Optics: measuring and testing – By light interference – Having polarization
Reexamination Certificate
2009-07-23
2011-12-20
Lee, Hwa (Department: 2886)
Optics: measuring and testing
By light interference
Having polarization
Reexamination Certificate
active
08081315
ABSTRACT:
A laser interferometric measuring instrument includes: a light source that emits a laser beam of 1064 nm and another laser beam of 532 nm; a polarizing beam splitter; a dichroic mirror that splits a long-wavelength laser beam provided in a measurement optical path; a long-wavelength corner cube that reflects the split laser beam; a measurement corner cube that is displaceable along the measurement optical path; a reference corner cube that is displaceable along a reference optical path; a optical path changing unit that changes an optical path length of the long-wavelength laser beam; a phase detector that outputs interference signals; a sum signal computer that calculates a sum signal; a displacement controller that displaces the reference corner cube so as not to change a phase of the sum signal; a reference displacement detector that detects a displacement of the reference corner cube; and a measurement displacement computer that calculates a displacement of the measurement corner cube.
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Banh Quoc et al., “Development of laser interferometer with picometer resolution using frequency tunable laser—The 5threport: Compensation of the displacement measurement due to the fluctuation of the air refractive index-”, collected papers for spring lecture of the Japan Society for Precision Engineering, 2008, pp. 441-442, vol. F—No. 02.
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Hatsuzawa et al., “Precise Measurements of Micro-linewidths by using a Micro-Interferometer and a Scanning Electron Microscope,” 1994, pp. 1582-1585, vol. 60—No. 11 (with Abstract).
Lee Hwa
Mitutoyo Corporation
Oliff & Berridg,e PLC
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