US3866038A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for measuring surface flatness
Assignee: International Business Machines Corp
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Filing: 1973-11-13
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Granted: 1975-02-11
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Expires: 1993-11-13
Abstract
Abstract The flatness of a surface is measured using a scanning beam of light. For scanning the surface, a light beam is periodically deflected by a rotating polygonal mirror. The periodic displacement of the scanning beam reflected on the surface is fully compensated by its reflection on the same face of the polygonal mirror. As a consequence, a beam leaves the polygonal mirror substantially on the same path and in the opposite direction as the beam exiting from a light source such as a laser. If the scanning beam reflected from the surface impinges on an embossment or recess the reflected beam is displaced perpendicularly to the scan direction, this displacement not being compensated by its reflection on the polygonal mirror. This displacement, which is a function of the distance of the scanned point from a perfectly plane surface, is sensed by a linear array of photodetectors.
Inventors
- 👤 Hans E Korth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:46
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/30; G01B11/303
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
175 words
Apparatus for measuring the flatness of a surface comprising: means for producing a beam of light; deflection means for producing a deflected beam by periodically deflecting said beam in a known manner, said deflection means being of such a nature that when said deflected beam is reflected back to said deflecting means, said deflected beam will be again deflected in a manner which is substantially equal and opposite to, and thus compensates for, said original deflection; a first mirror for reflecting said deflected beam onto said surface at a predetermined angle; a second mirror for reflecting said deflected beam, after it has been reflected at said surface, back toWard said deflection means; and sensing means, positioned to receive said deflected beam after it has been deflected a second time by said deflection means, for sensing the displacement between the twice-deflected beam and the orginal beam of light; said displacement being a function of the height, in relation to the rest of said surface, of the point on said surface upon which said deflected beam impinged.
Claim 2
Dependent Claim
175 words
Apparatus for measuring the flatness of a surface comprising: means for producing a beam of light; deflection means for producing a deflected beam by periodically deflecting said beam in a known manner, said deflection means being of such a nature that when said deflected beam is reflected back to said deflecting means, said deflected beam will be again deflected in a manner which is substantially equal and opposite to, and thus compensates for, said original deflection; a first mirror for reflecting said deflected beam onto said surface at a predetermined angle; a second mirror for reflecting said deflected beam, after it has been reflected at said surface, back toWard said deflection means; and sensing means, positioned to receive said deflected beam after it has been deflected a second time by said deflection means, for sensing the displacement between the twice-deflected beam and the orginal beam of light; said displacement being a function of the height, in relation to the rest of said surface, of the point on said surface upon which said deflected beam impinged.
Claim 3
Dependent Claim
13 words
The apparatus of claim 1 wherein said deflection means comprises an electro-optical element.
Claim 4
Dependent Claim
14 words
The apparatus of claim 1 wherein said deflection means comprises a rotating polygonal mirror.
Claim 5
Dependent Claim
71 words
The apparatus of claim 3 further including: a spherical lens in the path of said deflected beam between said polygonal mirror and said first and second mirrors; a prism, in the path of said deflected beam between said spherical lens and said first mirror, for lateral deflection of said deflected beam; and focusing means, between said polygonal mirror and said sensing means, for focusing said twice-deflected beam upon said sensing means.
Claim 6
Dependent Claim
100 words
The apparatus of claim 3 further including: a first Wollaston prism in the path of said beam of light prior to its impingement upon said polygonal mirror; a second Wollaston prism in the path of said deflected beam between said polygonal mirror and said first and second mirrors; a first spherical lens in the path of said deflected beam between said second Wollaston prism and said first and second mirrors; and a second spherical lens, in the path of said twice-deflected beam between said first Wollaston prism and said sensing means, for focusing said twice-deflected beam onto said sensing means.
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) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |