The Global Ultraviolet Imager of the NASA Thermosphere, Ionosphere, and Mesosphere Energetics and Dynamics mission has been calibrated at the Optical Calibration Facility of the Applied Physics Laboratory. This spectrographic imager has a 0.74 degree(s) X 11.6 degree(s) field-of-view, a 140 degree(s) X 11.6 degree(s) field-of-regard and collects data in 176 wavelength bins in the spectral range from 120 - 180 nm. The calibration of this far ultraviolet instrument requires continuously variable wavelengths and angles within a high- vacuum system from the light source to the instrument. An optical calibration facility has been developed providing a bright, uniform, wavelength-selectable, collimated light beam, which is mapped in situ to correct for intensity drifts in the lamp. The facility design and the calibration procedure are discussed.
As was previously reported, a spatial light modulator (SLM) is being fabricated that exploits vanadium dioxide's (VO<SUB>2</SUB>) thermally induced transition from a semiconductive-to-metallic state. This transformation causes the film to change from a state of low to high reflectivity in the 3 - 12 micrometers region. Thermal control of the VO<SUB>2</SUB> is provided by an array of p-n junction diodes, each diode constituting the center of a single `pixel' in the SLM. As power is applied to a diode, it generates heat, thereby providing an electrical means of controlling the reflective state of the VO<SUB>2</SUB> film on its surface. The design of the SLM is driven by the need for a high optical contrast, large scale implementation, and high refresh rate. Unfortunately, these requirements are not conducive to each other, so compromises must be made. Optimizations of this design using either microchannel or chemical vapor deposition diamond heat sinks are reported. Both of these simulated designs attained pixel switching times in excess of 650 Hz.