Murray S. Welkowsky

Status Of The Hughes Charge-Coupled-Device-Addressed Liquid Crystal Light Valve

This paper discusses the present state of development of the Hughes charge-coupled-device-addressed liquid crystal light valve (CCD LCLV). The device is based on the photoactivated silicon LCLV and is suitable for a range of applications, including adaptive optics and as a programmable mask for optical data processing systems.

High performance single crystal silicon liquid crystal light valve with good image uniformity

This paper is composed of two distinct portions. In the first part, we introduce modified versions of the Hughes silicon liquid crystal light valve with wavefront distortions of better than lambda/4, a resolution of 16 line pairs/mm at 50% modulation concurrent with a contrast ratio of 20:1. In the second portion, we present the results and analysis of a thorough study of the dependence of the performance of this device on its various operating parameters. The contrast ratio of this device was found to be very sensitive to the accumulation phase voltage and pulse width of the driving waveform, while the resolution is strongly dependent on the depletion phase pulse width.

Infrared Liquid Crystal Light Valve

An advanced dynamic infrared (IR) image projection system based on liquid crystal light valve (LCLV) technology is described. The IR-LCLV is capable of presenting a complex IR dynamic image with high spatial and temperature resolution and wide dynamic range at video frame rates. Experimental results obtained from an IR-LCLV utilizing a cathode ray tube as the input source and an extended IR source (blackbody) as the projection beam are presented.

A Submicron Metal Grid Mirror Liquid Crystal Light Valve For Optical Processing Applications

A submicron metal grid mirror was incorporated into the structure of a silicon liquid light valve. In our experiment, a 0.5 μm-period, aluminum wire grid mirror was used in conjunction with a 90°-twisted nematic configuration. A sharp threshold with a peak-to-threshold ratio of 3:1 was experimentally observed. The threshold intensity level was tunable from 2.5 μW/cm2 to 50 μW/cm2 by changing the bias voltage from about 5 to 25 volts. These properties allow the polarization-sensitive mirror-based LCLV to be used as a non-linear SLM with applications in optical computing (bistable device) and adaptive image thresholding. The device can also be used as an interfacing device for an optical co-processor as well as for optical implementation of Hopfield-Anderson association and phase conjugation.

Liquid crystal light valves: A review of recent studies

Recent studies of the dynamics of nematic liquid crystals as well as in modeling of the photoactivated and CCD-addressed liquid crystal light valves are described. Recent developments in the visible to IR dynamic image converter are reviewed.

Charge-coupled-device-addressed liquid-crystal light valve: an update

The status of the Hughes CCD-addressed liquid crystal light valve is reported. 256 X 256 array devices with good output uniformity and full video operations are demonstrated.

The Liquid Crystal Spatial Light Modulators: Recent Studies

Recent studies in the areas of the photoactivated and CCD-addressed liquid crystal light valves, as well as improvements in the operation of the visible to IR dynamic image converter (VIDIC) will be discussed.