11 November 2010 Sinusoidal wavelength-scanning common-path interferometer with a beam-scanning system for measurement of film thickness variations
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Abstract
Two light beams reflected from a front and rear surfaces of a glass film of 20 micron thickness interfere with each other in a common path interferometer. Sinusoidal wavelength-scanning light with the scanning amplitude of 5 nm and frequency of 15 KHz is used to generate a sinusoidal phase-modulated interference signal with the modulation amplitude of 2.6 rad. The phase of the interference signal provides the thickness variation of the film, whose measurement accuracy is a few nanometers. Moreover, in order to achieve a high spatial resolution and a wide measurement region a focused beam is scanned on the surface of the film with a rotating mirror.
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Osami Sasaki, Osami Sasaki, Takafumi Morimatsu, Takafumi Morimatsu, Samuel Choi, Samuel Choi, Takamasa Suzuki, Takamasa Suzuki, } "Sinusoidal wavelength-scanning common-path interferometer with a beam-scanning system for measurement of film thickness variations", Proc. SPIE 7855, Optical Metrology and Inspection for Industrial Applications, 78550S (11 November 2010); doi: 10.1117/12.871030; https://doi.org/10.1117/12.871030
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