Extended vertical range roughness measurements in non-ideal environments

Katherine Creath

doi:10.1117/12.895996

27 September 2011 Extended vertical range roughness measurements in non-ideal environments

Katherine Creath

Proceedings Volume 8126, Optical Manufacturing and Testing IX; 81260Y (2011) https://doi.org/10.1117/12.895996
Event: SPIE Optical Engineering + Applications, 2011, San Diego, California, United States

Abstract

This paper describes recent research into developing an extended range dynamic interferometry technique where the range is extended vertically to enhance surface roughness measurements made in non-ideal environments. Utilizing short pulses from two sources on either side of a frame transfer in a CCD sensor, data can be taken fast enough in noisy shop environments to make measurements in the presence of vibration, and air turbulence. A key application of this technique is monitoring of surface roughness of large optics during the polishing process by making in situ measurements from fine grind through to the final polish. It is anticipated that this monitoring can help speed up what is now a very lengthy process. This same technique is applicable to many other types of measurements including MEMS devices, as it is not affected by dispersion in windows covering devices, and for measuring features on flat panel display glass or semiconductor wafers. This paper describes the technique, and presents results of a variety of sample measurements including: bare glass in various states of polish from fine grind to final polish, scratches and pits in a roughened semiconductor wafer, a DMD MEMS device, and various calibration standards. Performance in terms of repeatabilitity of step heights and roughness for this proof of concept is in the +/-2% range.

Citation Download Citation

Katherine Creath "Extended vertical range roughness measurements in non-ideal environments", Proc. SPIE 8126, Optical Manufacturing and Testing IX, 81260Y (27 September 2011); https://doi.org/10.1117/12.895996

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