1 November 1997 Interferogram acquisition using a high-frame-rate CCD camera
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Abstract
Phase-shifting interferometry measures surface height error by acquiring multiple interferograms. Analysis of these data is affected by the accuracy of individual measurements and the ability to compare subsequent measurements. The accuracy of individual measurements relies on producing constant phase shifts between the interferograms. Interferometric testing o large aperture telescope optics can be limited by vibration as the optical path difference increase. To minimize the effect of vibration, a series of interferograms would be acquired as quickly as possible. To accurately compare subsequent measurements, fiducials are used to provide registration. Accurate fiducial location is essential. This paper will describe the implementation of a high frame rate CCD camera and frame grabber system operating on an IBM PC compatible computer platform. This system quickly acquires a series of six consecutive digitized interferograms which are evaluated for proper phase shift before being reduced in a commercial phase-shift analysis program. The speed and storage advantages of the frame grabber also allow the system to produce a time- averaged fringe contrast map which enables fiducials to be easily an accurate located.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Lee R. Dettmann, David L. Modisett, "Interferogram acquisition using a high-frame-rate CCD camera", Proc. SPIE 3134, Optical Manufacturing and Testing II, (1 November 1997); doi: 10.1117/12.295144; https://doi.org/10.1117/12.295144
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