This PDF file contains the front matter associated with SPIE Proceedings Volume 7442, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Atmospheric turbulence along with the background noise is a major limiting factor in a typical free space optical communication link. As compared to terrestrial links, Earth based optical receivers operating in near-space and deepspace communication links are affected more severely by the turbulence, as these systems have to look directly towards the sky to maintain line of sight with the transmitter. Especially during the daytime when the optical turbulence effect is at its peak and atmospheric seeing is the worst, the presence of the diffuse background light from the sky severely degrades the performance of an optical communication receiver. In this paper, we analyze the origin of the turbulence and simulate turbulence effects in an Earth-space optical channel. The photon counting focal plane detector arrays obeying Poisson statistics are employed in the receiver. We develop the concept of a pre-processor for optical communication receivers, which employ 2-D adaptive Wiener filter based practical algorithms for mitigation of turbulence and background noise effects. It is shown through simulations that for photon counting receivers observing Poisson distributed optical signals, performance improvements of 4-7 dB can be achieved under adverse conditions. This performance improvement is not only significant but the implementation of the pre-processor is also cost effective and practical.

Optical elements are preferred to electronic ones for military computing and communications to reduce vulnerability to electromagnetic pulses from nuclear explosion, electromagnetic bombs or lightning. Equations are derived for an optical micro ring resonator and for a nonlinear ring resonator that uses Kerr material so that the resonant frequency changes with light intensity in the ring. The switch can be modulated at faster than 10 Gbps for compatibility with electronic switches and equipment. A two-by-two switch is described based on the nonlinear ring resonator. A Benes network is constructed using the two-by-two switches. This allows full permutations of the inputs by means of an algorithm for setting the switches. Several rings are used for each frequency with slightly different frequencies to allow switching of wavelength division multiplexed signals.

We show how the reconstruction of digital holograms can be speeded up on ordinary computers by precomputing the chirp factor in the Fresnel transform for a given detector array size. The speedup in time is shown for various hologram sizes. We also run the same algorithm on a Nvidia GPU. The speedup and the error introduced due to quantizing to different levels is investigated. Additionally a variance based

Digital holography is the process where an object's phase and amplitude information is retrieved from intensity images obtained using a digital camera (e.g. CCD or CMOS sensor). In-line digital holographic techniques offer full use of the recording device's sampling bandwidth, unlike off-axis holography where object information is not modulated onto carrier fringes. Reconstructed images are obscured by the linear superposition of the unwanted, out of focus, twin images. In addition to this, speckle noise degrades overall quality of the reconstructed images. The speckle effect is a phenomenon of laser sources used in digital holographic systems. Minimizing the effects due to speckle noise, removal of the twin image and using the full sampling bandwidth of the capture device aids overall reconstructed image quality. Such improvements applied to digital holography can benefit applications such as holographic microscopy where the reconstructed images are obscured with twin image information. Overcoming such problems allows greater flexibility in current image processing techniques, which can be applied to segmenting biological cells (e.g. MCF-7 and MDA-MB- 231) to determine their overall cell density and viability. This could potentially be used to distinguish between apoptotic and necrotic cells in large scale mammalian cell processes, currently the system of choice, within the biopharmaceutical industry.

Lawrence Livermore National Laboratory is a large, multidisciplinary institution that conducts fundamental and applied research in the physical sciences. Research programs at the Laboratory run the gamut from theoretical investigations, to modeling and simulation, to validation through experiment. Over the years, the Laboratory has developed a substantial research component in the areas of signal and image processing to support these activities. This paper surveys some of the current research in signal and image processing at the Laboratory. Of necessity, the paper does not delve deeply into any one research area, but an extensive citation list is provided for further study of the topics presented.

A graphic processing unit (GPU) is much attractive for large scale information processing. Especially, a GPU is considered to be suitable for SIMD processing to image data. We have developed some methods based on SIMD pattern processing and study on implementation of these methods. In this research, design of GPU implementation for the traveling salesman problem (TSP) is reported. Usefulness of GPU implementation is shown by verification.

Compressive sensing of imagery is a topic of much current research activity. The general field was started by Candès, Romberg, and Tao [1] when considering signals which are Sparse in the Fourier domain. This was generalized to signals sparse in general bases by Candes and Tao [2]. Donoho [3] considered further lines of research in his paper in 2006. The field is growing rapidly with new models for sparsity and algorithms for signal reconstruction being presented in the literature regularly. For signal processing applications, the speed of research and development towards particular applications has been remarkable. The application termed "analog-to-Information" has been researched extensively and an architecture for sampling wide-band signals is given by Laska, et. al. [4]. The possible applications involving image acquisition and exploitation have lagged behind the one dimensional counterpart. The single pixel camera built at Rice University and discussed by Wakin et. al. [5] has allowed algorithm research to go forward on compressive imaging but has not, as of yet, spurned new thoughts on application architectures in the same way as the Analog-to-Information community developed new sensors for wideband signals. We consider several Compressive imaging applications which offer fundamental improvements to current imaging sensors for target tracking and recognition.

In this research, a scheme for SIMD (Single Instruction stream Multi Data stream) pattern processing for two dimensional (2D) image data is applied to the traveling salesman problem (TSP). Firstly, 2D SIMD pattern processing for the TSP is designed. In the processing, two kinds of image data are prepared to represent graph data. By cross correlation between the prepared images, a set of pathlength is obtained. The tour with the minimum path length is extracted from post pattern processing. Numerical analysis verifies that the scheme is effective for the TSP.

Cellular simultaneous recurrent networks (CSRN)s have been traditionally exploited to solve digital control and conventional maze traversing problems. In a previous work [1], we investigate the use of CSRNs for image registration under affine transformations for binary images. In Ref. [1], we attempt to register simulated binary images with in-plane rotations between ±20° using two different CSRN implementations such as with 1) a general multi-layered perceptron (GMLP) architecture; and (2) a modified MLP architecture with multi-layered feedback. Our results in Ref. 1 show that both architectures achieve moderate local registration, with our modified MLP architecture producing a best result of around 64% for cost function accuracy and 98% for image registration accuracy. In this current work, for the first time in literature, we investigate gray scale image registration using CSRNs. We exploit both types of CSRNs for registration of realistic images and perform complete evaluation of both binary and gray-scale image registration. Simulation results with both CSRN architectures show an average cost function accuracy of 40.5% and an average image accuracy of 33.2%, with a best result of 46.2% and 40.3%, respectively. Image results clearly show that the CSRN shows promise for use in registration of gray-scale images.

We report on the implementation of different phase contrast methods using an SLM in a microscope. The ease of generating complex phase filters with the SLM opens the possibility to realize standard filters adapted to the specimen and the possibility to develop new phase contrasting methods. Due to the real-time addressing we can obtain a number of different images from each specimen recorded nearly simultaneously with the same microscope objective. We demonstrate how to realize different versions of differential interference contrast imaging, Zernike-type imaging and dark-field imaging and the combination of the different images by simple post processing. Experimental results for biological as well as technical specimens are presented.

The self-imaging phenomenon under coherent illumination or Talbot effect has been widely used in different fields including optical metrology. According to the Talbot effect, when a periodic grating is illuminated with spatially and temporary collimated coherent light, the grating is self-imaged at a certain distance, Z_T, which depends on the inverse of the wavelength λ of the incident light and the square of the period, d, of the grating. This means that they can be seen at different positions Z_T by changing either d or λ. Using the wavelength dependence of the self-images, and a fixed period, d, an application of the Talbot effect for three-dimensional and step-height measurement using a two-wavelength laser, appeared recently in the literature. We propose in this work to use an LCD to display a tunable grating. In our setup, we used a fixed wavelength and a dynamic 1-D grating to adjust the step-height measurement capabilities. We also analyze the possibility of measuring continuously varying surfaces with this technique. We include the preliminary results of our proposal.

Liquid Crystal Displays (LCD) technology has shown to be very useful in numerous optical applications because of its capability to work as Spatial Light Modulators (SLM). The Liquid Crystal on Silicon (LCoS) displays are reflective LCDs that, because of the double pass of the incident beam through the device, give higher phase modulation than transmission LCDs with the same thickness of the LC layer. In recent works, we have thoroughly analyzed the response of a twisted nematic LCoS display working in normal incidence and we have detected that the kind of electrical signal addressed to our display produces fluctuations as a function of time of the LCoS display molecules optical axis orientation. Moreover, the temporal fluctuations produce two different physical effects that can adversely affect in optical applications. On one hand, the molecules fluctuations may produce changes at the reflected state of polarization as a function of time, introducing certain amount of effective depolarization. On the other hand, it has been demonstrated that the molecules fluctuations produce phase fluctuations that may affect the efficiency of diffractive optics elements. Here, we have characterized an Electrically Controlled Birrefrigence (ECB) LCoS display that allows us to manipulate the electrical signal addressed to it. Then, by selecting the appropriate electrical signal we can increase or decrease the fluctuation phenomena. Therefore, we have performed a polarimetric study of our (ECB) LCoS, analyzing its response dependence with different electrical addressed signals and taking special attention to the depolarization and retardance response of our device.

Fabrication of scattering media by femtosecond laser pulse irradiation in Poly(methyl methacrylate) (PMMA) material is presented. Focused femtosecond laser pulse can fabricate void with a few μm in PMMA material. Random distribution of voids can work as a scattering medium. We measure the scattering properties of fabricated void structure by changing the void density. By comparing the experimental results and numerical results, we discuss the possibility of control of scattering coefficient by void density.

An image quantization and mixed-signal processing technique presented in this paper significantly increases speed and resolution of image digitization while consuming minimum energy. It also performs image compression in the mixed signal domain. This has been achieved by exploiting strong correlation between neighboring pixels within each frame and between successive frames. The correlation is utilized by adaptive combining of several quantizers with different sampling rates and numbers of bits and by quantizing the entire image in a small fraction of frames while generating only discontinuity signals in the rest of the frames.

A new hard X - ray hologram with using crystal Fresnel zone plates (ZP) has been described. An image of Fourier hologram for hard X- ray is presented. X-ray phase contrast methods for medical diagnostics techniques are presented. We have developed an X-ray microscope, based on micro focus source which is capable of high resolution phasecontrast imaging and holograms. We propose a new imaging technique with the x-ray energy 8 keV. The method is expected to have wide applications in imaging of low absorbing samples such as biological and medical tissue. We used FIB to reproduction three dimension structures of damaged spinal cord of rat before and after combined treatment with NT3 and NR2D. PUBLISHER'S NOTE 12/16/09: This SPIE Proceedings paper has been updated with an erratum correcting several issues throughout the paper. The corrected paper was published in place of the earlier version on 9/1/2009. If you purchased the original version of the paper and no longer have access, please contact SPIE Digital Library Customer Service at CustomerService@SPIEDigitalLibrary.org for assistance.

We propose a phase unwrapping method for processing two phase distributions simultaneously based on a deterministic phase unwrapping method using a composite complex function in which the real and imaginary parts are assigned by two separate phase distributions. Hardly any crosstalk between the real and imaginary parts was observed in the actual numerical computation. We developed a Fourier transform-based 3D measurement method that primarily consists of a fast Fourier transform (FFT) algorithm. Since the proposed method is employed in the frequency domain, the 3D retrieval process can be performed effectively even if the deformed grating pattern uses a high-resolution image format. To accelerate the FFT computation, we implemented the proposed method using a graphics processing unit. The experimental results showed that 3D measurement could be performed in real time using a deformed grating pattern of 1024×1024 pixels.

Pattern recognition in hyperspectral imagery is a challenging problem due to the minute nature of the target signature and the requirement to process huge amount of data. In this paper, we investigate the recent trends and advancements in joint transform correlation (JTC) based pattern recognition in hyperspectral imagery. In particular, we investigate the application of spectral fringe-adjusted JTC for efficient target recognition in hyperspectral imagery. Techniques for eliminating false target detection, minimizing effects of noise and other artifacts are considered. The performance of the spectral fringe-adjusted JTC has been compared with the existing techniques by generating ROC curves using real life hyperspectral datasets.

An optical information processing system for biometric authentication using the spatial-frequency correlation of input and registered biometric identifiers is proposed. The merit of our system is to speed up the authentication because it composed of all optical elements. In this study, we adopted fingerprints as an example of biometric identifiers and analyzed the basic properties of our system by regarding fingerprints as the 1D finite rectangular wave with a period of 0.5mm and the whole width of 15mm. Concretely, the behavior of the second maximum value of the intensity distribution of the spatial-frequency correlation function of input and registered fingerprint images was numerically analyzed by considering the ending points in the input fingerprint. As a result, the threshold level for the fingerprint recognition in our system was determined. In addition, the effects of the random noise added to the input fingerprint on the second maximum value were statistically analyzed. Furthermore, the behavior of the second maximum value was numerically analyzed to investigate the effects of various kinds of shifts of the input fingerprint on the recognition. As a result, the false reject rate (FRR) was the highest for the transverse shift in comparison with the longitudinal and rotational shifts.

The fractional Fourier transform (FT) is a powerful tool with relevant applications in optical and digital information processing. Such applications demand a programmable and versatile optical system able to perform the fractional FT almost at real time. We have recently developed an optical setup satisfying these requirements. In contrast with other proposed setups, it offers the following advantages: the operation is achieved without additional scaling and/or phase factors and a minimal number of lenses, located at fixed position, are utilized.¹ In this work we present the main design features of the fractional FT processor and discuss its performance for some relevant applications.

Motivated by the non-linear interpolation and generalization abilities of the hybrid optical neural network filter between the reference and non-reference images of the true-class object we designed the modifiedhybrid optical neural network filter. We applied an optical mask to the hybrid optical neural network's filter input. The mask was built with the constant weight connections of a randomly chosen image included in the training set. The resulted design of the modified-hybrid optical neural network filter is optimized for performing best in cluttered scenes of the true-class object. Due to the shift invariance properties inherited by its correlator unit the filter can accommodate multiple objects of the same class to be detected within an input cluttered image. Additionally, the architecture of the neural network unit of the general hybrid optical neural network filter allows the recognition of multiple objects of different classes within the input cluttered image by modifying the output layer of the unit. We test the modified-hybrid optical neural network filter for multiple objects of the same and of different classes' recognition within cluttered input images and video sequences of cluttered scenes. The filter is shown to exhibit with a single pass over the input data simultaneously out-of-plane rotation, shift invariance and good clutter tolerance. It is able to successfully detect and classify correctly the true-class objects within background clutter for which there has been no previous training.

A new face recognition system is proposed using a nonlinear image enhancement algorithm incorporated in a synthetic discriminant function based shifted phase-encoded fringe-adjusted joint transform correlation (SDF-SPFJTC) technique as a preprocessing step. The given input image recorded from a long distance is improved by using adaptive dynamic range compression and local contrast enhancement schemes. The Viola-Jones technique is then applied to detect any human face in the scene and hence correct its size. Finally the SDF-SPFJTC technique yields the recognition of the target face along with its location. Computer simulation performed on real life scenes shows efficient and successful recognition performance in varying environmental conditions.

We have proposed a compact three-dimensional shape-measurement system for intraoral diagnosis, in which multiwavelength pattern projectors based on diffractive optical elements (DOEs) are integrated in the lens gaps of a compound-eye camera. We have built a prototype module with blue and green pattern projectors in both sides of the compound-eye camera to increase in-plane spatial resolution. With the two projectors, the stripe pitch was reduced to 0.73 mm in average from about 1.4 mm for one wavelength. Root-mean-square (rms) error of the measured depth map of a plane board was 0.27 mm at the distance of 40 mm. The rms errors for the measured results of the gums and teeth of a plaster figure and an examinee were 0.37 and 0.40 mm, respectively.

Millimeter-waves have found wide application in various fields. In this paper, three ways of millimeter-wave generation are discussed. By modeling these three systems and applying different situations of transmission links and fixed bit rate of 2.5 Gb/s, different results were found. These results showed that each system has its own strengths and weaknesses based on the type of link and distance.

In this work we applied a ferroelectric liquid crystal on silicon (FLCoS) display for implementing monochrome and color diffractive optical elements (DOE). We first apply a reverse engineering process specifically adapted to characterize the optical parameters of a commercial FLCoS display, specifically the phase shift and the tilt angle. We then analyze the performance of the device for implementing a binary polarization diffraction grating (PDG), and how it adopts the form of either a binary amplitude grating or a binary phase grating as particular cases when the polarization states emerging from the display are projected to an analyzer. As a final experiment, we have applied the FLCoS display to generate RGB improved dynamic color binary-phase Fourier computer-generated holograms (CGHs). We have electronically synchronized the properly scaled image addressed to the display with a color filter wheel with RGB filters. Experimental results show an excellent chromatic compensation of the color image reconstruction.

We have developed prototype of a compact optical correlator for video copyright protection that integrates the optical correlation technology used in FARCO (Fast Recognition Optical Correlation) and a holographic storage system. Using the ability of parallel transformation as optical holographic memory, the recognition rate can be vastly improved. In addition, large capacity of optical storage allowed us to increase the amount of reference database. Using its rapid processing capability, a robust recognition system can be constructed by registering video image data. We expect that this optical correlation system is simple and energy-saving, and provides ultrahigh speed system compared with conventional server. This system enables use of an image search system in various fields where it has not previously been possible to use such systems.

This work shows a characterization and a polarimetric analysis of a Liquid Crystal on Silicon (LCoS) display, device that works with reflection of the light. We have observed that the optical axis of the LCoS display molecules fluctuates as a function of the time as a consequence of the type of electrical signal addressed to the device. These time fluctuations lead to two different physical phenomena that may decrease the efficiency when addressing diffractive elements to the display: the effective depolarization and the phase-fluctuations phenomena. We have developed a study of these two phenomena and its influence on diffractive elements. In particular, two different characterization methodologies suitable to obtain the Mueller matrix of the LCoS display are shown. The obtained results are provided and processed to perform a polarimetric study. Next, an intensity or a phase optimization of the LCoS display response is done, in order to obtain configurations of external polarizers and waveplates that allow us to improve the use of this device in optical applications. This study is done as a function of the incident angle and as a function of the wavelength, in order to detect the influence of these parameters on the effective depolarization origin and of the phase-fluctuations. In addition, we have analyzed the influence of the phase-fluctuations phenomena on the efficiency of a phase grating and a digital hologram addressed to the LCoS display.

The phase errors due to the nonlinear chirp of tunable laser reduce the range resolution in synthetic aperture imaging ladar(SAIL). The compensating algorithms establishing matched and nonmatched reference paths were developed, and the phase errors were compensated in the whole echo pulse. In this paper a compensating algorithm by scan filtering is proposed. Compared to the compensation in the whole echo pulse, this compensating algorithm promotes precision and range resolution. Every echo pulse includes different echo components from all target points in footprint. The heterodyne signals of these different echoes are scan filtered from the heterodyne signal of one whole echo pulse in the spectrum. The phase errors of these heterodyne signals are measured by phase shifting algorithm in nonmatched reference path and compensated separately. Then the compensated signals are combined into whole heterodyne pulse and compressed in range. After all echo pulses are compressed in range the azimuth compensation and compression is followed. The mathematical flow of this algorithm is established. The simulation of the airborne SAIL model validates the feasibility, and the BW of range compression decreases obviously. The effects of width of the scan filter and nonlinear chirp are discussed. The conclusion of adequate width of the scan filter is given finally.

Linear chirp laser signal is often employed as the transmitted signal of synthetic aperture laser radar (SAL). However, actual properties of frequency sweep of fiber laser always produces nonlinear terms such as quadratic and higher order terms. Existence of nonlinear terms of frequency produces phase errors during pulse time, leading to blurring of target in range direction and further reduces imaging resolution of range direction. It makes compensation of the nonlinear chirp from laser source a requirement. In this paper, we develop an algorithm of matched filtering in frequency spectrum to overcome the phase error from nonlinear chirp. The results of simulation show that the image in range direction can be well compressed. At the same time, we also analyze effects of signal compression in the range direction under different parameter situations such as reference channel length as well as ratio of nonlinear contribution.

News ticker is used to show breaking news or news headlines in conventional 2-D broadcasting system. For the case of the breaking news, the fast creation is need, because the information should be sent quickly. In addition, if holographic 3- D broadcasting system is started in the future, news ticker will remain. On the other hands, some approaches for generation of CGH patterns have been suggested like the ray-tracing method and look-up table (LUT) method. However, these methods have some drawbacks that needs much time or needs huge memory size for look-up table. Recently, a novel LUT (N-LUT) method for fast generation of CGH patterns of 3-D objects with a dramatically reduced LUT without the loss of computational speed was proposed. Therefore, we proposed the method to efficiently generate the holographic news ticker in holographic 3DTV or 3-D movies using N-LUT method. The proposed method is largely consisted of five steps: construction of the LUT for each character, extraction of characters in news ticker, generation and shift of the CGH pattern for news ticker using the LUT for each character, composition of hologram pattern for 3-D video and hologram pattern for news ticker and reconstruct the holographic 3D video with news ticker. To confirm the proposed method, moving car in front of the castle is used as a 3D video and the words 'HOLOGRAM CAPTION GENERATOR' is used as a news ticker. From this simulation results confirmed the feasibility of the proposed method in fast generation of CGH patterns for holographic captions.

Recently, many research works are actively being done on three-dimensional (3-D) recognition using correlation method throughout the world. To recognize the 3-D object from the target image, the reference image is needed. That is, target image is captured using lenslet array as a form of elemental image array (EIA) by integral imaging method. Then, the EIA is reconstructed at each depth plane as a form of plane object image (POI) using computational integral imaging reconstruction method. Then, the correlation process is performed at all POIs with reference image. In general, twodimensional image that is the scene from the front view of the object is used as a reference image. Thus if target has big depth range, the reconstructed POIs are not clear at all depth range because some part is focused whereas the other ones are blurred. Therefore, there are no POIs having clear 3-D object. In other words, it is not able to find the accurate location of 3-D object if 2-D image is used as a reference image. Accordingly, in this paper a new method to find the accurate location of 3-D object by using 3-D reference images that is captured by integral imaging method is proposed. That is, the correlation process is performed the reconstructed POIs of target image and reconstructed POIs of reference image at all depth range. To confirm the proposed method, 'car' is used as a 3-D object. From this simulation results confirmed the feasibility of the proposed method to extract the location of 3-D object.

Based on Fourier transform of heterodyne signal and linear fitting of phase time-evolution, a nonlinearity-induced phase error correction technique for synthetic aperture ladar is experimentally studied. The problem of beat frequency matching in the conventional method for nonlinearity-induced phase error correction in target channel by designing a reference channel and phase shift equations is practically analyzed, and its limitation on application under the condition of large time delay in target channel is verified. According to this problem, a new method of directly nonlinearity-induced phase error correction by linear fitting of phase time-evolution in target channel is proposed. In experiments, the rang resolution of 2 mm is gained at 1.5 μm wavelength, which is coincident well with theory. The results show that this technique can overcome the problem of beat frequency matching in two channels and is effective for practical applications with different time delay in target channel.

In this paper, we propose a fast local reconstruction method of the 3-D image in the computational integral imaging system. In the proposed method, after selecting a reconstruction plane, the pixel of the reconstruction plane is obtained by calculating the average of the pixel values corresponding to each elemental image. That is called here a backward computational integral imaging reconstruction, which doesn't need the normalization process after reconstruction. Then, the elemental image array transformed by using sub-image transforms to produce a sub-image array. Finally, we use the stereo matching algorism for detecting the area of the object image in the each sub-image. To show the feasibility of the proposed method, we implement various computer simulations and present the results.

A new method to design correlation filters for target recognition is presented. The method is based on a heuristic optimization of performance metrics. By the use of the heuristic algorithms the impulse response of a conventional composite filter is iteratively synthesized until a prespecified value of the used quality metric is obtained. Computer simulation results obtained with the proposed method are provided and compared with those of common correlation filters in terms of recognition performance measures in cluttered and noisy input scenes.

In this paper, it is tried to provide an innovative method to overcome several limitations of state of the art of logical gates and microprocessors, by implementation of micron-scaled optical gates. This technology can overcome such limitations, i.e. processing speed, heat dissipation, electromagnetic radiation and electrical noise immunity. This technology can be fully or partially feasible by substitution of common semiconductor technology with optical logic gates. By implementation of micron-scale optical fiber, optical couplers, fiber optical amplifiers, or fiber lasers, optical attenuators, optical fiber brag grating, femto-second optical lasers, and implementation of fundamental properties of optical coherent light, e.g. superposition, interference, phase delay, etc, it is possible to fabricate micron-scale universal logical gates, i.e. optical NAND gates, optical NOR gates, optical Exclusive-OR, optical exclusive-NOR gates and subsequently fabrication of sequential circuits (optical flip-flops), that all are fundamental blocks of microprocessors. Optical coherent light is produced by femtosecond lasers and is supplied to a network of micron-scaled fiber optics, fiber optical lasers, attenuators, fiber optical couplers, and finally are supplied to opto-couplers that change optical signals to electrical signals to be read by output console or to be written on memory cells. It is also possible to implement a combination of optical and semiconductor gates to decrease above mentioned limitations. The method of fabrication of optical gates is discussed in details and all necessary logical and technical aspects are provided too. The fundamental implemented aspect is superposition of coherent lights in fiber optic couplers. By implementation of femtosecond laser pulses, it is possible to reach to much higher frequencies of about hundreds to thousands of terahertz. Alternative optical method is provided here, e.g. implementation of fiber loops as clock circuit or even as an optical oscillator. By implementation of this technology, there will be one hundred years advance in respect to state of the art technology.

Photovoltaic absorbers ought to be optically thick to allow almost total light absorption and photocarrier current collection. They are typically semiconductors with a thickness more than the optical absorption length. When the absorber layer thickness is reduced significantly, then the quality of the absorber material could considerably increase by allowing resourceful photocarrier collection across tiny distances in structures such as quantum wells or quantum dots. For absorber layers with fine surface passivation, the capability to reduce the solar cell base thickness by means of plasmonic design improves carrier collection. The objective of this paper is to show how plasmonics could be exploited to our benefit in high efficiency photovoltaics.

Digital holography is the process where an object's phase and intensity information is retrieved from intensity images obtained using a digital camera (CCD or CMOS sensor). Unlike off-axis holography, object information is not modulated onto carrier fringes, thus in-line digital holography makes optimum use of the recording device's sampling bandwidth resulting in higher resolution digital holograms. However, reconstructed images are obscured by the linear superposition of the unwanted out of focus twin images. In addition to this, speckle noise degrades overall quality of the reconstructed images. The speckle effect is an optical phenomenon arising when laser sources are used in digital holographic systems. Minimizing the effects due to speckle noise, removal of the twin image and using the full sampling bandwidth of the capture device, aids overall reconstructed image quality. Using interferometric techniques, it is possible to record whole field information about an object. Digital processing of the reconstructed holograms can remove or suppress the twin image while effects from speckle noise can also be reduced numerically. Machine vision techniques can then be applied to segment and distinguish objects of interest in the hologram. Coding the resulting phase information onto a spatial light modulator (SLM), real world, three dimensional images of objects can be reconstructed using the computer generated hologram.

A joint transform correlator (JTC) is presented. In the proposed setup the joint transform of the images to be correlated is filtered by an infinite Ronchi ruling, which is generated by a spatial light modulator, SLM, at the Fourier plane. A lens produces the spatial integral of the product of the joint transform of the composite input and the amplitude transmittance of the spatial light modulator, and a photodetector acquire the total light energy transmitted by the SLM. The proposed technique significantly reduces the processing time needed for real-time applications.

Optical ID tags have been shown as a useful tool for surveillance by detection and verification of a signature. Previous work on the topic made ID tags robust to rotations and scale variations by spatially multiplexing the information on the tag. To achieve this goal, however, a large amount of pixels had to be encoded on the final tag. To overcome this drawback an improved design is presented. The information distribution on the ID tag has been modified to optimize the area occupied by the tag. Moreover, a set of reference points has been introduced to achieve resistance against distortions that can affect the tag in remote acquisition. We pay special attention to affine and projective (rotation, scale, shear, perspective) transformations as well as to distortion (barrel, pincushion) caused by the imaging system. In comparison to prior designs, the novel optical ID tag has two additional advantages: it permits a significant reduction of the tag size, even if the verification is remote and affected by the aforementioned distortions. Verification results are presented for a number of practical situations.

An important aspect of research in the continued development of cochlear implants is the in vivo assessment of signal processing algorithms. One technique that has been used is evoked potentials, the recording of neural responses to auditory stimulation. Depending on the latency of the observed response, the evoked potential indicates neural activity at the various neurological structures of the auditory system. Electrically evoked ABRs are commonly measured in hearing-impaired patients who have cochlear implants, via electrical stimulation delivered by electrodes in the implanted array. This research explores the use of MATLAB for the purpose of developing a model for electrically evoked auditory brainstem responses (ABRs). The simulation model developed in this study takes as its input the stimulus current intensity level, and uses function vectors and equations derived from measured ABRs, to generate an approximation of the evoked surface potentials. A function vector is used to represent the combined firing of the neurons of the auditory nervous system that are needed to elicit a measurable response. Equations have been derived to represent the latency and stimulus amplitude scaling functions. The simulation also accounts for other neural activity that can be present in and contaminate an ABR recording, and reduces it through time-locked averaging of the simulated response. In the MATLAB simulation, the model performs well and delivers results that compare favorably with the results measured from the research subjects.

Fiducials imprinted on laser beams are used to perform video image based alignment of the 192 laser beams in the National Ignition Facility (NIF) of Lawrence Livermore National Laboratory. In many video images, matched filtering is used to detect the location of these fiducials. Generally, the highest correlation peak is used to determine the position of the fiducials. However, when the signal to-be-detected is very weak compared to the noise, this approach totally breaks down. The highest peaks act as traps for false detection. The active target images used for automatic alignment in the National Ignition Facility are examples of such images. In these images, the fiducials of interest exhibit extremely low intensity and contrast, surrounded by high intensity reflection from metallic objects. Consequently, the highest correlation peaks are caused by these bright objects. In this work, we show how the shape of the correlation is exploited to isolate the valid matches from hundreds of invalid correlation peaks, and therefore identify extremely faint fiducials under very challenging imaging conditions.

Hyperspectral sensors can facilitate automatic pattern recognition in cluttered imagery since man made objects often differ considerably from the natural background in absorbing and reflecting the radiation at various wavelengths i.e., the identification of the objects is based on spectral signature of the objects in the scene. Normalized cross spectrum (cross-phase spectrum) has been extensively used for image registration. In this paper, we introduce preliminary results for a new approach for object detection in hyperspectral imagery by employing normalized cross spectrum. Normalized cross spectrum is employed as similarity measure between the spectral signature of known object and the investigated spectral signatures in the data. The new algorithm uses the advantages of the shape of the peak of the correlation to detect the pattern of interest. The proposed algorithm has been tested using real life hyperspectral imagery and the results show the effectiveness of the proposed approach.

A dynamically configurable optical add/drop multiplexer (OADM) device was proposed based on volume holographic gratings in doubly doped lithium niobate crystals and the principles of optical crystallography. The device consists of a wavelength demultiplexer module and an array of 2×2 electro-optic switches based on the internal reflection on the surface of the crystal. Two design schemes were presented: OADM based on discrete crystals with unifunctional integration and OADM based on monolithic crystal with multifunctional integration. This device can dynamically select signal channels that need to be added or dropped and simultaneously add/drop arbitrary signal channels. The suggested OADM has superior properties of simple and compact construction, convenient manipulation, lowered insertion losses and resistance to environmental perturbation.