US3922093A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for measuring the roughness of a surface
Assignee: BBC BROWN BOVERI and CIE
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Filing: 1973-11-16
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Granted: 1975-11-25
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Expires: 1993-11-16
Abstract
Abstract An apparatus is disclosed for measuring the roughness of a surface with improved accuracy. The apparatus, several embodiments of which are disclosed, includes a device for illuminating a surface being studied and a photosensitive detector for determining the maximum intensity of light reflected on the surface. Apparatus is also provided for detemining two points at which the intensity of the reflected light has fallen to a selected fraction of its maximum intensity. The distance between these two points is then measured along the intersection of the plane of incidence of the illuminating beam with a plane perpendicular to the direction of specular reflection. This distance provides an accurate quantitative measure of the roughness of the surface being studied.
Inventors
- 👤 Rene Dandliker
- 👤 Francois M Mottier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:49
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/30; G01B11/303
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
104 words
A method for measuring the roughness of a surface where the surface is illuminated with a light beam and where the spatial distribution of the intensity of the reflected light is photoelectrically measured comprising: determining the intensity maximum of the reflected light; determining two points at which the intensity of the reflected light has fallen to a selected fraction of the intensity maximum; and measuring the distance between the two points along the intersection of the plane of incidence of the illuminating light beam with a plane perpendicular to the direction of the specular reflection, the distance providing a measure of the surface roughness.
Claim 2
Independent Claim
104 words
A method for measuring the roughness of a surface where the surface is illuminated with a light beam and where the spatial distribution of the intensity of the reflected light is photoelectrically measured comprising: determining the intensity maximum of the reflected light; determining two points at which the intensity of the reflected light has fallen to a selected fraction of the intensity maximum; and measuring the distance between the two points along the intersection of the plane of incidence of the illuminating light beam with a plane perpendicular to the direction of the specular reflection, the distance providing a measure of the surface roughness.
Claim 3
Dependent Claim
12 words
A method as in claim 1 wherein the selected fraction is 0.5.
Claim 4
Dependent Claim
16 words
A method as in claim 1 wherein the surface is illuminated with a collimated light beam.
Claim 5
Dependent Claim
23 words
A method as in claim 1 wherein ambient light is shielded from the photoelectric measurement and the surface is illuminated with monochromatic light.
Claim 6
Dependent Claim
38 words
A method as in claim 1 wherein the illuminating light beam is collimated to a diameter of from 1 to 20 mm and the beam is projected on the surface at an angle of from 50* to 85*.
Claim 7
Dependent Claim
44 words
A method as in claim 1 wherein the situs of the photoelectric measurement is moved along the intersection through the reflected light whereby the spatial variation in the intensity of the reflected light is measured and the distance between the two points is obtained.
Claim 8
Dependent Claim
25 words
A method as in claim 1 wherein the intensity distribution of the reflected light is determined by a chain of photodetectors positioned along the intersection.
Claim 9
Dependent Claim
106 words
A method as in claim 1 wherein the intensity distribution of the reflected light is determined by a TV camera focussed at infinity and positioned in the path of light reflected in the direction of specular reflection, the TV camera is scanned so that the direction of the scanning lines is perpendicular to the plane of incidence of the illuminating light beam, the value of the maximum intensity of the reflected light during the first half frame is stored and the number of scanning lines in which the scanned image includes a light intensity greater than the selected fraction is determined during the second half frame.
Claim 10
Dependent Claim
29 words
A method as in claim 5 wherein the intensity distribution of the reflected light is measured on a circular surface having a diameter of from 0.2 to 4.0 mm.
Claim 11
Dependent Claim
19 words
A method as in claim 6 wherein the light beam for illuminating the surface is provided by a laser.
Claim 12
Dependent Claim
31 words
A method as in claim 7 wherein the reflected light is passed through a converging lens and wherein the chain of photodetectors lies in the focal plane of the converging lens.
Claim 13
Dependent Claim
55 words
A method as in claim 7 wherein the intensity distribution of the reflected light is further determined by electronic flip-flops coupled to the photodetectors and lamps coupled to the electronic flip-flops so that the lamps are turned on if the intensity of the reflected light is greater than the selected fraction at a particular photodetector.
Claim 14
Dependent Claim
58 words
A method as in claim 7 wherein the intensity distribution of the reflected light is further determined by electronic flip-flops coupled to the photodetectors, current is generated proportional to the number of photodetectors at which the intensity of the reflected light is greater than the selected fraction and the proportional current is transmitted to a responsive pointer instrument.
Claim 15
Dependent Claim
25 words
A method as in claim 8 wherein the intensity maximum during the first frame half is determined through the use of a peak value detector.
Claim 16
Dependent Claim
43 words
A method as in claim 8 wherein a digital signal proportional to the number of scanning lines in which the scanned image includes a light intensity greater than the Selected fraction is provided by the TV camera and a luminous readout coupled thereto.
Claim 17
Dependent Claim
43 words
A method as in claim 8 wherein an analog signal proportional to the number of scanning lines in which the scanned image includes a light intensity greater than the selected fraction is provided by the TV camera and a pointer meter coupled thereto.
Claim 18
Dependent Claim
37 words
A method as in claim 8 wherein the illuminating light beam is pulsed so that the duration of each illuminating pulse is less than the time required for the TV camera to scan through two half frames.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-11-24 | 1979-05-26 | 1979-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-24 | 1983-05-26 | 1983-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-24 | 1987-05-26 | 1987-11-25 | $7700.00 | Window Closed / Lapsed |