Title:
OPTICAL LENGTH MEASURING DEVICE
Document Type and Number:
Japanese Patent JPS6350702
Kind Code:
A
Abstract:
PURPOSE:To measure an absolute distance in addition to a relative distance, by providing a diffraction lattice on an object to be measured and allowing two-frequency laser beam to irradiate said diffraction lattice to obtain primary diffracted beams through diffraction at every frequency and detecting the mutual interval of said diffracted beams. CONSTITUTION:The laser beam l0 outputted from two-frequency laser 1 is divided by a beam splitter 2. The laser beam l5 among the divided beams is reflected by a beam splitter 3 and the distance measuring beam l3 obtained through a 1/4 wavelength plate 7 is allowed to irradiate a diffraction lattice R. Since said beam l3 contains beams of frequencies f1, f2 different from each other, two primary diffracted beams l11, l12 (frequencies; f1, f2) slightly different in a diffraction direction are obtained corresponding to said beams and the intensities of both diffracted beams become equal to each other by the wavelength plate 7. The interval between the diffracted beams l11, l12 becomes long according to the distance from the lattice R. Then, a linear array type position sensor 11 having a plurality of beam receiving elements arranged thereto in a line is arranged at a predetermined fixing position to receive two diffracted beams l11, l12. From the interval (l) between the beam receiving points thereof, an absolute distance L can be obtained.
Inventors:
WAKANA SHINICHI
Application Number:
JP19290586A
Publication Date:
March 03, 1988
Filing Date:
August 20, 1986
Export Citation:
Assignee:
FUJITSU LTD
International Classes:
G01B9/02; G01S17/08; (IPC1-7): G01B9/02; G01S17/08
Attorney, Agent or Firm:
Yoshiyuki Osuga
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