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A polarizer which works upon the combination effect of birefringence and diffraction has been designed and realized experimentally. According to the design the polarizer may be consisting of a sheet of birefringent material or two birefringence plates, on which surface one dimensional grooves with a sawtooth profile or echelon profile are carved. In experiment, a periodic grooves of a sawtooth profile were fabricated on the surface of calcite plate by mechanical and optical manufacture techniques. This sample polarizer was test for its polarized feature with a non-polarized HeNe laser, and the results show the polarizer is of a good polarized performance.

In this paper, combining refractive and diffractive effects, a new kind of infrared lenses with wavelength 10.6 mu m was designed and produced for CO2 laser material processing. This refractive-diffractive lens (RDL) converts a CO2 laser beam into the rectangular shape with light intensity distribution in the concave shape at x-direction. A method which employs input aperture division and geometrical transformation technique for obtaining a better initial phase distribution of the iteration is presented. The experimental results show that the desired shape of the output light beam was obtained with a high efficiency in energy utilization.

Ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) (001) and (Mn,Sn) doped-PZT (PMSZT) (001) thin films have been integrated to high Tc superconducting c-oriented YBa2Cu3O7-x (YBCO) films for use as infrared detectors. The films were grown on LaAlO3(100) substrates by the pulsed laser deposition technique. The photocurrent responses of the PZT/YBCO and PMSZT/YBCO heterostructures fabricated as infrared (IR) detector have been measured from room temperature up to the ferroelectric phase transition temperatures. A stable photocurrent was observed to increase with increasing temperature throughout the temperature range. It was observed that the photocurrent of PMSZT/YBCO IR detector was significantly higher than that of the PZT/YBCO IR detectors in the temperature range of 20 - 170 degree(s)C. The current enhancement with temperature was found to be strongly polarization dependent and is due to the change of the pyroelectric coefficient of the PZT and PMSZT thin films with temperature. The YBCO thin films in the heterostructure were not used for their superconducting properties, but for their IR reflector-conductive electrode properties and as an atomic template for PZT/PMSZT epitaxial growth. With the high dielectric constants of PZT (600 - 800) and PMSZT (300 - 450) measured in this work, and the stable photocurrent in the infrared region (above 1 micrometers ), the PZT/YBCO and PMSZT/YBCO heterostructures are believed to be suitable materials for use in infrared detectors applicable at temperatures higher than room temperature.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper, a kind of diffractive optical element (DOE) was designed and fabricated. For the design, an improved Gerchberg-Saxton algorithm and an approach of aperture division are presented. The DOE was generated by means of photolithogrpahy and ion etching techniques with 16 phase levels. The experimental results of quenching processing of steel parts by inserting the DOE into CO2 laser beam are satisfactory. The DOE is of an advantage of that applicable to a variety of multimode laser beams.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A hybrid character recognition system is described. It is composed of two parts, the feature extractor and the inner-product correlator. Ten Arabic characters from 0 to 9 are tested for their recognition by the system. The experimental results show that all the printing charactersare perfectly recognized with rotational invariance of 15° angle, and for hand-writing characterstheir recognized ratio is over sixty percent. 1. INTRODUCTION For the consideration of rapidly image identifying and pattern recognizing, the researchon image processing by various optical processors and hybrid processors has become an active subject.' —6 The techniques of feature extraction, optical correlation and artificial neural network, we think, are most useful for image processing and pattern recognition. In practice, however, the number of object class that requires identification is large and an object includes ahuge information. So that only use of one image processing technique always bears beyond it'sability for object recognition, and a combination of several such techniques has developed forimage processing and object recognition. Such three optical information processing techniques7have been suggested to be combined to achieve the best benefits in image processing.

A modified model of artificial neural networks is suggested, the interconnective matrix of which is consisting of summation of matrices T1 and T2, where T1 is the outer- product matrix of memory vectors and T2 is the complementary vectors one, respectively. Since all of elements of the interconnective matrix are non-negative values, the model is more suitable for implementation in optics. An optical neural network system is set up in laboratory to implement the model, which is composed of a green LED array for writing, a red LED array for read out, a PROM for recording interconnective matrix, a photodetector for measuring the output and a feedback system. In the meantime it is also executed by computer simulation. The experimental results of associative memory of two, three and four vectors with eight bits show that the model is of more capacity of associative memory, especially for non-orthogonal vector's memory.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this report, two modified models of artificial neural network based on the Hopfield modelare suggested. For the models the composition ofthe memory matrices is revised. And an optical system constructed with a spatial light modulator PROM is set up to implement the modelsthat are executed 1w computer simulation in the meantime. The experimental results show that the storage capacity and the searching-identification of the neural network for associativememory are improved. 1. INTRODUCTION Recently, based on the Hopfield model an optical neural network system that can perform the parallel computation and the function of intelligence has become an attractive subject'5. However optical realization of the bipolar and multivalue interconnective matrix of the Hoplield model is difficult because of the restriction in the function of many optical storage devices.Almost in all of the optical neural network . therefore. the memory matrix often has to beclipped into bipolar trinary matrix(4%O1) or to be transformed into unipolar binary matrix

A hybrid optical-digital system consisting of a holographic mask, two lenses, a CCD detector, and a microcomputer is presented to compute the invariant moments of images in real-time. Some English letters are tested as input patterns to extract invariant moments. Experimental results show that the invariant moments of a letter are largely independent of shift and rotation, and the moments are distinct with different letters.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Observe and study that the device PROM exhibits an optical isodeusity behavior, which may cause some interest in image processing.PROM is a device constructing with photorefractive crystal BSO (Bai2SiO2o), which is usually used to convert an optical image from incoherent to coherent. Recently, more attention has been devoted to developing applications of PROM in the fields of optical holography, optical informationprocessing and optical computing. In this paper, an optical isodensity behavior ofthe PROM device is observed and measured. Under considerations of the optical nonlinearity of BSO, a relation oftransmission light intensity I with the voltage V within BSO crystal is written by IIosin2(), (1) where Vh S the halfwave voltage of the BSO. As V = Vh, I reaches maximum value Io. It maybe seen that I trends to minimum in the vicinity of zero voltage. The voltage V is sum of appliedexternal voltage V and inner voltage V1 in BSO, whkh is induced by writing exposure E on to BSO. Therefore, by turning V onto —V1 value, a minimum transmission occurs, which corresponds