Laser heterodyne surface profiler

Patent · Tue Oct 12 04:00:00 EDT 1982

OSTI ID:6950823

Sommargren, G E

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
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360000* -- Materials
42 ENGINEERING
420300 -- Engineering-- Lasers-- (-1989)
BEAM SPLITTING
COMPUTERIZED CONTROL SYSTEMS
CONTROL SYSTEMS
DEPTH
DIGITAL SYSTEMS
DIMENSIONS
FREQUENCY SELECTION
LASERS
MEASURING METHODS
MOTION
OPTICAL PROPERTIES
PHASE SHIFT
PHYSICAL PROPERTIES
ROTATION
ROUGHNESS
SIGNALS
SURFACE PROPERTIES
SURFACES