液晶电视用作图像编/解码实时光学相关滤波器

文章介绍了一种一维光学相关器,在其傅里叶平面内,将液晶电视（ Ｌ Ｃ Ｔ Ｖ） 编码成单极二元纯位相滤波器用于图像实时编码或解码。给出了初步光学实验结果     

纯相位二值化匹配滤波器的优化设计

通过采用神经网络中的Clipping方法和MonteCarlo修改学习算法,对用于光学模式识别的纯相位二值化匹配滤波器进行了优化设计。计算机模拟结果表明,和传统的纯相位匹配滤波器的相关输出结果相比,其识别输出的信噪比和信号相关峰值得到了明显的提高,从而为今后的光学实现奠定了良好的基础。     

Optical computing and interconnects

This paper discusses the present status of optical computing and interconnects, including device technology, and recent progress in three types of optical computing-analog, digital, and neural-is introduced. Examples of technologies used in an analog computing system, a technique for the optimal design of coherent phase-only spatial filters, and a new version of incoherent filtering are presented. The use of the modified sign digit number representation and its applications to digital optical computing are also described. Some architectures for optical neural computing are introduced, and the importance of optical interconnect technology in parallel computing is stressed. Permutation techniques, the board-to-board level interconnection techniques, and switching techniques are reviewed. Recent developments in optoelectronic devices and passive optical elements are outlined and finally some technological issues in optical computing and interconnects for practical use are discussed     

液晶光阀记录二元纯位相滤波器的实验研究

本文利用液晶光阀记录二元纯位相滤波器进行了实验研究,实验结果显示出液晶光阀记录二元纯位相滤波器具有高效率光学再现能力。同时还给出了制作二元纯位相滤波器的简单方法。     

仅位相型滤波器实现彩色图像的非相干光识别

本文提出了一种用非相干系统识别采色图像的方法,将彩色图像分成三个单色像处理,设计一可实现的仅位相型光学传递函数（ＯＴＦ）,对其进行带通优化,从而提高信噪比并使相关峰锐化,通过一对滤波器的来合成该ＯＴＦ。介绍了滤波器制作原理和方法,获得了彩色图像相关识别的实验结果。     

Use of phase diversity and modified phase congruence for edge enhancement in ultrasonic imaging

Enhancement of boundaries is essential for the classification of suspicious regions in ultrasonic medical B scan images of internal organs so that malignancies can be identified and detected. Phase congruence has been suggested as a means to delineate the boundaries in images. Estimation of phase congruence requires the use of log-Gabor filters. In this work, spatial phase-only filters are used to generate the phase and magnitude information necessary for the estimation of phase congruence. Taking into account the multiplicative non-Rayleigh nature of speckle in these images, a modified version of phase congruence is used alongside pre-filtering with median filters to reduce speckle. Processing was undertaken on two computer-synthesized images and two B scan images of tissue-mimicking phantoms acquired using a commercial ultrasonic imaging unit. The results show that the modified phase congruence estimated after the filtering with four spatial phase-only filters enhances the boundaries of target-like regions in these images. Since these phase-only filters require fewer parameters than log-Gabor filters, the technique demonstrated in this work can provide a simple means to use phase congruence to highlight boundaries in ultrasonic images corrupted by speckle.     

3f多路光电混合实时模式识别系统

介绍一种新型的3f多路光电混合实时模式识别系统。采用一平面微透镜列阵器件得到输入物体的多路傅里叶变换,匹配滤波器是构造在石英基片上的石英BPOF。该系统实现输入图像与存储的多个参考图像的实时并行相关。     

Continuous-time MOSFET-C filters in VLSI

The desirable features of fully integrated, VLSI-compatible continuous-time filters are discussed. A recently proposed integrated continuous-time filter technique is reviewed, in which MOS transistors are used in place of resistors along with the nonlinearity cancellation and on-chip automatic tuning. The filters obtained using this technique are compared to switched-capacitor filters, digital filters, and continuous-time filters using different techniques. Representative experimental results are given, demonstrating the high performance that can be achieved.     

灰阶纯位相匹配滤波器编码方法研究

根据空间光调制器的相位调制作用,提出了一种灰阶纯位相匹配滤波器编码方法.计算机仿真和光学实验结果均表明该方法在相关峰值、信噪比和峰相关能量比等方面比二元纯位相编码方法均有较大提高.另外还给出了相关峰的位置变化规律,有利于对目标的定位.     

Digital filter design techniques in the frequency domain

Digital filtering is the process of spectrum shaping using digital components as the basic elements. Increasing speed and decreasing size and cost of digital components make it likely that digital filtering, already used extensively in the computer simulation of analog filters, will perform, in real-time devices, the functions which are now performed almost exclusively by analog components. In this paper, using the z-transform calculus, several digital filter design techniques are reviewed, and new ones are presented. One technique can be used to design a digital filter whose impulse response is like that of a given analog filter; other techniques are suitable for the design of a digital filter meeting frequency response criteria. Another technique yields digital filters with linear phase, specified frequency response, and controlled impulse response duration. The effect of digital arithmetic on the behavior of digital filters is also considered.     

Liquid Crystal Television Spatial Light Modulator

The liquid crystal televison spatia light modulator(LCTVSLM)characterized is usable in optical processing applications.e.g.,optical pattern recognition,associative memory,optical computing,correlation detection and optical data processing systems.The array performance and real-time optical correlation applications are reviewed.     

Phase-only Correlation Measurement with Computer-controlled LCD and CCD Image Processing System

Using computer-controlled liquid crystal display(LCD)as an image processor and a CCD camera as a detector,phase-only correlation measurement is performed with the aid of joint transform correlation method(JTC).This computer -controlled LCD-CCD image processing system may be a powerful tool for defect detection,position control and pattern recognition.It enables new possibilities in analog real-time image processing.This is of great interest in microelectronic manufacturing today and in the future.     

Coherent optical processing

The principles of communication theory were applied in the 1950's to optical imaging systems and to the analysis of images. Optical systems were analyzed in much the same way as linear systems (modulation transfer functions and channel capacities) and images were characterized in ways analogous to time signals (space-bandwidth products, spatial frequency content, etc.). Both coherently and incoherently illuminated optical systems can be treated using these concepts. Coherently illuminated systems are most useful for performing operation such as convolution, cross correlation, and spectral analysis because the Fourier transform of an optical signal physically exists and can, therefore, be measured or modified. The basic Fourier transform relationship for coherently illuminated systems is developed in this paper. It can be detected directly and used to estimate the distribution of spatial frequencies contained in the signal. Methods for constructing complex-valued spatial filters are described; these filters can be used to realize such operations as convolution or cross correlation, addition or subtraction, and differentiation or integration. Experimental results are given to illustrate the concepts and to susgest potential applications. To extend the range of applications, interface devices are needed to allow optical processing of two-dimensional raster-scanned time signals, wide bandwidth electrical signals, and incoherent optical signals. Interface devices are often needed to convert the output optical signal to an electrical signal for post-processing by a digital computer. For some applications, interface devices are needed to construct spatial filters in real time, so different operations can be performed on a given signal. The desired characteristics of these three interface devices and the current state of their development are briefly reviewed.     

Charge-transfer filtering

Linear discrete-time (sampled-data) filters can be implemented in monolithic form on an MOS chip using a variety of recently developed and newly emerging techniques without requiring analog-to-digital conversion. An analog signal sample can be represented by an isolated quantity of charge and such packets of charge can be stored, transferred, and manipulated in other ways to perform signal processing operations. Best known of these techniques is the use of a charge-coupled device (CCD) to operate as an analog shift register. A simple modification of the CCD shift register allows the realization of transversal filters. Other techniques can implement recursive filter operations offering a great flexibility for filter design. The possibilities and limitations of charge-transfer filtering are reviewed and examined.     

Comparison of optical processing techniques for optical microwavesignal generation

Recently, there have been several proposals on using the higher RF harmonics of detected pulses from mode-locked semiconductor lasers as a source of microwave and millimeter waves. This paper compares the performance of three optical techniques of signal processing that have been proposed to select a higher harmonic of a mode-locked laser, by using extensive numerical simulations. We show that techniques using delays and splitters are insensitive to the coherence properties of the source, but can introduce amplitude patterning if pulses overlap when recombined. We see that techniques relying on optical filtering to select optical modes require extremely high-Q filters and, thus, are extremely sensitive to tuning. A Fabry-Perot interferometer (FPI) is the optimum fitter method in terms of power efficiency for low harmonics, but using two separate bandpass filters can give comparable efficiency when selecting higher harmonics. We also show that gain-switched lasers are unsuitable as sources when used with narrow-band optical filtering techniques because of their low pulse-to-pulse optical coherence     

General-purpose optical pattern recognition image processors

A general-purpose programmable optical image processor architecture is described. A correlator architecture is used with different filter functions employed to implement a variety of different operations required in the different levels of computer vision. We consider input scenes with a number of objects present in clutter with a number of different object classes, distortions, and contrasts. The system locates all objects and identifies the class of each. The optical image processing operations performed include morphological low-level nonlinear functions, detection of candidate regions of interest, fusion of correlation outputs to reduce false alarms, image enhancement, and feature extraction. The optical correlation filters to realize each operations, examples of each, and real-time optical correlator hardware are described     

Optical computing, an example of change

Some ways in which the new technologies of optical computing can add, and thereby change, the growing capabilities of present day digital techniques, are briefly reviewed. Among these are two-dimensional Fourier transforms, including complex (holographic) two-dimensional filters, the remarkable parallel nature of certain optical applications in radar, and the significant increase in bit packing densities offered by holographic memories.     

Glass waveguides on silicon for hybrid optical packaging

Work on deposited glass waveguides on silicon to form waveguides and filters is reviewed. The choice of these particular waveguides makes sense only as part of a consistent approach to optoelectronic packaging. Hybrid optical packaging on silicon (HOPS) is described and briefly compared with other techniques. For these packages, two waveguides were developed: a tight mode waveguide with a silicon nitride rib core for matching a semiconductor laser and a loose mode waveguide with a phosphosilicate glass core for matching an optical fiber     

Study of the imaging property of a fluorescent confocal microscopy with a phase-only filter in an extended source

The phase information of an enlarged source is reconstructed with an annular two-zone phase-only filter in a fluorescent confocal scanning optical microscope for resolution improvement. The dependences of its resolution on the source size and on the phase transmission of the outer annular zone of the filter are investigated theoretically by use of its three-dimensional optical transfer function (3D OTF ). The increased source size and the required phase value of the outer annular zone of the phase-only filter for an optimal 3D OTF of the optical system are presented.