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Simultaneous measurement of several near-parallel surfaces with wavelength-shifting interferometry and a tunable phase-shifting method

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Title: Simultaneous measurement of several near-parallel surfaces with wavelength-shifting interferometry and a tunable phase-shifting method
Authors: Burke, Jan1, Hibino, Kenichi2, Hanayama, Ryohei3, Oreb, Bozenko F.1
Source: Optics & Lasers in Engineering. Feb2007, Vol. 45 Issue 2, p326-341. 16p.
Subjects: Optical measurements, Spectrum analysis, Interferometry, Optics
Abstract: Abstract: Wavelength-shifting interferometry can distinguish in frequency space interference signals from different surfaces, and therefore allows the measurement of optical thickness variation between several quasi-parallel surfaces of a composite transparent object. Frequency analysis of the signal spectrum with a tunable phase-shifting formula can then detect the phase of the individual signals. We have devised a tunable phase-shifting method which uses a freely adjustable number of intensity samples and can be adapted to any frequency spectrum. To extract the signal reliably, two properties of the phase-shifting method are particularly important: it should suppress cross-talk from unwanted frequencies, and it should allow for some variation in the signal frequency. We show that a carefully designed sampling function envelope will combine these benefits, and demonstrate the technique in measurements of three different composite objects each consisting of three reflecting surfaces. The importance of phase-shift linearisation is discussed, and methods for selecting optimal set-up parameters are given. [Copyright &y& Elsevier]
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Database: Engineering Source
Description
Abstract:Abstract: Wavelength-shifting interferometry can distinguish in frequency space interference signals from different surfaces, and therefore allows the measurement of optical thickness variation between several quasi-parallel surfaces of a composite transparent object. Frequency analysis of the signal spectrum with a tunable phase-shifting formula can then detect the phase of the individual signals. We have devised a tunable phase-shifting method which uses a freely adjustable number of intensity samples and can be adapted to any frequency spectrum. To extract the signal reliably, two properties of the phase-shifting method are particularly important: it should suppress cross-talk from unwanted frequencies, and it should allow for some variation in the signal frequency. We show that a carefully designed sampling function envelope will combine these benefits, and demonstrate the technique in measurements of three different composite objects each consisting of three reflecting surfaces. The importance of phase-shift linearisation is discussed, and methods for selecting optimal set-up parameters are given. [Copyright &y& Elsevier]
ISSN:01438166
DOI:10.1016/j.optlaseng.2005.12.009