Title:
LENGTH MEASURING APPARATUS BASED ON LASER INTERFERENCE
Document Type and Number:
Japanese Patent JPH0399203
Kind Code:
A
Abstract:
PURPOSE:To decrease the effect of the fluctuation of atmosphere with respect to length measurement by arranging a beam-diameter converter in a light path at a position which is close to a beam splitter between the beam splitter and a moving reflector. CONSTITUTION:In a Michelson's interferometer 1, incident laser light 2 is split through a beam splitter 3. One split luminous flux 2a is reflected with a fixed reflector 4. The other split luminous flux 2b is reflected with a moving reflector 5. A beam-diameter converter 6 is arranged in a light parth at a position close to the beam splitter 3 between the beam splitter 3 and the moving reflector 5. The parallel luminous flux from the beam splitter 3 is converted into the parallel luminous flux whose diameter is reduced. The parallel luminous flux from the moving reflector 5 is converted into the parallel luminous flux whose diameter is expanded. A photodetector 7 detects the intensity of interference light 2c. A length measuring circuit 8 measures the length from a reference point to the moving reflector 5 by using the output of the photodetector 7 with the effect of atmosphere being reduced.
Inventors:
KITAJIMA HIRONOBU
Application Number:
JP23592389A
Publication Date:
April 24, 1991
Filing Date:
September 12, 1989
Export Citation:
Assignee:
FUJITSU LTD
International Classes:
G01B9/02; (IPC1-7): G01B9/02
Attorney, Agent or Firm:
Teiichi Ijiba (2 outside)
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