Recent interest in liquid crystal spatial light modulators as a potential replacement to traditional optical beam steering methods have engendered experiments to determine the technology's resistant to gamma radiation such as may be encountered in a space environment. We previously investigated the effects of exposure of liquid crystal devices to ionizing radiation to total dose levels consistent with a 14-year mission at geostationary orbits (GEO). We reported on the parameters of retardation, contrast ratio and primary power current, which were monitored at various dosing intervals for liquid crystal cells and a spatial light modulator. Here we present for the first time measurements of spatial light modulators' beam steering characteristics taken while they are undergoing gamma irradiation. We examine data on angular deflection, intensity, and beam spread for the liquid crystal spatial light modulators obtained during irradiation. The modulators were in continuous operation during irradiation at approximately 23 Rad (Si)/s, and, again the total ionizing dose reached levels consistent with 14 years at GEO. We observed minimal to no degradation in performance, either from dose rate effects or from total ionizing dose, in these environments.
This paper describes radiation and drop testing performed in support of the U.S. Army Strategic Defense Command's program to develop more robust baffle materials. It gives the shock and vibration environments and describes the techniques used to capture and count the particles generated. Also, observations are made on the effect of shock and radiation on the optical performance of the baffle materials.
The ability of optical seeker/sensor systems to acquire, discriminate, and lock on to their targets is essential to the success of all interceptor systems. A telescope primary mirror is highly vulnerable to x-ray exposure, which may result in increased scatter as well as permanent and/or transient distortion. Interceptor target discrimination and tracking is thus compromised. We have fielded several experiments to examine the effects of nuclear radiation on a variety of mirror samples representing those technologies which might be applicable for an optical sensor/seeker system. Mirror deformation and scatter measurements were performed in real-time, providing dynamic response and recovery data. Post-test measurements included scatter, reflectance, and permanent distortion as well as microscopic examination of the mirror surfaces. Results from these experiments are presented along with comparisons to analytical models.