Holographic methods for imaging into scattering volume media are described. The holography is carried out with light that has reduced coherence, either spatial coherence or temporal coherence or both, leading to either confocal imaging or photon migration imaging.

Diffraction properties of light can be derived from Quantum Mechanics and Relativity. Using the fact that position and momentum are conjugate variables, we show that the momentum distribution of light coincides with the well-known angular spectrum distribution. The momentum distribution links quantum theory and relativity to classical diffraction theory. We also show that the Huygens Principle and the momentum distribution are conjugate expressions at the diffraction aperture. These considerations lead to the geometrical theory of diffraction.

The control of light is a basic process that enables the realization of novel devices and systems. Traditional optics deals with information being delivered in time, as in optical fibers or in space between 'input' and 'output' planes, as in an imaging system. However, the increasing demand for novel functionalities has raised the need to deliver information in multiple dimensions in space and in space-time. Different approaches for the synthesis of three-dimensional and spatio- temporal light-fields are discussed. The mathematical tools include spatial, spectral, and modal domain synthesis.

We present a method to recognize three-dimensional objects from phase-shift digital holograms. The holograms are used to reconstruct various views of the objects. These views are combined to create nonlinear composite filters in order to achieve distortion invariance. We present experiments to illustrate the recognition of a 3D object in the presence of out-of-plane rotation and longitudinal shift along the z-axis.

A real time system for three-dimensional (3-D) object recognition based on Fourier transform profilometry technique is presented. We demonstrate the performance of the proposed method in two different types of correlators: the joint transform correlator and the classical convergent correlator. The projection of a regular fringe pattern onto the 3-D object surface permits to obtain a distorted grating pattern that carries all the 3-D information of the object. The analysis of such patterns is the basis of the method for recognizing 3-D objects in real time. With this method is also possible to obtain rotation-invariant and scale-invariant 3-D object recognition. The experimental results demonstrate the theory and show the utility of the proposed method.

The operation of a joint transform correlator is based on two Fourier transforms in cascade. The first one produces the joint power spectrum; the second one yields the correlation. In this work, we study the influence of the aberrations that affect the optical systems that produce the two Fourier transforms, by computing the wave aberration of the diffraction setups from data obtained by ray tracing. First, we consider the aberration only in the power spectrum, then only in the transformation of power spectrum to give the correlation and finally, in the two steps at the same time. In the study, real conditions have been reproduced and the dimensions and resolutions of real liquid crystal-displays have been used. The results show that the quality of the correlation is determined mostly by the aberrations of the first diffraction stage.

In this paper, a new VHOE-based multiview stereoscophic 3D video display system which can allow viewers to observe 3D images in real-time is proposed. A photopolymer-based VHOE, which can be made from volume holographic recording materials, is newly introduced for projecting multiview images to the spatially different directions sequentially in time. Since this technique is based on the photopolymer-based VHOE, instead of the conventional parallax barrier or lenticular sheet, several parameters such as resolution and viewing angle etc. can be limited by the photopolymer's physical and optical properties. Accordingly, in this paper, the optical and physical characteristics of the photopolymer-based VHOE such as distortion of the displayed image, uniformity of the diffracted light intensity, angular selectivity, and diffraction efficiency are measured and analyzed through some experiments by using the photopolymer of Du-Pont HRF series.

The essential problem in stereo vision system is to search for correspondence points between two different object images projected from the left and right cameras to detect the stereo disparity. So far, several methods were proposed to handle this correspondence problem, but most of them are complicated, need a long calculation time and show the low accuracy of the estimation value because of fixed windowing, etc. The proposed algorithm, firstly, extracted the target object by removing the background noises through the difference image information of the sequential left images and then, controlled the pan/tilt and convergence angle of the stereo camera by using the coordinates of the target position obtained from the optical BPEJTC which was executed between the extracted target image and the input image. Also, we propose a novel 3D vision system to detect and segment the moving object adaptively through controlling the pan/tilt system of stereo cameras by using optical BPEJTC (Binary Phase Extraction joint transform correlator).

The polarization change that accompanies diffraction from sub- wavelength features is used as a sensitive measure of the feature shape. This sub-wavelength measurement capability is explored by comparing vector-based diffraction models with experimentally obtained data from a novel imaging ellipsometer. This imaging ellipsometer is able to measure samples with high spatial resolution in a parallel fashion by using a high-numerical-aperture lens. Two-dimensional surface maps can be generated without scanning. Our novel metrology tool could provide a solution to the imminent metrology challenges in semiconductor industry.

A novel multiplexed computer-generated hologram (CGH) is designed with polygonal apertures. The multiplexed CGH is encoded with elementary rectangular cells divided into arbitrary-shaped polygonal apertures. The division is identical in all cells. The phase values of the apertures are assigned during the design. The polygonal apertures of same locations inside the cells constitute a subhologram. The cells are further divided in pixel arrays to exploit the huge number of degrees of freedom provided by electron-beam lithography. With the Abbe transform that has never been used, to our knowledge, in other CGH designs, the subhologram subimages are obtained by fast Fourier transforms. Hence, it is possible to design a multiplexed CGH that has a size thousands times larger than the manageable size of a conventional CGH designed with the iterative Fourier-transform algorithm. A much larger object window than that of the conventional CGH can also be achieved with the multiplexed polygonal-aperture CGH, because of its much larger number of pixels. A new iterative gradient descent algorithm results in a high performance of the multiplexed polygonal-aperture CGH. The noise appearing in other multiplexed-CGH designs is avoided.

In order to help hepatic surgery planning, an unsupervised method is needed to automate the delineation of liver tumors. Moreover, due to the large amount of images acquired by Computer Tomography Scanner (CT-Scan), the processing has to be fast for a clinical use. Current methods are based on filterings and have the drawback of being time consuming. In this paper, to reach the purpose of speed and quality, we propose a fast unsupervised method which is implementable on an opto-electronical processor. The proposed method is based on the expansion/compression paradigm and combines a multiresolution approach with the principal component analysis (PCA). The multiresolution representation is done by several Gaussian filterings. The compression of the expanded information is then achieved by only keeping the first PCA factorial image. Endly, the object of interest is detected and delineated using the standard valley thresholding technique which is applied to the first factorial image. For the delineation of liver tumors, regions of interest (ROI) containing tumors have been preliminary extracted before applying PCA. Experimental results obtained by the processing of difficult clinical cases show, according to the radiologist experts, that our method is able to efficiently delineate liver tumors. Because Gaussian filterings are time consuming when carried out on a digital processor, we propose to implement them on an optical correlator. Clinical cases have been processed using the resulting opto-electronical processor to show the feasibility of such an implementation.

We discuss the performance of the double-phase holographic encoding of complex modulation, implemented with a phase-only spatial light modulator (SLM). A macro-pixel formed with two phase-modulated pixels of the SLM is required to encode each sampled value of the desired complex modulation. This complex modulation is obtained in the zero order term of the Fourier series associated to the macro-pixel structure. We discuss the performance of this holographic method with explicit consideration to the pixelated structure of the SLM. We show that an exact copy of the desired complex function, only attenuated by the SLM fill factor, is generated by the holographic code (with some additional high order off-axis terms). We derive a formula for the signal field reconstruction efficiency. This formula shows that the efficiency is dependent on the absorption (or modulus) of the encoded complex modulation. As an application, we show that the holographic code can be adapted (with slight modifications) to implement a highly isotropic edge enhancement filter.

We study the geometrical phase transition for fractal transmittances, to determine the limits from which it must be considered like fractal structure, according with the density of diffractive elements contained in such planar transmittance. For such objective two considerations are made: (1) the diffracted field from the transmittance is analyzed at the Fourier plane, (2) the autocorrelation of the same is studied by means of the joint transform correlator.

Optical correlation for pattern recognition with selective and adjustable discrimination capability is based on the Dual Nonlinear Correlation (DNC) algorithm and on a two-step Joint Transform Correlator (JTC) architecture. The DNC encompasses nonlinear power-law processing operating independently on the spectra of the input image and the reference target. But the eventual capabilities of the system strongly depend on some experimental conditions such as quantization, gray-level dynamic range, saturation and other technical characteristics of both the camera and the spatial light modulator used in the JTC. In this work we explore these capabilities for three available modulators (Epson and two different CRLs) acting in both the input and the modified joint power spectra planes for the first and second steps of the JTC, respectively.

We present the investigation which was conducted to improve the spatial and temporal performances of a deflecting system for display addressing. In a first part we describe the operation principle used to increase the optical deflection angle of an acousto-optic deflector. We show that it is possible to obtain an angular amplification simply by using a grating at grazing incidence angle; the diffraction is then close to 90 degrees. Experimental tests made with a 1200 gr/mm grating have shown that an amplification of the deflection angle as high as 10 can be obtained. In a second part we introduce a complete set-up composed by the association of MEMS, Acousto-optic and grating. All those components are used to achieve a compact addressing system.

In avionic systems, data integrity and high data rates are necessary for stable flight control. Unfortunately, conventional electronic control systems are susceptible to electromagnetic interference (EMI) that can reduce the clarity of flight control signals. Fly-by-Light systems that use optical signals to actuate the flight control surfaces of an aircraft have been suggested as a solution to the EMI problem in avionic systems. Fly-by-Light in avionic systems reduces electromagnetic interference hence improving the clarity of the control signals. A hybrid approach combining a silicon photoreceiver module with a SiC power transistor is proposed. The resulting device uses a 5 mW optical control signal to produce a 150 A current suitable for driving an electric motor.

A compact, low loss, optical tap technology is critical for the incorporation of optical interconnects into mainstream CMOS processes. A recently introduced multimode interference effect based device has the potential for very high speed performance in a compact geometry and in a CMOS compatible process. For this work, 2-D and 3-D device simulations confirm a low excess optical loss on order of 0.1 dB, and a nominal 40% (2.2 dB) optical coupling into the CMOS circuitry over a wide range of guide to substrate distances. Simulated devices are on the order of 25micrometers in length and as narrow as 1 um. High temperature, hybrid polymer materials used for commercial CMOS inter-metal dielectric layers are targeted for tap fabrication and are incorporated into the models. Low cost, silicon CMOS based processing makes the new tap technology especially suitable for computer multi-chip module and board level interconnects, as well as for metro fiber to the home and desk telecommunications applications.

We report on a bridge structure PZT [Pb(Zr_xTi_{1- x})O₃] thin film microtransducer with proof mass that has been fabricated successfully at the Microtechnology Laboratory (MTL) of the University of Minnesota. The bridge microtransducer is made on silicon wafer using bulk micromachining of microelectromechanical systems (MEMS) and special techniques for deposition of a PZT thin film. The bridge is 300 micrometers wide, 1000 micrometers long, and a few micrometers thick. A proof mass made from the silicon wafer is loaded under the bridge at the central region, its area is 300 X 300 square micrometers and its thickness is 475 micrometers (same as the wafer). Used as an accelerometer, the microtransducer is calibrated using a Vibration Test Systems (VTS), which is a commercial accelerometer calibration instrument. The sensitivity of the microtransducer is constant over the range of frequencies from zero to 10 kHz, 240(mu) V/g at 0.5g with a dc bias voltage of 0.2 volts and a deviation of 5%. The Brownian thermal noise equivalent acceleration is 9.072(mu) g/(root)Hz. Design of a bridge structure with mass loading is modeled using ANSYS. Simulation analysis shows that the fundamental natural frequency of the microtransducer is 11.352 kHz, which is close to the measured resonant frequency of 12.28 kHz.

Optical microdisk array fabrication with sol-gel techniques was investigated. The characteristics of the microdisk array doped with Rhodamine B were studied with pulsed laser excitation. The whispering-gallery mode (WGM) emission spectra were observed. The WGM is very sensitive to the external circumstance under certain condition. The possible application of microdisk array as sensor also was investigated. We found the amplified spontaneous emission produced from microdisk array is very sensitive to the trace of material detected. The result showed that the microdisk as a kind of sensor has potential application in integrated optics.

Optimal performance of a Liquid Crystal on Silicon (LCoS) device requires an integrated approach incorporating both optical and electrical design elements. In particular, during the design of both the IC back plane and the voltage waveforms used to drive fast switching Ferroelectric LC (FLC) the electro-optical properties of the LC must be considered to ensure that the best use is made of the FLC. Although, SPICE equivalent circuits for FLC materials have been developed and can be used for this purpose their accuracy relies upon the measurement of a number of parameters. Unfortunately, the accuracy of measuring key parameters is often poor, resulting in a relatively large margin of error in the final model. However, this need not be the case. In this paper we present a methodology which uses standard IC parameter extraction software to simulate and optimize the FLC SPICE model parameters such that the model closely matches the measured response of the sample. By using this approach we identify a set of parameters which when combined provide a SPICE equivalent circuit which models the FLC repsonse to a given input waveform.

With the explosion of Internet and multi-service traffic, telecommunication transport networks today are turning to Wavelength Division Multiplexing. Optical cross-connects (OXCs) allow flexible rerouting of wavelength channels. It has been shown that 2-D free-space beam deflection by nematic liquid crystal gratings provide a good solution for the realization of optical switches in OXCs. Operating in the telecom 1.5 micrometers wavelength region they serve as an active holographic element. Liquid Crystal on Silicon (LCOS) combined with VLSI technologies allow the fabrication of large capacity, low cost and low consumption compact free-space switches. An N X N optical switch can be built by cascading two LCOS-based spatial light modulators (SLMs). The first part of the paper describes a circuit that provides the physical support as well as piloting circuitry for such SLMs. It is capable of piloting beams from a linear array of 8 incoming fibers towards a similar array of 8 outgoing fibers. The electrode command voltages are analog while the external interface as well as on-chip memory is digital. The chip has been implemented in a CMOS 0.5 (mu) process with 600,000 transistors while die size is 320 mm² (80 mm² active area).

The design and simulation results of a 64 X 64 pixels smart CMOS photodiode sensor array are presented. The chip is capable of capturing an image as well as performing real time on-chip signal processing on 3 X 3 kernel array of the image. The size of the optical system is significantly reduced by integrating the signal processing circuits on chip. It is particularly suitable for applications such as optical correlators or image processing system. The chip is designed using 0.8 micrometers standard CMOS process technology. It is incorporated with processing circuitry to implement low-pass and high-pass image filters as well as the processing algorithm required by a 1/f binary phase optical correlation system.

Tristate antiferroelectric and v-shaped liquid crystal materials have recently offered the promise of both the fast switching of ferroelectric materials and the analogue switching of nematic materials at drive voltages compatible with those available from standard CMOS technology thereby making them, at least in principle, suitable for consideration in microdisplay and other photonic applications. AFLC development is in its early stages and the materials are not yet mature enough for widespread commercial use. The object of the ESPRIT funded MINDIS project has been to evaluate AF-LCoS technology. The electro-optical characteristics of a number of experimental materials have been experimentally measured in test cells that emulate the situation of a silicon backplane (e.g., aluminum reflective back electrode etc). Some candidate materials been shown to exhibit high contrast, uniformity and repeatability. A CMOS active matrix backplane with 1000 line resolution has been designed and fabricated. The backplane is capable of operating in digital or analogue modes for FLC and AFLC respectively. Planarization techniques have been applied to the CMOS wafers but planarization has been shown to be more problematic than with previous backplanes. The reasons for this are discussed. The technology has been theoretically evaluated for use in microdisplays for both projection and near-to-eye applications.

Amorphous silicon photodiode technology is a very attractive option for image array integrated circuits because it enables large die-size reduction and higher light collection efficiency than c-Si arrays. The concept behind the technology is to place the photosensing element directly above the rest of the circuit, thus eliminating the need to make areal tradeoffs between photodiode and pixel circuit. We have developed an photodiode array technology that is fully compatible with a 0.35 um CMOS process to produce image sensors arrays with 10-bit dynamic range that are 30% smaller than comparable c-Si photodiode arrays. The work presented here will discuss performance issues and solutions to lend itself to cost-effective high-volume manufacturing. The various methods of interconnection of the diode to the array and their advantages will be presented. The effect of doped layer thickness and concentration on quantum efficiency, and the effect of a-Si:H defect concentration on diode performance will be discussed. The photodiode dark leakage current density is about 80 pA/cm², and its absolute quantum efficiency peaks about 85% at 550 nm. These sensors have 50% higher sensitivity, and 2x lower dark current when compared to bulk silicon sensors of the same design. The cell utilizes a 3 FET design, but allows for 100% photodiode area due to the elevated nature of the design. The VGA (640 X 480), array demonstrated here uses common intrinsic and p-type contact layers, and makes reliable contact to those layers by use of a monolithic transparent conductor strap tied to vias in the interconnect.

We describe the design, fabrication and functionality of two different 0.5 micron CMOS optoelectronic integrated circuit (OEIC) chips based on the Peregrine Semiconductor Ultra-Thin Silicon on insulator technology. The Peregrine UTSi silicon- on-sapphire (SOS) technology is a member of the silicon-on- insulator (SOI) family. The low-loss synthetic sapphire substrate is optically transparent and has good thermal conductivity and coefficient of thermal expansion properties, which meet the requirements for flip-chip bonding of VCSELs and other optoelectronic input-output components. One chip contains transceiver and network components, including four channel high-speed CMOS transceiver modules, pseudo-random bit stream (PRBS) generators, a voltage controlled oscillator (VCO) and other test circuits. The transceiver chips can operate in both self-testing mode and networking mode. An on- chip clock and true-single-phase-clock (TSPC) D-flip-flop have been designed to generate a PRBS at over 2.5 Gb/s for the high-speed transceiver arrays to operate in self-testing mode. In the networking mode, an even number of transceiver chips forms a ring network through free-space or fiber ribbon interconnections. The second chip contains four channel optical time-division multiplex (TDM) switches, optical transceiver arrays, an active pixel detector and additional test devices. The eventual applications of these chips will require monolithic OEICs with integrated optical input and output. After fabrication and testing, the CMOS transceiver array dies will be packaged with 850 nm vertical cavity surface emitting lasers (VCSELs), and metal-semiconductor- metal (MSM) or GaAs p-i-n detector die arrays to achieve high- speed optical interconnections. The hybrid technique could be either wire bonding or flip-chip bonding of the CMOS SOS smart-pixel arrays with arrays of VCSELs and photodetectors onto an optoelectronic chip carrier as a multi-chip module (MCM).

A challenging task facing the designers for the next generation of archival storage system is to provide storage capacities several orders of magnitude larger than existing systems while maintaining current data access times. To meet this challenge, we have developed a smart optoelectronic database filter suitable for large capacity relational database systems that use page-oriented optical storage devices. The photonic VLSI device technology based database filter monolithically integrates optical detectors, photoreceiver circuits, data manipulation logic, and filter control circuitry onto a single CMOS chip. This paper presents the design and system level analysis of the database filter system. Simulation data suggested that a 32 X 32-bit filter fabricated in a 1.5 micrometers CMOS process could have an optical page read rate of 87 Mpages/s and support 123 Mrecords/s transfer rate to a host computer. Queuing theory is used to show that even with the limitation of finite queue capacity, a database filter chip could be controlled to work at near optimal performance where database search time is limited by the data transfer rate going into the host computer. Since only valid search data is passed through to the host computer, the introduction of a database filter can dramatically reduce database search time.

The design, demonstration and evaluation of a general purpose, smart pixel based photonic information processing unit is presented. Based on a photonic VLSI device technology that can be implemented using a standard 1.5-micrometers CMOS, each pixel incorporates a photoreceiver with a RISC processor and produces a device that is suitable for prototyping photonic information processing systems.

The design, demonstration and evaluation of a general purpose, field programmable smart pixel based photonic information processing system is presented. This novel architecture incorporates photoreceiver cells into a field programmable gate array (FPGA). Implemented with a photonic VLSI technology the device is suitable for prototyping photonic information processing systems. We report here on the photoreceiver design methodology and measure device performance.

The U.S. Army Night Vision and Electronic Sensors Directorate (NVESD) currently has efforts internally and externally to develop advanced readout integrated circuits (ROICs) with on- chip processing capabilities. We have funded Raytheon Infrared Operations through a Dual Use Science and Technology program to develo and fabricate an advance ROIC with processing features including non-uniformity correction, extended charge handling, motion detection and edge enhancement. This advanced ROIC has been demonstrated through the successful development of the 'Adaptive Infrared Sensors' camera. Discussions of the circuit concepts and architecture of the 'AIRS' ROIC/FPA, as well as simulation results and test results of the camera is presented. Our internal investigations has resulted in an advanced readout design capable of real-time spatial and temporal filtering, to perform edge detection, edge enhancement, motion detection, and motion enhancement. The details of the circuit design, simulation results, as well as test data is presented.