The scanning long-wave optical test system (SLOTS) is under development at the University of Arizona to provide rapid and accurate measurements of aspherical optical surfaces during the grinding stage. It is based on the success of the software configurable optical test system (SCOTS) which uses visible light to measure surface slopes. Working at long wave infrared (LWIR, 7-14 μm), SLOTS measures ground optical surface slopes by viewing the specular reflection of a scanning hot wire. A thermal imaging camera collects data while motorized stages scan the wire through the field. Current experiments show that the system can achieve a high precision at micro-radian level with fairly low cost equipment. The measured surface map is comparable with interferometer for slow optics. This IR system could be applied early in the grinding stage of fabrication of large telescope mirrors to minimize the surface shape error imparted during processing. This advantage combined with the simplicity of the optical system (no null optics, no high power carbon dioxide laser) would improve the efficiency and shorten the processing time.

Date Published: 26 September 2011
PDF: 10 pages
Proc. SPIE 8126, Optical Manufacturing and Testing IX, 81260E (26 September 2011); doi: 10.1117/12.892666

Published in SPIE Proceedings Vol. 8126:
Optical Manufacturing and Testing IX
James H. Burge; Oliver W. Fähnle; Ray Williamson, Editor(s)