Showing papers by "James M. Florence published in 1990"

Deformable Mirror Light Modulators For Image Processing

Abstract: The operational characteristics of deformable mirror device (DMD) spatial light modulators for image processing applications are presented. The two DMD pixel structures of primary interest are the torsion hinged pixel for amplitude modulation and the flexure hinged or piston element pixel for phase modulation. The optical response characteristics of these structures are described. Experimental results detailing the performance of the pixel structures and addressing architectures are presented and are compared with the analytical results. Special emphasis is placed on the specification, from the experimental data, of the basic device performance parameters of the different modulator types. These parameters include modulation range (contrast ratio and phase modulation depth), individual pixel response time, and full array address time. The performance characteristics are listed for comparison with those of other light modulators (LCLV, LCTV, and MOSLM) for applications in the input plane and Fourier plane of a conventional coherent optical image processing system. The strengths and weaknesses of the existing DMD modulators are assessed and the potential for performance improvements is outlined.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Design Considerations For Phase-only Correlation Filters

Abstract: The effect of variation of design parameters on the performance of phase-only and binary phase-only correlation filters is presented. Correlation performance is analyzed from the perspective of optimized extraction of a target from an input scene consisting of the target, a natural background, and additive noise. It was found empirically that the dominant factor affecting the filter performance was the target image background level and that the optimum choice depends on the relative values of the target average value and the background average value in the input scene. The behavior is explained analytically by describing the target object in terms of a target silhouette function that specifies the target region, and a target detail function describing the target variations within the silhouette. The optimum choice for the target image background is shown to be that which results in the addition (rather that subtraction) of the detail and silhouette autocorrelations.

Improved DMD configurations for image correlation

Abstract: Two novel deformable mirror structures have been developed for spatial light modulators: an 'AM torsion beam' and a 'phase-mostly single-quadrant cantilever' beam Both devices are well-suited to optical correlator input and filtering functions Which the optical modulation characteristic of the torsion-beam modulator is essential amplitude only, which is well suited for use as the input modulator of the optical correlator, the characteristic of the one-quadrant modulator is a phase-mostly modulation whose amplitude changes are coupled to the phase changes; this renders it operable in the Fourier plane of the optical correlator as the filtering device