optical Fibers using Rayleigh Scatter

    NASA Technical Reports Server (NTRS)

    Froggatt, Mark E. (Inventor); Moore, Jason P. (Inventor)

    2003-01-01

    An apparatus and method for measuring strain in an optical fiber using the spectral shift of Rayleigh scattered light. The interference pattern produced by an air gap reflector and backscattered radiation is measured. Using Fourier Transforms, the spectrum of any section of fiber can be extracted. Cross correlation with an unstrained measurement produces a correlation peak. The location of the correlation peak indicates the strain level in the selected portion of optical fiber.

  9. Method of bistable optical information storage using antiferroelectric phase PLZT ceramics

    DOEpatents

    Land, Cecil E.

    1990-01-01

    A method for bistable storage of binary optical information includes an antiferroelectric (AFE) lead lanthanum zirconate titanate (PLZT) layer having a stable antiferroelectric first phase and a ferroelectric (FE) second phase obtained by applying a switching electric field across the surface of the device. Optical information is stored by illuminating selected portions of the layer to photoactivate an FE to AFE transition in those portions. Erasure of the stored information is obtained by reapplying the switching field.

  10. Method of bistable optical information storage using antiferroelectric phase PLZT ceramics

    DOEpatents

    Land, C.E.

    1990-07-31

    A method for bistable storage of binary optical information includes an antiferroelectric (AFE) lead lanthanum zirconate titanate (PLZT) layer having a stable antiferroelectric first phase and a ferroelectric (FE) second phase obtained by applying a switching electric field across the surface of the device. Optical information is stored by illuminating selected portions of the layer to photoactivate an FE to AFE transition in those portions. Erasure of the stored information is obtained by reapplying the switching field. 8 figs.

  11. Optical methods in the study of protein-protein interactions.

    PubMed

    Masi, Alessio; Cicchi, Riccardo; Carloni, Adolfo; Pavone, Francesco Saverio; Arcangeli, Annarosa

    2010-01-01

    Förster (or Fluorescence) resonance energy transfer (FRET) is a physical process in which energy is transferred nonradiatively from an excited fluorophore, serving as a donor, to another chromophore (acceptor). Among the techniques related to fluorescence microscopy, FRET is unique in providing signals sensitive to intra- and intermolecular distances in the 1-10 nm range. Because of its potency, FRET is increasingly used to visualize and quantify the dynamics of protein-protein interaction in living cells, with high spatio-temporal resolution. Here we describe the physical bases of FRET, detailing the principal methods applied: (1) measurement of signal intensity and (2) analysis of fluorescence lifetime (FLIM). Although several technical complications must be carefully considered, both methods can be applied fruitfully to specific fields. For example, FRET based on intensity detection is more suitable to follow biological phenomena at a finely tuned spatial and temporal scale. Furthermore, a specific fluorescence signal occurring close to the plasma membrane (< or = 100 nm) can be obtained using a total internal reflection fluorescence (TIRF) microscopy system. When performing FRET experiments, care must be also taken to the method chosen for labeling interacting proteins. Two principal tools can be applied: (1) fluorophore tagged antibodies; (2) recombinant fluorescent fusion proteins. The latter method essentially takes advantage of the discovery and use of spontaneously fluorescent proteins, like the green fluorescent protein (GFP). Until now, FRET has been widely used to analyze the structural characteristics of several proteins, including integrins and ion channels. More recently, this method has been applied to clarify the interaction dynamics of these classes of membrane proteins with cytosolic signaling proteins. We report two examples in which the interaction dynamics between integrins and ion channels have been studied with FRET methods. Using

  12. A method of rapidly evaluating image quality of NED optical system

    NASA Astrophysics Data System (ADS)

    Sun, Qi; Qiu, Chuankai; Yang, Huan

    2014-11-01

    In recent years, with the development of technology of micro-display, advanced optics and the software and hardware, near-to-eye display ( NED) optical system will have a wide range of potential applications in the fields of amusement and virtual reality. However, research on the evaluating image quality of this kind optical system is comparatively lagging behind. Although now there are some methods and equipment for evaluation, they can't be applied in commercial production because of their complex operation and inaccuracy. In this paper, an academic method is proposed and a Rapid Evaluation System (RES) is designed to evaluate the image of optical system rapidly and exactly. Firstly, a set of parameters that eyes are sensitive to and also express the quality of system should be extracted and quantized to be criterion, so the evaluation standards can be established. Then, some parameters can be detected by RES consisted of micro-display, CCD camera and computer and so on. By process of scaling, the measuring results of the RES are exact and creditable, relationship between object measurement, subjective evaluation and the RES will be established. After that, image quality of optical system can be evaluated just by detecting parameters of that. The RES is simple and the results of evaluation are exact and keeping with human vision. So the method can be used not only for optimizing design of optical system, but also for evaluation in commercial production.

  13. Modeling hemoglobin at optical frequency using the unconditionally stable fundamental ADI-FDTD method.

    PubMed

    Heh, Ding Yu; Tan, Eng Leong

    2011-04-12

    This paper presents the modeling of hemoglobin at optical frequency (250 nm - 1000 nm) using the unconditionally stable fundamental alternating-direction-implicit finite-difference time-domain (FADI-FDTD) method. An accurate model based on complex conjugate pole-residue pairs is proposed to model the complex permittivity of hemoglobin at optical frequency. Two hemoglobin concentrations at 15 g/dL and 33 g/dL are considered. The model is then incorporated into the FADI-FDTD method for solving electromagnetic problems involving interaction of light with hemoglobin. The computation of transmission and reflection coefficients of a half space hemoglobin medium using the FADI-FDTD validates the accuracy of our model and method. The specific absorption rate (SAR) distribution of human capillary at optical frequency is also shown. While maintaining accuracy, the unconditionally stable FADI-FDTD method exhibits high efficiency in modeling hemoglobin.

  14. A surface intrinsic feature based method (SIFBM) for the characterization of optical microstructure

    NASA Astrophysics Data System (ADS)

    Cheung, C. F.; Kong, L. B.; Lee, W. B.; To, S.

    2008-12-01

    Optical microstructures are small scale topologies which are generally classified as grooves, pyramids, microlens arrays, lenticulations, echells, etc. They are widely used in advanced optics applications. Currently, there is lack of methods for the characterization of surface quality for optical microstructures with sub-micromenter form accuracy and surface finish in the nanometer range. This paper presents a Surface Intrinsic Feature Based Method (SIFBM) which makes use of surface intrinsic properties such as curvatures, normal vectors, torsion, intrinsic frames, etc. They are mapped as special images and image processing techniques are then employed to conduct image registration or correspondences searching by some algorithms such as correlation functions. The surface matching is optimized by corresponding vectors deviations. In the present study, a prototype surface characterization system has been built based on the SIFBM. Primary experimental work has been conducted to validate the proposed method. The results demonstrate that the SIFBM has potential advantages over existing methods.

  15. Study of linear and nonlinear optical properties of dendrimers using density matrix renormalization group method

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.; Ramasesha, S.

    2009-08-01

    We have used the density matrix renormalization group (DMRG) method to study the linear and nonlinear optical responses of first generation nitrogen based dendrimers with donor acceptor groups. We have employed Pariser-Parr-Pople Hamiltonian to model the interacting π electrons in these systems. Within the DMRG method we have used an innovative scheme to target excited states with large transition dipole to the ground state. This method reproduces exact optical gaps and polarization in systems where exact diagonalization of the Hamiltonian is possible. We have used a correction vector method which tacitly takes into account the contribution of all excited states, to obtain the ground state polarizibility, first hyperpolarizibility, and two photon absorption cross sections. We find that the lowest optical excitations as well as the lowest excited triplet states are localized. It is interesting to note that the first hyperpolarizibility saturates more rapidly with system size compared to linear polarizibility unlike that of linear polyenes.

  16. Modeling hemoglobin at optical frequency using the unconditionally stable fundamental ADI-FDTD method

    PubMed Central

    Heh, Ding Yu; Tan, Eng Leong

    2011-01-01

    This paper presents the modeling of hemoglobin at optical frequency (250 nm – 1000 nm) using the unconditionally stable fundamental alternating-direction-implicit finite-difference time-domain (FADI-FDTD) method. An accurate model based on complex conjugate pole-residue pairs is proposed to model the complex permittivity of hemoglobin at optical frequency. Two hemoglobin concentrations at 15 g/dL and 33 g/dL are considered. The model is then incorporated into the FADI-FDTD method for solving electromagnetic problems involving interaction of light with hemoglobin. The computation of transmission and reflection coefficients of a half space hemoglobin medium using the FADI-FDTD validates the accuracy of our model and method. The specific absorption rate (SAR) distribution of human capillary at optical frequency is also shown. While maintaining accuracy, the unconditionally stable FADI-FDTD method exhibits high efficiency in modeling hemoglobin. PMID:21559129

  17. Method for determiantion of the frequency-contrast characteristics of electronic-optic systems

    NASA Astrophysics Data System (ADS)

    Mardirossian, Garo; Zhekov, Zhivko

    The frequency-contrast characteristics is an important criterion to judge the quality of electronic-optic systems, which boast an increasing application in space research, astronomy, martial art etc. The paper provides a brief description of the methods for determining the frequency-contrast characteristics of optic systems, developed at the Space Research Institute of the Bulgarian Academy of Science. The suggested methods have been used to develop a couple of electronic-optic systems participated in the designed ground-based and aerospace scientific-research equipment. Based on the obtained practical results, the conclusion was made that the methods provide to obtain sufficiently precise data, which coincide well with the results, obtained when using other methods.

  18. Study of linear and nonlinear optical properties of dendrimers using density matrix renormalization group method.

    PubMed

    Mukhopadhyay, S; Ramasesha, S

    2009-08-21

    We have used the density matrix renormalization group (DMRG) method to study the linear and nonlinear optical responses of first generation nitrogen based dendrimers with donor acceptor groups. We have employed Pariser-Parr-Pople Hamiltonian to model the interacting pi electrons in these systems. Within the DMRG method we have used an innovative scheme to target excited states with large transition dipole to the ground state. This method reproduces exact optical gaps and polarization in systems where exact diagonalization of the Hamiltonian is possible. We have used a correction vector method which tacitly takes into account the contribution of all excited states, to obtain the ground state polarizibility, first hyperpolarizibility, and two photon absorption cross sections. We find that the lowest optical excitations as well as the lowest excited triplet states are localized. It is interesting to note that the first hyperpolarizibility saturates more rapidly with system size compared to linear polarizibility unlike that of linear polyenes.

  19. Non-focusing optics spectrophotometer, and methods of use

    DOEpatents

    Kramer, David M.; Sacksteder, Colette A.

    2004-11-02

    In one aspect, the present invention provides kinetic spectrophotometers that each comprise: (a) a light source; and (b) a compound parabolic concentrator disposed to receive light from the light source and configured to (1) intensify and diffuse the light received from the light source, and (2) direct the intensified and diffused light onto a sample. In other aspects, the present invention provides methods for measuring a photosynthetic parameter, the methods comprising the steps of: (a) illuminating a plant leaf until steady-state photosynthesis is achieved; (b) subjecting the illuminated plant leaf to a period of darkness; (c) using a kinetic spectrophotometer of the invention to collect spectral data from the plant leaf treated in accordance with steps (a) and (b); and (d) determining a value for a photosynthetic parameter from the spectral data.

  20. A method for studying the effects of thermal deformations on optical systems for space application

    NASA Astrophysics Data System (ADS)

    Segato, Elisa; Da Deppo, Vania; Debei, Stefano; Cremonese, Gabriele

    2010-04-01

    Optical instruments for space missions work in hostile environment, it's thus necessary to accurately study the effects of ambient parameters variations on the equipment performance. In particular, optical instruments are very sensitive to ambient conditions, especially temperature. This variable can cause dilatation and misalignment of the optical elements, and can also lead to rise of dangerous stresses in the optics. Optical elements displacements and surface deformations degrade the quality of the sampled images. In this work a method for simulating and studying the effects of the thermal deformations, particularly the impact on the expected optical performance, is presented. Optical elements and their mountings are modelled and processed by a thermo-mechanical Finite Element Model (FEM) analysis, reproducing expected operative conditions. The FEM output is elaborated into a MATLAB optimisation code; a non-linear least square algorithm is used to determine the equation of the best fitting nth degree polynomial, or the spherical surface of the deformed lenses and mirrors; model accuracy is 10-8 m. The obtained mathematical surface representations are then directly imported into ZEMAX raytracing software for sequential raytrace analysis. The results are spot diagrams, chief ray coordinates on the detector, MTF curves and Diffraction Encircled Energy variations due to simulated thermal loads. This analysis helps to design and compare different optical housing systems for finding a feasible mounting solution. The described method has been applied successfully to the optics and mountings of a stereo-camera for the BepiColombo mission. Different types of lenses and prisms constraints have been designed and analysed. The results show the preferable use of kinematic constraints, instead of using glue, to correctly maintain the instrument focus in orbit around Mercury considering an operative temperature range between -20°C and +30°C.

  1. Reliable clarity automatic-evaluation method for optical remote sensing images

    NASA Astrophysics Data System (ADS)

    Qin, Bangyong; Shang, Ren; Li, Shengyang; Hei, Baoqin; Liu, Zhiwen

    2015-10-01

    Image clarity, which reflects the sharpness degree at the edge of objects in images, is an important quality evaluate index for optical remote sensing images. Scholars at home and abroad have done a lot of work on estimation of image clarity. At present, common clarity-estimation methods for digital images mainly include frequency-domain function methods, statistical parametric methods, gradient function methods and edge acutance methods. Frequency-domain function method is an accurate clarity-measure approach. However, its calculation process is complicate and cannot be carried out automatically. Statistical parametric methods and gradient function methods are both sensitive to clarity of images, while their results are easy to be affected by the complex degree of images. Edge acutance method is an effective approach for clarity estimate, while it needs picking out the edges manually. Due to the limits in accuracy, consistent or automation, these existing methods are not applicable to quality evaluation of optical remote sensing images. In this article, a new clarity-evaluation method, which is based on the principle of edge acutance algorithm, is proposed. In the new method, edge detection algorithm and gradient search algorithm are adopted to automatically search the object edges in images. Moreover, The calculation algorithm for edge sharpness has been improved. The new method has been tested with several groups of optical remote sensing images. Compared with the existing automatic evaluation methods, the new method perform better both in accuracy and consistency. Thus, the new method is an effective clarity evaluation method for optical remote sensing images.

  2. Design of diffractive optical surfaces within the nonimaging SMS design method

    NASA Astrophysics Data System (ADS)

    Mendes-Lopes, João.; Benítez, Pablo; Miñano, Juan C.

    2015-09-01

    The Simultaneous Multiple Surface (SMS) method was initially developed as a design method in Nonimaging Optics and later, the method was extended for designing Imaging Optics. We show an extension of the SMS method to diffractive surfaces. Using this method, diffractive kinoform surfaces are calculated simultaneously and through a direct method, i. e. it is not based in multi-parametric optimization techniques. Using the phase-shift properties of diffractive surfaces as an extra degree of freedom, only N/2 surfaces are needed to perfectly couple N one parameter wavefronts. Wavefronts of different wavelengths can also be coupled, hence chromatic aberration can be corrected in SMS-based systems. This method can be used by combining and calculating simultaneously both reflective, refractive and diffractive surfaces, through direct calculation of phase and refractive/reflective profiles. Representative diffractive systems designed by the SMS method are presented.

  3. Simply scan--optical methods for elemental carbon measurement in diesel exhaust particulate.

    PubMed

    Forder, James A

    2014-08-01

    This article describes a performance assessment of three optical methods, a Magee Scientific OT21 Transmissometer, a Hach-Lange Microcolor II difference gloss meter, and a combination of an office scanner with Adobe Photoshop software. The optical methods measure filter staining as a proxy for elemental carbon in diesel exhaust particulate (DEP) exposure assessment and the suitability of each as a replacement for the existing Bosch meter optical method. Filters loaded with DEP were produced from air in a non-coal mine and the exhaust gases from a mobile crane. These were measured with each apparatus and then by combustion to obtain a reference elemental carbon value. The results from each apparatus were then plotted against both the Bosch number and reference elemental carbon values. The equations of the best fit lines for these plots were derived, and these gave functions for elemental carbon and Bosch number from the output of each new optical method. For each optical method, the range of DEP loadings which can be measured has been determined, and conversion equations for elemental carbon and Bosch number have been obtained. All three optical methods studied will effectively quantify blackness as a measure of elemental carbon. Of these the Magee Scientific OT21 transmissometer has the best performance. The Microcolor II and scanner/photoshop methods will in addition allow conversion to Bosch number which may be useful if historical Bosch data are available and functions for this are described. The scanner/photoshop method demonstrates a technique to obtain measurements of DEP exposure without the need to purchase specialized instrumentation.

  4. Optical Methods For Transient Plasmas Studies By Multichannel TEA Nitrogen Laser

    NASA Astrophysics Data System (ADS)

    Ursu, Ioan; Popescu, Ion M.; Ivascu, M.; Baltog, I.; Mihut, L.; Zambreanu, V.; Zoita, V.

    1989-05-01

    A multichannel TEA nitrogen laser has been realized for some optical diagnostics. The following methods have been applied on the plasma focus device (PFD): interferometry, schlieren, shadowgraphy and a new combination of the last two. The background of these methods and some qualitative and quantitative results obtained in plasma focus (PF) studies are presented.

  5. Method for spatially modulating X-ray pulses using MEMS-based X-ray optics

    DOEpatents

    Lopez, Daniel; Shenoy, Gopal; Wang, Jin; Walko, Donald A.; Jung, Il-Woong; Mukhopadhyay, Deepkishore

    2015-03-10

    A method and apparatus are provided for spatially modulating X-rays or X-ray pulses using microelectromechanical systems (MEMS) based X-ray optics. A torsionally-oscillating MEMS micromirror and a method of leveraging the grazing-angle reflection property are provided to modulate X-ray pulses with a high-degree of controllability.

  6. Acousto-Optic Tunable Filter Hyperspectral Microscope Imaging Method for Characterizing Spectra from Foodborne Pathogens.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral microscope imaging (HMI) method, which provides both spatial and spectral characteristics of samples, can be effective for foodborne pathogen detection. The acousto-optic tunable filter (AOTF)-based HMI method can be used to characterize spectral properties of biofilms formed by Salmon...

  7. Method for studying the phase function in tunable diffraction optical elements

    SciTech Connect

    Paranin, V D; Tukmakov, K N

    2014-04-28

    A method for studying the phase function in tunable diffraction optical elements is proposed, based on measurement of the transmission of interelectrode gaps. The mathematical description of the method, which is approved experimentally, is developed. The instrumental error effects are analysed. (laser applications and other topics in quantum electronics)

  8. Measurement of Black (BC) and Elemental (EC) Carbon by an Optical and a Thermal- optical Method: An Intercomparison

    NASA Astrophysics Data System (ADS)

    Ahmed, T.; Dutkiewicz, V. A.; Khan, A. R.; Husain, L.

    2009-05-01

    Elemental or Black carbon (EC or BC) aerosol emitted into the atmosphere from incomplete combustion of fossil fuel, biomass and forest fires absorbs solar radiations and contributes to global warming. EC or BC is defined based on different analytical methods used for measuring the same fraction of carbonaceous aerosol. The different methods give different results which can vary widely. There is no accepted standard available to accurately quantify EC and therefore measurements between different methods need to be compared to reduce the bias. In this study intercomparison of data between two widely used techniques, BC obtained using optical method (non-destructive technique) and EC obtained using thermal-optical methods (destructive technique) are performed on aerosol samples collected on Whatman 41 filter paper from two rural sites, Whiteface Mountain (WFM) and Mayville, NY. Daily aerosol samples from six months at Mayville collected during 1998 and 2002 and fourteen months from WFM collected during 1996 and 2002 were analyzed using Sunset thermal-optical transmittance (TOT) elemental/organic carbon (EC/OC) analyzer and Magee Scientific Transmissiometer (Model OT-21). Total numbers of samples analyzed from the two sites were around 400. Transmissiometer used for BC measurement is based on optical attenuation of light and its working principle is similar to that of widely used Aethalometer. Whatman 41 filters are not suitable for direct EC measurement using EC/OC analyzer, so a pretreatment technique was developed and EC was subsequently transferred on 47 mm quartz filter paper. The total analysis time for individual sample using Transmissiometer is short (˜ 3-5 min) compared with ˜ 20-25 minutes for EC/OC analyzer excluding the time required for chemical pre-treatment (which can be up to 60 min). Reasonably good correlation, r2>0.8 and BC/EC slope close to 1 was obtained for concentrations up to 600 ngm- 3. For concentration >600 ngm-3 the relationship tends to

  9. Optical method of measuring angular displacement using a diffraction pattern.

    PubMed

    Ami, M; Sato, K; Yamamoto, S; Kamada, O; Shibanuma, H

    1987-10-01

    We investigate a method of measuring the angular displacement of an aperture when the diffraction pattern rotates. The data that are on a rectangular coordinate are transformed into the data on a polar coordinate. We calculate a cross-correlation function between the diffraction pattern that is rotated and the reference pattern. When the angular displacement is within +/-5 degrees , the error is <0.050. Then, we calculated the angular displacement of the pattern on a spherical coordinate system by personal computer simulation. Consequently, when the azimuth and the elevation of its rotation axis are within +/-6 degrees , the error is <0.1 degrees .

  10. Differentiated protection method in passive optical networks based on OPEX

    NASA Astrophysics Data System (ADS)

    Zhang, Zhicheng; Guo, Wei; Jin, Yaohui; Sun, Weiqiang; Hu, Weisheng

    2011-12-01

    Reliable service delivery becomes more significant due to increased dependency on electronic services all over society and the growing importance of reliable service delivery. As the capability of PON increasing, both residential and business customers may be included in a PON. Meanwhile, OPEX have been proven to be a very important factor of the total cost for a telecommunication operator. Thus, in this paper, we present the partial protection PON architecture and compare the operational expenditures (OPEX) of fully duplicated protection and partly duplicated protection for ONUs with different distributed fiber length, reliability requirement and penalty cost per hour. At last, we propose a differentiated protection method to minimize OPEX.

  11. Holographic optical grating and method for optimizing monochromator configuration

    DOEpatents

    Koike, Masato

    1999-01-01

    This invention comprises a novel apparatus for recording a holographic groove pattern on a diffraction grating blank. The recording apparatus is configured using newly developed groups of analytical equations. The invention further comprises the novel holographic diffraction grating made with the inventive recording apparatus. The invention additionally comprises monochromators and spectrometers equipped with the inventive holographic diffraction grating. Further, the invention comprises a monochromator configured to reduce aberrations using a newly developed group of analytical equations. Additionally, the invention comprises a method to reduce aberrations in monochromators and spectrometers using newly developed groups of analytical equations.

  12. Optical methods for molecular sensing: Supplementing imaging of tissue microstructure with molecular information

    NASA Astrophysics Data System (ADS)

    Winkler, Amy Marie

    More and more researchers and clinicians are looking to molecular sensing to predict how cells will behave, seeking the answers to questions like will these tumor cells become malignant? or how will these cells respond to chemotherapy? Optical methods are attractive for answering these questions because optical radiation is safer and less expensive than alternative methods, such as CT which uses X-ray radiation, PET/SPECT which use gamma radiation, or MRI which is expensive and only available in a hospital setting. In this dissertation, three distinct optical methods are explored to detect at the molecular level: optical coherence tomography (OCT), laser-induced fluorescence (LIF), and optical polarimetry. OCT has the capability to simultaneously capture anatomical information as well as molecular information using targeted contrast agents such as gold nanoshells. LIF is less useful for capturing anatomical information, but it can achieve significantly better molecular sensitivity with the use of targeted fluorescent dyes. Optical polarimetry has potential to detect the concentration of helical molecules, such as glucose. All of these methods are noninvasive or minimally invasive. The work is organized into four specific aims. The first is the design and implementation of a fast, high resolution, endoscopic OCT system to facilitate minimally invasive mouse colon imaging. The second aim is to demonstrate the utility of this system for automatically identifying tumor lesions based on tissue microstructure. The third is to demonstrate the use of contrast agents to detect molecular expression using OCT and LIF. The last aim is to demonstrate a new method based on optical polarimetry for noninvasive glucose sensing.

  13. Application of the linear muffin-tin-orbital band-structure method to calculate optical properties of solids

    NASA Astrophysics Data System (ADS)

    Zemach, R.; Ashkenazi, J.; Ehrenfreund, E.

    1989-01-01

    Optical matrix elements have been derived for crystals by applying the theory of optical transitions within the formalism of the linear muffin-tin-orbital band-structure method and using Racah algebra. A Brillouin-zone integration by the tetrahedron method allows straightforward numerical computation of the optical function ɛ2(ω) [or σ(ω)]. Other optical functions may be derived by using a Kramers-Kronig analysis.

  14. Generalized method of eigenoscillations for near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Bor-Yuan; Zhang, Lingfeng; Castro Neto, Antonio; Basov, Dimitri; Fogler, Michael

    2015-03-01

    Electromagnetic interaction between a sub-wavelength particle (the ``probe'') and a material surface (the ``sample'') is studied theoretically. The interaction is shown to be governed by a series of resonances (eigenoscillations), corresponding to surface polariton modes localized near the probe. The resonance parameters depend on the dielectric function and geometry of the probe, as well as the surface reflectivity of the material. Calculation of such resonances is carried out for several axisymmetric particle shapes (spherical, spheroidal, and pear-shaped). For spheroids an efficient numerical method is proposed, capable of handling cases of large or strongly momentum-dependent surface reflectivity. The method is applied to modeling near-field spectroscopy studies of various materials. For highly resonant materials such as aluminum oxide (by itself or covered with graphene) a rich structure of the simulated signal is found, including multi-peak spectra and nonmonotonic approach curves. These features have a strong dependence on physical parameters, e.g., the probe shape. For less resonant materials such as silicon oxide the dependence is weaker, and the spheroid model is generally applicable.

  15. Method for optic nerve intensity characterization in mice from Mn2+ enhanced MR images

    NASA Astrophysics Data System (ADS)

    Xiao, D.; Ribic, J.; Butzkueven, H.; Fang, K.; Kilpatrick, T. J.; Egan, G. F.; Salvado, O.

    2009-02-01

    Investigating whether manganese transport is impaired in the optic nerve of small animal model is a new approach for evaluating optic neuritis. One needs to quantify signal intensity enhancement due to Mn2+ after intra-orbital injection, along the optic nerve from MR images. Quantification is very challenging as the optic nerve (ON) is not straight, its location does not correspond to standard slice orientation, the noise is substantial, and the signal is subject to inhomogeneity from the coil sensitivity. In this paper, we propose a semi-automatic method whereby 1) the retina point and the start of the chiasm in a mouse brain MR image are defined manually in a 3D visualization environment, 2) optic nerve in reformatted slices perpendicular to the optic nerve segment is semi-manually selected, 3) an automatic algorithm extracts the intensities along the optic nerve while correcting for intensity inhomogeneity, and 4) a model for the Mn2+ diffusion with a exponential decay function is fitted to the intensity profile. Results for the study of experimental autoimmune encephalomyelitis (EAE) are reported whereby statistically significant differences were found between the EAE and the control group.

  16. Organic solid state optical switches and method for producing organic solid state optical switches

    DOEpatents

    Wasielewski, M.R.; Gaines, G.L.; Niemczyk, M.P.; Johnson, D.G.; Gosztola, D.J.; O`Neil, M.P.

    1993-01-01

    This invention consists of a light-intensity dependent molecular switch comprised of a compound which shuttles an electron or a plurality of electrons from a plurality of electron donors to an electron acceptor upon being stimulated with light of predetermined wavelengths, and a method for making said compound.

  17. Systems and Methods for Correcting Optical Reflectance Measurements

    NASA Technical Reports Server (NTRS)

    Yang, Ye (Inventor); Soller, Babs R. (Inventor); Soyemi, Olusola O. (Inventor); Shear, Michael A. (Inventor)

    2014-01-01

    We disclose measurement systems and methods for measuring analytes in target regions of samples that also include features overlying the target regions. The systems include: (a) a light source; (b) a detection system; (c) a set of at least first, second, and third light ports which transmit light from the light source to a sample and receive and direct light reflected from the sample to the detection system, generating a first set of data including information corresponding to both an internal target within the sample and features overlying the internal target, and a second set of data including information corresponding to features overlying the internal target; and (d) a processor configured to remove information characteristic of the overlying features from the first set of data using the first and second sets of data to produce corrected information representing the internal target.

  18. Advanced Motion Compensation Methods for Intravital Optical Microscopy

    PubMed Central

    Vinegoni, Claudio; Lee, Sungon; Feruglio, Paolo Fumene; Weissleder, Ralph

    2013-01-01

    Intravital microscopy has emerged in the recent decade as an indispensible imaging modality for the study of the micro-dynamics of biological processes in live animals. Technical advancements in imaging techniques and hardware components, combined with the development of novel targeted probes and new mice models, have enabled us to address long-standing questions in several biology areas such as oncology, cell biology, immunology and neuroscience. As the instrument resolution has increased, physiological motion activities have become a major obstacle that prevents imaging live animals at resolutions analogue to the ones obtained in vitro. Motion compensation techniques aim at reducing this gap and can effectively increase the in vivo resolution. This paper provides a technical review of some of the latest developments in motion compensation methods, providing organ specific solutions. PMID:24273405

  19. Method and apparatus for fiber optic multiple scattering suppression

    NASA Technical Reports Server (NTRS)

    Ackerson, Bruce J. (Inventor)

    2000-01-01

    The instant invention provides a method and apparatus for use in laser induced dynamic light scattering which attenuates the multiple scattering component in favor of the single scattering component. The preferred apparatus utilizes two light detectors that are spatially and/or angularly separated and which simultaneously record the speckle pattern from a single sample. The recorded patterns from the two detectors are then cross correlated in time to produce one point on a composite single/multiple scattering function curve. By collecting and analyzing cross correlation measurements that have been taken at a plurality of different spatial/angular positions, the signal representative of single scattering may be differentiated from the signal representative of multiple scattering, and a near optimum detector separation angle for use in taking future measurements may be determined.

  20. Systems and methods for correcting optical reflectance measurements

    NASA Technical Reports Server (NTRS)

    Yang, Ye (Inventor); Soller, Babs R. (Inventor); Soyemi, Olusola O. (Inventor); Shear, Michael A. (Inventor)

    2009-01-01

    We disclose measurement systems and methods for measuring analytes in target regions of samples that also include features overlying the target regions. The systems include: (a) a light source; (b) a detection system; (c) a set of at least first, second, and third light ports which transmit light from the light source to a sample and receive and direct light reflected from the sample to the detection system, generating a first set of data including information corresponding to both an internal target within the sample and features overlying the internal target, and a second set of data including information corresponding to features overlying the internal target; and (d) a processor configured to remove information characteristic of the overlying features from the first set of data using the first and second sets of data to produce corrected information representing the internal target.

  1. Fiber optic pressure sensing method based on Sagnac interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Zhuang, Zhi; Chen, Ying; Yang, Yuanhong

    2014-11-01

    Pressure method using polarization-maintaining photonic crystal fiber (PM-PCF) as sensing element based on Sagnac interferometer is proposed to monitor inter layer pressure in especial compact structure. Sensing model is analyzed and test system is set up, which is validated by experiment. The birefringence can be modified by the deformation of PM-PCF under transverse pressure, realizing pressure measurement by detecting the wavelength shift of one specific valley from output of the Sagnac interferometer. The experiment results show that the output interference fringes were shifted linearly with pressure. The dynamic range of 0 kN ~10kN, sensing precision of 2.6%, and pressure sensitivity of 0.4414nm/kN are achieved, and the strain relaxation phenomenon of cushion can be observed obviously. The sensor has better engineering practicability and capability to restrain interference brought up by fluctuation of environment temperature, which temperature sensitivity is -11.8pm/°C.

  2. New researches on teratogenic effects of singulair using optical methods

    NASA Astrophysics Data System (ADS)

    Valiulis, A.; Gaidelis, P.; Januskevicius, A.

    2005-11-01

    It was proved that singulair does not cause macroscopical and histological alterations on the animals, but it is not known its influence on the molecular level. The purpose of our work is to explore teratogenic effects of singulair on the animals by using our non-standard method (which is preciser than standard method, because it showes not only macroscopical, but also and molecular alterations in the damage tissue), hoping, that it would be the help for the pregnant women to decide can they take this drug or not. We injected singulair (25 mg/kg of rat) to one group of pregnant rats in rareripe period (from the first to the eight day) of embryogenesis. Another group of pregnant rats got injections of teratogenic substance ochratoxin A (25 pg/kg of rat) in the same period of embryogenesis. The third group got injections of physiological solution. There were taken 10 rats to everyone group. In the end of rareripe period we took a blood sample from each rat of the rats and wrote a spectrum of everyone sample by using spectrophotometer. We got, that spectra of solutions from the first and the third group were very similar (there were no statistical difference) and spectra of solutions from the second group were very similar (there were no statistical difference), but statistical difference was between the first and the third group together and the second group in the zone of 200-350 nm. At the twentieth day of pregnancy we made Caesarean section to all of the rats, compared embryos interpendent and did not find any defects in anyone of them through all the first and the third group, but everyone embryo from the second group had a lot of defects.

  3. On convergence of the Horn and Schunck optical-flow estimation method.

    PubMed

    Mitiche, Amar; Mansouri, Abdol-Reza

    2004-06-01

    The purpose of this study is to prove convergence results for the Horn and Schunck optical-flow estimation method. Horn and Schunck stated optical-flow estimation as the minimization of a functional. When discretized, the corresponding Euler-Lagrange equations form a linear system of equations We write explicitly this system and order the equations in such a way that its matrix is symmetric positive definite. This property implies the convergence Gauss-Seidel iterative resolution method, but does not afford a conclusion on the convergence of the Jacobi method. However, we prove directly that this method also converges. We also show that the matrix of the linear system is block tridiagonal. The blockwise iterations corresponding to this block tridiagonal structure converge for both the Jacobi and the Gauss-Seidel methods, and the Gauss-Seidel method is faster than the (sequential) Jacobi method.

  4. Method to Enhance the Operation of an Optical Inspection Instrument Using Spatial Light Modulators

    NASA Technical Reports Server (NTRS)

    Trolinger, James; Lal, Amit; Jo, Joshua; Kupiec, Stephen

    2012-01-01

    For many aspheric and freeform optical components, existing interferometric solutions require a custom computer-generated hologram (CGH) to characterize the part. The overall objective of this research is to develop hardware and a procedure to produce a combined, dynamic, Hartmann/ Digital Holographic interferometry inspection system for a wide range of advanced optical components, including aspheric and freeform optics. This new instrument would have greater versatility and dynamic range than currently available measurement systems. The method uses a spatial light modulator to pre-condition wavefronts for imaging, interferometry, and data processing to improve the resolution and versatility of an optical inspection instrument. Existing interferometers and Hartmann inspection systems have either too small a dynamic range or insufficient resolution to characterize conveniently unusual optical surfaces like aspherical and freeform optics. For interferometers, a specially produced, computer-generated holographic optical element is needed to transform the wavefront to within the range of the interferometer. A new hybrid wavefront sensor employs newly available spatial light modulators (SLMs) as programmable holographic optical elements (HOEs). The HOE is programmed to enable the same instrument to inspect an optical element in stages, first by a Hartmann measurement, which has a very large dynamic range but less resolution. The first measurement provides the information required to precondition a reference wave that avails the measurement process to the more precise phase shifting interferometry. The SLM preconditions a wavefront before it is used to inspect an optical component. This adds important features to an optical inspection system, enabling not just wavefront conditioning for null testing and dynamic range extension, but also the creation of hybrid measurement procedures. This, for example, allows the combination of dynamic digital holography and Hartmann

  5. Method of developing all-optical trinary JK, D-type, and T-type flip-flops using semiconductor optical amplifiers.

    PubMed

    Garai, Sisir Kumar

    2012-04-10

    To meet the demand of very fast and agile optical networks, the optical processors in a network system should have a very fast execution rate, large information handling, and large information storage capacities. Multivalued logic operations and multistate optical flip-flops are the basic building blocks for such fast running optical computing and data processing systems. In the past two decades, many methods of implementing all-optical flip-flops have been proposed. Most of these suffer from speed limitations because of the low switching response of active devices. The frequency encoding technique has been used because of its many advantages. It can preserve its identity throughout data communication irrespective of loss of light energy due to reflection, refraction, attenuation, etc. The action of polarization-rotation-based very fast switching of semiconductor optical amplifiers increases processing speed. At the same time, tristate optical flip-flops increase information handling capacity.

  6. Mixed Total Variation and L1 Regularization Method for Optical Tomography Based on Radiative Transfer Equation

    PubMed Central

    Bi, Bo; Li, Li

    2017-01-01

    Optical tomography is an emerging and important molecular imaging modality. The aim of optical tomography is to reconstruct optical properties of human tissues. In this paper, we focus on reconstructing the absorption coefficient based on the radiative transfer equation (RTE). It is an ill-posed parameter identification problem. Regularization methods have been broadly applied to reconstruct the optical coefficients, such as the total variation (TV) regularization and the L1 regularization. In order to better reconstruct the piecewise constant and sparse coefficient distributions, TV and L1 norms are combined as the regularization. The forward problem is discretized with the discontinuous Galerkin method on the spatial space and the finite element method on the angular space. The minimization problem is solved by a Jacobian-based Levenberg-Marquardt type method which is equipped with a split Bregman algorithms for the L1 regularization. We use the adjoint method to compute the Jacobian matrix which dramatically improves the computation efficiency. By comparing with the other imaging reconstruction methods based on TV and L1 regularizations, the simulation results show the validity and efficiency of the proposed method. PMID:28280517

  7. Mixed Total Variation and L(1) Regularization Method for Optical Tomography Based on Radiative Transfer Equation.

    PubMed

    Tang, Jinping; Han, Bo; Han, Weimin; Bi, Bo; Li, Li

    2017-01-01

    Optical tomography is an emerging and important molecular imaging modality. The aim of optical tomography is to reconstruct optical properties of human tissues. In this paper, we focus on reconstructing the absorption coefficient based on the radiative transfer equation (RTE). It is an ill-posed parameter identification problem. Regularization methods have been broadly applied to reconstruct the optical coefficients, such as the total variation (TV) regularization and the L(1) regularization. In order to better reconstruct the piecewise constant and sparse coefficient distributions, TV and L(1) norms are combined as the regularization. The forward problem is discretized with the discontinuous Galerkin method on the spatial space and the finite element method on the angular space. The minimization problem is solved by a Jacobian-based Levenberg-Marquardt type method which is equipped with a split Bregman algorithms for the L(1) regularization. We use the adjoint method to compute the Jacobian matrix which dramatically improves the computation efficiency. By comparing with the other imaging reconstruction methods based on TV and L(1) regularizations, the simulation results show the validity and efficiency of the proposed method.

  8. Hybrid diversity method utilizing adaptive diversity function for recovering unknown aberrations in an optical system

    NASA Technical Reports Server (NTRS)

    Dean, Bruce H. (Inventor)

    2009-01-01

    A method of recovering unknown aberrations in an optical system includes collecting intensity data produced by the optical system, generating an initial estimate of a phase of the optical system, iteratively performing a phase retrieval on the intensity data to generate a phase estimate using an initial diversity function corresponding to the intensity data, generating a phase map from the phase retrieval phase estimate, decomposing the phase map to generate a decomposition vector, generating an updated diversity function by combining the initial diversity function with the decomposition vector, generating an updated estimate of the phase of the optical system by removing the initial diversity function from the phase map. The method may further include repeating the process beginning with iteratively performing a phase retrieval on the intensity data using the updated estimate of the phase of the optical system in place of the initial estimate of the phase of the optical system, and using the updated diversity function in place of the initial diversity function, until a predetermined convergence is achieved.

  9. Optical devices and methods employing nanoparticles, microcavities, and semicontinuous metal films

    NASA Technical Reports Server (NTRS)

    Armstrong, Robert L. (Inventor); Shalaev, Vladimir M. (Inventor); Smith, Harold V. (Inventor); Sarychev, Andrey K. (Inventor); Ying, Z. Charles (Inventor)

    2006-01-01

    An optical sensing enhancing material (and corresponding method of making) comprising: a medium, the medium comprising a plurality of aggregated nanoparticles comprising fractals; and a microcavity, wherein the medium is located in a vicinity of the microcavity. Also an optical sensor and sensing method comprising: providing a doped medium, the medium comprising a plurality of aggregated nanoparticles comprising fractals, with the material; locating the doped medium in the vicinity of a microcavity; exciting the doped medium with a light source; and detecting light reflected from the doped medium. Also an optical sensing enhancing material comprising a medium, the medium comprising a semicontinuous metal film of randomly distributed metal particles and their clusters at approximately their percolation threshold. The medium preferably additionally comprises a microcavity/microresonator. Also devices and methods employing such material.

  10. Hybrid freeform TIR optics construction in Cartesian coordinate system: a new composite ray mapping method

    NASA Astrophysics Data System (ADS)

    Ma, Donglin; Feng, Zexin; Wang, Chengliang; Liang, Rongguang

    2015-09-01

    In this paper, we propose a new composite ray mapping method to design freeform total internal reflective (TIR) optics for LED illumination. We sample the ray intensity distribution into rectangular grids which have the best topological match to those rectangular grids on the target surface. With the multiple-to-one mapping relationships between the source intensity distribution and target irradiance distribution, we can construct the freeform TIR surfaces and freeform refractive surface using Snell's law. Compared to our previous design using uv-θϕ composite ray mapping method, this design approach is expected to have much less surface error and improve the illumination uniformity further because of the better topological match. In addition, due to the overlapping mechanism by multiple-to-one (composite) ray mapping, the method could lead to a more robust freeform optics compared to traditional freeform optics designs.

  11. 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

  12. Effect of Sn on the optical band gap determined using absorption spectrum fitting method

    SciTech Connect

    Heera, Pawan; Kumar, Anup; Sharma, Raman

    2015-05-15

    We report the preparation and the optical studies on tellurium rich glasses thin films. The thin films of Se{sub 30}Te{sub 70-x} Sn{sub x} system for x= 0, 1.5, 2.5 and 4.5 glassy alloys prepared by melt quenching technique are deposited on the glass substrate using vacuum thermal evaporation technique. The analysis of absorption spectra in the spectral range 400nm–4000 nm at room temperature obtained from UV-VIS-NIR spectrophotometer [Perkin Elmer Lamda-750] helps us in the optical characterization of the thin films under study. The absorption spectrum fitting method is applied by using the Tauc’s model for estimating the optical band gap and the width of the band tail of the thin films. The optical band gap is calculated and is found to decrease with the Sn content.

  13. Fiber-optic apparatus and method for measurement of luminescence and raman scattering

    DOEpatents

    Myrick, Michael L.; Angel, Stanley M.

    1993-01-01

    A dual fiber forward scattering optrode for Raman spectroscopy with the remote ends of the fibers in opposed, spaced relationship to each other to form a analyte sampling space therebetween and the method of measuring Raman spectra utilizing same. One optical fiber is for sending an exciting signal to the remote sampling space and, at its remote end, has a collimating microlens and an optical filter for filtering out background emissions generated in the fiber. The other optical fiber is for collecting the Raman scattering signal at the remote sampling space and, at its remote end, has a collimating microlens and an optical filter to prevent the exciting signal from the exciting fiber from entering the collection fiber and to thereby prevent the generation of background emissions in the collecting fiber.

  14. Fiber-optic apparatus and method for measurement of luminescence and Raman scattering

    DOEpatents

    Myrick, M.L.; Angel, S.M.

    1993-03-16

    A dual fiber forward scattering optrode for Raman spectroscopy with the remote ends of the fibers in opposed, spaced relationship to each other to form a analyte sampling space therebetween and the method of measuring Raman spectra utilizing same are described. One optical fiber is for sending an exciting signal to the remote sampling space and, at its remote end, has a collimating microlens and an optical filter for filtering out background emissions generated in the fiber. The other optical fiber is for collecting the Raman scattering signal at the remote sampling space and, at its remote end, has a collimating microlens and an optical filter to prevent the exciting signal from the exciting fiber from entering the collection fiber and to thereby prevent the generation of background emissions in the collecting fiber.

  15. Fabrication of double layer optical tissue phantom by spin coating method: mimicking epidermal and dermal layer

    NASA Astrophysics Data System (ADS)

    Park, Jihoon; Bae, Yunjin; Bae, Youngwoo; Kang, Heesung; Lee, Kyoung-Joung; Jung, Byungjo

    2013-02-01

    Methodologies to fabricate a solid optical tissue phantom (OTP) mimicking epidermal thin-layer have been developed for in vitro human skin experiment. However, there are cumbersome and time-consuming efforts in fabrication process such as a custom-made casting and calculation of solvent volume before curing process. In a previous study, we introduced a new methodology based on spin coating method (SCM) which is utilized to fabricate a thin-layer OTP analogous to epidermal thickness. In this study, a double layer solid OTP which has epidermal and dermal layers was fabricated to mimic the morphological and optical similarity of human tissue. The structural characteristic and optical properties of fabricated double layer OTP were measured using optical coherence tomography and inverse adding doubling algorithms, respectively. It is expected that the new methodology based on the SCM may be usefully used in the fabrication of double layer OTP.

  16. An all-optical method of developing data communication system with error detection circuit

    NASA Astrophysics Data System (ADS)

    Mandal, Sumana; Mandal, Dhoumendra; Garai, Sisir Kumar

    2014-03-01

    The basic criterion of data communication is that received data should exactly be the replica of the transmitting data. If any error is introduced in the received data, then data transmission should be stopped immediately. In this article the authors have developed an all-optical method of data communication system with error detection mechanism that works with frequency encoded data. Basic building blocks of the proposed data communication scheme are parity generator and parity checker which are developed from all optical XOR logic gates. Simulation results testify the feasibility of the proposed scheme. These logic gates are developed exploiting nonlinear polarization rotation based frequency conversion and switching character of semiconductor optical amplifiers. The scheme with frequency encoded data, high speed of frequency conversion and polarization switching action of semiconductor optical amplifier offers secure, error free, faster data communication network.

  17. Method used to test the imaging consistency of binocular camera's left-right optical system

    NASA Astrophysics Data System (ADS)

    Liu, Meiying; Wang, Hu; Liu, Jie; Xue, Yaoke; Yang, Shaodong; Zhao, Hui

    2016-09-01

    To binocular camera, the consistency of optical parameters of the left and the right optical system is an important factor that will influence the overall imaging consistency. In conventional testing procedure of optical system, there lacks specifications suitable for evaluating imaging consistency. In this paper, considering the special requirements of binocular optical imaging system, a method used to measure the imaging consistency of binocular camera is presented. Based on this method, a measurement system which is composed of an integrating sphere, a rotary table and a CMOS camera has been established. First, let the left and the right optical system capture images in normal exposure time under the same condition. Second, a contour image is obtained based on the multiple threshold segmentation result and the boundary is determined using the slope of contour lines near the pseudo-contour line. Third, the constraint of gray level based on the corresponding coordinates of left-right images is established and the imaging consistency could be evaluated through standard deviation σ of the imaging grayscale difference D (x, y) between the left and right optical system. The experiments demonstrate that the method is suitable for carrying out the imaging consistency testing for binocular camera. When the standard deviation 3σ distribution of imaging gray difference D (x, y) between the left and right optical system of the binocular camera does not exceed 5%, it is believed that the design requirements have been achieved. This method could be used effectively and paves the way for the imaging consistency testing of the binocular camera.

  18. Optical design and multi-objective optimization with fuzzy method for miniature zoom optics

    NASA Astrophysics Data System (ADS)

    Sun, Jung-Hung; Hsueh, Bo-Ren

    2011-07-01

    In this paper a thinning L-type zoom lens design was proposed to exploit the reflecting and refracting surfaces connected by a prism. However, in the L-type designs, the modulation transfer function (MTF) value is comparatively low compared with that in its coaxial counterparts. If we increase the MTF, that would cause the relative illuminace (RI) degradation. We propose a combination of the Taguchi method and fuzzy approach to improve both the RI and MTF in L-type zoom systems. The resulting experimental values of orthogonal array L9 of the Taguchi method were used as inputs for fuzzy approach to obtain the MPCI value. The MPCI value was then analyzed by variance, revealing that the two most significant factors were (1) the surface 7 to image length and (2) the semi-aperture of the front element. In our proposed method, the appropriate weight of MTF and RI for the inputs of fuzzy controllers increased the MTF by 3.74%, but the RI only reduced by 0.13% in the systematic wide-angle end, respectively.

  19. Microminiature optical waveguide structure and method for fabrication

    DOEpatents

    Strand, O.T.; Deri, R.J.; Pocha, M.D.

    1998-12-08

    A method for manufacturing low-cost, nearly circular cross section waveguides comprises starting with a substrate material that a molten waveguide material can not wet or coat. A thin layer is deposited of an opposite material that the molten waveguide material will wet and is patterned to describe the desired surface-contact path pedestals for a waveguide. A waveguide material, e.g., polymer or doped silica, is deposited. A resist material is deposited and unwanted excess is removed to form pattern masks. The waveguide material is etched away to form waveguide precursors and the masks are removed. Heat is applied to reflow the waveguide precursors into near-circular cross-section waveguides that sit atop the pedestals. The waveguide material naturally forms nearly circular cross sections due to the surface tension effects. After cooling, the waveguides will maintain the round shape. If the width and length are the same, then spherical ball lenses are formed. Alternatively, the pedestals can be patterned to taper along their lengths on the surface of the substrate. This will cause the waveguides to assume a conical taper after reflowing by heat. 32 figs.

  20. Microminiature optical waveguide structure and method for fabrication

    DOEpatents

    Strand, Oliver T.; Deri, Robert J.; Pocha, Michael D.

    1998-01-01

    A method for manufacturing low-cost, nearly circular cross section waveguides comprises starting with a substrate material that a molten waveguide material can not wet or coat. A thin layer is deposited of an opposite material that the molten waveguide material will wet and is patterned to describe the desired surface-contact path pedestals for a waveguide. A waveguide material, e.g., polymer or doped silica, is deposited. A resist material is deposited and unwanted excess is removed to form pattern masks. The waveguide material is etched away to form waveguide precursors and the masks are removed. Heat is applied to reflow the waveguide precursors into near-circular cross-section waveguides that sit atop the pedestals. The waveguide material naturally forms nearly circular cross sections due to the surface tension effects. After cooling, the waveguides will maintain the round shape. If the width and length are the same, then spherical ball lenses are formed. Alternatively, the pedestals can be patterned to taper along their lengths on the surface of the substrate. This will cause the waveguides to assume a conical taper after reflowing by heat.

  1. Electro-Optical Sensing Apparatus and Method for Characterizing Free-Space Electromagnetic Radiation

    DOEpatents

    Zhang, Xi-Cheng; Libelo, Louis Francis; Wu, Qi

    1999-09-14

    Apparatus and methods for characterizing free-space electromagnetic energy, and in particular, apparatus/method suitable for real-time two-dimensional far-infrared imaging applications are presented. The sensing technique is based on a non-linear coupling between a low-frequency electric field and a laser beam in an electro-optic crystal. In addition to a practical counter-propagating sensing technique, a co-linear approach is described which provides longer radiated field--optical beam interaction length, thereby making imaging applications practical.

  2. Optical characterization of high speed microscanners based on static slit profiling method

    NASA Astrophysics Data System (ADS)

    Alaa Elhady, A.; Sabry, Yasser M.; Khalil, Diaa

    2017-01-01

    Optical characterization of high-speed microscanners is a challenging task that usually requires special high speed, extremely expensive camera systems. This paper presents a novel simple method to characterize the scanned beam spot profile and size in high-speed optical scanners under operation. It allows measuring the beam profile and the spot sizes at different scanning angles. The method is analyzed theoretically and applied experimentally on the characterization of a Micro Electro Mechanical MEMS scanner operating at 2.6 kHz. The variation of the spot size versus the scanning angle, up to ±15°, is extracted and the dynamic bending curvature effect of the micromirror is predicted.

  3. New teaching methods in use at UC Irvine's optical engineering and instrument design programs

    NASA Astrophysics Data System (ADS)

    Silberman, Donn M.; Rowe, T. Scott; Jo, Joshua; Dimas, David

    2012-10-01

    New teaching methods reach geographically dispersed students with advances in Distance Education. Capabilities include a new "Hybrid" teaching method with an instructor in a classroom and a live WebEx simulcast for remote students. Our Distance Education Geometric and Physical Optics courses include Hands-On Optics experiments. Low cost laboratory kits have been developed and YouTube type video recordings of the instructor using these tools guide the students through their labs. A weekly "Office Hour" has been developed using WebEx and a Live Webcam the instructor uses to display his live writings from his notebook for answering students' questions.

  4. Simulation of polarization-sensitive optical coherence tomography images by a Monte Carlo method.

    PubMed

    Meglinski, Igor; Kirillin, Mikhail; Kuzmin, Vladimir; Myllylä, Risto

    2008-07-15

    We introduce a new Monte Carlo (MC) method for simulating optical coherence tomography (OCT) images of complex multilayered turbid scattering media. We demonstrate, for the first time of our knowledge, the use of a MC technique to imitate two-dimensional polarization-sensitive OCT images with nonplanar boundaries of layers in the medium like a human skin. The simulation of polarized low-coherent optical radiation is based on the vector approach generalized from the iterative procedure of the solution of Bethe-Saltpeter equation. The performances of the developed method are demonstrated both for conventional and polarization-sensitive OCT modalities.

  5. Optical fiber termination method for the Dark Energy Spectroscopic Instrument (DESI)

    NASA Astrophysics Data System (ADS)

    Poppett, Claire; Edelstein, Jerry; Ishikawa, Yuzo; Meghrouni-Brown, Zakios; Fagrelius, Parker

    2016-08-01

    The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We will describe the method we use to optically terminate the fibers which offers many advantages over methods that have been used in the past.

  6. A new optical flat surface measurement method based on machine vision and deflectometry

    NASA Astrophysics Data System (ADS)

    Kewei, E.; Li, Dahai; Yang, Lijie; Guo, Guangrao; Li, Mengyang; Wang, Xuemin; Zhang, Tao; Xiong, Zhao

    2016-10-01

    Phase Measuring Deflectometry(PMD) is a non-contact, high dynamic-range and full-field metrology which becomes a serious competitor to interferometry. However, the accuracy of deflectometry metrology is strongly influenced by the level of the calibrations. Our paper presents a calibration-based PMD method to test optical flat surface with a high accuracy. In our method, a pin-hole camera was set next to the LCD screen which is used to project sinusoidal fringes to the test flat. And the test flat was placed parallel to the direction of the LCD screen, which makes the geometry calibration process are simplified. The photogrammetric methods used in computer vision science was used to calibrate the pin-hole camera by using a checker pattern shown on another LCD display at six different orientations, the intrinsic parameters can be obtained by processing the obtained image of checker patterns. Further, by making the last orientation of checker pattern is aligned at the same position as the test optical flat, the algorithms used in this paper can obtain the mapping relationship between the CCD pixels and the subaperture coordinates on the test optical flat. We test a optical flat with a size of 50mm in diameter using our setup and algorithm. Our experimental results of optical flat figure from low to high order aberrations show a good agreement with that from the Fizeau interferometer.

  7. Quick acquisition and recognition method for the beacon in deep space optical communications.

    PubMed

    Wang, Qiang; Liu, Yuefei; Ma, Jing; Tan, Liying; Yu, Siyuan; Li, Changjiang

    2016-12-01

    In deep space optical communications, it is very difficult to acquire the beacon given the long communication distance. Acquisition efficiency is essential for establishing and holding the optical communication link. Here we proposed a quick acquisition and recognition method for the beacon in deep optical communications based on the characteristics of the deep optical link. To identify the beacon from the background light efficiently, we utilized the maximum similarity between the collecting image and the reference image for accurate recognition and acquisition of the beacon in the area of uncertainty. First, the collecting image and the reference image were processed by Fourier-Mellin. Second, image sampling and image matching were applied for the accurate positioning of the beacon. Finally, the field programmable gate array (FPGA)-based system was used to verify and realize this method. The experimental results showed that the acquisition time for the beacon was as fast as 8.1s. Future application of this method in the system design of deep optical communication will be beneficial.

  8. A new calibration method between an optical sensor and a rotating platform in turbine blade inspection

    NASA Astrophysics Data System (ADS)

    Li, Wen-Long; Wu, An; Li, Zi-Cheng; Zhang, Gang; Yu, Wen-Yong

    2017-03-01

    Thin-walled turbine blades with complex features are a critical part of an aviation engine, and a small change in their geometric shape can erode the performance of the aviation engine. Inspecting the blade with an optical device is a promising technique. One key task involved is the calibration of the optical sensor with the rotating platform. This paper presents a novel calibration method for the optical inspection of the blade. Three target spheres are measured by a high-precision laser tracker and an optical sensor. The positions of the sphere centers are used to build a coordinate system and an approximated plane. Following that, the rotation axis and the rotation center of the rotating platform are easily calculated. According to a direction vector from the measured stripe, the transformation parameters between the optical sensor and rotating platform are further calculated. This calibration method is simple to carry out, and it guarantees that all the measured points are represented in the same coordinate system for subsequent parameter extraction and profile error evaluation of the blade surface. The experiments demonstrate the feasibility of the proposed method, and it found that the measurement error after calibration is within 0.02 mm.

  9. Improved method for determination of optical constants of organic thin films from reflection and transmission measurements.

    PubMed

    Djurisić, A B; Fritz, T; Leo, K; Li, E H

    2000-03-01

    A new technique for determining the optical properties of organic thin films is presented. A detailed evaluation of the accuracy of the determined optical constants has been performed, and the best combination of measured values yielding the smallest errors in the index of refraction for realistic experimental uncertainties has been found. The proposed method utilizes the fact that optical constants are smooth continuous functions, which reduces the possibility of encountering multiple solutions. The method consists of two steps. In the first step the optical constants at all wavelengths and the film thickness are determined. In the second step the thickness and the imaginary part of the index of refraction are kept fixed while we reevaluate the real part of the index of refraction by using a different objective function with improved sensitivity to the refractive index. After verifying that the proposed method is capable of an accurate estimation of optical constants, we determine the index of refraction data of vanadyl-phthalocyanine in the visible spectral range.

  10. 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.

  11. Unified optical distortion correction method for imaging systems using a concise geometrical transformation model

    NASA Astrophysics Data System (ADS)

    Chang, Shengqian; Liu, Siqi; Yuan, Fei; Zheng, Zhenrong

    2017-01-01

    Since optical distortion has been a big trouble for various kinds of imaging systems, finding a simple correction method with wide applications is of significant importance. In this paper, we propose a unified and simple correction method, performing well for both photographic and projective imaging systems. The basic idea is regarding the optical distortion as geometrical deformation between the object and image, without considering the specific features of an optical system. First of all, a calibration template is employed to establish the geometrical transformation model (GTM) for the distortion of a built optical system. Two alternative algorithms are given to estimate the GTM in algebraic form. The computation is very simple because no intrinsic parameters of the optical system are needed to establish the GTM. Besides, the errors introduced by the fabricating and assembling process can be eliminated. Then, the corrected image of the photographic system or the pre-distorted image of the projective systems can be obtained accordingly utilizing the GTM. Experiments are conducted to demonstrate the effectiveness of our method with wide applications.

  12. Mathematic models for a ray tracing method and its applications in wireless optical communications.

    PubMed

    Zhang, Minglun; Zhang, Yangan; Yuan, Xueguang; Zhang, Jinnan

    2010-08-16

    This paper presents a new ray tracing method, which contains a whole set of mathematic models, and its validity is verified by simulations. In addition, both theoretical analysis and simulation results show that the computational complexity of the method is much lower than that of previous ones. Therefore, the method can be used to rapidly calculate the impulse response of wireless optical channels for complicated systems.

  13. Application of the optical method in experimental cardiology: action potential and intracellular calcium concentration measurement.

    PubMed

    Ronzhina, M; Cmiel, V; Janoušek, O; Kolářová, J; Nováková, M; Babula, P; Provazník, I

    2013-01-01

    It has been shown that, in addition to conventional contact electrode techniques, optical methods using fluorescent dyes can be successfully used for cardiac signal measurement. In this review, the physical and technical fundamentals of the method are described, as well as the properties of the most common systems for measuring action potentials and intracellular calcium concentration. Special attention is paid to summarizing limitations and trends in developing this method.

  14. Reference optical phantoms for diffuse optical spectroscopy. Part 1--Error analysis of a time resolved transmittance characterization method.

    PubMed

    Bouchard, Jean-Pierre; Veilleux, Israël; Jedidi, Rym; Noiseux, Isabelle; Fortin, Michel; Mermut, Ozzy

    2010-05-24

    Development, production quality control and calibration of optical tissue-mimicking phantoms require a convenient and robust characterization method with known absolute accuracy. We present a solid phantom characterization technique based on time resolved transmittance measurement of light through a relatively small phantom sample. The small size of the sample enables characterization of every material batch produced in a routine phantoms production. Time resolved transmittance data are pre-processed to correct for dark noise, sample thickness and instrument response function. Pre-processed data are then compared to a forward model based on the radiative transfer equation solved through Monte Carlo simulations accurately taking into account the finite geometry of the sample. The computational burden of the Monte-Carlo technique was alleviated by building a lookup table of pre-computed results and using interpolation to obtain modeled transmittance traces at intermediate values of the optical properties. Near perfect fit residuals are obtained with a fit window using all data above 1% of the maximum value of the time resolved transmittance trace. Absolute accuracy of the method is estimated through a thorough error analysis which takes into account the following contributions: measurement noise, system repeatability, instrument response function stability, sample thickness variation refractive index inaccuracy, time correlated single photon counting system time based inaccuracy and forward model inaccuracy. Two sigma absolute error estimates of 0.01 cm(-1) (11.3%) and 0.67 cm(-1) (6.8%) are obtained for the absorption coefficient and reduced scattering coefficient respectively.

  15. Reference-free, high-resolution measurement method of timing jitter spectra of optical frequency combs

    PubMed Central

    Kwon, Dohyeon; Jeon, Chan-Gi; Shin, Junho; Heo, Myoung-Sun; Park, Sang Eon; Song, Youjian; Kim, Jungwon

    2017-01-01

    Timing jitter is one of the most important properties of femtosecond mode-locked lasers and optical frequency combs. Accurate measurement of timing jitter power spectral density (PSD) is a critical prerequisite for optimizing overall noise performance and further advancing comb applications both in the time and frequency domains. Commonly used jitter measurement methods require a reference mode-locked laser with timing jitter similar to or lower than that of the laser-under-test, which is a demanding requirement for many laser laboratories, and/or have limited measurement resolution. Here we show a high-resolution and reference-source-free measurement method of timing jitter spectra of optical frequency combs using an optical fibre delay line and optical carrier interference. The demonstrated method works well for both mode-locked oscillators and supercontinua, with 2 × 10−9 fs2/Hz (equivalent to −174 dBc/Hz at 10-GHz carrier frequency) measurement noise floor. The demonstrated method can serve as a simple and powerful characterization tool for timing jitter PSDs of various comb sources including mode-locked oscillators, supercontinua and recently emerging Kerr-frequency combs; the jitter measurement results enabled by our method will provide new insights for understanding and optimizing timing noise in such comb sources. PMID:28102352

  16. Reference-free, high-resolution measurement method of timing jitter spectra of optical frequency combs

    NASA Astrophysics Data System (ADS)

    Kwon, Dohyeon; Jeon, Chan-Gi; Shin, Junho; Heo, Myoung-Sun; Park, Sang Eon; Song, Youjian; Kim, Jungwon

    2017-01-01

    Timing jitter is one of the most important properties of femtosecond mode-locked lasers and optical frequency combs. Accurate measurement of timing jitter power spectral density (PSD) is a critical prerequisite for optimizing overall noise performance and further advancing comb applications both in the time and frequency domains. Commonly used jitter measurement methods require a reference mode-locked laser with timing jitter similar to or lower than that of the laser-under-test, which is a demanding requirement for many laser laboratories, and/or have limited measurement resolution. Here we show a high-resolution and reference-source-free measurement method of timing jitter spectra of optical frequency combs using an optical fibre delay line and optical carrier interference. The demonstrated method works well for both mode-locked oscillators and supercontinua, with 2 × 10‑9 fs2/Hz (equivalent to ‑174 dBc/Hz at 10-GHz carrier frequency) measurement noise floor. The demonstrated method can serve as a simple and powerful characterization tool for timing jitter PSDs of various comb sources including mode-locked oscillators, supercontinua and recently emerging Kerr-frequency combs; the jitter measurement results enabled by our method will provide new insights for understanding and optimizing timing noise in such comb sources.

  17. Optical analysis methods for material films condensed on cryogenic surfaces of spacecraft

    NASA Astrophysics Data System (ADS)

    Palmer, K. F.; Williams, M. Z.; Budde, B. A.; Bertrand, W. T.

    1994-08-01

    Exhaust gases from rocket motors and outgassing products of spacecraft materials can migrate, in a space environment, to other surfaces of the spacecraft and affect their functions. Cryogenically cooled optical systems are particularly vulnerable to these contaminants as are thermal control surfaces and solar cells. One of the goals of the contamination program at AEDC (Arnold Encineering Development Center) is to predict the optical effects of contaminant layers on optical systems from laboratory measurements of the optical indices, n and k, of contaminant materials. Because the cloud of contaminant molecules, which eventually form a condensate, contain a mixture of molecular species, researchers are seeking ways to predict the optical properties of films composed of constituents using the known properties of each constituent. In this report, the authors examine the physics which describe the optical properties of thin films composed of mixtures of constituents. Examples of the analysis methods are presented for thin films composed of mixtures using AEDC data on 20K thin films of simple molecules and 80K films condensed from the outgassing products of selected spacecraft materials.

  18. Optical power transfer and communication methods for wireless implantable sensing platforms

    NASA Astrophysics Data System (ADS)

    Mujeeb-U-Rahman, Muhammad; Adalian, Dvin; Chang, Chieh-Feng; Scherer, Axel

    2015-09-01

    Ultrasmall scale implants have recently attracted focus as valuable tools for monitoring both acute and chronic diseases. Semiconductor optical technologies are the key to miniaturizing these devices to the long-sought sub-mm scale, which will enable long-term use of these devices for medical applications. This can also enable the use of multiple implantable devices concurrently to form a true body area network of sensors. We demonstrate optical power transfer techniques and methods to effectively harness this power for implantable devices. Furthermore, we also present methods for optical data transfer from such implants. Simultaneous use of these technologies can result in miniaturized sensing platforms that can allow for large-scale use of such systems in real world applications.

  19. Systems and methods for optically measuring properties of hydrocarbon fuel gases

    DOEpatents

    Adler-Golden, S.; Bernstein, L.S.; Bien, F.; Gersh, M.E.; Goldstein, N.

    1998-10-13

    A system and method for optical interrogation and measurement of a hydrocarbon fuel gas includes a light source generating light at near-visible wavelengths. A cell containing the gas is optically coupled to the light source which is in turn partially transmitted by the sample. A spectrometer disperses the transmitted light and captures an image thereof. The image is captured by a low-cost silicon-based two-dimensional CCD array. The captured spectral image is processed by electronics for determining energy or BTU content and composition of the gas. The innovative optical approach provides a relatively inexpensive, durable, maintenance-free sensor and method which is reliable in the field and relatively simple to calibrate. In view of the above, accurate monitoring is possible at a plurality of locations along the distribution chain leading to more efficient distribution. 14 figs.

  20. Systems and methods for optically measuring properties of hydrocarbon fuel gases

    DOEpatents

    Adler-Golden, Steven; Bernstein, Lawrence S.; Bien, Fritz; Gersh, Michael E.; Goldstein, Neil

    1998-10-13

    A system and method for optical interrogation and measurement of a hydrocarbon fuel gas includes a light source generating light at near-visible wavelengths. A cell containing the gas is optically coupled to the light source which is in turn partially transmitted by the sample. A spectrometer disperses the transmitted light and captures an image thereof. The image is captured by a low-cost silicon-based two-dimensional CCD array. The captured spectral image is processed by electronics for determining energy or BTU content and composition of the gas. The innovative optical approach provides a relatively inexpensive, durable, maintenance-free sensor and method which is reliable in the field and relatively simple to calibrate. In view of the above, accurate monitoring is possible at a plurality of locations along the distribution chain leading to more efficient distribution.

  1. Method for in-depth characterization of electro-optic phase modulators.

    PubMed

    Arar, Bassem; Schiemangk, Max; Wenzel, Hans; Brox, Olaf; Wicht, Andreas; Peters, Achim; Tränkle, Günther

    2017-02-01

    A flexible method to measure the modulation efficiency and residual amplitude modulation, including non-linearities, of phase modulators is presented. The method is based on demodulation of the modulated optical field in the optical domain by means of a heterodyne interferometer and subsequent analysis of the I&Q quadrature components of the corresponding RF beat note signal. As an example, we determine the phase modulation efficiency and residual amplitude modulation for both the TE and TM modes of a GaAs chip-based phase modulator at the wavelength of 1064 nm. From the results of these measurements, we estimate the linear and quadratic electro-optic coefficients for a P-p-n-N GaAs/AlGaAs double heterostructure.

  2. Systems having optical absorption layer for mid and long wave infrared and methods for making the same

    DOEpatents

    Kuzmenko, Paul J

    2013-10-01

    An optical system according to one embodiment includes a substrate; and an optical absorption layer coupled to the substrate, wherein the optical absorption layer comprises a layer of diamond-like carbon, wherein the optical absorption layer absorbs at least 50% of mid wave infrared light (3-5 .mu.m wavelength) and at least 50% of long wave infrared light (8-13 .mu.m wavelength). A method for applying an optical absorption layer to an optical system according to another embodiment includes depositing a layer of diamond-like carbon of an optical absorption layer above a substrate using plasma enhanced chemical vapor deposition, wherein the optical absorption layer absorbs at least 50% of mid wave infrared light (3-5 .mu.m wavelength) and at least 50% of long wave infrared light (8-13 .mu.m wavelength). Additional systems and methods are also presented.

  3. A practical coordinate unification method for integrated tactile-optical measuring system

    NASA Astrophysics Data System (ADS)

    Li, Feng; Peter Longstaff, Andrew; Fletcher, Simon; Myers, Alan

    2014-04-01

    To meet the requirement of both high speed and high accuracy 3D measurements for dimensional metrology, multi-sensor measuring systems have been developed to measure, analyse and reverse engineer the geometry of objects. This paper presents a new development in coordinate unification called the "centroid of spherical centres" method, which can be used instead of the traditional method which uses three datum-points to perform the geometric transformation and unification of tactile and optical sensors. The benefits of the proposed method are improved accuracy in coordinate unification and the method is used to integrate a coordinate measuring machine (CMM) and optical sensors (structured light scanning system and FaroArm laser line probe). A sphere-plate artefact is developed for data fusion of the multi-sensor system and experimental results validate the accuracy and effectiveness of this method.

  4. Efficient uncertainty quantification of large two-dimensional optical systems with a parallelized stochastic Galerkin method.

    PubMed

    Zubac, Z; Fostier, J; De Zutter, D; Vande Ginste, D

    2015-11-30

    It is well-known that geometrical variations due to manufacturing tolerances can degrade the performance of optical devices. In recent literature, polynomial chaos expansion (PCE) methods were proposed to model this statistical behavior. Nonetheless, traditional PCE solvers require a lot of memory and their computational complexity leads to prohibitively long simulation times, making these methods non-tractable for large optical systems. The uncertainty quantification (UQ) of various types of large, two-dimensional lens systems is presented in this paper, leveraging a novel parallelized Multilevel Fast Multipole Method (MLFMM) based Stochastic Galerkin Method (SGM). It is demonstrated that this technique can handle large optical structures in reasonable time, e.g., a stochastic lens system with more than 10 million unknowns was solved in less than an hour by using 3 compute nodes. The SGM, which is an intrusive PCE method, guarantees the accuracy of the method. By conjunction with MLFMM, usage of a preconditioner and by constructing and implementing a parallelized algorithm, a high efficiency is achieved. This is demonstrated with parallel scalability graphs. The novel approach is illustrated for different types of lens system and numerical results are validated against a collocation method, which relies on reusing a traditional deterministic solver. The last example concerns a Cassegrain system with five random variables, for which a speed-up of more than 12× compared to a collocation method is achieved.

  5. Tracking and Measurement of the Motion of Blood Cells Using Optical Flow Methods

    PubMed Central

    Guo, Dongmin; Van de Ven, Anne L.; Zhou, Xiaobo

    2014-01-01

    The investigation of microcirculation is a critical task in biomedical and physiological research. In order to monitor human’s condition and develop effective therapies of some diseases, the microcirculation information, such as flow velocity and vessel density, must be evaluated in a noninvasive manner. As one of the tasks of microcirculation investigation, automatic blood cell tracking presents an effective approach to estimate blood flow velocity. Currently, the most common method for blood cell tracking is based on spatiotemporal image analysis, which has lots of limitations, such as the diameter of microvesssels cannot be too larger than blood cells or tracers, cells or tracers should have fixed velocity, and it requires the image with high qualification. In this paper, we propose an optical flow method for automatic cell tracking. The key algorithm of the method is to align an image to its neighbors in a large image collection consisting of a variety of scenes. Considering the method cannot solve the problems in all cases of cell movement, another optical flow method, SIFT (Scale Invariant Feature Transform) flow, is also presented. The experimental results show that both methods can track the cells accurately. Optical flow is specially robust to the case where the velocity of cell is unstable, while SIFT flow works well when there are large displacement of cell between two adjacent frames. Our proposed methods outperform other methods when doing in vivo cell tracking, which can be used to estimate the blood flow directly and help to evaluate other parameters in microcirculation. PMID:24058034

  6. Research on measurement method of optical transmittance of the artificial fog

    NASA Astrophysics Data System (ADS)

    Hu, Jianghua; Jian, Chaochao; Cui, Guangzhen; Lv, Xuliang; Rong, Xianhui

    2016-10-01

    The attenuation of light was a common result that the light was absorbed and scattered by the artificial fog particles when it transmitted in the artificial fog. The absorbing attenuation process of light transmission in the artificial fog was that the artificial fog converting incident light energy into other forms of internal energy (such as heat energy). The scattering attenuation process of light transmission in the artificial fog was that the artificial fog particles intercepting incident radiation energy to form infrasonic waves and to radiate peripherally so that the incident light energy was reduced on the original direction of transmission. The mechanism of light transmission attenuation in the artificial fog was analyzed. The formation method of the artificial fog was expounded and the measuring principle of the artificial fog transmittance was described. A simple and reliable measurement method of the optical transmittance of the artificial fog in the fog chamber was proposed. The optical transmittance measurement system of the artificial fog was built by using incandescent lamp, power with steady current and voltage, lens, selenium photocell, micro-galvanometer, optical bench, hygrothermograph, humidifier, etc. Under different conditions of humidity, the optical transmittance of the artificial fog was obtained on the basis of measuring the photocurrent before the fog was formed in the fog chamber. The test results show that the measurement system is stable and reliable. During the 43 minutes after the artificial fog was formed, the optical transmittance of the artificial fog was averagely less than 5 percent and the optical transmittance increased gradually with the extension of time. In addition, the optical transmittance of artificial fog didn't produce obvious change while air humidity increased from 68.7% to 85%. The measurement system can be used to measure transmittance of smoke screen, water mist and other aerosol.

  7. Optical Transcutaneous pCO2 Sensor using Soft Lithography Method for Arterial Blood Gas Analysis

    NASA Astrophysics Data System (ADS)

    Kang, Byoung-Ho; Kim, Do-Eok; Leem, Myoung-Kun; Kwon, Dae-Hyuk; Lee, Kwang-Man; Kang, Shin-Won

    2008-10-01

    In this study, we carried out development of non-invasive optical transcutaneous partial pressure of carbon dioxide, pCO2, monitoring system. The purpose of this system is to detect CO2 from outer skin, not from the arterial blood-gathering method. There are advantages about a reduction of analysis time and real-time monitoring that this system might be available. The measurement system is composed of the IR lamp, the pyroelectric sensor including a 4.26 μm optical filter, the optical gas reaction chamber and the signal processing circuit. The optical reaction length of chamber was reduced by 1 mm using the soft-lithography method which CO2 is exhausted in human body as we considered. The fabricated pCO2 monitoring system showed linear result of 6.50×10-6 absorbance/ppm sensitivity for CO2 concentration from 0 ˜5,000 ppm by MFC and about 2 seconds of fast response time. The proposed system can be used in the optical biosensor field for the medical diagnosis such as pCO2 monitoring system and environment monitoring systems.

  8. Effective star tracking method based on optical flow analysis for star trackers.

    PubMed

    Sun, Ting; Xing, Fei; Wang, Xiaochu; Li, Jin; Wei, Minsong; You, Zheng

    2016-12-20

    Benefiting from rapid development of imaging sensor technology, modern optical technology, and a high-speed computing chip, the star tracker's accuracy, dynamic performance, and update rate have been greatly improved with low power consumption and miniature size. The star tracker is currently one of the most competitive attitude measurement sensors. However, due to restrictions of the optical imaging system, difficulties still exist in moving star spot detection and star tracking when in special motion conditions. An effective star tracking method based on optical flow analysis for star trackers is proposed in this paper. Spot-based optical flow, based on a gray gradient between two adjacent star images, is analyzed to distinguish the star spot region and obtain an accurate star spot position so that the star tracking can keep continuous under high dynamic conditions. The obtained star vectors and extended Kalman filter (EKF) are then combined to conduct an angular velocity estimation to ensure region prediction of the star spot; this can be combined with the optical flow analysis result. Experiment results show that the method proposed in this paper has advantages in conditions of large angular velocity and large angular acceleration, despite the presence of noise. Higher functional density and better performance can be achieved; thus, the star tracker can be more widely applied in small satellites, remote sensing, and other complex space missions.

  9. Study of Optical Properties on Fractal Aggregation Using the GMM Method by Different Cluster Parameters

    NASA Astrophysics Data System (ADS)

    Chang, Kuo-En; Lin, Tang-Huang; Lien, Wei-Hung

    2015-04-01

    Anthropogenic pollutants or smoke from biomass burning contribute significantly to global particle aggregation emissions, yet their aggregate formation and resulting ensemble optical properties are poorly understood and parameterized in climate models. Particle aggregation refers to formation of clusters in a colloidal suspension. In clustering algorithms, many parameters, such as fractal dimension, number of monomers, radius of monomer, and refractive index real part and image part, will alter the geometries and characteristics of the fractal aggregation and change ensemble optical properties further. The cluster-cluster aggregation algorithm (CCA) is used to specify the geometries of soot and haze particles. In addition, the Generalized Multi-particle Mie (GMM) method is utilized to compute the Mie solution from a single particle to the multi particle case. This computer code for the calculation of the scattering by an aggregate of spheres in a fixed orientation and the experimental data have been made publicly available. This study for the model inputs of optical determination of the monomer radius, the number of monomers per cluster, and the fractal dimension is presented. The main aim in this study is to analyze and contrast several parameters of cluster aggregation aforementioned which demonstrate significant differences of optical properties using the GMM method finally. Keywords: optical properties, fractal aggregation, GMM, CCA

  10. [Comparison of correction methods for nonlinear optic path difference of reflecting rotating Fourier transform spectrometer].

    PubMed

    Jing, Juan-Juan; Zhou, Jin-Song; Xiangli, Bin; Lü, Qun-Bo; Wei, Ru-Yi

    2010-06-01

    The principle of reflecting rotating Fourier transform spectrometer was introduced in the present paper. The nonlinear problem of optical path difference (OPD) of rotating Fourier transform spectrometer universally exists, produced by the rotation of rotating mirror. The nonlinear OPD will lead to fictitious recovery spectrum, so it is necessary to compensate the nonlinear OPD. Three methods of correction for the nonlinear OPD were described and compared in this paper, namely NUFFT method, OPD replace method and interferograms fitting method. The result indicates that NUFFT was the best method for the compensation of nonlinear OPD, OPD replace method was better, its precision was almost the same as NUFFT method, and their relative error are superior to 0.13%, but the computation efficiency of OPD replace method is slower than NUFFT method, while the precision and computation efficiency of interferograms fitting method are not so satisfied, because the interferograms are rapid fluctuant especially around the zero optical path difference, so it is unsuitable for polynomial fitting, and because this method needs piecewise fitting, its computation efficiency is the slowest, thus the NUFFT method is the most suited method for the nonlinear OPD compensation of reflecting rotating Fourier transform spectrometer.

  11. Comparison Of Several Methods Of Implementing A Fiber Optic IEEE 802.3 Ethernet

    NASA Astrophysics Data System (ADS)

    Thompson, Geoffrey O.

    1987-01-01

    Several different methods of implementing a fiber optic version of IEEE 802.3 10BASE LANs have been proposed as a candidate for standardization by IEEE. There have been extensive discussions as to the relative merits and features of the several systems. This paper will discuss the merits of each for this particular application on a comparative basis.

  12. Cerebral blood flow and autoregulation: current measurement techniques and prospects for noninvasive optical methods.

    PubMed

    Fantini, Sergio; Sassaroli, Angelo; Tgavalekos, Kristen T; Kornbluth, Joshua

    2016-07-01

    Cerebral blood flow (CBF) and cerebral autoregulation (CA) are critically important to maintain proper brain perfusion and supply the brain with the necessary oxygen and energy substrates. Adequate brain perfusion is required to support normal brain function, to achieve successful aging, and to navigate acute and chronic medical conditions. We review the general principles of CBF measurements and the current techniques to measure CBF based on direct intravascular measurements, nuclear medicine, X-ray imaging, magnetic resonance imaging, ultrasound techniques, thermal diffusion, and optical methods. We also review techniques for arterial blood pressure measurements as well as theoretical and experimental methods for the assessment of CA, including recent approaches based on optical techniques. The assessment of cerebral perfusion in the clinical practice is also presented. The comprehensive description of principles, methods, and clinical requirements of CBF and CA measurements highlights the potentially important role that noninvasive optical methods can play in the assessment of neurovascular health. In fact, optical techniques have the ability to provide a noninvasive, quantitative, and continuous monitor of CBF and autoregulation.

  13. Methods and means of Stokes-polarimetry microscopy of optically anisotropic biological layers

    NASA Astrophysics Data System (ADS)

    Ushenko, A. G.; Dubolazov, A. V.; Ushenko, V. A.; Ushenko, Yu. A.; Sakhnovskiy, M. Yu.; Sidor, M.; Prydiy, O. G.; Olar, O. I.; Lakusta, I. I.

    2016-12-01

    The results of optical modeling of biological tissues polycrystalline multilayer networks have been presented. Algorithms of reconstruction of parameter distributions were determined that describe the linear and circular birefringence. For the separation of the manifestations of these mechanisms we propose a method of space-frequency filtering. Criteria for differentiation of benign and malignant tissues of the women reproductive sphere were found.

  14. Methods and means of laser polarimetry microscopy of optically anisotropic biological layers

    NASA Astrophysics Data System (ADS)

    Ushenko, A. G.; Dubolazov, A. V.; Ushenko, V. A.; Ushenko, Yu. A.; Sakhnovskiy, M. Y.; Olar, O. I.

    2016-09-01

    The results of optical modeling of biological tissues polycrystalline multilayer networks have been presented. Algorithms of reconstruction of parameter distributions were determined that describe the linear and circular birefringence. For the separation of the manifestations of these mechanisms we propose a method of space-frequency filtering. Criteria for differentiation of benign and malignant tissues of the women reproductive sphere were found.

  15. A content-based image retrieval method for optical colonoscopy images based on image recognition techniques

    NASA Astrophysics Data System (ADS)

    Nosato, Hirokazu; Sakanashi, Hidenori; Takahashi, Eiichi; Murakawa, Masahiro

    2015-03-01

    This paper proposes a content-based image retrieval method for optical colonoscopy images that can find images similar to ones being diagnosed. Optical colonoscopy is a method of direct observation for colons and rectums to diagnose bowel diseases. It is the most common procedure for screening, surveillance and treatment. However, diagnostic accuracy for intractable inflammatory bowel diseases, such as ulcerative colitis (UC), is highly dependent on the experience and knowledge of the medical doctor, because there is considerable variety in the appearances of colonic mucosa within inflammations with UC. In order to solve this issue, this paper proposes a content-based image retrieval method based on image recognition techniques. The proposed retrieval method can find similar images from a database of images diagnosed as UC, and can potentially furnish the medical records associated with the retrieved images to assist the UC diagnosis. Within the proposed method, color histogram features and higher order local auto-correlation (HLAC) features are adopted to represent the color information and geometrical information of optical colonoscopy images, respectively. Moreover, considering various characteristics of UC colonoscopy images, such as vascular patterns and the roughness of the colonic mucosa, we also propose an image enhancement method to highlight the appearances of colonic mucosa in UC. In an experiment using 161 UC images from 32 patients, we demonstrate that our method improves the accuracy of retrieving similar UC images.

  16. Optical floating zone method growth and optical properties of corundum Mg4Nb2O9 single crystal

    NASA Astrophysics Data System (ADS)

    Li, Liang; Duan, Defang; Zhou, Qiang; Xu, Dapeng; Cui, Tian; Liu, Bingbing; Yuan, Hongming

    2014-09-01

    Mg4Nb2O9 single crystals were prepared by the optical floating zone method. While the as-grown were boules polycrystalline and cracked with dimensions of ∅ 5-8 mm×L 91 mm, they contained single crystal regions as large as ∅ 4 mm×L 15 mm. The X-ray diffraction analysis showed that the crystals had the corundum structure, grew along the a-axis and cleaved parallel to the c plane. Polarized light microscopy, in a cross-transmission configuration measurement, showed that the crystal was free of low-angle grain boundaries and bubbles. The optical interband transitions were measured from the absorption spectrum of the crystal along the c-axes at room temperature in the range of 200-800 nm. Based on the theory of band-to-band transitions, the direct band gap was determined for the first time to be Eg=5.09 eV. The photoluminescence spectra exhibited a broad and strong blue emission band centered at 450 nm.

  17. Optical methods for determining thicknesses of few-layer graphene flakes

    NASA Astrophysics Data System (ADS)

    Ouyang, Wengen; Liu, Xin-Z.; Li, Qunyang; Zhang, Yingying; Yang, Jiarui; Zheng, Quan-shui

    2013-12-01

    Optical microscopy (OM) methods have been commonly used as a convenient means for locating and identifying few-layer graphene (FLG) on SiO2/Si substrates. However, it is less clear how reliably optical images of FLG could be used to determine the sample thickness. In this work, various OM methods based on color differences and color contrasts are presented and their reliabilities are evaluated. Our analysis shows that these color-based OM methods depend sensitively on certain parameters of the measuring system, particularly the light source and the reference substrate. These parameters have usually been overlooked and less controlled in routine experiments. From evaluating the performance of these OM methods with both virtual and real FLG samples, we propose some practical guidelines for minimizing the impact of these less-controlled experimental parameters and provide a user-friendly MATLAB script for facilitating the implementation.

  18. Distributed optical fiber-based theoretical and empirical methods monitoring hydraulic engineering subjected to seepage velocity

    NASA Astrophysics Data System (ADS)

    Su, Huaizhi; Tian, Shiguang; Cui, Shusheng; Yang, Meng; Wen, Zhiping; Xie, Wei

    2016-09-01

    In order to systematically investigate the general principle and method of monitoring seepage velocity in the hydraulic engineering, the theoretical analysis and physical experiment were implemented based on distributed fiber-optic temperature sensing (DTS) technology. During the coupling influence analyses between seepage field and temperature field in the embankment dam or dike engineering, a simplified model was constructed to describe the coupling relationship of two fields. Different arrangement schemes of optical fiber and measuring approaches of temperature were applied on the model. The inversion analysis idea was further used. The theoretical method of monitoring seepage velocity in the hydraulic engineering was finally proposed. A new concept, namely the effective thermal conductivity, was proposed referring to the thermal conductivity coefficient in the transient hot-wire method. The influence of heat conduction and seepage could be well reflected by this new concept, which was proved to be a potential approach to develop an empirical method monitoring seepage velocity in the hydraulic engineering.

  19. An image-based method to synchronize cone-beam CT and optical surface tracking.

    PubMed

    Fassi, Aurora; Schaerer, Joël; Riboldi, Marco; Sarrut, David; Baroni, Guido

    2015-03-08

    The integration of in-room X-ray imaging and optical surface tracking has gained increasing importance in the field of image guided radiotherapy (IGRT). An essential step for this integration consists of temporally synchronizing the acquisition of X-ray projections and surface data. We present an image-based method for the synchronization of cone-beam computed tomography (CBCT) and optical surface systems, which does not require the use of additional hardware. The method is based on optically tracking the motion of a component of the CBCT/gantry unit, which rotates during the acquisition of the CBCT scan. A calibration procedure was implemented to relate the position of the rotating component identified by the optical system with the time elapsed since the beginning of the CBCT scan, thus obtaining the temporal correspondence between the acquisition of X-ray projections and surface data. The accuracy of the proposed synchronization method was evaluated on a motorized moving phantom, performing eight simultaneous acquisitions with an Elekta Synergy CBCT machine and the AlignRT optical device. The median time difference between the sinusoidal peaks of phantom motion signals extracted from the synchronized CBCT and AlignRT systems ranged between -3.1 and 12.9 msec, with a maximum interquartile range of 14.4 msec. The method was also applied to clinical data acquired from seven lung cancer patients, demonstrating the potential of the proposed approach in estimating the individual and daily variations in respiratory parameters and motion correlation of internal and external structures. The presented synchronization method can be particularly useful for tumor tracking applications in extracranial radiation treatments, especially in the field of patient-specific breathing models, based on the correlation between internal tumor motion and external surface surrogates.

  20. Monte Carlo method for photon heating using temperature-dependent optical properties.

    PubMed

    Slade, Adam Broadbent; Aguilar, Guillermo

    2015-02-01

    The Monte Carlo method for photon transport is often used to predict the volumetric heating that an optical source will induce inside a tissue or material. This method relies on constant (with respect to temperature) optical properties, specifically the coefficients of scattering and absorption. In reality, optical coefficients are typically temperature-dependent, leading to error in simulation results. The purpose of this study is to develop a method that can incorporate variable properties and accurately simulate systems where the temperature will greatly vary, such as in the case of laser-thawing of frozen tissues. A numerical simulation was developed that utilizes the Monte Carlo method for photon transport to simulate the thermal response of a system that allows temperature-dependent optical and thermal properties. This was done by combining traditional Monte Carlo photon transport with a heat transfer simulation to provide a feedback loop that selects local properties based on current temperatures, for each moment in time. Additionally, photon steps are segmented to accurately obtain path lengths within a homogenous (but not isothermal) material. Validation of the simulation was done using comparisons to established Monte Carlo simulations using constant properties, and a comparison to the Beer-Lambert law for temperature-variable properties. The simulation is able to accurately predict the thermal response of a system whose properties can vary with temperature. The difference in results between variable-property and constant property methods for the representative system of laser-heated silicon can become larger than 100K. This simulation will return more accurate results of optical irradiation absorption in a material which undergoes a large change in temperature. This increased accuracy in simulated results leads to better thermal predictions in living tissues and can provide enhanced planning and improved experimental and procedural outcomes.

  1. Application of optical methods to the study of jet noise and turbulence

    NASA Technical Reports Server (NTRS)

    Sava, P. G.; Haertig, J.

    1980-01-01

    Optical methods are generally applied in fluid mechanics for either visualization or measurement. The use of a laser anemometer to study flow velocity in a jet and its relaton to the sound radiated is described. The same acoustic emission phenomenon is also measued by combining the signals from four Schlieren systems with that from an interferometer. The use of an optical Fourier transformation approach with real time analysis to determine the spatio-temporal structure of a field of mass volume such as a waveguide or free jet is also examined.

  2. Alignment method of optical registration for multi-channel CCD camera

    NASA Astrophysics Data System (ADS)

    Xin, Jia; Yue, Guo

    2016-10-01

    The mapping satellite is use of the multichip CCD assemble technology to meet the precision landscape positioning requirements. The size of a single CCD cannot meet the requirements of modern optical system. High cost and special technology are required for the resolution. In order to apply space camera to the measurement in large field of view and high resolution, the technology of optical assembly with several CCD is discussed. And a reflector based butting system was adopted. To extend the field of view, an optical butting system is proposed. Aiming at the problems of vignette and decline of modulation transfer function caused by butting, a reflector based butting system which has nine mirrors was investigated. This paper introduced the structure design of a long array and the principle of optical butting. The basic idea of this system is to split the optical image into several parts, so that they can be detected by different sensors. The mirror is used in conventional imaging system; divide the optical image into two parts. To eliminate the vignette distortion caused by the optical system and keep high signal to noise ratio, the sensors receiving the two focal image parts are placed with a little overlapping so that they can compensate each other. In order to ensure the key techniques of mirror location accuracy, a new alignment method was proposed about locating conversation components, mainly aimed at enhancing assembly accuracy of linear array CCD.A high quality image can be obtained by butting the two image parts. Its principle, methods of adjusting and testing as well as the structure of focal plane are described. The assembly with nine TDICCDs is finished on the facility which is composed of a long work-distance microscope and a precise X-Y rail, using the method in which the mechanical adjusting is applied. Compared with convention system, this method can satisfy the linearity accuracy and overlapping pixels tolerance of 0.2 detector pixel sizes. And can

  3. Laser diode fiber optic apparatus for acupuncture treatment by the Oriental method

    NASA Astrophysics Data System (ADS)

    Pham, Van Hoi; Phung, Huu A.; Bui, Huy; Hoang, Cao D.; Vu, Duc T.; Tran, Minh T.; Nguyen, Minh H.

    1998-08-01

    The laser acupuncture equipment using laser diodes of 850, 1300 nm and optical fibers as light needles is presented. The double-frequency modulation of laser beam gives the high efficiency treatment of the low-power laser therapy by the oriental acupuncture method. The laser spot from optical fiber of 50 microns is suitable for the irradiation into special points on body or auricular by the acupuncture treatment schema. The laser intensity in pulse regime of 5 - 40 W/cm2 and irradiation time of 5 - 15 minutes are optimum for treatment of neurosis symptoms and pain-relieving.

  4. Orientation function of optical mouse realized by digital speckle correlation method

    NASA Astrophysics Data System (ADS)

    Zhen, ZhiQiang; Tang, ZhengXin; Yan, Haitao; Lai, Fangming

    2008-12-01

    Used digital speckle correlation method (DSCM) to realize orientation function of optical mouse is researched. The experiment is designed to obtain the dynamic speckle patterns which are shot by CCD, Then the DSCM is used to process the sequential images and also the experiment is simulated. The experimental results show the DSCM can confirm orientation function of the optical mouse, and have a good agreement with the simulation results, and the resolution we obtained is higher than the resolution of mouse on the market.

  5. Used digital speckle correlation method to realize orientation function of optical mouse

    NASA Astrophysics Data System (ADS)

    Yan, Haitao; Wang, Ming; Ge, Yixian; Zhou, Junping

    2008-09-01

    Used digital speckle correlation method (DSCM) to realize orientation function of optical mouse is researched. The experiment is designed to obtain the dynamic speckle patterns which are shot by CCD, then the DSCM is used to process the sequential images and also the experiment is simulated. The experimental results show the DSCM can confirm orientation function of the optical mouse, and have a good agreement with the simulation results, and the resolution we obtained is higher than the resolution of mouse on the market.

  6. A spectral collocation method for a rotating Bose-Einstein condensation in optical lattices

    NASA Astrophysics Data System (ADS)

    Li, Z.-C.; Chen, S.-Y.; Chien, C.-S.; Chen, H.-S.

    2011-06-01

    We extend the study of spectral collocation methods (SCM) in Li et al. (2009) [1] for semilinear elliptic eigenvalue problems to that for a rotating Bose-Einstein condensation (BEC) and a rotating BEC in optical lattices. We apply the Lagrange interpolants using the Legendre-Gauss-Lobatto points to derive error bounds for the SCM. The optimal error bounds are derived for both H-norm and L-norm. Extensive numerical experiments on a rotating Bose-Einstein condensation and a rotating BEC in optical lattices are reported. Our numerical results show that the convergence rate of the SCM is exponential, and is independent of the collocation points we choose.

  7. Optical method for controlling emissions of heavy metals of industrial enterprise

    NASA Astrophysics Data System (ADS)

    Timchenko, E. V.; Timchenko, P. E.; Tregub, N. V.; Selezneva, E. A.

    2016-04-01

    In this research carried out control of heavy metals on the territory of a large aviation company using an optical method of control. As the biological indicators of heavy metals were used the leaves of plants. As a result of research was performed bivariate analysis entered the optical coefficients at wavenumbers 1150 cm-1, 1547 cm-1 and 1600 cm-1, on the basis of which the identified zones aircraft factory exposed most contaminated with manganese and copper. The research of results are confirmed by chemical analysis of the soil.

  8. Optical method for the characterization of laterally-patterned samples in integrated circuits

    DOEpatents

    Maris, Humphrey J.

    2001-01-01

    Disclosed is a method for characterizing a sample having a structure disposed on or within the sample, comprising the steps of applying a first pulse of light to a surface of the sample for creating a propagating strain pulse in the sample, applying a second pulse of light to the surface so that the second pulse of light interacts with the propagating strain pulse in the sample, sensing from a reflection of the second pulse a change in optical response of the sample, and relating a time of occurrence of the change in optical response to at least one dimension of the structure.

  9. Optical method and system for the characterization of laterally-patterned samples in integrated circuits

    DOEpatents

    Maris, Humphrey J.

    2008-03-04

    Disclosed is a method for characterizing a sample having a structure disposed on or within the sample, comprising the steps of applying a first pulse of light to a surface of the sample for creating a propagating strain pulse in the sample, applying a second pulse of light to the surface so that the second pulse of light interacts with the propagating strain pulse in the sample, sensing from a reflection of the second pulse a change in optical response of the sample, and relating a time of occurrence of the change in optical response to at least one dimension of the structure.

  10. Signal measurement system for intra-body communication using optical isolation method

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kazuki; Katsuyama, Jun; Sugiyama, Ryo; Takizawa, Yasuaki; Ishii, Seita; Shinagawa, Mitsuru; Kado, Yuichi

    2014-09-01

    In this paper, we describe an induced signal measurement on the human body for developing a high-performance transceiver of an intra-body communication system. It is important to isolate awearable transceiver from an electrical instrument for precise measurement. We have developed a probe system using an optical isolation method including a laser diode, photo-diode, and optical fiber. The probe system can be successfully applied to the precise measurement of a receiving signal power at a wearable transceiver. We verify that the experimental results agree with the simulation results based on our previous channel model of intra-body communication.

  11. On determination of sign of the piezo-optic coefficients using torsion method.

    PubMed

    Vasylkiv, Yurij; Savaryn, Viktoriya; Smaga, Ihor; Skab, Ihor; Vlokh, Rostyslav

    2011-06-10

    We have shown that a high-accuracy torsion method recently developed by the authors for measuring piezo-optic coefficients allows determining not only the absolute value of the coefficients but also their sign. The techniques and experimental procedures used for determination of the sign are described in detail and proven based on studies of α-BaB2O4 and LiNbO3 crystals. The piezo-optic coefficients are determined for both crystals, and a combination of the corresponding photoelastic coefficients is determined for the case of α-BaB2O4 crystals.

  12. Noncontact single-pulse optical method to measure interfacial properties in intact systems.

    PubMed

    Clark, David C; Kim, Myung K

    2012-12-15

    We introduce a noncontact purely optical approach to measuring the localized surface properties of an interface within a system using a single optical pressure pulse and a time-resolved digital holographic quantitative phase-imaging technique to track the propagating nanometric capillary disturbance. We demonstrate the proposed method's ability to measure the surface energy of deionized water, methanol, and chemical monolayers formed by surfactants with good agreement to published values. The development of this technique boasts immediate application to static and dynamic systems and near-future applications for living biological cell membranes.

  13. Method of vibration analysis using holographic interferometry and heterodyne optical detection

    NASA Technical Reports Server (NTRS)

    Vlad, V. I.; Maurer, J.; Popa, D.

    1974-01-01

    A method of studying thin plate vibrations with the aid of a laser beam is discussed. Through a suitable combination of time-average holographic interferometry, real-time holographic interferometry, and heterodyne optical detection, it is possible to obtain complete information on the vibration parameters of modes, amplitudes, frequencies, and phases. The method has the advantage of three dimensional global observation, noncontact, and high precision measurements.

  14. Optical matrix-matrix multiplication method demonstrated by the use of a multifocus hololens.

    PubMed

    Liang, Y Z; Liu, H K

    1984-08-01

    A method of optical matrix-matrix multiplication is presented. The feasibility of the method is also experimentally demonstrated by the use of a dichromated-gelatin multifocus holographic lens (hololens). With the specific values of matrices chosen, the average percentage error between the theoretical and experimental data of the elements of the output matrix of the multiplication of some specific pairs of 3 x 3 matrices is 0.4%, which corresponds to an 8-bit accuracy.

  15. Optical matrix-matrix multiplication method demonstrated by the use of a multifocus hololens

    NASA Technical Reports Server (NTRS)

    Liu, H. K.; Liang, Y.-Z.

    1984-01-01

    A method of optical matrix-matrix multiplication is presented. The feasibility of the method is also experimentally demonstrated by the use of a dichromated-gelatin multifocus holographic lens (hololens). With the specific values of matrices chosen, the average percentage error between the theoretical and experimental data of the elements of the output matrix of the multiplication of some specific pairs of 3 x 3 matrices is 0.4 percent, which corresponds to an 8-bit accuracy.

  16. Optical Remote Sensing Method to Determine Strength of Non-point Sources

    DTIC Science & Technology

    2008-09-01

    1989. “Air Toxics Monitoring: A Comparison Between Remote Sensing and Point Monitoring Techniques,” In Proceedings of American Chemical Society ... Method to Determine Strength of Non-point Sources September 2008 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden...SUBTITLE Optical Remote Sensing Method to Determine Strength of Non-point Sources 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

  17. Measurement of optic disc size: equivalence of methods to correct for ocular magnification

    PubMed Central

    Garway-Heath, D; Rudnicka, A; Lowe, T; Foster, P; Fitzke, F; Hitchings, R

    1998-01-01

    AIMS—To compare methods available to correct the magnification of images that result from the optics of the eye and identify errors, and source of error, of the methods.
METHODS—11 methods were applied to ocular biometry data from three independent cohorts. Each method was compared with the method of Bennett, which uses most biometric data. The difference between each method and Bennett's is the "error" of the method. The relation between the error and axial length, ametropia, and keratometry was explored by linear regression analysis.
RESULTS—Methods using axial length had the lowest mean (+0.5 to +2.6%) and standard deviation (0.6 to 1.2%) of errors. Of methods using keratometry and ametropia only, the lowest mean (−1.4% to +4.4%) and standard deviation (2.9 to 4.3%) of errors was found for a new method described in this paper, and that used by the Heidelberg retina tomograph (HRT). The highest mean error (+2.2 to +7.1%) was found for Littmann's method. Littmann's correction was larger than the HRT's by 3.5 to 3.7%. The mean difference between the new and HRT methods and the "abbreviated axial length" method of Bennett is −1.3 to +2.0%. The error of the "keratometry and ametropia" methods is related to axial length.
CONCLUSIONS—Methods using axial length are most accurate. The abbreviated axial length method of Bennett differs little from more detailed calculations and is appreciably more accurate than methods using keratometry and ametropia alone. If axial length is unknown, the new and the HRT methods give results closest to the abbreviated axial length method.

 Keywords: Littmann; magnification; optic disc; imaging PMID:9797665

  18. Method for Calculating the Optical Diffuse Reflection Coefficient for the Ocular Fundus

    NASA Astrophysics Data System (ADS)

    Lisenko, S. A.; Kugeiko, M. M.

    2016-07-01

    We have developed a method for calculating the optical diffuse reflection coefficient for the ocular fundus, taking into account multiple scattering of light in its layers (retina, epithelium, choroid) and multiple refl ection of light between layers. The method is based on the formulas for optical "combination" of the layers of the medium, in which the optical parameters of the layers (absorption and scattering coefficients) are replaced by some effective values, different for cases of directional and diffuse illumination of the layer. Coefficients relating the effective optical parameters of the layers and the actual values were established based on the results of a Monte Carlo numerical simulation of radiation transport in the medium. We estimate the uncertainties in retrieval of the structural and morphological parameters for the fundus from its diffuse reflectance spectrum using our method. We show that the simulated spectra correspond to the experimental data and that the estimates of the fundus parameters obtained as a result of solving the inverse problem are reasonable.

  19. Spectrophotometric method for optical band gap and electronic transitions determination of semiconductor materials

    NASA Astrophysics Data System (ADS)

    Sangiorgi, Nicola; Aversa, Lucrezia; Tatti, Roberta; Verucchi, Roberto; Sanson, Alessandra

    2017-02-01

    The optical band gap energy and the electronic processes involved are important parameters of a semiconductor material and it is therefore important to determine their correct values. Among the possible methods, the spectrophotometric is one of the most common. Several methods can be applied to determine the optical band gap energy and still now a defined consensus on the most suitable one has not been established. A highly diffused and accurate optical method is based on Tauc relationship, however to apply this equation is necessary to know the nature of the electronic transitions involved commonly related to the coefficient n. For this purpose, a spectrophotometric technique was used and we developed a graphical method for electronic transitions and band gap energy determination for samples in powder form. In particular, the n coefficient of Tauc equation was determined thorough mathematical elaboration of experimental results on TiO2 (anatase), ZnO, and SnO2. The results were used to calculate the band gap energy values and then compared with the information obtained by Ultraviolet Photoelectron Spectroscopy (UPS). This approach provides a quick and accurate method for band gap determination through n coefficient calculation. Moreover, this simple but reliable method can be used to evaluate the nature of electronic transition that occurs in a semiconductor material in powder form.

  20. An Intelligent Optical Dissolved Oxygen Measurement Method Based on a Fluorescent Quenching Mechanism.

    PubMed

    Li, Fengmei; Wei, Yaoguang; Chen, Yingyi; Li, Daoliang; Zhang, Xu

    2015-12-09

    Dissolved oxygen (DO) is a key factor that influences the healthy growth of fishes in aquaculture. The DO content changes with the aquatic environment and should therefore be monitored online. However, traditional measurement methods, such as iodometry and other chemical analysis methods, are not suitable for online monitoring. The Clark method is not stable enough for extended periods of monitoring. To solve these problems, this paper proposes an intelligent DO measurement method based on the fluorescence quenching mechanism. The measurement system is composed of fluorescent quenching detection, signal conditioning, intelligent processing, and power supply modules. The optical probe adopts the fluorescent quenching mechanism to detect the DO content and solves the problem, whereas traditional chemical methods are easily influenced by the environment. The optical probe contains a thermistor and dual excitation sources to isolate visible parasitic light and execute a compensation strategy. The intelligent processing module adopts the IEEE 1451.2 standard and realizes intelligent compensation. Experimental results show that the optical measurement method is stable, accurate, and suitable for online DO monitoring in aquaculture applications.

  1. An Intelligent Optical Dissolved Oxygen Measurement Method Based on a Fluorescent Quenching Mechanism

    PubMed Central

    Li, Fengmei; Wei, Yaoguang; Chen, Yingyi; Li, Daoliang; Zhang, Xu

    2015-01-01

    Dissolved oxygen (DO) is a key factor that influences the healthy growth of fishes in aquaculture. The DO content changes with the aquatic environment and should therefore be monitored online. However, traditional measurement methods, such as iodometry and other chemical analysis methods, are not suitable for online monitoring. The Clark method is not stable enough for extended periods of monitoring. To solve these problems, this paper proposes an intelligent DO measurement method based on the fluorescence quenching mechanism. The measurement system is composed of fluorescent quenching detection, signal conditioning, intelligent processing, and power supply modules. The optical probe adopts the fluorescent quenching mechanism to detect the DO content and solves the problem, whereas traditional chemical methods are easily influenced by the environment. The optical probe contains a thermistor and dual excitation sources to isolate visible parasitic light and execute a compensation strategy. The intelligent processing module adopts the IEEE 1451.2 standard and realizes intelligent compensation. Experimental results show that the optical measurement method is stable, accurate, and suitable for online DO monitoring in aquaculture applications. PMID:26690176

  2. Iterative total least-squares image reconstruction algorithm for optical tomography by the conjugate gradient method.

    PubMed

    Zhu, W; Wang, Y; Yao, Y; Chang, J; Graber, H L; Barbour, R L

    1997-04-01

    We present an iterative total least-squares algorithm for computing images of the interior structure of highly scattering media by using the conjugate gradient method. For imaging the dense scattering media in optical tomography, a perturbation approach has been described previously [Y. Wang et al., Proc. SPIE 1641, 58 (1992); R. L. Barbour et al., in Medical Optical Tomography: Functional Imaging and Monitoring (Society of Photo-Optical Instrumentation Engineers, Bellingham, Wash., 1993), pp. 87-120], which solves a perturbation equation of the form W delta x = delta I. In order to solve this equation, least-squares or regularized least-squares solvers have been used in the past to determine best fits to the measurement data delta I while assuming that the operator matrix W is accurate. In practice, errors also occur in the operator matrix. Here we propose an iterative total least-squares (ITLS) method that minimizes the errors in both weights and detector readings. Theoretically, the total least-squares (TLS) solution is given by the singular vector of the matrix [W/ delta I] associated with the smallest singular value. The proposed ITLS method obtains this solution by using a conjugate gradient method that is particularly suitable for very large matrices. Simulation results have shown that the TLS method can yield a significantly more accurate result than the least-squares method.

  3. Application of a discontinuous Galerkin time domain method to simulation of optical properties of dielectric particles.

    PubMed

    Tang, Guanglin; Panetta, R Lee; Yang, Ping

    2010-05-20

    We applied a discontinuous Galerkin time domain (DGTD) method, using a fourth-order Runga-Kutta time stepping of the Maxwell equations, to the simulation of the optical properties of dielectric particles in two-dimensional (2D) geometry. As examples of the numerical implementation of this method, the single-scattering properties of 2D circular and hexagonal particles are presented. In the case of circular particles, the scattering phase matrix was computed using the DGTD method and compared with the exact solution. For hexagonal particles, the DGTD method was used to compute single-scattering properties of randomly oriented 2D hexagonal ice crystals, and results were compared with those calculated using a geometric optics method. We consider both shortwave (visible) and longwave (infrared) cases, with particle size parameters 50 and 100. In the hexagonal case, scattering results are also presented as a function of both incident and scattering angles, revealing a structure apparently not reported before. Using the geometric optics method, we are able to interpret this structure in terms of contributions from varying numbers of internal reflections within the crystal.

  4. Method and program product for determining a radiance field in an optical environment

    NASA Technical Reports Server (NTRS)

    Reinersman, Phillip N. (Inventor); Carder, Kendall L. (Inventor)

    2007-01-01

    A hybrid method is presented by which Monte Carlo techniques are combined with iterative relaxation techniques to solve the Radiative Transfer Equation in arbitrary one-, two- or three-dimensional optical environments. The optical environments are first divided into contiguous regions, or elements, with Monte Carlo techniques then being employed to determine the optical response function of each type of element. The elements are combined, and the iterative relaxation techniques are used to determine simultaneously the radiance field on the boundary and throughout the interior of the modeled environment. This hybrid model is capable of providing estimates of the under-water light field needed to expedite inspection of ship hulls and port facilities. It is also capable of providing estimates of the subaerial light field for structured, absorbing or non-absorbing environments such as shadows of mountain ranges within and without absorption spectral bands such as water vapor or CO.sub.2 bands.

  5. A numerical study of gradient-based nonlinear optimization methods for contrast enhanced optical tomography.

    PubMed

    Roy, R; Sevick-Muraca, E

    2001-07-02

    Numerical performance of two gradient-based methods, a truncated-Newton method with trust region (TN) and a nonlinear conjugate gradient (NCG), is studied and compared for a given data set and conditions specific for the contrast enhanced optical tomography problem. Our results suggest that the relative performance of the two methods depends upon the error functions, specific to the problem to be solved. The TN outperforms the NCG when maps of fluorescence lifetime are reconstructed while both methods performed well when the absorption coefficient constitutes the parameter set that is to be recovered.

  6. Research on target tracking in coal mine based on optical flow method

    NASA Astrophysics Data System (ADS)

    Xue, Hongye; Xiao, Qingwei

    2015-03-01

    To recognize, track and count the bolting machine in coal mine video images, a real-time target tracking method based on the Lucas-Kanade sparse optical flow is proposed in this paper. In the method, we judge whether the moving target deviate from its trajectory, predicate and correct the position of the moving target. The method solves the problem of failure to track the target or lose the target because of the weak light, uneven illumination and blocking. Using the VC++ platform and Opencv lib we complete the recognition and tracking. The validity of the method is verified by the result of the experiment.

  7. Quantitative evaluation of registration methods for atlas-based diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Wu, Xue; Eggebrecht, Adam T.; Culver, Joseph P.; Zhan, Yuxuan; Basevi, Hector; Dehghani, Hamid

    2013-06-01

    In Diffuse Optical Tomography (DOT), an atlas-based model can be used as an alternative to a subject-specific anatomical model for recovery of brain activity. The main step of the generation of atlas-based subject model is the registration of atlas model to the subject head. The accuracy of the DOT then relies on the accuracy of registration method. In this work, 11 registration methods are quantitatively evaluated. The registration method with EEG 10/20 systems with 19 landmarks and non-iterative point to point algorithm provides approximately 1.4 mm surface error and is considered as the most efficient registration method.

  8. Adaptive optics in spinning disk microscopy: improved contrast and brightness by a simple and fast method.

    PubMed

    Fraisier, V; Clouvel, G; Jasaitis, A; Dimitrov, A; Piolot, T; Salamero, J

    2015-09-01

    Multiconfocal microscopy gives a good compromise between fast imaging and reasonable resolution. However, the low intensity of live fluorescent emitters is a major limitation to this technique. Aberrations induced by the optical setup, especially the mismatch of the refractive index and the biological sample itself, distort the point spread function and further reduce the amount of detected photons. Altogether, this leads to impaired image quality, preventing accurate analysis of molecular processes in biological samples and imaging deep in the sample. The amount of detected fluorescence can be improved with adaptive optics. Here, we used a compact adaptive optics module (adaptive optics box for sectioning optical microscopy), which was specifically designed for spinning disk confocal microscopy. The module overcomes undesired anomalies by correcting for most of the aberrations in confocal imaging. Existing aberration detection methods require prior illumination, which bleaches the sample. To avoid multiple exposures of the sample, we established an experimental model describing the depth dependence of major aberrations. This model allows us to correct for those aberrations when performing a z-stack, gradually increasing the amplitude of the correction with depth. It does not require illumination of the sample for aberration detection, thus minimizing photobleaching and phototoxicity. With this model, we improved both signal-to-background ratio and image contrast. Here, we present comparative studies on a variety of biological samples.

  9. Optically triggered high voltage switch network and method for switching a high voltage

    DOEpatents

    El-Sharkawi, Mohamed A.; Andexler, George; Silberkleit, Lee I.

    1993-01-19

    An optically triggered solid state switch and method for switching a high voltage electrical current. A plurality of solid state switches (350) are connected in series for controlling electrical current flow between a compensation capacitor (112) and ground in a reactive power compensator (50, 50') that monitors the voltage and current flowing through each of three distribution lines (52a, 52b and 52c), which are supplying three-phase power to one or more inductive loads. An optical transmitter (100) controlled by the reactive power compensation system produces light pulses that are conveyed over optical fibers (102) to a switch driver (110') that includes a plurality of series connected optical triger circuits (288). Each of the optical trigger circuits controls a pair of the solid state switches and includes a plurality of series connected resistors (294, 326, 330, and 334) that equalize or balance the potential across the plurality of trigger circuits. The trigger circuits are connected to one of the distribution lines through a trigger capacitor (340). In each switch driver, the light signals activate a phototransistor (300) so that an electrical current flows from one of the energy reservoir capacitors through a pulse transformer (306) in the trigger circuit, producing gate signals that turn on the pair of serially connected solid state switches (350).

  10. A simple growth method for Nb2O5 films and their optical properties

    DOE PAGES

    Dash, J. K.; Chen, L.; Topka, Michael R.; ...

    2015-04-13

    A simple method for the synthesis of Nb₂O₅ films of thicknesses ranging from tens to several hundreds of nanometers on amorphous silicon dioxide or quartz substrates is presented. Nb₂O₅ films were formed by annealing the sputter deposited Nb films under an Ar flow and without oxygen plasma in a quartz tube within a furnace at 850 °C. The structural, compositional, optical, and vibrational properties were characterized by grazing incidence X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet visible spectroscopy, and Raman scattering. Each of the Nb₂O₅ films is polycrystalline with an orthorhombic crystal structure. We observed vibrational modes includingmore » longitudinal optical, transverse optical, and triply degenerate modes, and measured the indirect optical band gap to be ~3.65 eV. The transmittance spectrum of the ~20 nm thick Nb₂O₅ film shows over 90% transmittance below the band gap energy in the visible wavelength range and decreases to less than 20% in the ultraviolet regime. As a result, the optical properties of the films in the UV-vis range show potential applications as UV detectors.« less

  11. Optical tomography reconstruction algorithm with the finite element method: An optimal approach with regularization tools

    SciTech Connect

    Balima, O.; Favennec, Y.; Rousse, D.

    2013-10-15

    Highlights: •New strategies to improve the accuracy of the reconstruction through mesh and finite element parameterization. •Use of gradient filtering through an alternative inner product within the adjoint method. •An integral form of the cost function is used to make the reconstruction compatible with all finite element formulations, continuous and discontinuous. •Gradient-based algorithm with the adjoint method is used for the reconstruction. -- Abstract: Optical tomography is mathematically treated as a non-linear inverse problem where the optical properties of the probed medium are recovered through the minimization of the errors between the experimental measurements and their predictions with a numerical model at the locations of the detectors. According to the ill-posed behavior of the inverse problem, some regularization tools must be performed and the Tikhonov penalization type is the most commonly used in optical tomography applications. This paper introduces an optimized approach for optical tomography reconstruction with the finite element method. An integral form of the cost function is used to take into account the surfaces of the detectors and make the reconstruction compatible with all finite element formulations, continuous and discontinuous. Through a gradient-based algorithm where the adjoint method is used to compute the gradient of the cost function, an alternative inner product is employed for preconditioning the reconstruction algorithm. Moreover, appropriate re-parameterization of the optical properties is performed. These regularization strategies are compared with the classical Tikhonov penalization one. It is shown that both the re-parameterization and the use of the Sobolev cost function gradient are efficient for solving such an ill-posed inverse problem.

  12. Method for auto-alignment of digital optical phase conjugation systems based on digital propagation

    PubMed Central

    Jang, Mooseok; Ruan, Haowen; Zhou, Haojiang; Judkewitz, Benjamin; Yang, Changhuei

    2014-01-01

    Optical phase conjugation (OPC) has enabled many optical applications such as aberration correction and image transmission through fiber. In recent years, implementation of digital optical phase conjugation (DOPC) has opened up the possibility of its use in biomedical optics (e.g. deep-tissue optical focusing) due to its ability to provide greater-than-unity OPC reflectivity (the power ratio of the phase conjugated beam and input beam to the OPC system) and its flexibility to accommodate additional wavefront manipulations. However, the requirement for precise (pixel-to-pixel matching) alignment of the wavefront sensor and the spatial light modulator (SLM) limits the practical usability of DOPC systems. Here, we report a method for auto-alignment of a DOPC system by which the misalignment between the sensor and the SLM is auto-corrected through digital light propagation. With this method, we were able to accomplish OPC playback with a DOPC system with gross sensor-SLM misalignment by an axial displacement of up to~1.5 cm, rotation and tip/tilt of ~5∘, and in-plane displacement of ~5 mm (dependent on the physical size of the sensor and the SLM). Our auto-alignment method robustly achieved a DOPC playback peak-to-background ratio (PBR) corresponding to more than ~30 % of the theoretical maximum. As an additional advantage, the auto-alignment procedure can be easily performed at will and, as such, allows us to correct for small mechanical drifts within the DOPC systems, thus overcoming a previously major DOPC system vulnerability. We believe that this reported method for implementing robust DOPC systems will broaden the practical utility of DOPC systems. PMID:24977504

  13. Brillouin Corrosion Expansion Sensors for Steel Reinforced Concrete Structures Using a Fiber Optic Coil Winding Method

    PubMed Central

    Zhao, Xuefeng; Gong, Peng; Qiao, Guofu; Lu, Jie; Lv, Xingjun; Ou, Jinping

    2011-01-01

    In this paper, a novel kind of method to monitor corrosion expansion of steel rebars in steel reinforced concrete structures named fiber optic coil winding method is proposed, discussed and tested. It is based on the fiber optical Brillouin sensing technique. Firstly, a strain calibration experiment is designed and conducted to obtain the strain coefficient of single mode fiber optics. Results have shown that there is a good linear relationship between Brillouin frequency and applied strain. Then, three kinds of novel fiber optical Brillouin corrosion expansion sensors with different fiber optic coil winding packaging schemes are designed. Sensors were embedded into concrete specimens to monitor expansion strain caused by steel rebar corrosion, and their performance was studied in a designed electrochemical corrosion acceleration experiment. Experimental results have shown that expansion strain along the fiber optic coil winding area can be detected and measured by the three kinds of sensors with different measurement range during development the corrosion. With the assumption of uniform corrosion, diameters of corrosion steel rebars were obtained using calculated average strains. A maximum expansion strain of 6,738 με was monitored. Furthermore, the uniform corrosion analysis model was established and the evaluation formula to evaluate mass loss rate of steel rebar under a given corrosion rust expansion rate was derived. The research has shown that three kinds of Brillouin sensors can be used to monitor the steel rebar corrosion expansion of reinforced concrete structures with good sensitivity, accuracy and monitoring range, and can be applied to monitor different levels of corrosion. By means of this kind of monitoring technique, quantitative corrosion expansion monitoring can be carried out, with the virtues of long durability, real-time monitoring and quasi-distribution monitoring. PMID:22346672

  14. Brillouin corrosion expansion sensors for steel reinforced concrete structures using a fiber optic coil winding method.

    PubMed

    Zhao, Xuefeng; Gong, Peng; Qiao, Guofu; Lu, Jie; Lv, Xingjun; Ou, Jinping

    2011-01-01

    In this paper, a novel kind of method to monitor corrosion expansion of steel rebars in steel reinforced concrete structures named fiber optic coil winding method is proposed, discussed and tested. It is based on the fiber optical Brillouin sensing technique. Firstly, a strain calibration experiment is designed and conducted to obtain the strain coefficient of single mode fiber optics. Results have shown that there is a good linear relationship between Brillouin frequency and applied strain. Then, three kinds of novel fiber optical Brillouin corrosion expansion sensors with different fiber optic coil winding packaging schemes are designed. Sensors were embedded into concrete specimens to monitor expansion strain caused by steel rebar corrosion, and their performance was studied in a designed electrochemical corrosion acceleration experiment. Experimental results have shown that expansion strain along the fiber optic coil winding area can be detected and measured by the three kinds of sensors with different measurement range during development the corrosion. With the assumption of uniform corrosion, diameters of corrosion steel rebars were obtained using calculated average strains. A maximum expansion strain of 6,738 με was monitored. Furthermore, the uniform corrosion analysis model was established and the evaluation formula to evaluate mass loss rate of steel rebar under a given corrosion rust expansion rate was derived. The research has shown that three kinds of Brillouin sensors can be used to monitor the steel rebar corrosion expansion of reinforced concrete structures with good sensitivity, accuracy and monitoring range, and can be applied to monitor different levels of corrosion. By means of this kind of monitoring technique, quantitative corrosion expansion monitoring can be carried out, with the virtues of long durability, real-time monitoring and quasi-distribution monitoring.

  15. Diffuse optical tomography reconstruction method using ultrasound images as prior for regularization matrix

    NASA Astrophysics Data System (ADS)

    Althobaiti, Murad; Vavadi, Hamed; Zhu, Quing

    2017-02-01

    Ultrasound-guided diffuse optical tomography (DOT) is a promising imaging technique that maps hemoglobin concentrations of breast lesions to assist ultrasound (US) for cancer diagnosis and treatment monitoring. The accurate recovery of breast lesion optical properties requires an effective image reconstruction method. We introduce a reconstruction approach in which US images are encoded as prior information for regularization of the inversion matrix. The framework of this approach is based on image reconstruction package "NIRFAST." We compare this approach to the US-guided dual-zone mesh reconstruction method, which is based on Born approximation and conjugate gradient optimization developed in our laboratory. Results were evaluated using phantoms and clinical data. This method improves classification of malignant and benign lesions by increasing malignant to benign lesion absorption contrast. The results also show improvements in reconstructed lesion shapes and the spatial distribution of absorption maps.

  16. The importance of optical methods for non-invasive measurements in the skin care industry

    NASA Astrophysics Data System (ADS)

    Stamatas, Georgios N.

    2010-02-01

    Pharmaceutical and cosmetic industries are concerned with treating skin disease, as well as maintaining and promoting skin health. They are dealing with a unique tissue that defines our body in space. As such, skin provides not only the natural boundary with the environment inhibiting body dehydration as well as penetration of exogenous aggressors to the body, it is also ideally situated for optical measurements. A plurality of spectroscopic and imaging methods is being used to understand skin physiology and pathology and document the effects of topically applied products on the skin. The obvious advantage of such methods over traditional biopsy techniques is the ability to measure the cutaneous tissue in vivo and non-invasively. In this work, we will review such applications of various spectroscopy and imaging methods in skin research that is of interest the cosmetic and pharmaceutical industry. Examples will be given on the importance of optical techniques in acquiring new insights about acne pathogenesis and infant skin development.

  17. A Fast Optical Method for the Determination of Liquid Levels in Microplates

    PubMed Central

    Thurow, Kerstin; Stoll, Norbert; Ritterbusch, Kai

    2011-01-01

    Parallel liquid handling systems are widely used in different applications of life sciences. In order to avoid false positive or negative results which lead to higher costs due to the replication of the experiments it is necessary to monitor the process and success of liquid delivery. An easy method for the determination of the liquid levels in microplates has been developed and evaluated. The optical method bases on the measurement of the liquid level using CCD cameras followed by special algorithms for the evaluation and visualization of the measured data. The proposed method was tested in changing environmental lighting for two different liquids. These tests confirm our approach towards optical liquid level determination for smallest volumes in microplates and also show the challenges regarding environmental lighting and different physical properties of fluids. PMID:21747734

  18. Quantitative measurement of ultrasound pressure field by optical phase contrast method and acoustic holography

    NASA Astrophysics Data System (ADS)

    Oyama, Seiji; Yasuda, Jun; Hanayama, Hiroki; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    A fast and accurate measurement of an ultrasound field with various exposure sequences is necessary to ensure the efficacy and safety of various ultrasound applications in medicine. The most common method used to measure an ultrasound pressure field, that is, hydrophone scanning, requires a long scanning time and potentially disturbs the field. This may limit the efficiency of developing applications of ultrasound. In this study, an optical phase contrast method enabling fast and noninterfering measurements is proposed. In this method, the modulated phase of light caused by the focused ultrasound pressure field is measured. Then, a computed tomography (CT) algorithm used to quantitatively reconstruct a three-dimensional (3D) pressure field is applied. For a high-intensity focused ultrasound field, a new approach that combines the optical phase contrast method and acoustic holography was attempted. First, the optical measurement of focused ultrasound was rapidly performed over the field near a transducer. Second, the nonlinear propagation of the measured ultrasound was simulated. The result of the new approach agreed well with that of the measurement using a hydrophone and was improved from that of the phase contrast method alone with phase unwrapping.

  19. Security enhanced optical one-time password authentication method by using digital holography

    NASA Astrophysics Data System (ADS)

    Gil, Sang Keun; Jeon, Seok Hee; Jeong, Jong Rae

    2015-03-01

    We propose a new optical one-time password(OTP) authentication method by using digital holography, which enhances security strength in the cryptosystem compared to the conventional electronic OTP method. In this paper, a challenge-response optical OTP authentication based on two-factor authentication is presented by 2-step quadrature phase-shifting digital holography using orthogonal polarization, and two-way authentication is also performed using the challenge-response handshake in both directions. The ID (identification), PW (password) and OTP information are encrypted with a shared key by applying phase-shifting digital holography, and these encrypted information are verified each other by the shared key. Because the encrypted digital holograms which are transmitted to the other party are expressed as random distribution, it guards against a replay attack and results in higher security level. Optically, encrypted digital hologram in our method is Fourier transform hologram and is recorded on CCD with 256 gray-level quantized intensities. The proposed method has an advantage that it does not need a time-synchronized OTP and can be applied to various security services. Computer experiments show that the proposed method is suitable for high secure OTP authentication.

  20. Direct optical band gap measurement in polycrystalline semiconductors: A critical look at the Tauc method

    NASA Astrophysics Data System (ADS)

    Dolgonos, Alex; Mason, Thomas O.; Poeppelmeier, Kenneth R.

    2016-08-01

    The direct optical band gap of semiconductors is traditionally measured by extrapolating the linear region of the square of the absorption curve to the x-axis, and a variation of this method, developed by Tauc, has also been widely used. The application of the Tauc method to crystalline materials is rooted in misconception-and traditional linear extrapolation methods are inappropriate for use on degenerate semiconductors, where the occupation of conduction band energy states cannot be ignored. A new method is proposed for extracting a direct optical band gap from absorption spectra of degenerately-doped bulk semiconductors. This method was applied to pseudo-absorption spectra of Sn-doped In2O3 (ITO)-converted from diffuse-reflectance measurements on bulk specimens. The results of this analysis were corroborated by room-temperature photoluminescence excitation measurements, which yielded values of optical band gap and Burstein-Moss shift that are consistent with previous studies on In2O3 single crystals and thin films.

  1. Roadmap on biosensing and photonics with advanced nano-optical methods

    NASA Astrophysics Data System (ADS)

    Di Fabrizio, Enzo; Schlücker, Sebastian; Wenger, Jérôme; Regmi, Raju; Rigneault, Hervé; Calafiore, Giuseppe; West, Melanie; Cabrini, Stefano; Fleischer, Monika; van Hulst, Niek F.; Garcia-Parajo, Maria F.; Pucci, Annemarie; Cojoc, Dan; Hauser, Charlotte A. E.; Ni, Ming

    2016-06-01

    This roadmap, through the contributions of ten groups worldwide, contains different techniques, methods and materials devoted to sensing in nanomedicine. Optics is used in different ways in the detection schemes. Raman, fluorescence and infrared spectroscopies, plasmonics, second harmonic generation and optical tweezers are all used in applications from single molecule detection (both in highly diluted and in highly concentrated solutions) to single cell manipulation. In general, each optical scheme, through device miniaturization and electromagnetic field localization, exploits an intrinsic optical enhancement mechanism in order to increase the sensitivity and selectivity of the device with respect to the complex molecular construct. The materials used for detection include nanoparticles and nanostructures fabricated with different 2D and 3D lithographic methods. It is shown that sensitivity to a single molecule is already accessible whether the system under study is a single cell or a multitude of cells in a molecular mixture. Throughout the roadmap there is an attempt to foresee and to suggest future directions in this interdisciplinary field.

  2. Using the power spectral density method to characterise the surface topography of optical surfaces

    NASA Astrophysics Data System (ADS)

    Alcock, Simon G.; Ludbrook, Geoff D.; Owen, Tommy; Dockree, Richard

    2010-08-01

    Power Spectral Density (PSD) is an alternative method for specifying optical surfaces, and quantifies the contribution of each spatial regime to the total surface error. This approach naturally includes mid-range spatial frequency errors, which are often overlooked. The PSD method has recently been adopted by the Space and Astronomy industries, but has not yet received general acceptance within the synchrotron community. To assess the suitability for specifying synchrotron optics using PSD, Fast Fourier Transforms were performed on topography data from a range of optical surfaces of varying quality and manufacturing techniques. For each grade of optic, the entire regime ({100nm to {50mm) of surface errors was measured, with overlapping bandwidths, using a micro-interferometer and a Fizeau interferometer. From this heuristic information, root-mean square "roughness" can be predicted over any desired spatial range, thus allowing direct comparison of metrology data obtained by instruments with different spatial bandwidths. We present an efficient approach for calculating 1-D and 2-D PSDs using MATLAB algorithms, and discuss analysis considerations, including "field of view" effects and instrument calibration.

  3. A rapid and reversible skull optical clearing method for monitoring cortical blood flow

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Zhao, Yanjie; Shi, Rui; Zhu, Dan

    2016-03-01

    In vivo cortex optical imaging is of great important for revealing both structural and functional architecture of brain with high temporal-spatial resolution. To reduce the limitation of turbid skull, researchers had to establish various skull windows or directly expose cortex through craniotomy. Here we developed a skull optical clearing method to make skull transparent. Laser speckle contrast imaging technique was used to monitor the cortical blood flow after topical treatment with the optical clearing agents. The results indicated that the image contrast increased gradually, and then maintained at a high level after 15 min for adult mice, which made the image quality and resolution of micro-vessels nearly approximate to those of exposed cortex. Both the cortical blood flow velocity almost kept constant after skull became transparent. Besides, the treatment of physiological saline on the skull could make skull return to the initial state again and the skull could become transparent again when SOCS retreated it. Thus, we could conclude that the skull optical clearing method was rapid, valid, reversible and safe, which provided us available approach for performing the cortical structural and functional imaging at high temporal-spatial resolution.

  4. Minimally invasive surgical method to detect sound processing in the cochlear apex by optical coherence tomography

    PubMed Central

    Ramamoorthy, Sripriya; Zhang, Yuan; Petrie, Tracy; Fridberger, Anders; Ren, Tianying; Wang, Ruikang; Jacques, Steven L.; Nuttall, Alfred L.

    2016-01-01

    Abstract. Sound processing in the inner ear involves separation of the constituent frequencies along the length of the cochlea. Frequencies relevant to human speech (100 to 500 Hz) are processed in the apex region. Among mammals, the guinea pig cochlear apex processes similar frequencies and is thus relevant for the study of speech processing in the cochlea. However, the requirement for extensive surgery has challenged the optical accessibility of this area to investigate cochlear processing of signals without significant intrusion. A simple method is developed to provide optical access to the guinea pig cochlear apex in two directions with minimal surgery. Furthermore, all prior vibration measurements in the guinea pig apex involved opening an observation hole in the otic capsule, which has been questioned on the basis of the resulting changes to cochlear hydrodynamics. Here, this limitation is overcome by measuring the vibrations through the unopened otic capsule using phase-sensitive Fourier domain optical coherence tomography. The optically and surgically advanced method described here lays the foundation to perform minimally invasive investigation of speech-related signal processing in the cochlea. PMID:26836207

  5. Minimally invasive surgical method to detect sound processing in the cochlear apex by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Ramamoorthy, Sripriya; Zhang, Yuan; Petrie, Tracy; Fridberger, Anders; Ren, Tianying; Wang, Ruikang; Jacques, Steven L.; Nuttall, Alfred L.

    2016-02-01

    Sound processing in the inner ear involves separation of the constituent frequencies along the length of the cochlea. Frequencies relevant to human speech (100 to 500 Hz) are processed in the apex region. Among mammals, the guinea pig cochlear apex processes similar frequencies and is thus relevant for the study of speech processing in the cochlea. However, the requirement for extensive surgery has challenged the optical accessibility of this area to investigate cochlear processing of signals without significant intrusion. A simple method is developed to provide optical access to the guinea pig cochlear apex in two directions with minimal surgery. Furthermore, all prior vibration measurements in the guinea pig apex involved opening an observation hole in the otic capsule, which has been questioned on the basis of the resulting changes to cochlear hydrodynamics. Here, this limitation is overcome by measuring the vibrations through the unopened otic capsule using phase-sensitive Fourier domain optical coherence tomography. The optically and surgically advanced method described here lays the foundation to perform minimally invasive investigation of speech-related signal processing in the cochlea.

  6. Research on optical fiber flow test method with non-intrusion

    NASA Astrophysics Data System (ADS)

    Shang, Ying; Liu, Xiaohui; Wang, Chang; Zhao, Wenan

    2014-06-01

    In the field of oil well logging, real-time monitoring of the fluid flow parameter provides a scientific basis for oil and gas optimization exploration and increase in reservoir recovery, so a non-intrusive flow test method based on turbulent vibration was proposed. The specific length of the sensor fiber wound tightly around the outer wall of the pipe was connected with the optical fiber gratings at both ends, and the sensor fiber and the optical fiber gratings composed the flow sensing unit. The dynamic pressure was generated by the turbulence when fluid flows through the pipe, and the dynamic pressure resulted in the light phase shift of the sensor fiber. The phase information was demodulated by the fiber optic interferometer technology, time division multiplexing technology, and phase generated carrier modulation and demodulation techniques. The quadratic curve relationship between the phase change and flow rate was found by experimental data analysis, and the experiment confirmed the feasibility of the optical fiber flow test method with non-intrusion and achieved the real-time monitoring of the fluid flow.

  7. Analysis of all-optically tunable functionalities in subwavelength periodic structures by the Fourier modal method

    NASA Astrophysics Data System (ADS)

    Bej, Subhajit; Tervo, Jani; Francés, Jorge; Svirko, Yuri P.; Turunen, Jari

    2016-05-01

    We propose the nonlinear Fourier Modal Method (FMM) [J. Opt. Soc. Am. B 31, 2371 (2014)] as a convenient and versatile numerical tool for the design and analysis of grating based next generation all-optical devices. Here, we include several numerical examples where the FMM is used to simulate all-optically tunable functionalities in sub-wavelength periodic structures. At first, we numerically investigate a 1-D periodic nonlinear binary grating with amorphous TiO2. We plot the diffraction efficiency in the transmitted orders against the structure depth for normally incident plane wave. Change in diffraction efficiencies for different incident field amplitudes are evident from the plots. We verify the accuracy of our implementation by comparing our results with the results obtained with the nonlinear Split Field-Finite Difference Time Domain (SF-FDTD) method. Next we repeat the same experiment with vertically standing amorphous Titanium dioxide (TiO2) nanowire arrays grown on top of quartz which are periodic in two mutually perpendicular directions and examine the efficiencies in the direct transmitted light for different incident field amplitudes. Our third example includes analysis of a form birefringent linear grating with Kerr medium. With FMM we demonstrate that the birefringence of such a structure can be tuned by all-optical means. As a final example, we design a narrow band Guided Mode Resonance Filter (GMRF). Numerical experiments based on the nonlinear FMM reveal that the spectral tunability of such a filter can be obtained by all-optical means.

  8. Novel image processing method study for a label-free optical biosensor

    NASA Astrophysics Data System (ADS)

    Yang, Chenhao; Wei, Li'an; Yang, Rusong; Feng, Ying

    2015-10-01

    Optical biosensor is generally divided into labeled type and label-free type, the former mainly contains fluorescence labeled method and radioactive-labeled method, while fluorescence-labeled method is more mature in the application. The mainly image processing methods of fluorescent-labeled biosensor includes smooth filtering, artificial gridding and constant thresholding. Since some fluorescent molecules may influence the biological reaction, label-free methods have been the main developing direction of optical biosensors nowadays. The using of wider field of view and larger angle of incidence light path which could effectively improve the sensitivity of the label-free biosensor also brought more difficulties in image processing, comparing with the fluorescent-labeled biosensor. Otsu's method is widely applied in machine vision, etc, which choose the threshold to minimize the intraclass variance of the thresholded black and white pixels. It's capacity-constrained with the asymmetrical distribution of images as a global threshold segmentation. In order to solve the irregularity of light intensity on the transducer, we improved the algorithm. In this paper, we present a new image processing algorithm based on a reflectance modulation biosensor platform, which mainly comprises the design of sliding normalization algorithm for image rectification and utilizing the improved otsu's method for image segmentation, in order to implement automatic recognition of target areas. Finally we used adaptive gridding method extracting the target parameters for analysis. Those methods could improve the efficiency of image processing, reduce human intervention, enhance the reliability of experiments and laid the foundation for the realization of high throughput of label-free optical biosensors.

  9. 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.

  10. Bend insensitive graded index multimode polymer optical waveguides fabricated using the Mosquito method

    NASA Astrophysics Data System (ADS)

    Takahashi, Asami; Ishigure, Takaaki

    2015-02-01

    We fabricate low-loss graded index (GI) circular core multimode polymer optical waveguides with 90o bending and demonstrate low bending loss even if the bend radius is as small as 1 mm. In the several fabrication methods for GI-core polymer waveguides already proposed, we adopt the "Mosquito method" that utilize a microdispenser because the Mosquito method makes it possible to fabricate waveguides directly on board at desired places on a printed circuit board, and to draw various patterns of cores including curves. However, in the waveguides including such curved cores, the additional transmission loss due to the bending (bending loss) is a concern. Thus, we characterize the fabricated GI-core polymer waveguides with bending: using two kinds of cladding monomer with different refractive indexes for fabricating waveguides with bending. We found when the NA of waveguides was as high as 0.35, no additional loss due to bending was observed even if the bending radius is as small as 1 mm. The core diameter of the fabricated waveguides is 50 μm, and it is possible to further decrease the bending loss in the waveguides with smaller core diameter. Furthermore, utilizing the Mosquito method, we fabricate waveguides with not only horizontally curved cores but also vertically curved ones. Waveguides with vertically curved cores could make it possible to realize three-dimensionally optical wiring applicable to on-board optical interconnects.

  11. Wavelength modulation-based method for interference phase detection with reduced optical complexity

    NASA Astrophysics Data System (ADS)

    Řeřucha, Šimon; Šarbort, Martin; Buchta, Zdeněk.; Mikel, Bretislav; Šmíd, Radek; Čížek, Martin; Jedlička, Petr; Řerucha, Jan; Lazar, Josef; Číp, Ondřej

    2013-04-01

    Although the laser interferometry represents the most precise class of techniques in the field of precise measurement of geometrical quantities, its wide use in measurement systems is still accompanied by many unresolved challenges. One of these challenges is the complexity of underlying optical systems. We present a novel approach to the interference phase detection - fringe subdivision - in the homodyne laser interferometry that aims at reduction of the optical complexity while the resolution is preserved. Our method employs a series of computational steps to infer a pair of signals in quadrature that allows to determine the interference phase with a sub-nanometre resolution from an interference signal from a non-polarising interferometer sampled by a single photodetector. The complexity trade-off is the use of laser beam with frequency modulation capability. The method was experimentally evaluated on a Michelson interferometer-based free-space setup and its performance has been compared to a traditional homodyne detection method. The results indicate the method is a feasible al­ ternative for the traditional homodyne detection since it performs with comparable accuracy (< 0.5nm standard deviation), especially where the optical setup complexity is principal issue and the modulation of laser beam is not a heavy burden, for instance in multi-axis measurement systems or laser diode based systems.

  12. Dynamic deformation measurement and analysis of active stressed lap using optical method

    NASA Astrophysics Data System (ADS)

    Zhang, Qican; Su, Xianyu; Liu, Yuankun; Xiang, Liqun

    2007-12-01

    The active stressed lap is the heart of polishing process. A novel non-contact optical method of dynamic deformation measurement and analysis of an active stressed lap is put forward. This method, based on structured illumination, is able to record full-field information of the bending and rotating stressed lap dynamically and continuously, while its profile is changed under computer control, and restore the whole process of lap deformation varied with time at different position and rotating angle. It has been verified by experiments that this proposed method will be helpful to the opticians to ensure the stressed lap as expected.

  13. A novel method for surface defect inspection of optic cable with short-wave infrared illuminance

    NASA Astrophysics Data System (ADS)

    Chen, Xiaohong; Liu, Ning; You, Bo; Xiao, Bin

    2016-07-01

    Intelligent on-line detection of cable quality is a crucial issue in optic cable factory, and defects on the surface of optic cable can dramatically depress cable grade. Manual inspection in optic cable quality cannot catch up with the development of optic cable industry due to its low detection efficiency and huge human cost. Therefore, real-time is highly demanded by industry in order to replace the subjective and repetitive process of manual inspection. For this reason, automatic cable defect inspection has been a trend. In this paper, a novel method for surface defect inspection of optic cable with short-wave infrared illuminance is presented. The special condition of short-wave infrared cannot only provide illumination compensation for the weak illumination environment, but also can avoid the problem of exposure when using visible light illuminance, which affects the accuracy of inspection algorithm. A series of image processing algorithms are set up to analyze cable image for the verification of real-time and veracity of the detection method. Unlike some existing detection algorithms which concentrate on the characteristics of defects with an active search way, the proposed method removes the non-defective areas of the image passively at the same time of image processing, which reduces a large amount of computation. OTSU algorithm is used to convert the gray image to the binary image. Furthermore, a threshold window is designed to eliminate the fake defects, and the threshold represents the considered minimum size of defects ε . Besides, a new regional suppression method is proposed to deal with the edge burrs of the cable, which shows the superior performance compared with that of Open-Close operation of mathematical morphological in the boundary processing. Experimental results of 10,000 samples show that the rates of miss detection and false detection are 2.35% and 0.78% respectively when ε equals to 0.5 mm, and the average processing period of one frame

  14. Analytical new method to generation of nonlinear optical pulses in wave guides and analysis of its stability

    NASA Astrophysics Data System (ADS)

    Amaro de Faria Júnior, A. C.

    2015-09-01

    We have developed a analitical method based on the general theory of modulation of Whitham7 where the variational method is a particular case to generate nonlinear optical pulses and Optical Solitons. We show the equivalence of the solutions of the Nonlinear Schrödinger Equation (NLS) and the solutions derived from the method proposed here, demonstrating that these solutions lead to the Optical Solitons. We developed a new method to check the stability of the NLS equations. We show that the Optical Solitons obtained from a Lagrangian density can propagate through a waveguide such as an optical fiber, and are equivalent to Optical Solitons guided by an optical fiber. To analyze the stability of system solutions we have expanded the Lagrangian density and from the expanded Lagrangian we obtain the system equations of motion and restrict the solutions that have oscillating behavior when disturbed. The stability analysis can also be performed by expansion of the optical field as it is presented in section 4. Thus obtain a self-value equation whose spectrum is positive indicating that the solutions with the characteristics of reproducing the NLS solutions are stable. This method can be used and implemented computationally for linear stability analysis of any optical system or any NLS solution. Another important aspect of our research has been the discovery of a relationship between the Lagrangian of optical system and the optical pulse propagating through a waveguide. The paper is organized as follows. Section 1 is devoted to a quick presentation of NLS systems. The section 2 provides a description of modeling of an optical network. Section 3 and 4 are devoted to the presentation of the proposed method for obtaining this class of solutions and their stability analysis. Section 5 presents conclusions and comments and section 6 provides references.

  15. Sighting optics including an optical element having a first focal length and a second focal length and methods for sighting

    DOEpatents

    Crandall, David Lynn

    2011-08-16

    Sighting optics include a front sight and a rear sight positioned in a spaced-apart relation. The rear sight includes an optical element having a first focal length and a second focal length. The first focal length is selected so that it is about equal to a distance separating the optical element and the front sight and the second focal length is selected so that it is about equal to a target distance. The optical element thus brings into simultaneous focus for a user images of the front sight and the target.

  16. Observation of Amorphous Recording Marks Using Reflection-Mode Near-Field Scanning Optical Microscope Supported by Optical Interference Method

    NASA Astrophysics Data System (ADS)

    Sakai, Masaru; Mononobe, Shuji; Yusu, Keiichiro; Tadokoro, Toshiyasu; Saiki, Toshiharu

    2005-09-01

    A signal enhancing technique for a reflection-mode near-field scanning optical microscope (NSOM) is proposed. Optical interference between the signal light, from an aperture at the tip of a tapered optical fiber, and the reflected light, from a metallic coating around the aperture, enhances the signal intensity. We used a rewritable high-definition digital versatile disc (HD DVD) with dual recording layers as a sample medium, and demonstrated observation of amorphous recording marks on the semitransparent (the first) recording layer. In spite of low optical contrast between the crystal region and the amorphous region on this layer, we successfully observed recording marks with good contrast.

  17. Laser surgery in dermatology with application of superthin optical fiber by contact and noncontact method

    NASA Astrophysics Data System (ADS)

    Garipova, A.; Denissov, I. A.; Solodovnikov, Vladimir; Digilova, I.

    1999-06-01

    At present nobody doubts the advantages of minor laser surgery over the conventional one.Bloodless manipulations, ablation, minor injury to the tissues while using laser equipment ensures its wide application in such fields as dermatology and cosmetology, especially since the semiconductor lasers because available at the technological market. No doubt CO2 and solid laser are still playing an important role, however, their imperfect fiber optic qualities limit their use in these field,s where advantages of diode lasers with flexible and fine quartz-polymeric optical fiber are obvious. The elaboration of new diode surgical lasers made it possible to invent new surgical equipment for solving many medical problems in the optimal way. Application of contact and noncontact laser methods in dermatology, gynecological plastic surgery and otolaryngology is discussed. A combined use of these methods demonstrates a positive effect on therapy results and healing time.

  18. Fiber optic detector and method for using same for detecting chemical species

    DOEpatents

    Baylor, Lewis C.; Buchanan, Bruce R.

    1995-01-01

    An optical sensing device for uranyl and other substances, a method for making an optical sensing device and a method for chemically binding uranyl and other indicators to glass, quartz, cellulose and similar substrates. The indicator, such as arsenazo III, is immobilized on the substrate using a chemical binding process. The immobilized arsenazo III causes uranyl from a fluid sample to bind irreversibly to the substrate at its active sites, thus causing absorption of a portion of light transmitted through the substrate. Determination of the amount of light absorbed, using conventional means, yields the concentration of uranyl present in the sample fluid. The binding of uranyl on the substrate can be reversed by subsequent exposure of the substrate to a solution of 2,6-pyridinedicarboxylic acid. The chemical binding process is suitable for similarly binding other indicators, such as bromocresol green.

  19. LASERS IN MEDICINE: Determination of the optical characteristics of turbid media by the laser optoacoustic method

    NASA Astrophysics Data System (ADS)

    Karabutov, Aleksander A.; Pelivanov, Ivan M.; Podymova, N. B.; Skipetrov, S. E.

    1999-12-01

    A method, based on the optoacoustic effect for determination of the spatial distribution of the light intensity in turbid media and of the optical characteristics of such media was proposed (and implemented experimentally). A temporal profile of the pressure of a thermo-optically excited acoustic pulse was found to be governed by the absorption coefficient and by the spatial distribution of the light intensity in the investigated medium. The absorption coefficient and the reduced light-scattering coefficient of model turbid water-like media were measured by the optoacoustic method. The results of a direct determination of the spatial light-intensity distribution agreed with a theoretical calculation made in the diffusion approximation.

  20. Modeling method and preliminary model of Asteroid Toutatis from Chang'E-2 optical images

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Yu; Qiao, Dong

    2014-06-01

    Shape modeling is fundamental to the analysis of dynamic environment and motion around asteroid. Chang'E-2 successfully made a flyby of Asteroid 4179 Toutatis and obtained plenty of high-resolution images during the mission. In this paper, the modeling method and preliminary model of Asteroid Toutatis are discussed. First, the optical images obtained by Chang'E-2 are analyzed. Terrain and silhouette features in images are described. Then, the modeling method based on previous radar model and preliminary information from optical images is proposed. A preliminary polyhedron model of Asteroid Toutatis is established. Finally, the spherical harmonic coefficients of Asteroid Toutatis based on the polyhedron model are obtained. Some parameters of model are analyzed and compared. Although the model proposed in this paper is only a preliminary model, this work offers a valuable reference for future high-resolution models.