The swing arm optical coordinate-measuring machine (SOC), a profilometer with a distance measuring interferometric sensor for in situ measurement of the topography of aspheric surfaces, has shown a precision rivaling the full aperture interferometric test. To further increase optical manufacturing efficiency, we enhance the SOC with an optical laser triangulation sensor for measuring test surfaces in their ground state before polishing. The calibrated sensor has good linearity and is insensitive to the angular variations of the surfaces under testing. Sensor working parameters such as sensor tip location, projection beam angle, and measurement direction are calibrated and incorporated in the SOC data reduction software to relate the sensor readout with the test surface sag. Experimental results show that the SOC with the triangulation sensor can measure aspheric ground surfaces with an accuracy of 100 nm rms or better.
© 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).
Subject terms: swing arm profilometer; profilometry; aspherics; optical testing; laser triangulation sensor; ground surface metrology.
Paper 120473 received Mar. 30, 2012; revised manuscript received May 16, 2012; accepted for publication May 30, 2012; published online Jul. 6, 2012.