US 4,729,654 AGranted

Laser interferometer

AssigneeNippon Seiko Kabushiki Kaisha

InventorsTomohiko Akuta, Masamitsu Naito

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Abstract

A laser interferometer wherein a laser beam emitted from a laser device at a fixed position impinges on an optical lens mounted on a movable member, and interference fringes are produced on a semitransparent mirror formed at an end of the optical lens opposite to the laser device. The interference fringes on the semitransparent mirror are converted to electrical signals by a photoelectric transducer including a bundle of optical fibers arranged along concentric circles and photodiodes located opposed to the end surface of the bundle of optical fibers. Based on the electrical signals from the photoelectric transducer, the number of the interference fringes passing by and the direction of movement of the interference fringes are detected to determine a relative distance between the laser device and the optical lens.

Claims5

Dependent claims

A laser interferometer comprising:

a laser device having a first semitransparent mirror formed at an emitting end which emits a substantially collimated beam of light;
an optical lens having an incident side and an emitting side and disposed movably relative to said laser device, said optical lens having an optical axis aligned with an optical axis of the collimated beam of light emitted form said laser device and a second semitransparent mirror formed at the emitting side thereof on which a beam of light passing through the incident side forms a focal point;
photoelectric transducer means for converting interference fringes produced at the emitting side of said optical lens to an electrical signal;
and
relative distance detecting means for detecting the number of the interference fringes passing through a predetermined point and the direction of movement of the interference fringes based on a detection signal of said photoelectric transducer means and for detecting the relative distance between said laser device and said optical lens.

2 more elements

Dependencies are inferred from the claim text.