PatentDOI
Sub-nyquist interferometry
TLDR
Sub-Nyquist interferometry (SNI), an extension of PSI, is described and demonstrated to overcome the inability to measure surfaces with large aspheric departures, and it preserves the measurement precision that is inherent to PSI.Abstract:
A technique is described for extending the measurement range of interferometry past the Nyquist limit of the sampling frequency of the interferogram. The absolute phase values measured by an interferometer are reconstructed by applying constraints based upon a priori knowledge of the absolute phase values. The constraints include the knowledge that one or more derivatives of the spatial distribution of phase values is a continuous function, and the knowledge of step heights to within λ/2.read more
Citations
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Journal ArticleDOI
Fourier fringe analysis: the two-dimensional phase unwrapping problem.
TL;DR: A new phase unwrapping algorithm is described that uses local phase information to mask out those parts of the field that cause inconsistencies in the unwraps and can produce an approximately correct unwrapped.
Book ChapterDOI
IV Advanced Evaluation Techniques in Interferometry
TL;DR: This chapter describes the advanced evaluation techniques in interferometry and identifies the types of error sources—namely, environmental errors, errors that are dependent on the method, and errors typically encountered in Interferometry.
Patent
Wireless local area network (WLAN) technology and applications including techniques of universal frequency translation
David F. Sorrells,Michael J. Bultman,Robert W. Cook,Richard C. Looke,Charley D. Moses,Gregory S. Rawlins,Michael W. Rawlins +6 more
TL;DR: Frequency translation and applications of same are described in this paper, including wireless local area network (WLAN) applications such as IEEE Standard 802.11 WLANs, such as, but are not limited to, frequency down-conversion, frequency up-concversion, enhanced signal reception, unified downconversion and filtering, and combinations of same.
Patent
Rough surface profiler and method
TL;DR: In this article, the rough surface of an object is estimated by moving the object along a z axis so that a highest point of the rough surfaces is optically aligned with and outside of the focus range of a solid-state imaging array.
Journal ArticleDOI
Measurement of large plane surface shapes by connecting small-aperture interferograms
TL;DR: In this article, the shape of a large plane surface is obtained by connecting phase distributions measured by a small-aperture interferometer, and the accuracy of connection increases in proportion to an exponent of 1.5 of the width of the common area.
References
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Two-wavelength phase-shifting interferometry (A)
Yeou-Yen Cheng,James C. Wyant +1 more
TL;DR: A technique that combines ideas of phase shifting interferometry (PSI) and two-wavelength interferometer (TWLI) to extend the phase measurement range of conventional single-wa wavelength PSI is described.
Journal ArticleDOI
Generalized Data Reduction For Heterodyne Interferometry
TL;DR: A generalized algorithm for use with digital heterodyne or fringe- scanning interferometers was developed that removes many of the restrictions that had previously applied to the data collection scheme.
Journal ArticleDOI
Two-wavelength phase shifting interferometry.
Yeou-Yen Cheng,James C. Wyant +1 more
TL;DR: In this article, a technique that combines ideas of phase shifting interferometry (PSI) and two-wavelength interference (TWLI) to extend the phase measurement range of conventional singlewavelength PSI is described.
Journal ArticleDOI
Use of an ac heterodyne lateral shear interferometer with real-time wavefront correction systems.
TL;DR: An analysis shows that for uniform circular or square sources larger than a derived minimum size, the wavefront measurement accuracy depends only upon the radiance of the source and not upon the angular subtense of the sources.
Journal ArticleDOI
A theory of scanning and its relation to the characteristics of the transmitted signal in telephotography and television
Pierre Mertz,Frank Gray +1 more
TL;DR: In this paper, a theory of scanning and the scanning system related to the signal used for the transmission is developed and the result of the complete process of transmission may be divided into two parts, (a) a reproduction of the original picture with a blurring similar to that caused in general by an optical system of only finite perfection, and (b) the superposition on it of an extraneous pattern not present in the original, but which is a function of both the original and scanning system.