Diffraction patterns of wedges are studied with special attention to the finish of the samples. We assume that the sharply finished vertex should generate two hemispherical waves by the end effect of the cylindrical waves issued from two sides of the wedge under illumination of the coherent light. It is found that the assumption is valuable to the investigation of the diffraction pattern appearing in the shadow region of the wedge.

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The cross-correlation properties of dichromatic light multiply-scattered by colloidal particles in a uniform flow are studied experimentally. It is shown that the correlation peak value of intensity fluctuations depends on the optical thickness of the sample and the number density of particles, whereas the decay time of cross-correlation functions is almost independent of the characteristics of particle suspensions. This result indicates that the number fluctuations as well as the speckle fluctuations contribute to the temporal variations in the intensity, and that the velocity of the uniform flow is measurable without being affected by the diffusive motion of the scatterers. The effect of wavelength difference is also examined.

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We present coherent and partially coherent beams that exhibit transverse pattern expansion and rotation upon free propagation. Coherent twisting beams may be generated by a suitable superposition of Laguerre-Gauss modes, while a model for partially coherent twisting beams is given by a continuous incoherent superposition of lowest order modes.

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A novel optical architecture based on the random iteration algorithm to decode iterated function system (IFS) codes is presented. The optical part of this system performs the affine transformations of IFS. The code values in the affine transformations of IFS are first translated into the modulation voltages of the electro-optic modulators (EOMs), with a specific probability. Then, the multiplication and addition operations can easily be performed. With the O/E and A/D converters, the light intensity is converted into an electrical signal to address a specific pixel at the display device. A fractal image is then progressively decoded pixel by pixel and superimposed on the display device. The computer simulation and some experimental results for the proposed architecture are provided for verification. The decoding speed is fast, the image quality is high, and the resolution of the generated fractals depends on the resolution of the display device itself.

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System stability of various membership functions and fuzzy control methods are compared by numerical simulations to determine the feasibility of optoelectronic fuzzy inference method. An inverted pendulum is used for the destination system. A Gaussian membership function is better than a triangular one. MIN operations of grade evaluation and modification of consequent membership functions are better than other operations. SUM operation of consequent operation is better than MAX operation.

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Optical parallel implementation of plural Hough-transforms is investigated for simultaneous detection of plural element shapes. Parallel detection is optically carried out using a two-dimensional array of computer-generated holograms, each of which simultaneously reconstructs plural rearranged parameter domains. A Hough-transform filter for parallel detection of lines and circles is demonstrated by composing a 16×16 computer-generated hologram array. It has excellent performance in quality of reconstructed images.

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Gabor's expansion of a signal into a discrete set of properly shifted and modulated versions of an elementary signal is introduced, and it is shown how the expansion coefficients can be determined via the Zak transform. An arrangement is described which is able to generate Gabor's expansion coefficients of a rastered, one-dimensional signal by coherent-optical means.

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A hybrid binary subtracted joint transform correlator was constructed using a Bi₁₂SiO₂₀ (BSO) spatial light modulator and a laser scanner. The usefulness of this system was confirmed experimentally using a large number of binary and half-tone images as the reference patterns.

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The authors have constructed a digital optical computing system, called hybrid-optical parallel array logic system 16² (H-OPALS16²). The system can execute neighborhood operations in parallel for two images consisting of 16×16 pixels. To achieve overall operation of the system, we developed an optical discrete correlator that enables the H-OPALS16² to execute programmable neighborhood operations. Noise reduction and lateral edge detection were executed to verify operation in the system. The frame rate of the system is 1.32 frame/s. We estimated that the speed of the constructed system can be increased up to 20 k frame/s.

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In this paper we propose a new design of a joint transform correlator in which two transform lenses are used to minimize the influence of their aberration, and a magnification lens is used to make the optics compact. Experimental results show the correlator can be used to recognize characters and/or half tone images in real time.

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We describe two-input optical logic gates implemented using grating interferometrers. AND, OR, and XOR logic functions are easily implemented with the same optical system, simply by changing the relative spatial phase of the gratings. We also describe an extension of this idea in which a four-grating interferometer is used as an optical half-adder, and demonstrate its operation with experimental results.

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In order to miniaturize optical disc drives, it is important to miniaturize and thin the optical pickup. We have developed two new optical parts: the hologram laser and the actuator. By optimizing the hologram pattern of the hologram laser, optical path length is shortened. The frequency characteristics of the actuator have been stabilized by improving the damping characteristics. Thus, we have developed a compact optical pickup for Mini Disc drives, and the pickup shows high performance when it reads out an optical disc.

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Intense photostimulated luminescence (PSL) with a peak at 420 nm is observed in ultraviolet (UV) light-irradiated europium-doped potassium chloride (KCl : Eu) crystalline phosphors. The PSL characteristics of UV-irradiated KCl : Eu phosphor for optical memory application were studied. The excitation and emission mechanisms of the 420 nm PSL, which are consistent with the results obtained, are discussed.

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A Phase Change Rewritable optical disk system with a high density of 0.57 μm/bit and high transfer rate up to 46.3 Mbps is presented. In this system, the Mark Edge Recording method is used to attain the total capacity of 19 GB in a double-sided 300 mm-diameter disk. Since this method requires precise recording mark length, a write compensation method, disk media and read data detection method suitable for a wide range of scanning linear velocities ranging from 10.7 to 27.4 m/s have been developed.

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A high density mark edge recording method on a phase change rewritable disk is reported. A carrier-to-noise ratio of 55 dB for a mark length of 0.55 μm is obtained by using a 680 nm, NA 0.6 head and a phase change rewritable disk. In mark edge recording, it is necessary to record each mark in correct length. A new laser power modulation pattern is proposed. This pattern consists of a first-pulse, a multi-pulse chain and a last-pulse. Both positions of the first-pulse and the last-pulse are movable. By adjusting these positions, a jitter, σ/T_w (T_w is window margin), is improved to 6.5% in high density EFM (Eight to Fourteen Modulation) recording of 0.4 μm/bit.

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Dynamic wavelength shifts of a monolithic, two-beam laser diode for a two-beam optical head in optical disk drives were analyzed with a streak camera system. The wavelength shift did not exceed 3 nm for the recording beam which was operated in a series of pulses, and the reproducing beam which was operated continuously showed no shift. The focusing characteristics on the basis of the wavelength shift and specifications of the optical head were also calculated. The dynamic displacement of the focal points caused by the wavelength shifts was so small as compared with the depth of focus in the optical head that the recording and reproducing characteristics were hardly influenced.

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We propose a method to produce a hard copy of a three-dimensional (3-D) image by a conventional high-resolution printer. Parallax information is recorded on a transparency by the printer, and a reflection-type holographic screen composed of a number of small elementary holograms is attached on the transparency. The quality of the 3-D image is investigated, and the characteristics of the proposed method are described. 3-D image of full-parallax is experimentally produced using a laser printer.

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An image processing technique to display a distortion-free reconstructed image from a rainbow type conical holographic stereogram is proposed. The method consists of forming a new set of 2D images from the original set by applying an image process. The image processing method is made through ray tracing equations. The results show that the performance of the proposed method is good as it removes distortion of the image.

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An improved shift- and rotational-invariant filter using wavelet transform and circular harmonic filtering at the same time is proposed. Computer simulation has shown that this is better than using a phase-only circular harmonic filter in peak sharpness, discriminating ability, SNR and tolerance of position error of the filter. Furthermore, this filter possesses moderate diffraction efficiency.

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In this paper, we describe blur identification and restoration of noisy degraded images. The point-spread function (PSF) can be characterized by the quantity of blur. Thus the blur identification problem can be solved as a parameter estimation problem. The estimation method is a generalized cross-validation (GCV) criterion that is known as a powerful measure that can be used to choose the optimal regularization parameter without a priori knowledge about noise. We use the iterative damped-least squares (DLS) algorithm which is based on the principle of damped least-squares for restoring noisy degraded images.

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A new interferometric technique that simultaneously acquires all optical data necessary to reconstruct a spectral image is proposed. The optical data is a two-dimensional array of two-dimensional interference patterns. The data are acquired by an optical system consisting of a two-dimensional lens array and a Michelson interferometer. The interference patterns are generally distorted by the errors in path differences. These errors can be estimated beforehand and corrected in the process of reconstruction of the spectral image. Experimental results obtained with this technique applied to a fast phenomenon are also presented.

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Two parallel blind deconvolution methods, each of which uses multiple frames or several images segmented from a single frame, were applied to solar images to reconstruct their fine structure. The influence of low-contrast intensity distribution on the solar images on their reconstruction was investigated with computer simulations. The methods are also applied to an observed solar image.

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The relation between image quantization and network structure is described. Halftoning methods are interpreted as special network types and a learning algorithm for halftoning is presented.

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A optoelectronic integrated device in which six heterojunction phototransistors and two laser diodes are vertically and directly integrated is developed to achieve new functions important for optical signal processing and optical computing. It is demonstrated that the device has a bistable flip-flop function, in which the output portion is switched alternately by the corresponding optical input. The function is extended to a tristable flip-flop, which is especially important for multistable logic, by using multiple HPTs and their internal optical and/or electrical couplings. Moreover, an astable multivibrator function or a self-oscillating function, is successfully demonstrated by applying the interconnecting technique to the bistable flip-flop function.

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It is found from a series of numerical simulations that a simple relation, ΔtΔf_c=0.4α, holds between an amount of down-chirp (Δf_c) and a pulsewidth (Δt) for pulses from an injection-modulated semiconductor laser having a known α-parameter value. This relation is useful for estimating the amount of chirp existing in pulses. The validity of the relation is examined by a direct observation of chirped pulses using a combination of a streak camera and a spectrometer.

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Stable and precise pulsations are generated by an AlGaAs self-pulsating laser diode under strong feedback in an external cavity. Self-pulsation frequency dependency versus bias current is reduced from 159 MHz/mA to less than 7 MHz/mA, while the equivalent Q factor of the pulsation, defined in analogy with the Q factor of electrical pulsation, is enhanced by more than an order of magnitude from about 110 to more than 1,750 at 532 MHz.

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We present a model for second harmonic generation in a two-dimensional array of quantum dots. We show that the combined effect of the electromagnetic local field of the array and the intrinsic electronic resonances due to the spatial confinement in the quantum dot produce giant enhancements of the second order non-linear susceptibilities, hence giving a very large efficiency in the second harmonic generation.

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Direct frequency doubling of a wavelength locked laser diode with an optical bandpass filter in a confocal optical configuration is demonstrated. The wavelength of the laser diode was locked in single longitudinal mode oscillation and tuned to phase-matching wavelength of a quasi-phase-matched second harmonic generation device based on a LiTaO₃ waveguide. Stable blue light of 4.2 mW was obtained for incident power of 48 mW.

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In this study, we investigate the performance of a high-efficiency KNSBN:Cu double phase-conjugate mirror (DPCM). A phase-conjugate transmissivity as high as 58% and a phase-conjugate reflectivity as high as fivefold are observed. Experimental results also show that the DPCM has a good fidelity of phase-conjugate image. Also, amplified phase-conjugate images are observed.

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Two-beam coupling gain and speed of Cr-doped strontium barium niobate in the visible and near-infrared spectral regions are measured. It is found that the sample still exhibits the appreciable photorefractive gain in the near-infrared spectrum. Photorefractive parameters such as effective trap density, effective electrooptic coefficient and mobility-recombination-time product are obtained from the measurement. The photorefractive spectra of the coupling gain and speed in the sample are compared with those of Cr-doped KNSBN.

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A BSO spatial light modulator (BSO-SLM) was operated applying ac voltage. The basic properties of the operation correspond to those in a usual lock-in detector and a 2-dimensional lock-in detector array (2D-LOCK-IN) was implemented by the optical modulator. The properties of the 2D-LOCK-IN using a BSO-SLM were investigated theoretically and experimentally. As an application of the 2D-LOCK-IN, oscillating amplitude were observed on simple vibrating objects.

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Potassium lithium niobate (KLN) fiber crystals have been grown by pulling down method. The KLN fibers doubled around 806 nm radiation for type I noncritical phase matching at room temperature. We observed ~0.6 mW output power from single-pass second harmonic generation at an input power of 700 mW.

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Erythrosin B-doped polyvinyl alcohol (EB/PVA) film, a methyl-orange-doped polyvinyl alcohol (MO/PVA) film and a (EB+MO)/PVA film serve as not only phase conjugators but also hologram-recording media. A phase-conjugate (PC) wave is generated even when a probe wave is linear-polarized orthogonal to the pump polarization direction. Using these dye-doped films, we demonstrate optical PC processing for detecting the phase and amplitude difference between two objects and a moving or time-varying object in a backward degenerate four-wave mixing arrangement.

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Formulae have been derived for eliminating main aberrations on the center of field of the tilted two-mirror system (TTS). The spherical aberration may be eliminated by considering the TTS as a co-axial system. The coma on the center of field will be reduced by conserving certain relationships between the tilting angles of the primary mirror and the secondary. In order to cancel the astigmatism on the center of field, one of the two mirrors must have bi-curvature at the vertex of the mirror. Ray tracing shows that the TTS solved by the given equations produces quite good image quality within a small field of view. In order to increase the useful field of view, the bi-curvature mirror with the shape of an inverse ellipsoid must have high order terms in its surface equation.

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Use of an aspherical surface in the design of a lens system for one-to-many optical-interconnects (OTM-OI), composed of a doublet lens and a gradient-index (GRIN) lens array has been investigated. Applying the procedure of ALSIE (Automatic Lens design by Solving InEqualities), the off-axis lens systems, which feature the optical performance of the OTM-OI lens system, are optimized at 0.1 numerical aperture with a total field of view of 2 Three aspherical designs with the aspherical surface for different surfaces are presented. The aspherical designs show preferable modulation transfer function (MTF) for high frequency as compared with the spherical design.

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Some formulae on correlative match of both optical aperture and wave aberration to determine image quality are derived in this paper. The optimizing match zone on optical aperture and wave aberration were found both theoretically and experimentally. The results are importantly different from traditional criteria for image quality.

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A method was developed for solving zoom lens layout. It can be used to solve both the optically and the mechanically compensated zoom systems. The number of moving components is not limited by this method. The damped least squares method is used for finding the solution of zoom lens and the polynomial equations are used for fitting zoom run during the optimization process. Several constraints are also used for smoothing and minimizing the sensitivity of the zoom system. The principles of the method are described, together with some examples that are given to confirm the techniques.

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Some technical issues in the design, fabrication and evaluation process of the photographic objective lens are treated. In the design process, a unique design technique called the quasi-equivalent glass method is applied. Also, a convenient method is described for the determination of tolerances of the refractive index profile. Performance evaluation showed that the GRIN material made by sol-gel method is usable for photographic lenses.

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Double focus interferometers are attractive for reducing the influence of ambient conditions due to their common-path configuration. This paper describes the influence of sample setting errors in these interferometers. They have been divided into two types, i.e. the normal illumination type and the oblique illumination type. For each type, an equation of the measurement error due to sample setting error has been derived with Gaussian optics. The measurement error of the normal illumination type becomes a parabolic function of the position on the sample surface. The derived error equations have been verified by ray tracing and by experiment. The error of the oblique type is smaller than that of the normal type.

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In phase shifting interferometry, phase errors due to harmonic components of a fringe signal can be minimized by applying synchronous phase shifting algorithms with more than four samples. However, when the phase shift calibration is inaccurate, these algorithms cannot eliminate the effects of a non-sinusoidal waveform. It is shown that by taking a number of samples beyond one period of the fringe pattern, phase errors due to the harmonic components of the fringe signal can be eliminated, even when there exists a constant error in the phase shift interval. A general procedure for constructing phase shifting algorithms that eliminate these errors is derived. A seven-sample phase shifting algorithm is derived as an example, in which the effect of the second harmonic component can be eliminated in the presence of a constant error in the phase shift interval.

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It is reported that the first partial derivative of the phase distribution for a transparent object can be measured automatically by a personal computer with an image processor. The moire pattern is formed by superimposing the Fourier image distorted by the transparent object on the master grating. But if only the moire patterns are observed, it is not shown if the fringe order numbers increase or decrease. The fringe scanning method is presented to overcome the fringe order numbers. The four-step method is used to calculate the first partial derivative. By a simple experiment, the first partial derivative can be shown in the three dimensional graphics.

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This paper describes the mapping of the spatiotemporal principal stress distribution evolved with time in an epoxy photoelastic sample. In the optical heterodyne polarimeter exploited, the signal beam of light transmitted by the sample under continuously loaded condition is photomixed with the local oscillator beam of light made up of orthogonal linearly polarized two-frequency components. Every pixel of a MOS video camera used generates a beat photocurrent that possesses the two orthogonal field components of the elliptically polarized signal beam. The spatiotemporal principal stress distributions can be uniquely determined simultaneously and independently from these two orthogonal field components, and are successfully mapped in a time-sequential form. The spatial and temporal resolutions in the maps are 0.18 mm and 2.9 ms, respectively.

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A generalized phase-shifting algorithm is implemented in the electron-wave interferometry with a transmission electron microscope, based on simultaneous measurement of the initial phases of the interferograms. The initial phase of each interferogram that has inherent linear carrier fringes is calculated using the Fourier co-efficients of the interferogram itself corresponding to the carrier-frequency. Taking advantage of this phase-shifting method in both spatial resolution and precision, the phase distribution of a biological weak phase object is successfully measured. This promises to be one of the most spectacular application fields for this new technology.

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Interferometry for measuring the shape of large aspherical surfaces is reported. The interference fringe pattern between the parallel reference beam and the reconstructed wavefront from the master zone plate which is drawn by an electron-beam drawing machine is recorded on a hologram plate with off-axis optical arrangement. The hologram plate used as the standard element is reconstructed by the conjugate beam in a modified Twyman-Green interferometer. Insufficient parallelism of commercial hologram plates can be compensated by this method. It is also easy to make replicas. Some experimental results are also presented.

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TV-holography can hold a great potential in non-destructive diagnostics of the state of conservation and preservation of artworks. Its use in revealing debonds, cracks, voids, delaminations or residual stress in both ancient paintings on wooden panels, statuaries and mural supports has been proven. The method is easy to apply and very functional for the basic objectives of conservation; its compactness enables detection of microdisplacements even in non laboratory environments. Measurements in field of microcracks and subsurface detachments on ancient frescoes and panel paintings are reported.

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The construction of a hybrid measurement system for measuring lateral and vertical dimensions and its applications to industrial inspection are described. This system uses an acoustooptic deflector, and includes optical heterodyne, confocal and non confocal laser scan microscopy functions in one and the same optical device. These functions are used individually or collectively depending on the purpose of the measurement. For example, by using the optical heterodyne and non confocal microscopy functions at the same time, lateral and vertical dimensions can be measured simultaneously.

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It is shown that a multiple beam wedge plate shear interferometry can be used to represent the lateral aberration curve of a lens more accurately. For larger shear, some new artifacts appear in the interferogram which have been explained by considering contributions of higher order terms in the Taylor's series expansion of the path function.

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A new method for measuring objects with steps is proposed in which two gratings with different pitches are projected on the object surface. The method is demonstrated with sinusoidal gratings made of laser interference fringes and also sinusoidal gratings formed by liquid crystal controlled by computer. An object with step height of 20 mm is measured with standard variation below 3%.

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The effects of the pressure of ambient gas and sample temperature on photo-acoustic displacement (PAD) were studied quantitatively using an extremely sensitive laser interferometric probe. For silicon, the PAD signal measured at atmospheric pressure increased by about 18% as compared to that obtained in a vacuum, and varied by less than 0.7% for a change in pressure of 5% around 1 atm. This effect was attributed to the decrease in refractive index of the gas adjacent to the sample. Temperature rise caused PAD to increase proportionally, and for GaAs, PAD varied 0.4% per degree. The variation of PAD with temperature was accurately explained by the temperature dependence of thermal expansion coefficient and thermal conductivity of the sample.

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This paper describes interference microscopy using a liquid-crystal panel as a rewritable medium. This system makes it possible to observe the dynamic behavior of a magnetic field. Experimental results obtained while observing dynamic domain-wall motion in a thin permalloy film are shown.

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