EP0270778A2
Expired / Lapsed
EP
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Holographic scanner having adjustable sampling rate
Assignee: International Business Machines Corp
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Filing: 1987-10-16
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Granted: —
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Expires: 2007-10-16
Abstract
Abstract Holographic scanner of the type having a coherent light source (18), a rotating holographic optical element (10) having a plurality of facets (16) for deflecting the coherent light beam along predetermined scan lines, said facets having the capability of focussing the coherent light beam at different focal lengths from the optical element (10), a photosensitive detector (34) for detecting light reflected from an object and a sampling circuit for periodically sampling signals produced by the detector (34), comprising an analog-to-digital converter (38) for sampling and digitizing the signals produced by the detector (34) and varying means (44) for varying the sampling frequency as a function of the focal length of the facet currently employed to generate a scan line.
Inventors
- 👤 Eric Charles Broockman
- 👤 Robert Thomas Cato
- 👤 William Durward Gregory, Jr.
- 👤 George Jospeh Laurer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 12:59
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: 8
Claim 1
Independent Claim
132 words
Holographic scanner having adjustable sampling rate, and having a coherent light source (18), a rotating holographic optical element (10) having a plurality of facets (16) for deflecting the coherent light beam along predetermined scan lines, said facets having the capability of focussing the coherent light beam at different focal lengths from the optical element, a photosensitive detector (34) for detecting light reflected from an object and a sampling circuit (38, 44) for periodically sampling signals produced by the detector; said scanner being characterized in that said sampling circuit comprises : - an analog-to-digital converter (38) for sampling and digitizing the signals produced by said detector, and - varying means (44) for varying the sampling frequency as a function of the focal length of the facet currently employed to generate a scan line.
Claim 2
Dependent Claim
132 words
Holographic scanner having adjustable sampling rate, and having a coherent light source (18), a rotating holographic optical element (10) having a plurality of facets (16) for deflecting the coherent light beam along predetermined scan lines, said facets having the capability of focussing the coherent light beam at different focal lengths from the optical element, a photosensitive detector (34) for detecting light reflected from an object and a sampling circuit (38, 44) for periodically sampling signals produced by the detector; said scanner being characterized in that said sampling circuit comprises : - an analog-to-digital converter (38) for sampling and digitizing the signals produced by said detector, and - varying means (44) for varying the sampling frequency as a function of the focal length of the facet currently employed to generate a scan line.
Claim 3
Dependent Claim
29 words
The holographic 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
60 words
The holographic scanner as defined in Claim 1 or 2 further comprising means (60) for generating a signal identifying the facet currently used in generating a scan line, and means (40 responsive to the facet-identifying signal for operating on said varying means (44) to generate a sampling signal having a frequency related to the focal length of the identified facet.
Claim 5
Dependent Claim
95 words
The holographic scanner as defined in Claim 1, 2 or 3 wherein timing indicia are placed on the periphery of said optical element with the angular spacing of the indicia in a given sector being a function of the focal length of one of said facets; and further comprising : - means (76, 78) for generating a spatial frequency signal related to the angular spacing of the indicia, and - means (80, 82, 84) responsive to the spatial frequency signal for adjusting the frequency of the sampling signals as a function of the spatial frequency.
Claim 6
Dependent Claim
25 words
The holographic scanner as defined in Claim 4 wherein the angular spacing of the indicia is proportional to the focal length of the associated facet.
Claim 7
Dependent Claim
46 words
The holographic scanner as defined in Claim 5 wherein said means for generating a spatial frequency signal comprises a light source (76) located on one side of said optical element (10) and a light detector (78) located on the opposite side of the holographic optical element.
Claim 8
Dependent Claim
113 words
The holographic scanner as defined in Claim 4, 5 or 6 wherein said means for adjusting the frequency of the sampling signals as a function of the spatial frequency comprises : - a phase locked loop (80) receiving the output signals from said photodetector (78), - a voltage controlled oscillator (82) regulated by said phase locked loop, and - a divider circuit (84) connected between an input of said phase locked loop and the output of said voltage controlled oscillator, whereby said phase locked loop compares the frequency of signals derived from said timing marks with the divided output from said voltage controlled oscillator to regulate the output of said voltage controlled oscillator.
References Cited (Backward Citations)
No citation records indexed.
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