Showing papers on "Spatial light modulator published in 1979"

Optical phase measurement in real time

Abstract: A method has been developed for the real-time measurement of optical phase. The optical wave whose phase is to be measured is interfered with a spatially coherent plane-wave reference on the face of a photodetector array. The irradiance is measured simultaneously at all array elements for each of three specific phase shifts of the reference, and the phase and magnitude at each array element are calculated from the three measured irradiances by a simple algorithm. The method can be used for hybrid optical-digital analog computation of 2-D Fourier transforms: information is introduced coherently into the front focal plane of a lens with a spatial light modulator, and the phase and magnitude are measured in the back focal plane. Experimental results of the Fourier transform technique are described.

High speed ambiguity function evaluation by optical processing

Abstract: An optical system which computes the ambiguity integral using one-dimensional spatial light modulators rather than the two-dimensional data masks or spatial light modulators used in the prior art is revealed. The coding is accomplished by compressing the light beam along one dimension, passing it through a one-dimensional spatial light modulator, and re-expanding the beam along the compressed dimension. The signal may be rotated to produce a linear dependence. In the preferred embodiment an acousto-optic cell commonly known as a Bragg cell is the one-dimensional spatial light modulator chosen.

Multi-stable optical system

Abstract: A multi-stable optical device and system which utilizes an active optical element such as a spatial light modulator (SLM) in a feedback path configuration. The elementary system consists of a pair of image element (pixels) on the SLM whose input and outputs are coupled to each other by purely optical means. In another arrangement, multi-stable performance is achieved by optical path geometry defining a single pixel which performs in conjunction with a feedback path. Analysis is provided identifying the equilibrium states of the system as well as those equilibrium states which are stable in nature.

Photo-DKDP light valve in optical data processing

Abstract: Various real-time optical data processing experimentst using the photo-DKDP spatial light modulator are described. These include the performance of image subtraction and contrast reversal directly on the light valve and their application to practical pattern recognition situations in which the input and reference objects differ. Examples of real-time optical correlation on coded waveforms for signal processing are presented, and the accuracy of the optically produced ambiguity function outputs are compared to the theoretically expected ones. Real-time optical image pattern recognition experiments are also presented, together with comparative data obtained with off-line correlations performed using film.

Resolution of an electron-beam spatial light modulator using a DKDP crystal

Abstract: An investigation was made of a spatial light modulator based on an electro-optic DKDP crystal. A theoretical and experimental study was made of the frequency-contrast characteristic and resolution of the modulator.

Microchannel Spatial Light Modulator As A Storage Medium

Abstract: The Microchannel spatial light modulator is an optically-addressed spatial light modulator that is being developed for low-light-level, real-time, optical signal processing. In addition to its framed or continuous real-time mode of operation, it can also be used for short-time (hours), low resolution (less than 20 cycles/mm) optical information storage. In this Paper we describe the structure of the device, its principles of operation, some of its preliminary characteristics, and the first attempts at optical information storage.

Development Of A Charge-Coupled Device (CCD) Addressed Light Modulator

Abstract: A spatial light modulator is being developed that takes a time dependent electrical signal and formats it into a two dimensional array of phase modulators. This is accomplished with a charge coupled device to shift electrical charge into a two dimensional array, and metallized membranes which deform by an amount proportional to the charge. Preliminary results indicate adequate membrane sensitivity and frequency response to permit real time operation of large time-bandwidth product light modulators.