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.
Optical interferometry is a cost-effective means to extend the resolving power of astronomical instruments. Typically, the light from separate small and movable telescopes is brought through vacuum pipes to a central beam combiner. We are developing a new generation of AO systems to enhance the performance of interferometers in which the vacuum lines are replaced with optical fibers. The AO, included on each of the telescopes, concentrates light on the fiber inputs to achieve the greatest optical throughput. We describe the design approach to the AO systems, how their requirements differ from those of a traditional system, and how the addition of AO enables further enhancements to the design of optical interferometers.
The NIRCam instrument on the James Webb Space Telescope (JWST) will provide a coronagraphic
imaging capability to search for extrasolar planets in the 2 - 5 microns wavelength range. This capability is
realized by a set of Lyot pupil stops with patterns matching the occulting mask located in the JWST
intermediate focal plane in the NIRCam optical system. The complex patterns with transparent apertures
are made by photolithographic process using a metal coating in the opaque region. The optical density
needs to be high for the opaque region, and transmission needs to be high at the aperture. In addition, the
Lyot stop needs to operate under cryogenic conditions. We will report on the Lyot stop design, fabrication
and testing in this paper.
Raman spectroscopy is a well understood phenomenon and can be useful for remote material identification. Raman spectroscopy is performed by directing a laser (pump) beam onto a specimen, an extended scene, to induce Raman scatter. Since Raman scatter is a relatively weak phenomenon, a telescope is often used to collect the scattered signal and a narrow band filter is used to reject the pump scatter. The Raman scatter is processed using a spectrometer to identify the Raman signal. This spectrometer could be a dispersive (grating) spectrometer or a Fourier Transform Imaging Spectrometer (FTIS) using a traditional Michelson interferometer. We propose an experiment using an FTIS but with a Fizeau interferometer that takes the form of a multi-aperture imaging system to identify the Raman scattering. An advantage to using an FTIS with a Fizeau interferometer is it occurs naturally in a multi-aperture imaging system, i.e., no additional hardware is needed obtain spectral information. Therefore, a multi-aperture system can have both high spatial and spectral resolution. In this paper, the processing of the data for the Fizeau FTIS is similar to the standard methods but can be enhanced with non-linear restoration algorithms.