Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Patent
1995-07-10
1996-12-31
Gonzalez, Frank
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
356345, G01B 902
Patent
active
055899382
ABSTRACT:
A method and system for providing interferometric measurements having reduced sensitivity to vibrations. An interference pattern from an interferometer (35) is amplitude split into first and second interferograms and imaged onto first and second detectors (10,11), respectively, such as CCD cameras (10,11). The two cameras (10,11) have different data acquisition rates, such as a fast:slow camera ratio of at least 2:1, and are so disposed such that the image fields substantially overlap and are synchronized with each other so that the frame integration periods are identical and overlap in time. During data acquisition a phase shifter (45) changes the phase difference between the beams in the interferometer (35) while data from both cameras (10,11) is taken by a frame grabber (15) and saved in a computer (25). During data analysis, the phase at each image point on each frame of the fast data set is calculated by the computer (25), with the phase difference between interferograms in the slow data set being determined from the phases derived from the fast data set and with the slow data set then being analyzed for phase at each image point using the measured phase increments.
REFERENCES:
patent: 4594003 (1986-06-01), Sommargren
patent: 4624569 (1986-11-01), Kwon
patent: 4653921 (1987-03-01), Kwon
patent: 5410405 (1995-04-01), Schultz et al.
P. deGroot, "Vibration in phase shifting interferometry", J. Opt. Soc. Am. A 12, 354-365 (1995).
C. T. Farrell and M. A. Player, "Phase-step insensitive algorithms for phase-shifting interferometry", Meas. Sci. Tech. 5 648-652 (1994).
I. Kong and S. Kim, "General algorithm of phase-shifting interferometry by iterative least-squares fitting", Opt. Eng. 34, 183-188 (1995).
J. L. Seligson, C. A. Callari, J. E. Greivenkamp, J. W. Ward, "Stability of a lateral-shearing heterodyne Twyman-Green interferometer", Opt. Eng. 23, 353-356 (1984).
J. A. Meiling, "Interferometric Metrology of Surface Finish Below 1 Angstrom RMS", Proceedings of the ASPE spring topical meeting on precision interferometric metrology, Apr. 1992.
R. Smythe and R. Moore, "Instantaneous phase measuring interferometry", Opt. Eng. 23, 361-364 (1984).
J. E. Greivenkamp, "Generalized data reduction for heterodyne interferometry", Optical Engineering, vol. 23 No. 4, 350-352 (Jul./Aug. 1984).
Peter L. Wizinowich, "Phase shifting interferometry in the presence of vibration: a new algorithm and system", Applied Optics, vol. 29, No. 22, 3271-3279, (1 Aug. 1990).
J. Schwider et al., "Digital wave-front measuring interferometry: some systematic error sources", Applied Optics, vol. 22, No. 21, 3421-3432 (1 Nov. 1983).
K. Kinnstaetter et al., "Accuracy of phase shifting interferometry", Applied Optics, vol. 27, No. 24, 5082-5089 (15 Dec. 1988).
Johannes van Wingerden et al, "Linear approximation for measurement errors in phase shifting interferometry", Applied Optics, vol. 30, No. 19, 2718-2729 (1 Jul. 1991).
Mauro Melozzi et al., "Vibration-insensitive interferometer for on-line measurements", Applied Optics, vol. 34, No. 25, 5595-5601 (1 Sep. 1995).
Gonzalez Frank
Kim Robert
Zygo Corporation
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