OCA Applied Optics has developed and demonstrated a rapid, automated technique for the surface figuring of precision aspheric silicon and silicon-clad optical elements using a patented plasma assisted chemical etching (PACE) methodology. In this paper we discuss the preprocessing methods and suitable PACE removal depth strategies to ensure that final PACE- finished silicon surfaces meet current low-scatter optical standards. An aspheric surface figuring model for the PACE process is also described.
OCA Applied Optics has developed and demonstrated a rapid, automated technique for the fuguring of precision aspheric surfaces on fused silica optical elements using plasma assisted chemical etching (PACE) methodology. In this paper we discuss the pre-processing methods and suitable PACE removal depth strategies for fused silica necessary to ensure that final PACE-finished surfaces meet current low-scatter optical standards. We also describe models for aspheric surface figuring using the patented PACE process which account for substrate dielectric losses and other effects and allow us to define the parameters needed to efficiently correct surface figure errors. FInally, we demonstrate the capabilities of the final PACE figuring method on a fused silica test substrate.
OCA Applied Optics has devised and optimized methods for designing, building and testing precision mirror systems whose performance is not compromised by large changes in environmental temperature. A key to our approach is the use of a single material for the construction of all telesope components to minimize the differences in the contraction and expansion of the components with changes in the operating temperature. Specifically, we designed and built a simple, on-axis, monometallic telescope suitable for cryogenic testing in order to investigate and optimize methods for accurately testing the optical performance at cryogenic temperatures. We then designed and built a sophisticated, off-axis monometallic telescope representative of the current technology in advanced spectrometer instruments for deep-space applications. The novel design of this telescope facilitated assembly, alignment, and testing. We characterized the performance of the instrument in both laboratory and cryogenic environmental conditions. The results of these tests show that the instrument focus position and image quality showed negligible change at cryogenic temperatures, compared to a room temperature environment. This research has already contributed to improved performance and reduced cost for advanced reflective optical instruments for several space applications.