Acoustooptic processor for adaptive radar noise environment characterization

A new 2-D acoustooptic processor that estimates the angular as well as spectral distributions of jammers in the far field of an adaptive phased array radar is described. The operating modes of the system are discussed together with the estimation accuracy achieved. Experimental results are presented to illustrate the operation of the processor, and different acoustooptic cell operating modes are discussed.

Direct and implicit optical matrix-vector algorithms

New direct and implicit algorithms for optical matrix-vector and systolic array processors are considered. Direct rather than indirect algorithms to solve linear systems and implicit rather than explicit solutions to solve second-order partial differential equations are discussed. In many cases, such approaches more properly utilize the advantageous features of optical systolic array processors. The matrix-decomposition operation (rather than solution of the simplified matrix-vector equation that results) is recognized as the computationally burdensome aspect of such problems that should be computed on an optical system. The Householder QR matrix-decomposition algorithm is considered as a specific example of a direct solution. Extensions to eigenvalue computation and formation of matrices of special structure are also noted.

Frequency-multiplexed and pipelined iterative optical systolic array processors

Optical matrix processors using acoustooptic transducers are described with emphasis on new systolic array architectures using frequency multiplexing in addition to space and time multiplexing. A Kalman filtering application is considered as our case study from which the operations required on such a system can be defined. This also serves as a new and powerful application for iterative optical processors. The importance of pipelining the data flow and the ordering of the operations performed in a specific application of such a system are also noted. Several examples of how to effectively achieve this are included. A new technique for handling bipolar data on such architectures is also described.

Fine delay estimation with time integrating correlators

The bias and variance of the delay estimation from a time integrating acoustooptic correlator are considered. A parabolic interpolation of the sampled correlation output is included. General expressions for the bias and variance are derived that include the effect of finite detector element area. Quantitative data are provided for the case of an exponential autocorrelation signal model as functions of various system, signal, and noise parameters. These results show that the estimate is biased. They also provide guidelines on the delay estimation variance obtainable from a given system and on the design of a system to achieve a desired estimation accuracy.

Applications of the Priz light modulator

The Priz light modulator suppresses input data at zero spatial frequency, can provide directional spatial filtering, and can perform dynamic image selection or change detection. In this paper, we summarize the Priz's performance and provide experimental confirmation of the above three image processing applications of this device.

Optical system to compute intensity moments: design

A frequency-multiplexed coherent optical processor is described that can compute the intensity moments of a gray-scale input image. The space-bandwidth product and dynamic range of the system's components are discussed. A major feature of the system is the ability to operate easily on its outputs to obtain bipolar moments and to correct for various component errors, nonlinearities, and nonuniformities.

Acoustooptic matched filter correlator

The signal model used and the output SNR(0) measure chosen are shown to affect the performance of an acoustooptic time-integrating correlator. Nonuniform acoustic fields are also shown to affect the results, but these error sources can be overcome with a new hybrid time- and space-integrating acoustooptic matched filter correlator that we describe and for which initial simulation data are provided.

Product code processing on a triple-product processor

A new application of the acoustooptic triple-product processor is described. Processing of spread spectrum communications and radar data for self-synchronization, message demodulation, and high-resolution ranging with a large processing gain for large time-bandwidth product signals is possible on the optical signal processor described.

Acoustooptic transducers in iterative optical vector-matrix processors

The use of acoustooptic transducers that are commercially available in iterative optical vector-matrix processors is considered. Deconvolvers using space and time integration are described. The use of multichannel systems to solve large vector-matrix equations in which the matrices are banded is also addressed.

Microprocessor-based fiber-optic iterative optical processor

The design and fabrication of an iterative optical vector-matrix processor are described. Microprocessor feedback is used to produce an iterative processor capable of solving simultaneous linear equations. It also facilitates scaling and biasing of the data and the handling of bipolar and complex-valued data as well as correction for selected system error sources. Fiber-optic interconnections are used to improve the system's alignment and to reduce its size, weight, and errors. The design, fabrication, and performance of the system are analyzed.

Test and evaluation of the Soviet Prom and Priz spatial light modulators

Five Soviet bismuth silicon oxide Prom and Priz spatial light modulators were recently tested in the United States. In this program, their performance was quantified and compared with that of the U.S. Prom. The resultant laboratory data show that the Soviet Prom is comparable with the U.S. device and that the Soviet Priz has over ten times the diffraction efficiency and over ten times more usable resolution than the Prom. Theoretical models of the dependence of diffraction efficiency on spatial frequency were also verified by experiments performed on these devices.

Eigenvector determination by iterative optical methods

Three power methods to compute the eigenvalues and eigenvectors of a matrix on an iterative optical processor (IOP) are analyzed. Each is appropriate for a different eigenvalue and eigenvector application. When implementation on an IOP and the processing speed are considered, the second method is found to be preferable to others recently described.

Binarization effects in a correlator with noisy input data

Correlations of binarized data and gray-scale data in the presence of additive noise are compared using two performance criteria (mean ratio and peak-to-sidelobe ratio). General expressions are provided to evaluate these performance measures as a function of input data length, bandwidth, and signal-to-noise ratio. We find that binarized correlators outperform gray-scale correlators when the input SNR(i) exceeds a threshold level that depends on input bandwidth and sequence length.