US3734626A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light apparatus for testing surfaces
Assignee: Control Data Corp
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Filing: 1972-01-14
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Granted: 1973-05-22
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Expires: 1992-01-14
Abstract
Abstract Apparatus for testing surface flatness of an object such as a magnetic disc. A laser light beam is reflected off the surface to be tested, is caught and returned by a corner cube reflector so that the returning rays are directed parallel to the incoming beam and are again reflected off of the same spot area receiving the incoming laser beam. The light returning from the corner cube reflector is then reflected from the surface to be tested onto a beam splitter from which it is reflected to a spot-forming lens which forms a light spot at the focal plane, and which light spot diameter is a measure of the surface irregularity of the area tested on the disc or object. The position of the light spot always remains stably at the same point. If the tested area of the disc were perfectly flat when the light spot at the principal focal plane would be of a minimum diameter. Any enlargement from this minimum diameter is a measure of surface irregularity of the disc or object surface being tested. Means are provided for scanning the size of the light spot which is also made independent of the angular plane or level of the disc tested. Light detection means working in conjunction with an aperture scanning means provide a display showing the amount of deviation from flatness of the surface area tested. The sensitivity of the apparatus is such that it can easily detect surface deviations at least 35 micro-inches per inch per inch from flatness.
Inventors
- 👤 D Roberts
- 👤 D George
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:29
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/30; G01B11/303
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
121 words
An apparatus for determining deviations of a reflecting surface from an ideal surface comprising: means for exposing an area of said reflecting surface to light rays of a collimated beam of light, said means including a light source and means for projecting light from said source onto said reflecting surface; means for taking said reflected light from said reflecting surface and returning it along substantially parallel beams to the same exposed area of said reflecting surface; means for directing said returned light beam to form a light spot in space; said light spot in space always appearing at the same fixed point and having a size which is a function of the deviation of said exposed area from an ideal surface.
Claim 2
Independent Claim
121 words
An apparatus for determining deviations of a reflecting surface from an ideal surface comprising: means for exposing an area of said reflecting surface to light rays of a collimated beam of light, said means including a light source and means for projecting light from said source onto said reflecting surface; means for taking said reflected light from said reflecting surface and returning it along substantially parallel beams to the same exposed area of said reflecting surface; means for directing said returned light beam to form a light spot in space; said light spot in space always appearing at the same fixed point and having a size which is a function of the deviation of said exposed area from an ideal surface.
Claim 3
Dependent Claim
22 words
The apparatus as in claim 1 including: means for measuring the size of a spot of light reflected from said exposed surface.
Claim 4
Dependent Claim
52 words
The apparatus of claim 1 including: indicating means for indicating the ratio of the amount of light due to an elongated spot in space derived from reflection from the exposed surface and the amount of light from a light spot in space derived from the exposed surface when it is ideally flat.
Claim 5
Dependent Claim
39 words
The apparatus of claim 1 including: means for measuring the size change of said light spot in space in relationship to a minimum size diameter spot in space which is dependent on a function of an ideal exposed surface.
Claim 6
Dependent Claim
92 words
Apparatus for the sensing of surface shape comprising: a source of substantially diffraction-limited light; means for regulating the cross-sectional area of said beam of light; means for reflecting said beam of light from an exposed surface area of a surface to be sensed; means for directing said reflected beam through a spot-forming lens to a fixed spot in space; means for detecting the diameter size of said fixed spot in space; said diameter of said fixed spot in space being a function of the surface condition of the surface to be tested.
Claim 7
Dependent Claim
92 words
Apparatus for the sensing of surface shape comprising: a source of substantially diffraction-limited light; means for regulating the cross-sectional area of said beam of light; means for reflecting said beam of light from an exposed surface area of a surface to be sensed; means for directing said reflected beam through a spot-forming lens to a fixed spot in space; means for detecting the diameter size of said fixed spot in space; said diameter of said fixed spot in space being a function of the surface condition of the surface to be tested.
Claim 8
Dependent Claim
170 words
Apparatus for sensing the amount of deviation of surface flatness of an object from an ideally flat surface comprising: means for providing collimated light; means for shaping said light into a beam of a desired cross section; means for collimating said light beam and directing it to reflective exposure on a surface to be tested; retro-reflector means for taking the light reflected from the exposed test surface area and returning it back again to the reflective test surface area on beams precisely parallel to the beam reflected from the test surface area; means for directing the beam so doubly-reflected from the test surface area to a light spot-forming means which forms a light-spot at a fixed position in space; said means for directing the doubly-reflected beams, said spot forming means, said retro-reflector means and said test surface area working in such cooperation so as to make said fixed light spot have a size which is a function of the deviation of the test surface area from an ideally flat condition.
Claim 9
Dependent Claim
170 words
Apparatus for sensing the amount of deviation of surface flatness of an object from an ideally flat surface comprising: means for providing collimated light; means for shaping said light into a beam of a desired cross section; means for collimating said light beam and directing it to reflective exposure on a surface to be tested; retro-reflector means for taking the light reflected from the exposed test surface area and returning it back again to the reflective test surface area on beams precisely parallel to the beam reflected from the test surface area; means for directing the beam so doubly-reflected from the test surface area to a light spot-forming means which forms a light-spot at a fixed position in space; said means for directing the doubly-reflected beams, said spot forming means, said retro-reflector means and said test surface area working in such cooperation so as to make said fixed light spot have a size which is a function of the deviation of the test surface area from an ideally flat condition.
Claim 10
Dependent Claim
83 words
The apparatus of claim 6 suitable for rapid surface testing of both of a flat surface including: movable reflective means for directing a diffraction-limited light beam to reflectively scan different areas of both sides of said flat surface; means for rotating said flat surface to present different test areas to be scanned by said diffraction-limited light beam; means, synchronized with said movable reflective means and said surface rotating means, for measuring the amount of light doubly reflected from each test surface area scanned.
Claim 11
Independent Claim
24 words
The apparatus of 1 wherein the area-exposing means comprises a light source and means for projecting a substantially diffraction-limited beam onto the reflecting surface.
Claim 12
Independent Claim
24 words
The apparatus of 1 wherein the area-exposing means comprises a light source and means for projecting a substantially diffraction-limited beam onto the reflecting surface.
Claim 13
Dependent Claim
21 words
The apparatus of claim 1, wherein the means taking reflected light from the reflecting surface and returning it comprises a retro-reflector.
Claim 14
Dependent Claim
22 words
The apparatus of claim 6, wherein the collimated light source means further comprises means for causing the light to be substantially diffraction-limited.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |