US4800256A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Halographic scanner having adjustable sampling rate
Assignee: International Business Machines Corp
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Filing: 1986-12-08
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Granted: 1989-01-24
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Expires: 2006-12-08
Abstract
Abstract An improved holographic scanner includes circuitry for adjusting the frequency with which an analog photodetector signal is sampled in accordance with the focal length of the scanning beam produced by the active holographic facet. Two embodiments are shown. In one embodiment, facet-edge signals are used to track the facets. A processor retrieves a predetermined frequency scaling factor appropriate for each facet. In the other embodiment, a holographic disk carries an auxiliary data track. The track has timing indicia with spatial frequencies dependent upon the focal length of the adjacent facet. The timing indicia are used to control the output of a voltage controlled oscillator in a circuit including a phase locked loop.
Inventors
- 👤 Eric C. Broockman
- 👤 Robert T. Cato
- 👤 William D. Gregory, Jr.
- 👤 George J. Laurer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:40
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10544; G06K7/10821; G06K7/10861; G06K7/10871; G02; G02B; G02B26/00; G02B26/08; G02B26/10; G02B26/106
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
100 words
In an optical scanner of the type having a coherent light source, a rotating holographic optical element having a plurality of facets for deflecting the coherent light beam along predetermined scan lines, said facets having the capability of focusing the coherent light beam at different focal lengths from the optical element, a photosensitive detector for detecting light reflected from an object and a sampling circuit for periodically sampling signals produced by the detector, the improvement comprising means for varying the sampling frequency as a function of the focal length of the facet currently being employed to generate a scan line.
Claim 2
Dependent Claim
100 words
In an optical scanner of the type having a coherent light source, a rotating holographic optical element having a plurality of facets for deflecting the coherent light beam along predetermined scan lines, said facets having the capability of focusing the coherent light beam at different focal lengths from the optical element, a photosensitive detector for detecting light reflected from an object and a sampling circuit for periodically sampling signals produced by the detector, the improvement comprising means for varying the sampling frequency as a function of the focal length of the facet currently being employed to generate a scan line.
Claim 3
Dependent Claim
29 words
An optical scanner as defined in claim 1 wherein the sampling frequency is varied in direct proportion to the change in focal length relative to a minimum focal length.
Claim 4
Dependent Claim
42 words
An optical scanner as defined in claim 2 wherein said sampling circuit comprises an analog to digital converter and wherein said varying means comprises means for varying the frequency with which an analog signal provided by the detector is sampled and digitized.
Claim 5
Dependent Claim
135 words
In an optical scanner of the type having a coherent light source, a rotating holographic optical element having a plurality of facets for deflecting the coherent light beam along predetermined scan lines, said facets having the capability of focusing the coherent light beam at different focal lengths from the optical element, a photosensitive detector for detecting light reflected from an object, a clock circuit, and a sampling circuit for sampling the signal produced by the photosensitive detector with a frequency determined by the output of the clock circuit, the improvement comprising: means for generating a signal identifying the facet currently used in generating a scan line; means responsive to the facet-identifying signal for operating on the clock circuit to generate a sampling signal having a frequency related to the focal length of the identified facet.
Claim 6
Dependent Claim
135 words
In an optical scanner of the type having a coherent light source, a rotating holographic optical element having a plurality of facets for deflecting the coherent light beam along predetermined scan lines, said facets having the capability of focusing the coherent light beam at different focal lengths from the optical element, a photosensitive detector for detecting light reflected from an object, a clock circuit, and a sampling circuit for sampling the signal produced by the photosensitive detector with a frequency determined by the output of the clock circuit, the improvement comprising: means for generating a signal identifying the facet currently used in generating a scan line; means responsive to the facet-identifying signal for operating on the clock circuit to generate a sampling signal having a frequency related to the focal length of the identified facet.
Claim 7
Dependent Claim
36 words
An optical scanner as defined in claim 4 wherein said responsive means changes the frequency of the sampling signal as a function of the focal length of the identified facet relative to a minimum focal length.
Claim 8
Dependent Claim
40 words
An optical scanner as defined in claim 5 wherein said sampling circuit includes an analog to digital converter which samples and digitizes the signal produced by the photosensitive detector with a frequency dependent upon the output of the clock circuit.
Claim 9
Dependent Claim
135 words
An optical scanner comprising: a light source for producing a coherent light beam; a rotating holographic optical element having a plurality of facets for deflecting the coherent light beam along predetermined scan lines and timing indicia on the periphery thereof, the angular spacing of the indicia in a given sector of said ring being a function of the focal length of one of said facets; means for detecting light reflected from an object in the path of one of the scan lines; means for producing sampling signals for periodically sampling the signal produced by said detecting means; means for generating a spatial frequency signal related to the angular spacing of the indicia; and means responsive to the spatial frequency signal for adjusting the frequency of the sampling signals as a function of the spatial frequency.
Claim 10
Dependent Claim
135 words
An optical scanner comprising: a light source for producing a coherent light beam; a rotating holographic optical element having a plurality of facets for deflecting the coherent light beam along predetermined scan lines and timing indicia on the periphery thereof, the angular spacing of the indicia in a given sector of said ring being a function of the focal length of one of said facets; means for detecting light reflected from an object in the path of one of the scan lines; means for producing sampling signals for periodically sampling the signal produced by said detecting means; means for generating a spatial frequency signal related to the angular spacing of the indicia; and means responsive to the spatial frequency signal for adjusting the frequency of the sampling signals as a function of the spatial frequency.
Claim 11
Dependent Claim
25 words
An optical scanner as defined in claim 7 wherein the angular spacing of the indicia is proportional to the focal length of the associated facet.
Claim 12
Dependent Claim
44 words
An optical scanner as defined in claim 8 wherein said means for generating a spatial frequency signal comprises a light source located on one side of the holographic optical element and a light detector located on the opposite side of the holographic optical element.
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) | 1992-01-24 | 1992-07-25 | 1993-01-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-24 | 1996-07-25 | 1997-01-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-24 | 2000-07-25 | 2001-01-24 | $7700.00 | Window Closed / Lapsed |