L-3 Integrated Optical Systems (IOS) Division has been selected by the National Solar Observatory (NSO) to design and
produce the Top End Optical Assembly (TEOA) for the 4-meter Advanced Technology Solar Telescope (ATST) to
operate at Haleakalā, Maui. ATST will perform to a very high optical performance level in a difficult thermal
environment. The TEOA, containing the 0.65-meter silicon carbide secondary mirror and support, mirror thermal
management system, mirror positioning and fast tip-tilt system, field stop with thermally managed heat dump, thermally
managed Lyot stop, safety interlock and control system, and support frame, operates in the "hot spot" at the prime focus
of the ATST and so presents special challenges. In this paper, we describe progress in the L-3 technical approach to
meeting these challenges, including silicon carbide off-axis mirror design, fabrication, and high accuracy figuring and
polishing all within L-3; mirror support design; the design for stray light control; subsystems for opto-mechanical
positioning and high accuracy absolute mirror orientation sensing; Lyot stop design; and thermal management of all
design elements to remain close to ambient temperature despite the imposed solar irradiance load.
A broadband, low-distortion, 2:1 zoom collimator has been designed for projection of infrared scenes in the spectral region of 3.0 to 12.0 micrometers. This collimator provides dynamic scenes for the Kinetic Kill Vehicle Hardware-in-the Loop Simulation (KHILS) facility for testing of missile seekers and other FLIRs. This system, the Target Simulator Optical System (TSOS) is similar to the WISP Optical System already installed at KHILS by Brashear LP, but is lightweighted to allow mounting onto the outside axis of a Flight Motion Simulator. This paper explains the general requirements of the projection collimator optics and describes the system design, assembly and test. The collimator projects dynamic scenes generated by two 1024 x 1024 or 512 x 512 arrays of resistive-emitter elements. The system is composed of four off-axis, powered mirrors, a beamcombiner, spectral filters and array windows. Three of the mirrors are moveable to accommodate changing the field-of-view. Distortion is less than 1.0% at any field position.
Contraves Brashear Systems has designed and fabricated a low-distortion, 2:1 zoom collimator for projection of infrared scenes in the spectral region of 1.5 to 12.0 micrometers to provide dynamic scenes for the Wideband Infrared Scene Projector for testing of missile seekers and other FLIRs. This paper explains the general requirements of the projection collimator optics and describes the system design, assembly, and test. The collimator projects dynamic scenes generated by two 512 X 512 arrays of resistive- emitter elements. The system is composed of four off-axis, powered mirrors, a beamsplitter, spectral filters and array windows. Three of the mirrors and the arrays move to accommodate changing the field-of-view. The worst-case geometric spot size (85% encircled energy) at any field position is less than 0.8 of the angular subtense of an array element for the entire zoom range. Distortion is less than 0.7% and the overlap of the two arrays is better than 0.1 pixels at any field position.
An addressable mosaic array of resistively heated microbridges offers much flexibility for infrared scene simulations. In the Wide Band Infrared Scene Projector program, Honeywell has demonstrated high yield arrays up to size 512 X 512 capable of room temperature operation for a 2 band infrared projection system being designed and built by Contraves Inc. for the Wright Laboratory Kinetic Kill Vehicle Hardware In-the-Loop Simulator facility at Eglin Air Force Base, FL. The arrays contain two different pixel designs, one pixel designed for kHz frame rates and high radiance achieved at a power level of 2.5 mWatts/pixel and the other pixel designed for more moderate 100 Hz frame rates at lower radiance and at maximum power levels of 0.7 mWatts/pixels. Tests on arrays and pixels have demonstrated dynamic ranges up to 850:1, radiance rise times on the order of 2 mseconds, and broadband pixel emissivities in the range of 70%. Arrays have been fabricated with less than 0.1% pixel outages and no row or column defects. These arrays are mounted in a specialized vacuum assembly containing an IR window, vacuum package, cooling block, and pump out manifold.