US3779647A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interferometric device for indicating displacement along one dimension during motion along another dimension
Assignee: Bendix Corp
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Filing: 1971-09-07
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Granted: 1973-12-18
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Expires: 1991-09-07
Abstract
Abstract An apparatus for measuring the displacement of a part such as a work performing tool or a measuring probe of a flatness measuring instrument. The apparatus includes means for providing a collimated laser beam that is disposed parallel to and displaced slightly from a predetermined plane of motion. Two identical prisms are placed side by side to intercept different portions of the laser beam. These prisms direct the intercepted portions of the laser beam to intersect and provide an interference pattern comprising a series of adjacent interference planes. An optical grating is attached to a part that is to be moved nominally along the predetermined plane of motion. This grating intercepts the interference planes and provides a Moire fringe output signal that varies in response to any displacement of the part perpendicular to the plane of motion. Electronic apparatus detects and measures this Moire fringe pattern variation and provides an output indicating the magnitude and direction of any perpendicular displacement.
Inventors
- 👤 J Dawson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:41
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/38
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
181 words
A method of checking for the presence of inherent inaccuracies in a system for making surface profile measurements along a surface comprising the steps of: projecting an interference pattern parallel to said surface, said pattern being spaced at a predetermined distance from said surface; positioning a grating means to intercept said interference pattern and produce a Moire fringe pattern; providing a relative motion between said interference pattern and said grating means indicative of variations of said surface as a probe is moved along said surface, said relative motion producing variations in said Moire fringe pattern; measuring said Moire fringe pattern variations to determine the magnitude of said surface variations; inverting said interference pattern; providing a second relative motion between said interference pattern and said grating means identical to said relative motion to obtain second variations in said Moire fringe pattern; measuring said second variations in said Moire fringe pattern; and comparing said measured fringe pattern variations and said second measured fringe pattern variations, the absence of differences in said measurements being indicative of the absence of inherent inaccuracies in said system.
Claim 2
Independent Claim
181 words
A method of checking for the presence of inherent inaccuracies in a system for making surface profile measurements along a surface comprising the steps of: projecting an interference pattern parallel to said surface, said pattern being spaced at a predetermined distance from said surface; positioning a grating means to intercept said interference pattern and produce a Moire fringe pattern; providing a relative motion between said interference pattern and said grating means indicative of variations of said surface as a probe is moved along said surface, said relative motion producing variations in said Moire fringe pattern; measuring said Moire fringe pattern variations to determine the magnitude of said surface variations; inverting said interference pattern; providing a second relative motion between said interference pattern and said grating means identical to said relative motion to obtain second variations in said Moire fringe pattern; measuring said second variations in said Moire fringe pattern; and comparing said measured fringe pattern variations and said second measured fringe pattern variations, the absence of differences in said measurements being indicative of the absence of inherent inaccuracies in said system.
Claim 3
Dependent Claim
178 words
The method of claim 1 in which: said step of projecting an interference pattern comprises projecting a beam of coherent wave energy parallel to and spaced a distance from said surface, and positioning two identical deflecting means to receive different portions of said beam and deflect said received portions to intersect and provide a planar interference pattern, the planes of said pattern being of equal thickness; said step of positioning a grating means comprises mounting a grating means having alternate transparent and opaque lines on a probe so that said lines are substantially parallel to said interference planes of said planar interference pattern and intercept said interference pattern; said step of providing a relative motion comprises moving said probe across said surface along a predetermined path, movement of said probe over surface elevations and depressions causing said grating to be moved perpendicular to said planes of said interference pattern to provide variations in said Moire fringe pattern; and said step of providing a second relative motion also comprises moving said probe across said surface along said predetermined path.
References Cited (Backward Citations)
US3371335A
Cited
US3572937A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-17 | 1977-06-18 | 1977-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-17 | 1981-06-18 | 1981-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-17 | 1985-06-18 | 1985-12-18 | $7700.00 | Window Closed / Lapsed |