High-resolution Spatial Light Research Articles

Optically addressed high-resolution liquid crystal spatial light modulator with a diffraction efficiency above 50%

An optically addressed liquid crystal spatial light modulator (SLM) with a photosensitive amorphous hydrogenated silicon carbide (a-SiC:H) layer has been studied using holographic techniques. The maximum diffraction efficiency (DE) of the device amounted to ηmax = 50.5%. A decrease in the DE to a level of 0.5ηmax was observed at a spatial frequency of 75 mm−1. The high resolution and DE of the proposed SLM are due to features in the formation of an asymmetric grating line profile in the given structure.

Motionless multiresolution interferometry based on Talbot effect

We describe the principle of a motionless interferometer based on the Talbot effect. The test object is scanned by a convergent spherical beam with variable curvatures and lateral shifts. The wave- fronts are generated by a programmable off-axis Fresnel zone plate, implemented on a high resolution and high speed binary phase spatial light modulator. The aberrated field is then analyzed by passage through a fixed binary phase grating, detection by a sensor located in a fractional Talbot plane, and numerical phase retrieval from the Fourier analysis of the reconstructed intensity distribution. We describe the principle of the object multiresolution analysis. The system operation is then illustrated experimentally in a simple case exhibiting subwavelength resolution ca- pability. Finally, we give some orders of magnitude for the dynamic range that can be expected with such a system, as well as possible extension toward very high resolution measurements. © 1999 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(99)01212-X)

Recent trends in optical data processing

Optical data processing is an advancing field which has received much attention in recent years. Optical techniques have already shown their applicability in target identification, advanced signal processing operations and advanced linear algebra operations. The potential capabilities of processing of data using photons instead of electrons as the carrier of information have established, beyond any doubt, that the optical techniques will be the next generation technology surpassing electronic techniques in some important areas such as air traffic control, missile guidance and remote sensing. Although great strides have been made in all the areas of optical data processing, the goal of high performance, high speed and very accurate all-optical computers would be realised only around the year 1995. The main difficulty is that the required materials for high resolution and fast spatial light modulators and optical interconnects are yet to be perfected. The present paper reviews the recent trends and the future prospects of optical data processing.