A high speed matrix array processing analog optical computer architecture is described. The system is shown to be capable of a 32 x 32 el went matrix/matrix multiplication in 1.0 microsecond, or equivalently,>3.2 x 1010 multiply-adds/second.
This paper describes the system hardware and the performance of a GHz-bandwidth acousto-optic spectrum analyzer. It also discusses the effect of short radar pulses (-100 ns) on the achievable resolution and efficiency. The hardware described includes the laser diode, the collimating optics, the Bragg cell, a relay lens system, a Fourier lens system and a fiber imaging array that couples to discrete detector/amplifier channels. The bandwidth of the system is about 1 GHz, with a dynamic range of 40 dB and a frequency resolution of 50 MHz. The effect of optical window size on resolution and efficiency for short pulses is discussed.
This paper presents recent advancements in RF filtering techniques through the use of acousto-optics and a special purpose array of wideband photodiodes. An electronically programmable filter may be synthesized by inserting this array of photodiodes into the frequency plane of an optical spectrum analyzer. A description of the optical system, the photodiode array and some experimental results are presented.
Correlation of signals against a static mask is freauently used in signal processing. Many times it is useful to be able to rapidly change the mask. The programmable Excisor detector array can provide this capability when used as a combination mask and detector in an optical space integrating correlator. Such a correlator is described and experimental results are presented.
This paper discusses a new approach to coherently channelizing input rf signals that is similar to Bragg cell techniques but has the potential for operation at substantially higher bandwidths. The rf information from the environment is modulated on a laser beam. The modulated laser beam is then demultiplexed according to frequency by passing the beam through a dispersive device. The various channels are then each incident on the respective element of a detector array. Splitting a reference beam off from the main beam provides a local oscillator for heterodyne detection at the detector array. The optically encoded rf information is thereby translated back down to baseband or a common if band.
The design of wideband acousto-optic Bragg cells is described. Techniques for optimizing the device performance parameters are discussed. These techniques have been applied to increase the diffraction efficiency of wideband Bragg cells. Experimental re-sults obtained at 0.633 and 0.83 micrometer have demonstrated GHz bandwidth and diffrac-tion efficiencies of about 10 percent per RF watt.
We have made cross-talk measurements on our U-groove isolated phntodiode array by two independent techniques, the electrical measurement and the laser scanning method. These two methods are shown to correlate with each other. 'Vie cross-talk between two adjacent pixels of the U-groove isolated array was below 5x10-4, which compared favorably to the value of 10-1 for the conventional diffusion junction photodiode array. Also the effective diffusion length of the photogenerated carriers was measured to be 10 μm in the N-region and 6 μm in the top P-region. The advantages of the detector isolation technique for optical signal processing is presented.
The basic acousto-optic signal processing architectures (spectrum analyzer, space-inte-grating, time-integrating and triple product processor) systems and algorithms such as the chirp-Z transform are reviewed. We then describe new acousto-optic data processing systems and applications that utilize these basic architectures and new ones. These include a matched spatial filter acousto-optic processor, two new hybrid time and space-integrating systems, a triple product processor and four new matrix-vector iterative feedback systems.
A scheme is introduced and experimentally demonstrated for increasing the accuracy of an optical implementation of matrix-vector multiplication. The system is configured in a feedback loop to iteratively solve simultaneous equations. The technique is based upon a binary expansion of the matrix which is convolved with the binary expansion of the vector. This is implemented optically by the outer product synthesis of matrix products using crossed acousto-optic cells and a strobed light source.
The principles of operation of the Acousto-optic/CCD real-time SAR processor are reviewed and experimental results are presented. The interferometric detection method used in this system is also discussed.
This paper discusses the capabilities of an electrooptic signal processing device consisting of a light-emitting diode (LED), a matrix mask, and a customized charge-coupled device (CCD). Such a processor can perform a broad variety of useful one-dimensional operations including linear transformation (e.g., Fourier, Walsh, Hankel), multi-channel cross-correlation, filtering, and high-density read-only memory. Any desired window function can be designed into the mask and any desired amount of window overlap can be obtained by appropriate clocking of the CCD. Its strengths include high-speed, compact size, ruggedness, reliability, and potential low cost. However, as in other analog sampled-data systems, its accuracy is moderate (the equivalent of about 8 to 10 bits). The incorporation of a real-time programmable mask into this system expands its capabilities into the nonlinear and recursive filtering realms (in addition to programmable versions of the above-mentioned linear operations) at the expense of system size, complexity and cost. In many applications, the numerical computation capability of such a processor far surpasses that of its conventional electronic digital counterparts.
The separable nature of the geometric moment generating functions and the serial raster encoding of the image permits the 2-dimensional moment integral equation to be computed with a cascaded system of 1-dimensional integrations. In this paper new optical processing architectures are presented that use acousto-optic devices illuminated by pulsed sources to enter the data into the optical system. The advanced state of the art of the components used and the flexibility of these architectures can lead to the implementation of practical optical processing system for computing the moments of a real time high resolution image.