Description: In this work, we propose the development of a Sub-Nanometer Coordinate Measuring Machine (SNCMM) to complement the Nanometric Probe and complete the surface metrology solution. The SNCMM will enable larger, lower cost, and higher quality freeform and aspheric optics, and have performance that far surpasses areal interferometry as the primary means of feedback to optical fabrication and requirements verification. The SNCMM will have the capability to measure the prescription and mid- and low-order surface errors for meter-class segments for large astronomical telescopes. Accurate metrology of the prescription (i.e., radius of curvature, conic constant, and off-axis distances) will speed the fabrication, hence reducing costs, of primary mirror segments, because SNCMM metrology will have greater dynamic range than current CMM technology, allowing SNCMM to be used “deeper” into the fabrication process (i.e., from rough machining and grinding of blanks though the fine stages of optical polishing) before transitioning to an interferometric test, if that is even required for the final stages of polishing and verification. All SNCMM sub-systems save one - the test-piece positioning sub-system - have been substantially de-risked on previous SBIR projects. The proposed project entails the design, construction, and testing of a high-stability test-piece positioner that is believed to be capable of holding a test-piece within the SNCMM with surface position stability better than a few tens of picometers through the duration of a surface measurement.

Benefits: Potential NASA applications include metrology of freeform and other optical components for NASA missions, including flagship/decadal missions, small satellites, and everything between. Some specific applications: • Origins Space Telescope (OST) and the Habitable Worlds Observatory, which may use freeform optics. • Lynx, Advanced X-ray Imaging Satellite (AXIS), and other X-ray telescopes. • Large telescope mirrors, such as those for the Habitable Worlds Observatory and OST, requiring sub-nanometer metrology.

The proposed metrology probe would benefit many applications, including: Metrology of high-precision optical components for commercial products such as those used in lithographic steppers. Metrology of X-ray and neutron mirrors (Department of Energy).