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The data transfer rate as well as recording data density of holographic data storage systems can be improved by using a high-numerical aperture (NA) objective lens. However, a high-NA lens is likely to develop an inhomogeneous intensity profile of a reproduced holographic page data based on the polarization state of reference and signal beams during recording and readout. We analytically formulated how the polarization state of reference and signal beams during recording and readout affects signal intensity on a camera over the entire area of the page data. When Born approximation is applicable, we found that the signal amplitude of the reproduced page data can be expressed by multiplying signal amplitude calculated from scalar diffraction theory by an attenuation coefficient dependent on the polarization state. This means the intensity profile of the page data, taking polarization effect into account, can be calculated without using vector diffraction theory which requires high computational complexity. The validity of this analytical formulation was confirmed through a comparison of experiments with numerical analysis. The formulation led to a new method of increasing signal intensity of the page data area deteriorated by the polarization effect.

A hologram provides a useful model for explaining the associative memory of the brain. Recent advances in neuroscience emphasize that single neurons can store complex information and that subtle changes in neurons underlie the process of memorization. Experimental results suggest that memory has a localized character. This finding is inconsistent with the characteristics of holographic memory, because this memory has a delocalized, uniform distribution of refractive index in the recorded medium. The recently proposed columnar memory model has a discrete distribution of refractive index. In this study, we first examined the performance of columnar memory and found that it was comparable to holographic memory. Secondly, we showed that this model could explain the above-mentioned experimental results as well as associative memory.

The aim of this work is to enhance the Q value of a photonic crystal microring resonator that can be used to buffer optical signals (in a pulse train). A conventional photonic crystal microring resonator having 60° bends exhibits poor confinement of light due to the radiation losses at the bending points. Hence, we replaced conventional bent waveguides with circularly curved ones. The Q value of the resulting ring resonator is measured, and we demonstrate, as an example, an eightfold enhancement of the Q value at a wavelength of 1340 nm. Finally, we also estimate the Q value of a ring waveguide that excludes the optical coupling between the input/output waveguides, showing that the replacement of a sharply bent waveguide by a curved one increases the Q value by up to 5.2 times at a wavelength of 1340 nm.

To realize high-precision and wide-field measurements in retardation-modulated differential interference contrast (RM-DIC) microscope, we developed a new technique to stitch plural images taken by a high-magnification objective lens with attention paid to the high edge detection ability of the RM-DIC microscope. We showed some experimental results with grating samples and made sure that the developed new method had good performance for widening the measurement field of the RM-DIC microscope.

近年普及の著しい液晶カラーテレビをはじめとした，液晶ディスプレイに使用されているCF（カラーフィルター）の光学特性を測定し，そのコントラストを決定しているメカニズムについて考察した。カラーレジストを製造する際に，粒径の異なるジルコニアビーズを使い，分散条件を変えてモデルサンプルを作った。そしてその光学特性を測定したところ，粒径の小さいジルコニアビーズを使って分散したフォトレジストを使用したCFほど，偏光解消度が小さくなりその結果クロスニコルに配置した偏光板の間にCFを挿入した系のコントラストが向上することが示された。

While developing a three-dimensional (3-D) measurement technique for the retardation-modulated differential interference contrast (RM-DIC) microscope, we encountered a problem. The problem was that the measurement range was restricted in λ because it applies weak phase approximation. To overcome this drawback, we propose a 3-D reconstruction method with z-axis scanning. This technique needs high optical sectioning, like confocal microscopy. We investigated the characteristic of optical sectioning in a DIC microscope, then we confirmed experimentally that a DIC microscope has high optical sectioning. We also confirmed that a RM-DIC microscope has higher optical sectioning. By combining the optical sectioning of a RM-DIC microscope and z-scanning, we developed a new 3-D reconstruction method. This novel technique overcomes the observed problem as the measurement range is increased to micron order.

application/pdf, We propose a combination of ray optics and Fraunhofer multiple-slit diffraction theory for calculating the twodimensional triangular periodic grating in the resonance domain. The peak of the envelope pattern of angular distribution of diffraction efficiency is calculated by ray optics while the peak width is calculated using Fraunhofer theory. It was clarified, using rigorous coupled-wave analysis and a nonstandard-finite-difference timedomain method, that the envelope pattern of the diffraction of the grating could be calculated easily and understood intuitively for the design of displays and lighting.

application/pdf, Focus analysis techniques from computer vision are applied to digital holography to determine the depth (range) of multiple objects and their surfaces from a single hologram capture. With this method the depths of objects can be determined from a single hologram capture without the need for manual focusing and without prior information on object location. Variance and the Laplacian of Gaussian are analyzed as focus measures, and techniques are proposed for focus plane determination from the focus measure curves. The algorithm is described in detail and demonstrated through simulation and optical experiment.

While considering measurements of grating-type samples with the retardation-modulated differential interference contrast (RM-DIC) microscope, we found a problem of phase objects. The problem is that smaller measured values than the actual phase distribution are obtained when phase objects are beyond the weak phase approximation range. We analyze the image characteristics of phase objects and show that the problem is caused by the effect of an image component which is proportional to the square of the phase distribution. To overcome this disadvantage, we propose a new analysis method named self phase-correction (SPC). The SPC method corrects the phase distribution of the first order approximation under the weak phase condition and obtains the actual phase distribution of an object’s phase beyond the weak phase approximation range. We propose a two-image SPC method and a three-image SPC method for the RM-DIC microscope, and examine the suitability of these methods. We confirm that the three-image SPC method effectively overcomes the problem, and that the measurement range of the RM-DIC microscope can thus be extended to a half-wavelength phase difference.

We investigated thermal-lensing effects in a side-pumped 1.3-μm Nd:YVO4 slab laser amplifier having a bounce geometry. The thermal-lens power during 1.3 μm laser action was 1.3-times larger than that without laser action. Excited-state absorption is the main cause for increased heat loading during laser operation. The heat-loading formula in end-pumped 1.3-μm vanadate lasers having low Nd doping can be extended to account for heat generation in diode-side-pumped vanadate bounce lasers having high Nd doping. Key words: Diode-pumped lasers, Thermal lensing, Interferometery PACS: 42.55.Xi, 65.40.-b

Based on weak phase approximation and the partial coherence theory, we analyze the image characteristics of a phase object using a microscope. We show that the image of the phase object is formed by the interplay between the phase distribution and the defocus. Using this theory, we also show the image characteristics of a differential interference contrast (DIC) microscope. We develop a method for extracting the phase component from the DIC image using two images with different retardation to reconstruct the phase distribution of the object. We call our new microscope a “retardation-modulated DIC (RM-DIC) microscope”. We describe the RM-DIC microscope and confirm our method using grating samples with depths of 20 and 50 nm. To measure the three-dimensional (3D) figures of the microstructures on the object using a DIC microscope we need to extract the phase component from the DIC image and to deconvolute the phase component by means of the modulation transfer function (MTF) of the DIC microscope. We conclude that our RM-DIC microscope can take quantitative measurements of the phase distribution, making it a very useful tool for 3D measurement of an object’s microstructures.

We have achieved high average power Raman output from a compact, diode-pumped, self-stimulating Nd 3+ :KGd(WO 4 ) 2 Raman laser. Maximum Raman output power of 0.8 W was achieved at a pulse repetition frequency (PRF) of 2 kHz. The optical efficiency from diode to Raman laser was 14%. By generating extra-cavity second harmonics using a LiB 3 O 5 crystal, it was possible to produce 0.2 W yellow output. The laser system was simulated numerically using rate equations and the results obtained were in good agreement with the experimental results.

We report fabrication of ultra-fast optical switches operated at a wavelength of 1064 nm using spin-coated one-dimensional polymeric photonic crystals doped with nonlinear-optical dyes. The optical switches are controlled either by an applied electric-field voltage or by a pump light by use of two different optical-configurations. The response time of the electro-optic switch and the all-optical switch are limited by the applied voltage and the laser used, respectively. The polymeric photonic crystals can be easily fabricated with low cost.

We propose a direct fabrication of light diffusers using azobenzene polymer films. Holographic recordings of surface relief diffusers are formed on the polymer film by exposure to an Nd:YAG laser (532 nm) through source diffusion materials. No post-treatment is needed, and it can be erased by heating or irradiating uniform laser beam. Diffusion pattern can be controlled by the polarization of the laser. Transmittance of over 88% is obtained at the wavelength of 633 nm.

Surface relief holograms are fabricated by irradiation of laser interference patterns on an azobenzene polymer film. The hologram needs no post-treatment, and can be erased by heating the films to above its glass transition temperature. Rewritable Fresnel holograms are fabricated on azo-polymer film. Replication of the surface relief hologram is also demonstrated. An application for business cards is considered.

Surface relief holograms were fabricated on azo-polymer films by the irradiation of interference laser fringes. The side-chain azo-polymer, poly-orange tom-1 isophoronediisocyanate, was used in this study. Recording characteristics of surface relief structures were investigated; they needed no post-treatment, and could be erased by heating or irradiating a uniform laser beam. The diffraction efficiency of the recorded hologram was markedly increased by corona charging. It was also controlled by irradiation of the laser beam (488 nm) with corona charging.

In the field of biology and medicine, observation object of the microscope has been changing from the thin specimen to the thick living tissue. Furthermore, observation of the internal structure of a living tissue is also desired by low invasion. However, the real structure of a phase object with three-dimensional distribution such as a living tissue is difficult to observe, because of the influence of the phase distribution before and behind of observation position. We enabled observation of the internal structure of living tissue without stain, by adding a new function to reduce the influence of phase distribution to our Retardation-Modulated differential interference contrast (RM-DIC) microscope system.

A surface measurement system was constructed in which a spectral interferometer and a joint transform correlator are combined. The setup is able to determine the three-dimensional (3-D) profile of an object to a resolution of 70 μm. Measurement of the pathlength difference of two arms of the Michelson interferometer and several experimental results using 3-D samples are described.

A spatial light modulator (SLM) is introduced to an optical manipulation system. The real-time reconfigurable feature of the SLM makes it possible to perform an optical manipulation of microparticles without mechanical movements of optical parts. A liquid crystal SLM incorporated in the system forms a Fresnel zone plate (FZP). The beam spot generated by the FZP is imaged on a sample solution by reduction optics. A microparticle in the sample solution is trapped by the beam and manipulated by changing the addressing position of the FZP onto the SLM from a computer. The nonmechanical optical manipulation of microparticles is demonstrated for the first time.

Nonlinear spatial filtering is realized due to the electro-optical effect in spatial light modulators (SLMs). Optical methods with nonlinear filtering are suggested for various optical applications such as optical inspection of photolithography masks, wavefront sensor, etc. A fast optical response of the SLM allows optical inspection with a video (or faster) rate. The optical system proposed is tolerant to the vibrations and temperature variations because of the dynamic properties of the SLM.

A method to synthesize a computer-generated hologram (CGH) of real-existing objects from projection images is proposed. Different from other similar methods, our method enables the synthesis of a CGH with only one-dimensional (1-D) mechanical scanning of the objects. Our method is connected with the three-dimensional (3-D) Fourier spectrum of the objects by the 3-D central slice theorem (CST). Two efficient recording techniques for projection images and numerical experiments to verify our principle is discussed. A comparison between the two techniques is also presented from the viewpoint of diffraction efficiency. © 2005 The Optical Society of Japan

We propose here a new optical modified signed-digit (MSD) adder module based on bit plane pattern encoding of MSD digits and pattern operations. The pattern operations required in the algorithm are duplication, combination and shifting. They are simply performed by using optical components such as beam splitters, mirrors and parallel plates, instead of optical logic arrays. An optical MSD adder module comprised of six properly interacting blocks with all optical components packaged on a common substrate is presented in detail. We analyze the system errors caused by manufacture and alignment of optical components, the information throughput, the intensity nonuniformity and the system volume of the adder module.

An interpolation method of image points reconstructed by a Fourier transform computer-generated hologram is described, so that a sufficient large size hologram can be synthesized by a small size hologram. We have made a mosaic hologram which consists of K × K subholograms with N × N sampling points multiplied by an appropriate weighting factor. It is shown that the mosaic hologram can reconstruct an image with NK × NK image points. The main advantage of the present algorithm is that a sufficiently large size hologram of NK × NK sample points is synthesized by K × K subholograms which are successively calculated from the data N × N sample points and also successively plotted.

We propose a novel parallel algorithm of modified signed-digit (MSD) computing, in which MSD digits are encoded to three bit plane (BP) patterns. The addition of two MSD data arrays is performed with two steps: calculating nine intermediate patterns from encoded BP patterns and calculating three BP patterns with the nine intermediate patterns. A system module constucted with nine beam splitter cubes is developed for optical demonstration. Preliminary experimental results are given.

The amplified signal beam of photorefractive two-wave mixing was stabilized by feedback system. The amplification factor of the two-wave mixing was controlled by changing the phase difference between the interference fringe and the index grating in BaTiO 3 . The interference fringe was shifted by frequency tuning of a laser diode. The short-term fluctuation of the output beam was reduced to 0.8%. We controlled the output intensity within the range from 10 to 4 mW although the change of the input power was 5%.

We demonstrate direct production of a high power Laguerre-Gaussian mode from a diode-pumped Nd:YVO(4) 1.3-mum bounce amplifier with an asymmetric cavity configuration. A maximum LG output of 7.7 W is obtained.

Thermal load in Nd3+ doped vanadate crystals with and without laser action at 1.34 mum is investigated. Excited state absorption contributes significantly to a fractional thermal loading as well as quantum defect.

Photoinduced birefringence in the film made of our azobenzene copolymer was demonstrated using blue excitation laser beams and observed by a red probe laser beam. The birefringence values was obtained by polarimeter. The polarization state of the probe beam was changed by the photoinduced birefringent film when the polarization state is not agreed with the polarization state of the excitation laser beam. Then, a polarization component orthogonal to the polarization state of the incident probe beam was observed. Using the principle, an image pattern was recorded in the film using one-beam.

We have developed a new multiplexing method for producing binary computer-generated holograms (CGH’s) for security applications. This method is based on double recording of two types of coding method upon binary CGH’s. The CGH synthesized by the proposed method can have multiple image planes from the region close to the hologram (image region) to infinity (Fraunhofer region) without severe degradation of reconstructed images in the image region. A CGH containing simultaneous image- and Fourier-type holograms is fabricated by electron-beam lithography. Some experimental results are presented.

application/pdf, We propose using blazed gratings in the resonance domain with period larger than the wavelength for antireflection and polarization selection. The inherent problem in this region is wavelength dispersion, which is solved by analyzing the total reflectivity and electric field distribution. The positional relationship between the area of strong electric field, and the side and tip of the grating is crucial to the wavelength dispersion of total reflectivity.

In this paper, we present the first demonstration, to the best of our knowledge, of a direct production of a high power (> 7 W) 1.3 μm LG mode from a diode-pumped Nd:YVO4 bounce amplifier with an asymmetric cavity configuration. This system does not require any additional phase elements such as a hologram and a phase plate for producing LG modes. An amplifier used was a 1 at.% Nd doped a-cut YVO4 slab with dimensions of 2 mm x 5 mm x 20 mm. A pump diode output was focused to be a line with dimensions of 0.2 mm x 18 mm onto the pump face. This laser can be extended to generate high intense pulses by Q-switching as well as mode-locking techniques, and it will open up a direct production of a high power optical vortex in visible as well as ultra-violet regime.

Surface relief holograms are fabricated by means of irradiation of laser interference patterns. The diffraction efficiency and the surface relief depth depend on the writing energy and the polarization of the writing laser beam. The formation and erasure of photoinduced surface relief gratings (SRGs) on azobenzene-containing polymers are simulated using a numerical model based on the moving-particle semi-implicit (MPS) method. Particle motions in SRG formation and erasure are calculated and the SRG pitch and polarization dependences of the SRG growing and erasing rates are investigated. These theoretical results coincide qualitatively with our experimental results.

The synthesis of spherical computer-generated holograms is investigated. To deal with the staggering calculation times required to synthesize the hologram, a fast calculation method for approximating the hologram distribution is proposed. In this method, the diffraction integral is approximated as a convolution integral, allowing computation using the fast-Fourier-transform algorithm. The principles of the fast calculation method, the error in the approximation, and results from simulations are presented.

We propose a new technique for obtaining three-dimensional phase distribution on differential interference contrast microscope to modulate relative phase retardation between two shear beams. Using partial coherent theory we extract the phase information from two different retardation images. For the object in a weak phase region, simple formula is derived. The images of nematomorph were obtained in vivo.

Fourier Domain Optical Coherence Tomography (SD-OCT) systems for dental measurements are demonstrated. Two systems have been developed. The first system is fiber based Michelson interferometer with super luminescent diodes at 1310 nm and 100 nm FWHM as a light source. The sensitivity of the system was 106 dB with depth measurement range in air of 2.5 mm. The second systems is a fiber based Mach-Zehnder interferometer with wavelength scanning laser as light source at center wavelength of 1310 nm, wavelength range of 110 nm and scanning rate of 20 KHz. The sensitivity of the system is 112 dB and depth measurement range in air is 6 mm. Both systems can acquire real-time three dimensional (3-D) images in the range of several second. The systems were applied for early caries detection in tooth, for diagnostics of tooth condition after operational tooth treatment, and for diagnostics of the alveolar bone structure. In-vivo measurements were performed on two volunteers. The systems were able to detect discontinuities in tooth and resin filling after tooth treatment. In addition early carries lesion was detected in one of the volunteers. The 3-D profile of the alveolar bone was acquired for first time with non-contact method.

In this paper, we present interferometric measurements of thermal lens effects in GdVO/sub 4/ crystal with and without 1.3/spl mu/m laser action.

We develop high-speed Fourier-domain optical coherence tomography. A-scan rate is 18700 Hz and system sensitivity is 90.3 dB with –50.3 dB reflector. In vivo human retinal structure and blood flow imaging are demonstrated.

We have presented a novel optical system, a spatio-temporal joint transform correlator (ST-JTC). The system based on similarity between a conventional spatial joint transform correlator, which is one of the most popular optical computing technique and a spectral filtering method, which is one of the most popular method of controlling the temporal profile of an ultra-fast light pulse. Based on ST-OCT, we have constructed a surfacemeasurement system. Then this principle is applied to a highly scattering biological issue. Fourier transform of the power spectrum is done by a numerical method. This system is called usually Fourier domain OCT. Finally polarization sensitive FD-OCT is discussed to measure birefringence property of biological issue.

Kinoform synthesis by an electro-optic hybrid system using an interpolation method is proposed. A programmable liquid crystal spatial light modulator is used as a kinoform. The phase distribution of the kinoform is optimized using the simulated annealing. The cost function is represented by the mean square error between a desired image stored in a computer and a reconstructed image detected by a charge coupled device camera. The interpolation method enables one to reduce the random noise effect in the reconstructed image. Some experimental results are presented.

In the image of laser scanning confocal microscope, an edge of a weak phase object is sometimes enhanced as bright and/or dark line. This phenomenon is thought to be caused by the interference effect of diffractive light from the edge. The imaging characteristics of this type of microscope are regarded as a product of the optical sectioning characteristics (I-Z response) and the optical property of its imaging system. The I-Z curve decreases monotonically with depth (Z) which is determined by a diameter of pinhole and a numerical aperture (NA) of imaging system. Analyzing partially coherent imaging system under the weak phase approximation, we found that intensity image generated with increasing a defocus in observing weak phase only object of step-like figure. Accordingly the peak in optical transfer function (OTF) arose at some point of specific defocused depth in response to the spatial frequency of an observing object, so we observe an edge enhancement in this type of microscope. In experiment, we used OLS1100 laser scanning microscope (Olympus Co., Ltd.) with NA=0.95 in 100-power objective. Light source is Ar-ion laser of 488nm. We prepare rectangular samples which have 5.0 micron in width, and 50 nm in depth. We observed edge enhancement in auto-focus mode for the above samples. After measuring defocus characteristics of I-Z response we evaluate our theory in good agreement for the edge enhancement on the image of laser scanning confocal microscope.

This work describes new method for the 3-D reconstruction of full-color real existing objects based on the previous report. In addition, methods for deciding certain parameters such as angular ranges, angular increments and projection numbers are presented for the purposes of making the magnifications constant for each color. Verification of this method by both numerical and optical reconstruction is also presented.

The formation of holographic surface relief gratings (SRGs) on azobenzene containing polymers are simulated using the moving particle semi-implicit (MPS) method. The gradient force of optical electric field and the influence of surface tension were considered as the driving forces for mass transport. The particle motions of SRG formation are calculated by giving particles two beams interference with various polarization states. The model for time evolution of SRG formation coincided with experimental results qualitatively.

A method of synthesizing computer-generated holograms of real existing objects is proposed, in which a series of projection images of an incoherently illuminated object are recorded in different points of view. According to the principle of computer tomography, the 3-D Fourier spectrum of the object is calculated by several projection images. A method of calculating a Fresnel hologram from the 3-D Fourier spectrum is proposed. Experimental results in the computer simulation and the optical reconstruction are presented.

We propose a new technique to make a surface relief structure on azo polymer films. Application for light diffuser and holograms are described. The diffraction efficiency of the device was dramatically increased by corona discharge.

Low coherence photorefractive holography is a wide-field technique for 3-D imaging that offers a unique mechanism to discriminate against a background of diffuse light. This provides a wide-field method to image through scattering materials that we have demonstrated may be implemented at frame rates as high as ~ 470/second. We present our recently developed low coherence photorefractive microscope and demonstrate how it may be realized using a spatially coherent broadband c.w. diode-pumped solid-state laser. This can provide real-time sectioned images of moving 3-D objects using only a simple uncooled 8-bit CCD camera. We also demonstrate a photorefractive 3-D imaging technique that exploits structured illumination and photorefractive holography to achieve a real-time wide-field sectioning microscope that may be applied to fluorescence, as well as reflected light. We also discuss issues for improving the sensitivity and spectral coverage of photorefractive holography using semi-insulating MQW devices.

The spatio-temporal behavior of a time domain microscope is numerically analyzed by using the spatio-temporal Wigner distribution function. By the Wigner function, the demanded computation time is dramatically reduced. Some conditions which induce spatio-temporal coupling are determined.

All optical and one dimensional scanning surface measurement system is constructed. The system uses the principleof spectral interference and optical Fourier transform, or the principle of joint transform correlator. It can determinethe three dimensional surface of an object in the accuracy of few 1Om.As a first demonstration, path-length difference of a Michelson interferomter is measured. Next, the surface ofan object which has stepped surface is measured. 1. INTRODUCTION Optical coherence tomography (OCT) has been largely used in the field of in vivo shape measurement.1,'? j this method, a reference beam and an object beam of a Michelson interferometer are interfered on a power meter. When a sample object is placed on the object-arm of the interferometer, the depth information of the object is encodedin the temporal interferogram. Hence, from the signal, we can obtain the shape of the sample with the accuracy determined by the coherence length of the light source. Generally, the OCT technique gives us the depth informationof the object, even if the object is a high scattering object. However, the method demands three dimensional (3-D)

The use of a broad-band interferometer and its fringe analysis method are presented in which the fractional fringe order method for measuring the absolute thickness. An approximate integer part of the fringe order is estimated by mechanical measurements, and the fractional part is determined by interferometric fringe pattern analysis. The fringe patterns are obtained with a Michelson interferometer by illumination of several selected wavelengths, respectively. The use of the fractional fringe order method can determine accurately more than 2(pi) phase jumps. The influence of wavelength and approximate integer part of fringe order on the measurement accuracy is discussed.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The retardation modulated DIC (RM-DIC) method is proposed for extracting phase information from a DIC image by analyzing the partial coherent theory, which is applied to quantitative measurements of phase objects. The experimental results using RM-DIC method are presented and the quantitative analysis of the phase grating are presented.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have developed a synthetic double exposure (SDE) method of the computer-generated holograms (CGHs) for security applications. This method is based on incoherent multiplexing of two types of coding methods on binary CGHs: a cell-oriented and a point-oriented. The CGH synthesized by the SDE can have multiple image planes from the image region to the Fraunhofer region. In fabrication process of the SDE, the point-oriented CGH, that is, the image-type hologram is erased slightly by the cell-oriented CGH. We estimate here the image quality and the diffraction efficiency of the reconstructed image in the image-type hologram by the SDE using numerical simulations. In our simulations, the cell-oriented CGH occupied only 14% of the entire hologram area. The diffraction efficiency of the image-type hologram by the SDE was about 80%. Therefore, the information of the image-hologram was preserved sufficiently. The CGH including image-, Fresnel- and Fourier-type holograms was fabricated using the direct writing of electron-beam resist in electron-beam lithography. These reconstructed images were almost identical to the desired ones.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.