US3771880A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Roughness analyzer
Assignee: United States Department of the Navy
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Filing: 1971-09-29
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Granted: 1973-11-13
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Expires: 1991-09-29
Abstract
Abstract A device for measuring surface irregularities of an optical surface. A light source strikes the surface to be tested and is both specularly reflected and scattered outside the specular direction. A reflecting cone directs some of that light outside the specular direction to a measuring device. Some of the scattered light falls on the device without striking the cone, as does the specularly reflected light. Thus the fraction of the reflected light which is within a given angle of the specular direction may be measured. Alternatively a light source passes through a hole in the back of a Coblentz sphere. Light within the specular direction returns through the hole and is measured with a light measuring device while light scattered without the specular direction is measured by a second light measuring device.
Inventors
- 👤 H Bennett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 17:18
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/55
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
181 words
A device for measuring the roughness of an optical surface comprising: a light source; means directing said source onto a surFace to be tested, and means for determining the ratio of scattered light to total light reflected from said surface comprising: a truncated cone reflector to be placed with the truncated portion adjacent a surface whose roughness is to be tested; a spherical mirror; a diaphragm; a transducer for transforming light energy to electrical energy; said cone reflector being so positioned with respect to said mirror, that light scattered from said test surface is reflected from said cone reflector onto said mirror where it images as a circle; light specularly reflected from said test surface images as a point within said circle; and said diaphragm is so positioned with respect to said mirror and said transducer that said circular image may be prevented from reaching said transducer; whereby the rms roughness and the autocovariance length of the surface can be determined from the formula R/Ro e (4 / ) +( 1-e (4 / ) ) ( 1-e ( a/ ) ).
Claim 2
Independent Claim
181 words
A device for measuring the roughness of an optical surface comprising: a light source; means directing said source onto a surFace to be tested, and means for determining the ratio of scattered light to total light reflected from said surface comprising: a truncated cone reflector to be placed with the truncated portion adjacent a surface whose roughness is to be tested; a spherical mirror; a diaphragm; a transducer for transforming light energy to electrical energy; said cone reflector being so positioned with respect to said mirror, that light scattered from said test surface is reflected from said cone reflector onto said mirror where it images as a circle; light specularly reflected from said test surface images as a point within said circle; and said diaphragm is so positioned with respect to said mirror and said transducer that said circular image may be prevented from reaching said transducer; whereby the rms roughness and the autocovariance length of the surface can be determined from the formula R/Ro e (4 / ) +( 1-e (4 / ) ) ( 1-e ( a/ ) ).
Claim 3
Independent Claim
152 words
A device for measuring the roughness of an optical surface comprising: a light source; means directing said source onto a surface to be tested; means for determining the ratio of scattered light to total light reflected from said surface comprising: a Coblentz sphere with a hole in the back; first and second pyroelectric detectors; means for comparing signals from said first and second detectors; and said sphere and first and second detectors being so positioned with respect to each other and to said test surface that specularly reflected light will pass back through said hole in said sphere and land on said first pyroelectric detector and scattered light will be reflected from said sphere onto said second pyroelectric detector; whereby the rms roughness and the autocovariance length of the surface can be determined from the formula R/Ro e (4 / ) +( 1-e (4 / ) )( 1-e ( a/ )2 )
Claim 4
Independent Claim
152 words
A device for measuring the roughness of an optical surface comprising: a light source; means directing said source onto a surface to be tested; means for determining the ratio of scattered light to total light reflected from said surface comprising: a Coblentz sphere with a hole in the back; first and second pyroelectric detectors; means for comparing signals from said first and second detectors; and said sphere and first and second detectors being so positioned with respect to each other and to said test surface that specularly reflected light will pass back through said hole in said sphere and land on said first pyroelectric detector and scattered light will be reflected from said sphere onto said second pyroelectric detector; whereby the rms roughness and the autocovariance length of the surface can be determined from the formula R/Ro e (4 / ) +( 1-e (4 / ) )( 1-e ( a/ )2 )
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-12 | 1977-05-14 | 1977-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-12 | 1981-05-14 | 1981-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-12 | 1985-05-14 | 1985-11-13 | $7700.00 | Window Closed / Lapsed |