Patent US2413187A successfully refreshed from Google Patents.
US3729634A
Expired / Lapsed
US
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Automatic beam ratio control system for holography
Assignee: Recognition Systems Inc
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Filing: 1971-09-20
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Granted: 1973-04-24
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Expires: 1991-09-20
Abstract
Abstract This invention comprises apparatus for controlling the ratio of the signal and reference beams in a system for making holographic filters for use in matched filter pattern recognition apparatus. Means is provided for measuring the intensity of the spatial frequencies of a signal beam, and means is provided for measuring the intensity of a reference beam. The difference between the measured beam ratio and the optimum beam ratio controls an attenuator placed in either the reference beam path or the signal beam path. A shutter may also be controlled so that uniformity of exposure is maintained as the beam ratio is adjusted.
Inventors
- 👤 N Jensen
- 👤 J Thomasson
- 👤 D Mead
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 00:31
CPC Classifications
G; G03; G03H; G03H1/00; Y; Y10; Y10S; Y10S359/00; Y10S359/90
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
175 words
A system for producing holographic filters comprising: a coherent light beam source; means for directing the beam from the source to illuminate an object for diffraction thereby in a signal beam; means for focusing the light diffracted by the object so as to form the optical Fourier transform of the object at a transform plane; means for directing a coherent reference light beam onto the transform plane at a non-normal angle of incidence; means for separately measuring the intensity of the signal beam light forming said optical Fourier transform of the object at a multiplicity of distinct spatial frequencies; means for measuring the intensity of the reference beam; means for comparing the measured intensities of the signal and reference beams; and means, responsive to the output of said means for comparing the measured intensities, for maintaining the beam intensities at a value such that the reference beam has an intensity substantially equal to the highest intensity measured for any spatial frequency in the signal beam other than the spatial frequencies near the zero spatial frequency.
Claim 2
Independent Claim
175 words
A system for producing holographic filters comprising: a coherent light beam source; means for directing the beam from the source to illuminate an object for diffraction thereby in a signal beam; means for focusing the light diffracted by the object so as to form the optical Fourier transform of the object at a transform plane; means for directing a coherent reference light beam onto the transform plane at a non-normal angle of incidence; means for separately measuring the intensity of the signal beam light forming said optical Fourier transform of the object at a multiplicity of distinct spatial frequencies; means for measuring the intensity of the reference beam; means for comparing the measured intensities of the signal and reference beams; and means, responsive to the output of said means for comparing the measured intensities, for maintaining the beam intensities at a value such that the reference beam has an intensity substantially equal to the highest intensity measured for any spatial frequency in the signal beam other than the spatial frequencies near the zero spatial frequency.
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) | 1976-04-23 | 1976-10-23 | 1977-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-23 | 1980-10-23 | 1981-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-23 | 1984-10-23 | 1985-04-24 | $7700.00 | Window Closed / Lapsed |