Space and launch environments demand robust, low mass, and thermally insensitive mechanisms and optical mount designs. The rotating prism mechanism (RPM), a component of the stabilized dispersive focal plane system (SDFPS), is a spectral disperser mechanism that enables the SDFPS to deliver spectroscopic or direct imaging functionality using only a single optical path. The RPM is a redundant, vacuum-compatible, self-indexing, motorized mechanism that provides robust, athermalized prism mounting for two sets of matching prisms. Each set is composed of a BK7 and a CaF2 prism, both 70 mm in diameter. With the prism sets separated by 1 mm, the RPM rotates the two sets relative to one another over a 180° range, and maintains their alignment over a wide temperature range (190-308K). The RPM design incorporates self-indexing and backlash prevention features as well as redundant motors, bearings, and drive trains. The RPM was functionally tested in a thermal vacuum chamber at 210K and <1.0x10-6 mbar, and employed in the top-level SDFPS system testing. This paper presents the mechanical design, analysis, alignment measurements, and test results from the prototype RPM development effort.
As the costs of space missions continue to rise, the demand for compact, low mass, low-cost technologies that maintain
high reliability and facilitate high performance is increasing. One such technology is the stabilized dispersive focal plane
system (SDFPS). This technology provides image stabilization while simultaneously delivering spectroscopic or direct
imaging functionality using only a single optical path and detector. Typical systems require multiple expensive optical
trains and/or detectors, sometimes at the expense of photon throughput. The SDFPS is ideal for performing wide-field
low-resolution space-based spectroscopic and direct-imaging surveys. In preparation for a suborbital flight, we have
built and ground tested a prototype SDFPS that will concurrently eliminate unwanted image blurring due to the lack of
adequate platform stability, while producing images in both spectroscopic and direct-imaging modes. We present the
overall design, testing results, and potential scientific applications.