Optics: measuring and testing – By light interference – Having polarization
Reexamination Certificate
2008-05-13
2008-05-13
Chowdhury, Tarifur R (Department: 2886)
Optics: measuring and testing
By light interference
Having polarization
C356S497000
Reexamination Certificate
active
11223928
ABSTRACT:
Provided is an optical image measuring apparatus capable of effectively receiving interference light, particularly an alternating current component thereof using a smaller number of photo sensors. The optical image measuring apparatus includes a polarizing plate for converting a light beam from a broad-band light source to linearly polarized light, a half mirror for dividing the light beam into signal light and reference light, a piezoelectric element for vibrating a reference mirror, a wavelength plate for converting the reference light to circularly polarized light, a polarization beam splitter for extracting two different polarized light components from interference light produced from the signal light and the reference light which are superimposed on each other by the half mirror, CCDs for detecting the two different polarized light components, and a signal processing portion for producing an image of an object to be measured based on the detected polarized light components. A frequency for intensity modulation of the light beam is synchronized with a beat frequency of the interference light. A frequency of vibration of the reference mirror is synchronized with the beat frequency of the interference light and an amplitude of vibration thereof is set to be equal to or smaller than a wavelength of the interference light.
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Akiba Masahiro
Chan Kinpui
Fukuma Yasufumi
Otsuka Hiroyuki
Tsukada Hisashi
Chowdhury Tarifur R
Edwards Angell Palmer & & Dodge LLP
Kabushiki Kaisha Topcon
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