US2966612A - Radiation detection - Google Patents
Radiation detection Download PDFInfo
- Publication number
- US2966612A US2966612A US664101A US66410157A US2966612A US 2966612 A US2966612 A US 2966612A US 664101 A US664101 A US 664101A US 66410157 A US66410157 A US 66410157A US 2966612 A US2966612 A US 2966612A
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- US
- United States
- Prior art keywords
- target
- infrared
- infrared radiation
- pyroelectric
- polarization
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000005855 radiation Effects 0.000 title description 20
- 238000001514 detection method Methods 0.000 title description 5
- 239000000463 material Substances 0.000 description 12
- 230000010287 polarization Effects 0.000 description 11
- 238000010894 electron beam technology Methods 0.000 description 9
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 6
- 229910002113 barium titanate Inorganic materials 0.000 description 6
- 239000013077 target material Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- LJCNRYVRMXRIQR-OLXYHTOASA-L potassium sodium L-tartrate Chemical compound [Na+].[K+].[O-]C(=O)[C@H](O)[C@@H](O)C([O-])=O LJCNRYVRMXRIQR-OLXYHTOASA-L 0.000 description 2
- 235000011006 sodium potassium tartrate Nutrition 0.000 description 2
- 239000012780 transparent material Substances 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 description 1
- 229940087748 lithium sulfate Drugs 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229940074439 potassium sodium tartrate Drugs 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 125000005402 stannate group Chemical group 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 description 1
- 239000011032 tourmaline Substances 0.000 description 1
- 229940070527 tourmaline Drugs 0.000 description 1
- 229910052613 tourmaline Inorganic materials 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J31/00—Cathode ray tubes; Electron beam tubes
- H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
- H01J31/49—Pick-up adapted for an input of electromagnetic radiation other than visible light and having an electric output, e.g. for an input of X-rays, for an input of infrared radiation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
- H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
- H01J29/36—Photoelectric screens; Charge-storage screens
- H01J29/39—Charge-storage screens
- H01J29/45—Charge-storage screens exhibiting internal electric effects caused by electromagnetic radiation, e.g. photoconductive screen, photodielectric screen, photovoltaic screen
- H01J29/458—Charge-storage screens exhibiting internal electric effects caused by electromagnetic radiation, e.g. photoconductive screen, photodielectric screen, photovoltaic screen pyroelectrical targets; targets for infrared or ultraviolet or X-ray radiations
Definitions
- FIG 2 P F*EXPOSE-+f- COOL '"i READOUT RESET 7 y Y LOW VELOCITY SCAN HIGH VELOCITY SCAN 6 1/60 1 50 1/20 1/75 L/l'2 Mo TIME (SECONDS) RAJ-TOTLAND IN V EN TOR.
- This invention relates to the detection of objects by means of the infrared radiation generated by the objects and to an electrical system whereby the objects are detected.
- a system for the conversion of infrared images to visible images in which a television camera tube provided with a target which includes a pyroelectric material is operated in syncnronism with a means for interrupting the reception of infrared radiation while the pyroelectric target is charged to a desired potential by means of the scanning electron beam and for permitting the infrared radiation to pass to the target during an interval in which the electron beam is not scanning the target.
- the infrared changes the polarization of the target material and hence the potential across the target, i.e., the charge on the surface, and this change is converted into a visible representation by suitable means.
- Figure 1 is a schematic representation of the system forming the present invention
- FIG 2 is a more detailed view of the receiver in Figure l;
- Figure 3 is a representation of the sequence of operation in a complete cycle.
- infrared radiation generated by a body B is received by a receiver R which may consist of a Vidicon, or an iconoscope, or other device in which the scanning of a target by means of an electron beam produces an electrical signal output indicative of the extent to which any incremental area of the target has been exposed to infrared radiation, and which consequently has developed an electrical charge on said incremental area of the target.
- a receiver R which may consist of a Vidicon, or an iconoscope, or other device in which the scanning of a target by means of an electron beam produces an electrical signal output indicative of the extent to which any incremental area of the target has been exposed to infrared radiation, and which consequently has developed an electrical charge on said incremental area of the target.
- the pickup device comprises a receiver having a target consisting of a suitable pyroelectric material 10 supported in one surface of an electrically conductive film 12, on the other surface of which there is disposed a window 14 which is transparent to infrared radiation.
- a single element (not shown) formed of an electrically conductive material which is transparent to infrared radiation may be substituted for film 12 and window 14.
- the receiver consists of a conventional Vidicon or iconoscope, such as that shown in U.S. Patents 2,654,852 and 2,687,484 except that the tube face has been modified.
- the electrically conductive film 12 is connected through an output load resistor 18 selectively by means of switch 20 either to a source of potential 22 or to a small reference potential 26, connected by lead 24 to ground.
- the target may be formed of any suitable pyroelectric material.
- pyroelectric is intended to describe that class of materials which States Patent f 2,966,612 Patented Dec. 27, 1960 2.. experience a change of polarization charges when they undergo a change in temperature.
- Known pyroelectric materials include quartz, tourmaline, lithium sulfate, potassium sodium tartrate (Rochelle salt), and ferroelectric materials such as barium titanate, other titanates, stannates, zirconates, niobates, and the like; These pyroelectric materials may be used either in the form of single crystals or as polycrystalline masses and targets may be formed of a single compound or of mixtures of pyroelectric materials.
- a suitable means 30 interrupts the infrared signal periodically in order to provide an exposure period during which the target receives infrared, radiation, and is thereby heated, and a second period during which the target is shielded from infrared radiation and during which the target is permitted to cool.
- the apparatus illustrated in the drawings was constructed using a standard, commercially available RCA Vidicon No. 6198 as the receiver.
- the pyroelectric portion of target was formed of a layer approximately 0.001 cm. thick composed of a thin platelet of barium titanate.
- Electrode 12 comprised a thin layer of metallic aluminum, deposited on the thin platelet of barium titanate by vacuum coating techniques Well known in the art.
- a suitable infrared transmitting material was then applied to the outer surface of the electrode 12, a Calwindow having been found satisfactory.
- a chopping wheel run at 10 cycles per second was placed between the target face and the source of infrared radiation.
- FIG 3 shows a complete cycle of operation on a time scale in which, for purposes of illustration, each unit is one-sixtieth 4 of one second.
- the switch is connected to the one volt source of potential and the shutter is open, thereby heating the target.
- the polarization of the barium titanate film decreases (pyroelectric effect).
- the heat image is thereby converted to a polarization image; the hot areas having a lower polarization than the cool area of the target.
- One-sixtieth of a second later the electron beam is caused to scan the rear surface of the barium titanate film.
- This low velocity beam deposits (as it scans) a charge per unit area related to the polarization of the barium titanate.
- the charge deposited is capacitively coupled, through the capacity of the film, to the load resistor; hence the charge generates an output voltage across the load resistor.
- the scanning beam has completed its scan and the chopping wheel cuts off the incident infrared radiation from the target.
- the target is now allowed to cool for one-twentieth of a second.
- the target is returned to ground potential by scanning the target with a high velocity electron beam and allowing the resultant secondary emission to charge the target down to the potential of a collector held at ground potential.
- the high velocity is imparted to the scanning beam by connecting the target substrate to the volt source of potential.
- One-sixtieth of a second later the whole target is returned to ground potential, the scanning beam has finished its scan, and the cycle is completed.
- the sensitivity of the device described will depend in large measure on the relative change in polarization produced by a unit change in temperature and that it is particularly advantageous to operate with the target at temperatures at which the change in polarization is a maximum. For many ferroelectric materials this will be at temperatures approaching their Curie point.
- infrared radiation is intended to apply to electromagnetic radiation having a wavelength between 0.7-30 microns.
- An apparatus for converting an infrared image into a visible image which comprises: an evacuated envelope, one end of which comprises a pyroelectric target material adapted to receive said infrared image; a layer of an infrared transparent material on the outer surface of said target and a transparent, electrically conductive layer between the pyroelectric target and the infrared transparent material; and an electron gun within said envelope for directing a stream of electrons onto said target material.
- a system for producing an output signal representing the image produced by exposure of a material which experiences a change in polarization when exposed to infrared radiation which comprises: a television camera tube having a target composed of a pyroelectric material supported on an infrared transparent electrically conductive metal backing; electron gun means capable of generating a low-velocity electron beam and a high-velocity electron beam, wherein said electron gun high-velocity beam is adapted to return said target to ground potential during an interval when said target is cut off from infrared radiation, and said electron gun low-velocity electron beam is adapted to scan said target during at least-a portion "of the interval during which the target is exposed to infrared radiation and'thereby deposit a charge on said target varying with the polarization of each increment of said target; means for cutting ofl the infrared radiation during one portion of an operating cycle and for exposing said target to a pattern of infrared radiation during another portion of the cycle of operation, thereby producing a change in polarization of said target
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Description
Dec. 27, 1960 A. FOTLAND 2,966,612
. RADIATION DETECTION Filed June 6. 1957 FIG I OUTPUT SIGNAL 22 20 .f
24 FIG 2 P" F*EXPOSE-+f- COOL '"i READOUT RESET 7 y Y LOW VELOCITY SCAN HIGH VELOCITY SCAN 6 1/60 1 50 1/20 1/75 L/l'2 Mo TIME (SECONDS) RAJ-TOTLAND IN V EN TOR.
oz m ,Q 32% RADIATION DETECTION Richard A. Fotland, Cleveland, Ohio, assignor to Horizons Incorporated, a corporation of New Jersey Filed June 6, 1957, Ser. No. 664,101 2 Claims. (Cl. 315-10 This invention relates to the detection of objects by means of the infrared radiation generated by the objects and to an electrical system whereby the objects are detected. More particularly it relates to a system for the conversion of infrared images to visible images in which a television camera tube provided with a target which includes a pyroelectric material is operated in syncnronism with a means for interrupting the reception of infrared radiation while the pyroelectric target is charged to a desired potential by means of the scanning electron beam and for permitting the infrared radiation to pass to the target during an interval in which the electron beam is not scanning the target. As a result, the infrared changes the polarization of the target material and hence the potential across the target, i.e., the charge on the surface, and this change is converted into a visible representation by suitable means.
The invention will be more fully understood by reference to the accompanying drawings, in which:
Figure 1 is a schematic representation of the system forming the present invention;
Figure 2 is a more detailed view of the receiver in Figure l; and
Figure 3 is a representation of the sequence of operation in a complete cycle.
As represented diagrammatically in Figure l, infrared radiation generated by a body B is received by a receiver R which may consist of a Vidicon, or an iconoscope, or other device in which the scanning of a target by means of an electron beam produces an electrical signal output indicative of the extent to which any incremental area of the target has been exposed to infrared radiation, and which consequently has developed an electrical charge on said incremental area of the target.
In the embodiment illustrated in the drawings, the pickup device comprises a receiver having a target consisting of a suitable pyroelectric material 10 supported in one surface of an electrically conductive film 12, on the other surface of which there is disposed a window 14 which is transparent to infrared radiation. In an alternative construction, a single element (not shown) formed of an electrically conductive material which is transparent to infrared radiation may be substituted for film 12 and window 14. As shown in Figure 2, the receiver consists of a conventional Vidicon or iconoscope, such as that shown in U.S. Patents 2,654,852 and 2,687,484 except that the tube face has been modified. It comprises an evacuated glass envelope 16 with an electron gun 17 for generating an electron beam and means (not shown) for focussing and for deflecting the beam so as to cause it to travel in any desired path. The electrically conductive film 12 is connected through an output load resistor 18 selectively by means of switch 20 either to a source of potential 22 or to a small reference potential 26, connected by lead 24 to ground.
In the device illustrated the target may be formed of any suitable pyroelectric material. The term pyroelectric is intended to describe that class of materials which States Patent f 2,966,612 Patented Dec. 27, 1960 2.. experience a change of polarization charges when they undergo a change in temperature. Known pyroelectric materials include quartz, tourmaline, lithium sulfate, potassium sodium tartrate (Rochelle salt), and ferroelectric materials such as barium titanate, other titanates, stannates, zirconates, niobates, and the like; These pyroelectric materials may be used either in the form of single crystals or as polycrystalline masses and targets may be formed of a single compound or of mixtures of pyroelectric materials. When a' polycrystalline ferroelectric target is employed, it should be polarized prior to operation of the detection system. A suitable means 30 interrupts the infrared signal periodically in order to provide an exposure period during which the target receives infrared, radiation, and is thereby heated, and a second period during which the target is shielded from infrared radiation and during which the target is permitted to cool.
A specific example will serve to further illustrate the practice of the present invention. The apparatus illustrated in the drawings was constructed using a standard, commercially available RCA Vidicon No. 6198 as the receiver. The pyroelectric portion of target was formed of a layer approximately 0.001 cm. thick composed of a thin platelet of barium titanate. Electrode 12 comprised a thin layer of metallic aluminum, deposited on the thin platelet of barium titanate by vacuum coating techniques Well known in the art. A suitable infrared transmitting material was then applied to the outer surface of the electrode 12, a Calwindow having been found satisfactory. For the interrupting means 30, a chopping wheel run at 10 cycles per second was placed between the target face and the source of infrared radiation.
Figure 3 shows a complete cycle of operation on a time scale in which, for purposes of illustration, each unit is one-sixtieth 4 of one second. In the system shown in Figure 1, at the start of a cycle, the switch is connected to the one volt source of potential and the shutter is open, thereby heating the target. As the target is heated, the polarization of the barium titanate film decreases (pyroelectric effect). The heat image is thereby converted to a polarization image; the hot areas having a lower polarization than the cool area of the target. One-sixtieth of a second later the electron beam is caused to scan the rear surface of the barium titanate film. This low velocity beam deposits (as it scans) a charge per unit area related to the polarization of the barium titanate. The charge deposited is capacitively coupled, through the capacity of the film, to the load resistor; hence the charge generates an output voltage across the load resistor. One-sixtieth of a second later, the scanning beam has completed its scan and the chopping wheel cuts off the incident infrared radiation from the target. The target is now allowed to cool for one-twentieth of a second. At the end of this time the target is returned to ground potential by scanning the target with a high velocity electron beam and allowing the resultant secondary emission to charge the target down to the potential of a collector held at ground potential. The high velocity is imparted to the scanning beam by connecting the target substrate to the volt source of potential. One-sixtieth of a second later the whole target is returned to ground potential, the scanning beam has finished its scan, and the cycle is completed.
It will be readily appreciated that the sensitivity of the device described will depend in large measure on the relative change in polarization produced by a unit change in temperature and that it is particularly advantageous to operate with the target at temperatures at which the change in polarization is a maximum. For many ferroelectric materials this will be at temperatures approaching their Curie point.
In the, above description, the term infrared radiation is intended to apply to electromagnetic radiation having a wavelength between 0.7-30 microns.
Having now described my invention in accordance with the patent statutes, I claim:
1. An apparatus for converting an infrared image into a visible image which comprises: an evacuated envelope, one end of which comprises a pyroelectric target material adapted to receive said infrared image; a layer of an infrared transparent material on the outer surface of said target and a transparent, electrically conductive layer between the pyroelectric target and the infrared transparent material; and an electron gun within said envelope for directing a stream of electrons onto said target material.
2. A system for producing an output signal representing the image produced by exposure of a material which experiences a change in polarization when exposed to infrared radiation which comprises: a television camera tube having a target composed of a pyroelectric material supported on an infrared transparent electrically conductive metal backing; electron gun means capable of generating a low-velocity electron beam and a high-velocity electron beam, wherein said electron gun high-velocity beam is adapted to return said target to ground potential during an interval when said target is cut off from infrared radiation, and said electron gun low-velocity electron beam is adapted to scan said target during at least-a portion "of the interval during which the target is exposed to infrared radiation and'thereby deposit a charge on said target varying with the polarization of each increment of said target; means for cutting ofl the infrared radiation during one portion of an operating cycle and for exposing said target to a pattern of infrared radiation during another portion of the cycle of operation, thereby producing a change in polarization of said target material; and a load resistor directly connected to said electrically conductive metal backing member of said target to generate an output signal representative of the charge deposited on said target during the low velocity scan.
References Cited in the file of this patent UNITED STATES PATENTS 2,373,395 Hefele -2 Apr. 10, 1945 2,654,853 Weimer Oct. 6, 1953 2,727,170 Rudy Dec. 13, 1955 2,816,954 Hufiman Dec. 17, 1957 2,879,401 Chicurel Mar. 24, 1959
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US664101A US2966612A (en) | 1957-06-06 | 1957-06-06 | Radiation detection |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US664101A US2966612A (en) | 1957-06-06 | 1957-06-06 | Radiation detection |
Publications (1)
Publication Number | Publication Date |
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US2966612A true US2966612A (en) | 1960-12-27 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US664101A Expired - Lifetime US2966612A (en) | 1957-06-06 | 1957-06-06 | Radiation detection |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3144575A (en) * | 1960-04-18 | 1964-08-11 | Victor A Babits | Parametric target for infrared televsion pickup tubes |
US3188506A (en) * | 1959-11-23 | 1965-06-08 | Machlett Lab Inc | Cathode ray tube with signal plate connected to contact ring having envelope diameter |
US3930157A (en) * | 1973-07-23 | 1975-12-30 | Secr Defence Brit | Pyroelectric camera tube systems |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2373395A (en) * | 1941-05-01 | 1945-04-10 | Bell Telephone Labor Inc | Electron discharge device |
US2654853A (en) * | 1949-02-28 | 1953-10-06 | Rca Corp | Photoelectric apparatus |
US2727170A (en) * | 1951-11-01 | 1955-12-13 | Rca Corp | Ceramic mosaic for camera pick-up tube |
US2816954A (en) * | 1952-10-23 | 1957-12-17 | David A Huffman | Infra-red television camera |
US2879401A (en) * | 1954-12-03 | 1959-03-24 | Gulton Ind Inc | Device for detecting electromagnetic radiations |
-
1957
- 1957-06-06 US US664101A patent/US2966612A/en not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2373395A (en) * | 1941-05-01 | 1945-04-10 | Bell Telephone Labor Inc | Electron discharge device |
US2654853A (en) * | 1949-02-28 | 1953-10-06 | Rca Corp | Photoelectric apparatus |
US2727170A (en) * | 1951-11-01 | 1955-12-13 | Rca Corp | Ceramic mosaic for camera pick-up tube |
US2816954A (en) * | 1952-10-23 | 1957-12-17 | David A Huffman | Infra-red television camera |
US2879401A (en) * | 1954-12-03 | 1959-03-24 | Gulton Ind Inc | Device for detecting electromagnetic radiations |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3188506A (en) * | 1959-11-23 | 1965-06-08 | Machlett Lab Inc | Cathode ray tube with signal plate connected to contact ring having envelope diameter |
US3144575A (en) * | 1960-04-18 | 1964-08-11 | Victor A Babits | Parametric target for infrared televsion pickup tubes |
US3930157A (en) * | 1973-07-23 | 1975-12-30 | Secr Defence Brit | Pyroelectric camera tube systems |
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