The Lockheed Martin Optical Payload Center of Excellence (OPCoE) collaborated with government customers and leading companies in the aerospace and optics industries to field a space imaging instrument, achieving multi-spectral, wide field, high resolution imaging capability in a compact, lightweight, all reflective architecture. The heart of the instrument is an unobscured three mirror anastigmat collimator. The afocal design consists of a physical entrance pupil accepting a collimated input, an intrinsic internal focus and pupil, and in a compact folded geometry to achieve a balance between critical sampling, radiometric sensitivity, and field of view. Light-weighted, thermally stable materials and robust coatings coupled with low stress, thermal and dynamically stable optical mounts have demonstrated diffraction limited performance during test and over predicted mission conditions. Metrology features were made a central part of the optical component design to facilitate the use of spatial analysis tools and alignment techniques for merit function prescription optimization. The optical components are mounted to a composite egg crate bench, designed to reduce structural mass while ensuring rigid alignment of the optical components. Active thermal control reduces diurnal variations to the optical alignment and ensures stable optical performance. Design innovations include a filter wheel assembly designed to minimize exported force and torque and an internal radiometric calibrator based on high reliability light emitting diodes for focal plane gain calibration. The instrument currently hosts a large format staring focal plane for wide field imaging, but the flexibility of the design can accommodate various sensor packages.
Lockheed Martin has built a Space Object Tracking (SPOT) facility at our Santa Cruz test site in Northern California. SPOT consists of three 1 meter optical telescopes controlled by a common site management system to individually or cooperatively task each system to observe orbital debris and earth orbiting satellites. The telescopes are mounted in Az/El fork mounts capable of rapid repointing and arc-sec class open loop tracking. Each telescope is installed in a separate clam shell dome and has aft mounted benches to facilitate installing various instrument suites. The telescope domes are mounted on movable rail carts that can be positioned arbitrarily along tracks to provide variable baselines for sparse aperture imaging. The individual telescopes achieved first light in June 2012 and have been used since to observe satellites and orbital debris. Typical observations consist of direct photometric imaging at visible and near infrared wavelengths, and also include spectroscopic and hypertemporal measurements.
Rayleigh beacon adaptive optical systems for atmospheric aberration correction and high rate J-Band trackers for each telescope will be added in 2015. Coherent combinations of the three telescopes as an interferometric imaging array using actively stabilized free space variable delay optical paths and fringe tracking sensors is also planned. The first narrow band (I band) interferometric fringes will be formed in the summer of 2014, with wide band (R, I, H) interferometric imaging occurring by early 2015.
The Near Infrared Camera (NIRCam) instrument for NASA's James Webb Space Telescope (JWST) has an optical prescription which terminates at two focal plane arrays for each module. The instrument will operate at 37K after experiencing launch loads at 293K. The focal plane array housings (FPAHs), including stray light baffles (SLBs) must accommodate all associated thermal and mechanical stresses. In addition, the stray light baffles must be installed in situ on the previously assembled flight modules. The main purpose of the FPAH SLBs is to effectively attenuate mission limiting stray light on the focal planes. This paper will provide an overview of the NIRCam stray light baffle design, mechanical and optical analysis, hardware implementation and test results.
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