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Patent Searching and Data


Title:
DISPLACEMENT INFORMATION DETECTOR
Document Type and Number:
Japanese Patent JPH11351821
Kind Code:
A
Abstract:

To raise the utilization of a light to detect displacement information at a high accuracy by converting and detecting the displacement information of a displaced body to four signals with quadrature phase differences.

Advanced phase axes are set at an angle of about 45° to a P- and S-polarization components between which a displaced body exists, a 1/4-wavelength plate 2 converts the P- and S-polarization components into circularity polarized lights in opposite directions, beam splitting means 3 splits an incident beam to two beams 4a, 4b, a 1/2-wavelength plate disposed in the advanced phase axis at an angle of about 22.5° changes the linear polarization orientation of one of the split incident beams, a polarization beam splitter 7 transmits the P-polarization component of the split light beam and reflects the S-polarization component, photo detectors 11a-11d detect the P- and S- polarization components of the two split light beams, and four sinusoidal signals with phase differences of about 90° are detected to detect the displacement information of the displaced body, by using them. According to this method the light utilization efficiency is raised and detection accuracy can be improved.


Inventors:
KADOSHIMA TAKAYUKI
ISHIZUKA AKIRA
Application Number:
JP1998000178115
Publication Date:
December 24, 1999
Filing Date:
June 10, 1998
Export Citation:
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Assignee:
CANON KK
International Classes:
G01B11/00; G01D5/28; G01D5/30; G01D5/34; G01D5/347; G02B5/30; (IPC1-7): G01B11/00; G01D5/28; G01D5/30; G01D5/34; G02B5/30
Attorney, Agent or Firm:
Takanashi Yukio