Laser heterodyne surface profiler
A method and apparatus is disclosed for testing the deviation of the face of an object from a flat smooth surface using a beam of coherent light of two plane-polarized components, one of a frequency constantly greater than the other by a fixed amount to produce a difference frequency with a constant phase to be used as a reference. The beam also is split into its two components with the separate components directed onto spaced apart points onthe face of the object to be tested for smoothness. The object is rotated on an axis coincident with one component which is directed to the face of the object at the center which constitutes a virtual fixed point. This component also is used as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a reflected frequency difference of a phase proportional to the difference in path length which is compared with the reference phase to produce a signal proportional to the deviation of the height of the surface along the circular track with respect to the fixed point at the center.
- Assignee:
- Department Of Energy
- Patent Number(s):
- US 4353650
- OSTI ID:
- 6950823
- Resource Relation:
- Patent File Date: Filed date 16 Jun 1980; Other Information: PAT-APPL-159893
- Country of Publication:
- United States
- Language:
- English
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Laser heterodyne surface profiler
Laser heterodyne surface profiler
Related Subjects
42 ENGINEERING
LASERS
BEAM SPLITTING
ROUGHNESS
MEASURING METHODS
SURFACES
COMPUTERIZED CONTROL SYSTEMS
DEPTH
DIGITAL SYSTEMS
FREQUENCY SELECTION
OPTICAL PROPERTIES
PHASE SHIFT
ROTATION
SIGNALS
CONTROL SYSTEMS
DIMENSIONS
MOTION
PHYSICAL PROPERTIES
SURFACE PROPERTIES
360000* - Materials
420300 - Engineering- Lasers- (-1989)