US3951552A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photometer-digitizer system
Assignee: Massachusetts Institute of Technology
•
Filing: 1972-08-07
•
Granted: 1976-04-20
•
Expires: 1992-08-07
Abstract
Abstract A long exposure photometer-digitizer operative in an integration mode to receive weak illumination as from celestial observations through a telescope or from field or laboratory observations of objects and to provide a recorded digital representation thereof. A silicon, vidicon illumination sensor is employed to provide a wide dynamic range, sensitive and linear response over a large spectral region. Cumulative photon interaction with the vidicon tube during a long exposure is achieved by operating the vidicon at a reduced temperature which minimizes dark current effects and promotes integration mode operation. After a predetermined vidicon exposure interval the image electrically stored in the target is read out by a scanning electron beam, digitized and recorded to provide an immediately available digital record of the object. The target is sensitized before each exposure.
Inventors
- 👤 Thomas B. McCord
- 👤 James A. Westphal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:14
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/44; G01J1/46
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
181 words
A method for providing long-term single photometer exposure to relatively weak radiation comprising the steps of: cooling the target of a vidicon tube to a lowered temperature which reduces dark currents in the target; establishing a predetermined charge across the P-N junction of the target of said vidicon type tube with the cooling of said target preventing discharge of said P-N junction; inhibiting electron beam scanning of the target of said vidicon type tube for a predetermined interval; exposing said target to said relatively weak radiation for a period within said predetermined interval, said period being substantially longer than the scan period for the vidicon type tube; the exposure of said target to said relatively weak radiation producing a cumulative discharge pattern on said target linearly representative of radiation incident on said target over a wide dynamic range, the reduction of dark currents by the cooling of said target preventing substantial distortion of the discharge pattern during said period; producing electron beam scanning of said target subsequent to said predetermined interval to produce an output signal representative of the discharge pattern.
Claim 2
Independent Claim
181 words
A method for providing long-term single photometer exposure to relatively weak radiation comprising the steps of: cooling the target of a vidicon tube to a lowered temperature which reduces dark currents in the target; establishing a predetermined charge across the P-N junction of the target of said vidicon type tube with the cooling of said target preventing discharge of said P-N junction; inhibiting electron beam scanning of the target of said vidicon type tube for a predetermined interval; exposing said target to said relatively weak radiation for a period within said predetermined interval, said period being substantially longer than the scan period for the vidicon type tube; the exposure of said target to said relatively weak radiation producing a cumulative discharge pattern on said target linearly representative of radiation incident on said target over a wide dynamic range, the reduction of dark currents by the cooling of said target preventing substantial distortion of the discharge pattern during said period; producing electron beam scanning of said target subsequent to said predetermined interval to produce an output signal representative of the discharge pattern.
Claim 3
Dependent Claim
23 words
The method of claim 1 further including the step of: providing a digital recording of said output signal representative of the discharge pattern.
Claim 4
Dependent Claim
183 words
Apparatus for providing integrating mode, relatively long-term, single exposure of the target of a vidicon type tube to relatively weak radiation comprising: a vidicon type tube having a target which includes a plurality of P-N junctions; means for producing electron beam scanning of the target of said vidicon type tube to produce a predetermined charge across the P-N junctions of said target; means for cooling the target of said vidicon type tube so as to maintain said charge pattern for relatively long exposures of the weak radiation; means for inhibiting scanning by said electron beam of said target for a predetermined interval; means for exposing the target of said vidicon type tube to said relatively weak radiation for a period within said predetermined interval; the exposure of said target to said relatively weak radiation producing integrating mode, cumulative discharge of the P-N junctions of said target in a pattern representative of said weak radiation; and means for causing scanning by said electron beam of said target subsequent to said predetermined interval to provide an output signal representing the discharge pattern on said target.
Claim 5
Dependent Claim
183 words
Apparatus for providing integrating mode, relatively long-term, single exposure of the target of a vidicon type tube to relatively weak radiation comprising: a vidicon type tube having a target which includes a plurality of P-N junctions; means for producing electron beam scanning of the target of said vidicon type tube to produce a predetermined charge across the P-N junctions of said target; means for cooling the target of said vidicon type tube so as to maintain said charge pattern for relatively long exposures of the weak radiation; means for inhibiting scanning by said electron beam of said target for a predetermined interval; means for exposing the target of said vidicon type tube to said relatively weak radiation for a period within said predetermined interval; the exposure of said target to said relatively weak radiation producing integrating mode, cumulative discharge of the P-N junctions of said target in a pattern representative of said weak radiation; and means for causing scanning by said electron beam of said target subsequent to said predetermined interval to provide an output signal representing the discharge pattern on said target.
Claim 6
Dependent Claim
21 words
The apparatus of claim 3 further including: means for providing a digital record of said output signal representing said discharge pattern.
References Cited (Backward Citations)
US3021433A
Cited
US3011089A
Cited
US3407322A
Cited
US3227885A
Cited
US3403284A
Cited
US3634692A
Cited
US3617626A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-04-20 | 1979-10-20 | 1980-04-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-20 | 1983-10-20 | 1984-04-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-20 | 1987-10-20 | 1988-04-20 | $7700.00 | Window Closed / Lapsed |