US3731373A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacturing an optical shaft encoder having a holagraphic code disk
Assignee: United States Department of the Army
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Filing: 1971-12-21
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Granted: 1973-05-08
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Expires: 1991-12-21
Abstract
Abstract A constant laser beam is directed toward a photosensitive code disk. A beam splitter diverts some light from the laser beam to drive first inputs of light modulators. The shaft of a standard reference shaft encoder is concentrically fixed to the disk and the encoder output bit lines are individually connected to second inputs of respective light modulators for selectively modulating the passage of light thereby generating light bit equivalents. The light bits are individually transmitted through fiber optics to projecting positions near the opposite side of the disk. By subjecting the disk to constant laser light on one side and changing bit light on the other side as the shaft turns, a diffraction grating is formed on the disk as a latent image. The photosensitive disk is developed and forms a permanent optical encoder disk for future use.
Inventors
- 👤 R Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:39
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/32; H; H03; H03M; H03M1/00; H03M1/12; H03M1/22; H03M1/24; H03M1/26; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
273 words
A method for manufacturing an analog to digital shaft angle encoder utilizing apparatus comprising: a standard shaft angle encoder as a reference; output terminals of the reference encoder connected to control terminals of respective light modulators located externally of the encoder undergoing manufacture, the output terminals being selectively energized in a predetermined code sequence as the shaft of the reference encoder is made to turn thereby actuating the modulators in a corresponding sequence; means connecting the shaft of the reference encoder to a shaft of the encoder undergoing manufacture so that both turn together; the steps of manufacture consisting of: subjecting a side of a photosensitive code disc, located on the shaft of the encoder being manufactured, to a reference beam of coherent light introduced by a source external of the encoder being manufactured; subjecting the light modulators to light which is mutually coherent with the light from the source for passage through actuated modulators; transmitting light along fiber optic light conducting means, from actuated modulators to fixed light projecting points adjacent an opposite side of the disc to form a latent holographic image on the disc; developing the image as the disc remains in situ; disconnecting the light conducting means from the modulators and connecting them instead to respective photo-detectors; and disconnecting the standard shaft encoder from the encoder undergoing manufacture thereby completiNg its manufacture; whereby subjecting the disc to coherent light at different angular positions of the manufactured encoder shaft produces automatically aligned precise light outputs at the fixed light projecting points that are converted by the detectors to electrical signals unique for each angular position of the manufactured encoder shaft.
Claim 2
Independent Claim
273 words
A method for manufacturing an analog to digital shaft angle encoder utilizing apparatus comprising: a standard shaft angle encoder as a reference; output terminals of the reference encoder connected to control terminals of respective light modulators located externally of the encoder undergoing manufacture, the output terminals being selectively energized in a predetermined code sequence as the shaft of the reference encoder is made to turn thereby actuating the modulators in a corresponding sequence; means connecting the shaft of the reference encoder to a shaft of the encoder undergoing manufacture so that both turn together; the steps of manufacture consisting of: subjecting a side of a photosensitive code disc, located on the shaft of the encoder being manufactured, to a reference beam of coherent light introduced by a source external of the encoder being manufactured; subjecting the light modulators to light which is mutually coherent with the light from the source for passage through actuated modulators; transmitting light along fiber optic light conducting means, from actuated modulators to fixed light projecting points adjacent an opposite side of the disc to form a latent holographic image on the disc; developing the image as the disc remains in situ; disconnecting the light conducting means from the modulators and connecting them instead to respective photo-detectors; and disconnecting the standard shaft encoder from the encoder undergoing manufacture thereby completiNg its manufacture; whereby subjecting the disc to coherent light at different angular positions of the manufactured encoder shaft produces automatically aligned precise light outputs at the fixed light projecting points that are converted by the detectors to electrical signals unique for each angular position of the manufactured encoder shaft.
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) | 1976-05-07 | 1976-11-06 | 1977-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-07 | 1980-11-06 | 1981-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-07 | 1984-11-06 | 1985-05-08 | $7700.00 | Window Closed / Lapsed |