Optical Omega network: a compact implementation technique

We propose a technique for the compact implementation of an optical Omega network. This technique utilizes the concept that both the perfect-shuffle interconnection and the switching stages can be realized by the same procedures, i.e., duplicate, shift, superimpose, and mask. As a result, a single set of optics is sufficient to realize the whole Omega network in a time-multiplexed recursive manner. Optical setups were designed and a proof-of-principle experiment was performed.     

Optical implementation of the Bode transform

The Bode transformation is a useful tool for determining and analyzing the frequency response of a system. It has a special importance for detecting the resonance frequencies of a linear system that, because of its linearity, can be totally characterized by its impulse response. An optical configuration that implements the Bode transformation of a function is suggested and demonstrated experimentally.     

Optical implementation of the hopfield neural network with matrix gratings

We propose a new method for the optical implementation of the Hopfield neural network with a universal tool. The tool is a matrix grating constituted with a group of element gratings. The algorithms for designing a matrix grating are proposed, and a matrix grating is created to execute recognition experiments by use of the Hopfield neural network. The experimental results demonstrate that the proposed method performs well. The stability of the light efficiencies of different optical components used in optical networks is also considered.     

Optical implementation of the continuous wavelet transform

A simple optical implementation for the one-dimensional wavelet transform (WT) is proposed. In contrast with previous WT optical implementations, the obtained WT is continuous along both axes (dilation and shift). An optical implementation to the inverse WT is proposed as well. Thus an optical continuous WT processor can be implemented.     

Optical implementation of fuzzy-set reasoning

New methods of optical fuzzy-logic operations and optical fuzzy-controller synthesis are proposed and experimentally demonstrated by use of optical fan-out elements to achieve multiple imaging and polarization-space/aperture data encoding to represent fuzzy variables in optics. Sixteen fuzzy-logic operations between two inputs are achieved by use of a simple polarization-space data-encoding and kernel-operation scheme. In addition, a max-min composition-based fuzzy controller is implemented by use of an aperture-data-encoding and a double-multi-imaging approach. Our systems exhibit a high operation speed, a large information throughput, and a high signal-to-noise ratio.     

Optical plastic refractive measurements in the visible and the near-infrared regions

Some new refractometric results are obtained in the visible and the near-infrared spectral regions. The main optical plastics are analyzed: poly(methyl methacrylate), polystyrene, polycarbonate, and styrene acrylonitrile. New materials, such as methyl methacrylate styrene copolmer, CTE-Richardson, Zeonex, Optorez, and Bayer are examined. The refractive indices are measured for wavelengths from 435.8 to 1052 nm with a new device. Abbe constants and dispersion coefficients are calculated. The measured and computed data is intended for designers and technologists.     

Optical implementation of segmented composite filtering

We investigate possible performance improvements of coherent optical correlators by using an appropriate filter design. Multidecision strategies are often required in high-level image-processing tasks. For an optical system characterized by a given space-bandwidth product we show that the filter design plays a crucial role in satisfying both system and processing requirements, with respect to the optimization of the encoding capacity. This leads us to the definition of segmented composite filtering, which is discussed in terms of processing performance. This filtering is assessed experimentally in the case of a face-recognition problem.     

Optical implementation of asynchronous-transfer-mode header-error control

The asynchronous transfer mode (ATM) is a promising technique for broadband switching that is capable of supporting high-bit-rate multimedia services. Progress in all-optical parallel processing shows that photonics may be used in the future in full-functionality ATM switching nodes. All-optical switching fabrics and buffers have already been demonstrated. Fewer studies have been dedicated to ATM header-processing functions. As an example of photonic header processing, the implementation of a header-error control (HEC) subsystem by means of an optical circuit is investigated. Although traditional electronic decoders perform HEC in a serial mode, the architecture chosen for the optical HEC subsystem is based on parallelism, and an appropriate parallel-decoding algorithm was used in designing it.     

Logic-operated mathematical morphology and its optical implementation

A more powerful tool for binary image processing, i.e., logic-operated mathematical morphology (LOMM), is proposed. With LOMM the image and the structuring element (SE) are treated as binary logical variables, and the multiply between the image and the SE in correlation is replaced with 16 logical operations. A total of 12 LOMM operations are obtained. The optical implementation of LOMM is described. The application of LOMM and its experimental results are also presented.     

Optical implementation of second-order nonlinear Volterra operators with use of triple correlation

Following the Volterra theorem, every nonlinear operator can be implemented with a sum of integrals applied over the input. The second-order Volterra operator that describes many useful systems can be related to a single integral that is a projection of an operation called the triple correlation. This operation may be easily implemented optically and thus be incorporated into fast real-time nonlinear control systems. We present a theoretical investigation of the relation existing between the Volterra operators and the triple correlation as well as an experimental demonstration that validates the theory.     

Optical implementation of the fractional Hilbert transform for two-dimensional objects

The classical Hilbert transform can be implemented optically as a spatial-filtering process, whereby half the Fourier spectrum is pi-phase shifted. Recently the Hilbert transform was generalized. The generalized version, called the fractional Hilbert transform, is quite easy to implement optically if the input is one dimensional. Here we show how to implement the fractional Hilbert transform for two-dimensional inputs. Hence the new transform is now suitable for image processing.     

Optical implementation of fuzzy-logic controllers. Part I

In recent years fuzzy-logic-based controllers have become the preferred tool for implementing control mechanisms in high-complexity systems. We suggest novel implementations of a basic fuzzy controller. First, we show the principles of fuzzy-logic control and explain the concept behind the optical controller. Next we review a one-dimensional fuzzy-logic-based optoelectronic controller that was suggested in 1994. Finally, we present a novel two-dimensional optical control approach accompanied by computer simulations of an inverted pendulum. The two-dimensional setup is first given for a dual-input controller and then expanded to a multi-input controller.     

Optical implementation of N-wavelet coding for pattern classification

A novel method, N-wavelet coding, for pattern detection and classification based on wavelet transform and coding theory is introduced. With this detection and classification technique it is possible to reduce the false-alarm rate while maintaining a constant probability of detection and noise level. A set of periodic continuous waveforms comprising six classes that span a cross-correlation coefficient between 0.68 and 0.99 is used to evaluate the N-wavelet coding technique. It is found that when the length N of the N-wavelet coding is increased it is possible to decrease the false-alarm rate while maintaining a constant probability of detection.     

Optical implementation of fuzzy-logic controllers. Part II

In part I of a previous study [Appl. Opt. 37, 6937 (1998)] we introduced what is believed to be a novel two-dimensional (2-D) fuzzy-logic optical controller. The complexity of such a setup when we deal with an N-dimensional control procedure leads to a more compact version both in planning demands and in space. Viewing the pros and cons of the 2-D setup, we seek a simpler model and find it in a one- dimensional (1-D) multilayer setup. Here we explain the process of finding the optimal 1-D setup and support the concept with true optical results. The new 1-D optical controller is modular and easy to build, and the results that it yields are quite satisfactory.     

Optical system for tablet variety discrimination using visible/near-infrared spectroscopy

An optical system based on visible/near-infrared spectroscopy (Vis/NIRS) for variety discrimination of ginkgo (Ginkgo biloba L.) tablets was developed. This system consisted of a light source, beam splitter system, sample chamber, optical detector (diffuse reflection detector), and data collection. The tablet varieties used in the research include Da na kang, Xin bang, Tian bao ning, Yi kang, Hua na xing, Dou le, Lv yuan, Hai wang, and Ji yao. All samples (n=270) were scanned in the Vis/NIR region between 325 and 1075 nm using a spectrograph. The chemometrics method of principal component artificial neural network (PC-ANN) was used to establish discrimination models of them. In PC-ANN models, the scores of the principal components were chosen as the input nodes for the input layer of ANN, and the best discrimination rate of 91.1% was reached. Principal component analysis was also executed to select several optimal wavelengths based on loading values. Wavelengths at 481, 458, 466, 570, 1000, 662, and 400 nm were then used as the input data of stepwise multiple linear regression, the regression equation of ginkgo tablets was obtained, and the discrimination rate was researched 84.4%. The results indicated that this optical system could be applied to discriminating ginkgo (Ginkgo biloba L.) tablets, and it supplied a new method for fast ginkgo tablet variety discrimination.     

基于可见光强度的室内定位技术研究

目的:欲提出一种基于接收信号强度检测的可见光室内定位技术。方法:由四个LED光源发出信号光,被待定位设备上的光探测器接收。利用带通滤波和傅里叶变换,降低噪声并提取源信号。采用三边法估算位置坐标,确定待定位设备的位置。结果:实验结果表明,RSSI可见光定位的误差在5 cm以内。结论:本技术有效提高了定位精度,具有实际应用意义。