Title:
OPTICAL RELATIVE DISPLACEMENT DETECTOR
Document Type and Number:
Japanese Patent JPH01301116
Kind Code:
A
Abstract:
PURPOSE:To prevent the detection result of relative displacement from having an error by operating a rotary mechanism according to the quantity of the deviation in the phase difference between 1st and 2nd intensity signals from a reference value when the phase difference deviates from the reference value. CONSTITUTION:In a normal state wherein a 1st diffraction grating and a 2nd diffraction grating are parallel to each other, the phase difference between the 1st intensity signal which is the intensity signal of light passed through both gratings 22 and 24 and the 2nd intensity signal which is the intensity signal of 2nd light passed through the grating 22 and a 3rd diffraction grating is set to the predetermined reference value. When the parallelism between both gratings is inferior, the phase difference between the 1st and 2nd intensity signals deviates from the reference value, so the rotary mechanism is operated according to the quantity of the deviation to set the gratings 22 and 24 parallel to each other. In this case, when the relative rotational positions of the gratings 22 and 24 are normal, both intensity signals become in phase with each other. Therefore, the detection result of the relative displacement is prevented from having an error owing to inferior parallelism between the gratings 22 and 24.
Inventors:
IIDA TAKAHIDE
MIYAKE HIROSHI
MIYAKE HIROSHI
Application Number:
JP13122188A
Publication Date:
December 05, 1989
Filing Date:
May 28, 1988
Export Citation:
Assignee:
TOYODA AUTOMATIC LOOM WORKS
International Classes:
G01D5/38; (IPC1-7): G01D5/38
Attorney, Agent or Firm:
Norikazu Kobe (2 outside)