Proceedings ArticleDOI
Multiple wavelength interferometry for surface profiling
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TLDR
In this article, the phase evaluation at the three wavelengths gives wrapped phase at any pixel corresponding to these wavelengths and the fringe order is obtained considering the fact the variation of phase with respect to a given profile height is linear.Abstract:
Interferometry is a well established technique for surface profiling. The conventional interferometric surface
profilers using a single wavelength offer excellent vertical resolution, but a serious limitation to their use is that
they can only handle smooth profiles and step heights less than half a wavelength. In the situation where the
surface profile is discontinuous, white light interferometry has been applied with great success. However the
scanning white light interferometry requires large number of frames to be recorded, whereas in spectrally
resolved white light interferometry only a line profile of the object is obtained, although the requirement on
number of frames is similar to the single wavelength phase shifting interferometry. In this paper we discuss three
wavelength interferometry in which a limited number of frames suitable for phase shifting technique are recorded
at three laser wavelengths. The phase evaluation at the three wavelengths gives wrapped phase at any pixel
corresponding to these wavelengths. The fringe order is obtained considering the fact the variation of phase with
wavenumber for a given profile height is linear. The slope of the phase verses wavenumber line gives the absolute
value of the profile height and is used to ascertain the fringe order. The fringe order along with the wrapped phase
gives the profile height with a resolution given by phase shifting technique. Experimental results on etched silicon
samples are presented.read more
Citations
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Journal ArticleDOI
3-D surface profilometry using simultaneous phase-shifting interferometry
TL;DR: In this paper, a new phase-shifting interferometer for 3D surface profilometry is proposed, which employs a single glass plate to generate simultaneous phase shifted interferograms.
Journal ArticleDOI
Measurement of large discontinuities using single white light interferogram.
Paul Kumar Upputuri,Li Gong,Haifeng Wang,Manojit Pramanik,Krishna Mohan Nandigana,Mahendra P. Kothiyal +5 more
TL;DR: Hilbert transformation analysis of a single white light interferogram acquired with a single-chip color CCD camera for step height measurement which lies beyond the unambiguous range of the monochromatic interferometry is discussed.
Journal ArticleDOI
Multi-colour microscopic interferometry for optical metrology and imaging applications
TL;DR: The recent advances in multi-colour interferometric techniques and their demanding applications for characterization of micro-systems, non-destructive testing, and bio-imaging applications are reviewed.
Dissertation
Investigation of line-scan dispersive interferometry for in-line surface metrology
TL;DR: In this article, an environmentally robust line-scan dispersive interferometry (LSDI) technique is presented for in-line surface inspection, which is suitable for applications in R2R manufacturing.
Journal ArticleDOI
Hilbert transform-based envelope substitution method for non-uniform sampling signal correction in white-light interferometry
TL;DR: In this article, an effective correction algorithm is presented, in which a Hilbert transform and a correlation analysis of the white light interference envelope curves, as well as the simulated ideal interference signal envelope, are employed for a robust and high precision signal correction.
References
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Book ChapterDOI
V Phase-Measurement Interferometry Techniques
TL;DR: The phase modulation in an interferometer can be induced by moving a mirror, tilting a glass plate, moving a grating, rotating a half-wave plate or analyzer, using an acoustooptic or electro-optic modulator, or using a Zeeman laser as mentioned in this paper.
Journal ArticleDOI
Surface Profiling by Analysis of White-light Interferograms in the Spatial Frequency Domain
Peter J. de Groot,Leslie L. Deck +1 more
TL;DR: In this article, a scanning white-light interferometer for high-precision surface structure analysis is described, where the interferogram for each of the image points in the field of view is generated simultaneously by scanning the object in a direction perpendicular to the object surface, while recording detector data in digital memory.
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
Multiple-wavelength phase-shifting interferometry
Yeou-Yen Cheng,James C. Wyant +1 more
TL;DR: By introducing the phase data of a third wavelength, one can measure the phase of a very steep wave front and the repeatability of the measurement is better than 25-A rms (λ = 6328 A).