US3735139A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photo detector system with dual mode capability
Assignee: General Dynamics Corp
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Filing: 1972-04-07
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Granted: 1973-05-22
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Expires: 1992-04-07
Abstract
Abstract A photo detector system is described which has dual modes of operation under both dim and bright illumination conditions. Optics image incoming illumination directly upon an array of semiconductor detector diodes as well as upon a photo cathode. When bright light is present the optical image is focused upon the diode detector array and no high voltage is applied to the photo cathode. The light will not damage the photo cathode since the high voltage is off. Also, no electrons are accelerated toward the photo diode detectors. Thus, during bright light operation, the signal current is caused primarily by the direct effect of light on the diode detectors. In dim light, high negative voltage is applied to the photo cathode and the optical image is focused on the photo cathode. The electron optic design causes the electrons emitted from the photo cathode to be imaged onto the same diode detectors that are used during bright light operation. These electrons strike the detectors with a high velocity induced by the applied voltage. The signal current due to this electron bombardment is therefore many times greater than the current due to the dim light striking the diodes directly. Detector response to dim levels of illumination is thus increased while retaining normal operational capability under bright illumination conditions.
Inventors
- 👤 A Kalitinsky
- 👤 J Crooks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:59
CPC Classifications
H; H01; H01J; H01J31/00; H01J31/08; H01J31/26
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
64 words
Apparatus for detecting radiant energy from a source of radiant energy which comprises: a. a photo electric element for providing an electric signal when irradiated by radiant energy from said source and by electrons, b. a photoemissive element for emitting electrons when irradiated by radiant energy from said source, and c. means for Irradiating said photoelectric element with electrons emitted by said photoemissive element.
Claim 2
Dependent Claim
64 words
Apparatus for detecting radiant energy from a source of radiant energy which comprises: a. a photo electric element for providing an electric signal when irradiated by radiant energy from said source and by electrons, b. a photoemissive element for emitting electrons when irradiated by radiant energy from said source, and c. means for Irradiating said photoelectric element with electrons emitted by said photoemissive element.
Claim 3
Dependent Claim
68 words
Apparatus for intensifying images which comprises: a. a photoelectric element, b. means for imaging radiant energy from said image upon said photoelectric element, c. a photoemissive element, d. means for also imaging radiant energy from said image upon said photoemissive element, and e. electron optical means for imaging the electrons emitted by said photoemissive element upon said photoelectric element whereby to intensify said image at said photoelectric element.
Claim 4
Dependent Claim
68 words
Apparatus for intensifying images which comprises: a. a photoelectric element, b. means for imaging radiant energy from said image upon said photoelectric element, c. a photoemissive element, d. means for also imaging radiant energy from said image upon said photoemissive element, and e. electron optical means for imaging the electrons emitted by said photoemissive element upon said photoelectric element whereby to intensify said image at said photoelectric element.
Claim 5
Dependent Claim
36 words
The invention as set forth in claim 2, wherein said means for imaging said radiant energy images upon said elements includes optical means for focussing said images upon either said photoelectric element or said photoemissive element.
Claim 6
Dependent Claim
28 words
The invention as set forth in claim 3 wherein said photoelectric element and said photoemissive element are spaced from each other along the path of said radiant energy.
Claim 7
Dependent Claim
41 words
The invention as set forth in claim 4, wherein said photoelectric element and said photoemissive element are also laterally offset from each other, said photoemissive element being disposed ahead of said photoelectric element in the direction of propagation of such energy.
Claim 8
Dependent Claim
71 words
Photoelectric detector apparatus which comprises: a. a photoelectric transducer, b. said transducer being disposed directly to receive illumination to be detected, c. a photoemissive element in spaced relationship with said photoelectric transducer, d. said element also being disposed directly to receive illumination to be detected, and e. electron optical means operative to direct electrons resulting from said illumination to said transducer for augmenting the effect of said illumination at said transducer.
Claim 9
Dependent Claim
71 words
Photoelectric detector apparatus which comprises: a. a photoelectric transducer, b. said transducer being disposed directly to receive illumination to be detected, c. a photoemissive element in spaced relationship with said photoelectric transducer, d. said element also being disposed directly to receive illumination to be detected, and e. electron optical means operative to direct electrons resulting from said illumination to said transducer for augmenting the effect of said illumination at said transducer.
Claim 10
Dependent Claim
28 words
The invention as set forth in claim 6 including means for rendering said electron optical means operative whereby to operate said apparatus selectively in augmented and normal modes.
Claim 11
Dependent Claim
35 words
The invention as set forth in claim 6 wherein said electron optical means includes means for accelerating the electrons emitted by said photoemissive element so that said electrons bombard said transducer to induce conduction therein.
Claim 12
Dependent Claim
27 words
The invention as set forth in claim 8, wherein said electron optical means further includes means for converging said electrons into a beam focused at said transducer.
Claim 13
Dependent Claim
23 words
The invention as set forth in claim 9 wherein said electron optical means further includes means for deflecting said beam across said transducer.
Claim 14
Dependent Claim
15 words
The invention as set forth in claim 9 wherein said transducer is a semiconductive photodiode.
Claim 15
Dependent Claim
36 words
The invention as set forth in claim 10 wherein said transducer comprises a substrate disposed in the path of said beam and an array of semiconductive photodiodes disposed in side by side relationship on said substrate.
Claim 16
Dependent Claim
37 words
The invention as set forth in claim 6 wherein said photoemissive element is a photocathode, and said electron optical means, includes means for applying voltage to said photocathode to make said photocathode more negative than said transducer.
Claim 17
Dependent Claim
59 words
The invention as set forth in claim 13, wherein said electron optical means includes a plurality of electrodes disposed in spaced relationship between said photocathode and said transducer, and means for applying negative voltages of successively higher magnitude to said electrodes with the highest of said voltages being applied to the one of said electrodes closest to said photocathode.
Claim 18
Dependent Claim
42 words
The invention as set forth in claim 14 wherein said transducer has a surface, and wherein said electron optical means includes a coil disposed around said electrodes for converging said electrons from said photocathode into a beam focused at said transducer surface.
Claim 19
Dependent Claim
54 words
The invention as set forth in claim 14 wherein said electron optical means includes a pair or array of permanent magnets, spaced laterally from each other, said transducer and said photocathode beinG disposed adjacent opposite ends of the region between said magnets, said magnets defining a focussing field for electrons emitted by said photocathode.
Claim 20
Dependent Claim
28 words
The invention as set forth in claim 16, wherein said photocathode is disposed along an axis extending longitudinally through said region, said photocathode being offset from said axis.
Claim 21
Dependent Claim
31 words
The invention as set forth in claim 17 including a mirror disposed between said photocathode and said transducer and offset from said axis, said mirror reflecting said illumination to said photocathode.
Claim 22
Dependent Claim
33 words
The invention as set forth in claim 18 wherein said transducer has photoconductive material having a surface, and wherein said electron optical means includes means for scanning said focussed electrons over said surface.
Claim 23
Dependent Claim
64 words
The invention as set forth in claim 6 further comprising an envelope having a window for the passage of said illumination at one end thereof, said transducer being disposed at the end of said envelope opposite from said window, said photoemissive element being a photocathode disposed on the inner surface of said window, said electron optical means comprising an electron gun within said envelope.
Claim 24
Dependent Claim
17 words
The invention as set forth in claim 20 wherein said photocathode is a layer of photoemissive material.
Claim 25
Dependent Claim
17 words
The invention as set forth in claim 21, wherein said layer is partially transparent to said illumination.
Claim 26
Dependent Claim
37 words
The invention as set forth in claim 21, wherein said transducer is located on the axis of said envelope and said photocathode is disposed upon a portion of said window which is laterally offset from said axis.
Claim 27
Dependent Claim
30 words
The invention as set forth in claim 21, including first lens means for focussing said illumination at said transducer, and second lens means for focussing said illumination at said photocathode.
Claim 28
Dependent Claim
24 words
The invention as set forth in claim 20, further comprising deflection coil means encompassing said envelope, and focussing coil means also encompassing said envelope.
Claim 29
Dependent Claim
39 words
The invention as set forth in claim 25, wherein said transducer is an array of semiconductive photodiodes, and leads to each of the diodes in said array extending from said diodes through said envelope at said one end thereof.
Claim 30
Dependent Claim
104 words
The invention as set forth in claim 20 wherein said electron gun comprises a plurality of conductive electrodes disposed within said envelope, said electrodes being coaxial with the axis of said envelopes, one of said electrodes being disposed upon said window and in contact with said photocathode, said electrodes being spaced from each other in a direction longitudinally along said axis, means for applying a first negative potential to said one electrode and negative potentials of successively lower magnitude than the magnitude of said one potential to the other ones of the other of said electrodes which are spaced successively closer to said transducer.
Claim 31
Dependent Claim
17 words
The invention as set forth in claim 27 including a cylinder of encapsulating material surrounding said envelope.
Claim 32
Dependent Claim
38 words
The invention as set forth in claim 28 including bar magnets encapsulated in said material and diametrically disposed in the direction of the axis of said envelope and diametrically opposite each other on opposite sides of said axis.
Claim 33
Dependent Claim
77 words
The invention as set forth in claim 29 wherein said photocathode is disposed to one side of said envelope, a mirror disposed within said envelope and spaced away from said window toward said transducer and to the opposite side of said envelope for reflecting illumination to said photocathode, said bar magnets being tilted with respect to the axis of said envelope for establishing a magnetic focussing field for focussing electrons emitted from said photocathode at said transducer.
Claim 34
Dependent Claim
24 words
The invention as set forth in claim 20 including a means for focussing electrons emitted from different portions of said photocathode upon said transducer.
Claim 35
Dependent Claim
21 words
The invention as set forth in claim 31 wherein said focussing means comprises deflection and focussing coil Means surrounding said envelope.
Claim 36
Dependent Claim
18 words
The invention as set forth in claim 31 including means for providing said portions with different spectral characteristics.
Claim 37
Dependent Claim
25 words
The invention as set forth in claim 33 wherein said spectral characteristic providing means comprises filters interposed in the path of illumination to said photocathode.
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) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |