Description: A new type of laser radar metrology inspection system is proposed that incorporates a novel, dual laser coherent detection scheme capable of eliminating both environmental and scanner based Doppler ranging error. Measurement of large telescope structures and optics requires both high accuracy and non-contact technology. Due to the non-contact, stand-off nature of this technology, this system can measure optics and provide nearly real-time feedback to figuring/polishing instruments without removing the part from the spindle or other optical grinding or polishing setup. For advanced levels of integration and test, the proposed large-volume metrology technology would allow fast, non-contact measurement of mirror rigid body alignment and prescription (i.e., radius, conic, aperture), with no special targets or references on the optic. This would allow these mirror parameters to be measured with respect to other optics, instruments, or mechanical- and spacecraft-related structures.

Benefits: The post-Phase III SBIR, non-NASA commercial applications are numerous and multi-discipline. Aerospace engineering fields that would benefit include: Spacecraft integration, optical telescope assembly, optical instrument assembly, optical component-level fabrication and characterization for both large and small optics, optical metering structure assembly and characterization, and mm-wave antenna fabrication and assembly. In addition, this improved scanner has implications for greatly improving metrology in support of the aircraft and ship-building industry. Similar scanner technologies are currently employed in these areas and this improved scanner would enable better uncertainty, resulting in improved products across the board.

Potential post-Phase III NASA applications for this innovation include improved performance and lower cost optical telescope assembly and instrument development. Examples of future NASA missions that will benefit include the Joint Dark Energy Mission (JDEM) and the International X-ray Observatory (IXO). For JDEM, telescope mirror fabrication and integration capabilities would be greatly enhanced. The scanner would measure the prescription and coarse figure of the large (~2m) mirror during fabrication and, after fabrication, characterize its final prescription and alignment to the telescope metering structure, with little or no custom fiducialization. The mechanical alignment of the JDEM instrument/camera would meet tighter specifications. For IXO, this improved scanner would be able to measure the super-thin, lightweight, off-axis x-ray segments in a non-contact fashion, eliminating the risk of damage and allowing measurement without distorting the segments.