US3445709A - Cylinder with internal photosensitive coating and prism on outer surface for admitting light at an angle to be totally internally reflected - Google Patents

Cylinder with internal photosensitive coating and prism on outer surface for admitting light at an angle to be totally internally reflected Download PDF

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Publication number
US3445709A
US3445709A US648459A US3445709DA US3445709A US 3445709 A US3445709 A US 3445709A US 648459 A US648459 A US 648459A US 3445709D A US3445709D A US 3445709DA US 3445709 A US3445709 A US 3445709A
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United States
Prior art keywords
prism
light
angle
layer
cylinder
Prior art date
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Expired - Lifetime
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US648459A
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English (en)
Inventor
Kenneth R Crowe
Howard A Leiter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TDK Micronas GmbH
ITT Inc
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Deutsche ITT Industries GmbH
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Assigned to ITT CORPORATION reassignment ITT CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: INTERNATIONAL TELEPHONE AND TELEGRAPH CORPORATION
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J40/00—Photoelectric discharge tubes not involving the ionisation of a gas
    • H01J40/02—Details
    • H01J40/04—Electrodes
    • H01J40/06—Photo-emissive cathodes

Definitions

  • a cylindrical phototube has a photosensitive layer on the inner surface of a glass envelope. Light is injected into a prism on the outer surface at an angle to cause total reflection along multiple paths within the glass between the photosensitive layer and outer surface around the tube. The photosensitive layer is responsive to changes in light intensity and provides an electrical output signal which varies accordingly.
  • the present invention relates to photosensitive tubes and particularly to an improved structure utilizing multireflected light.
  • Prior art phototubes have utilized reflected light to provide greater sensitivity and electron emission from photocathodes. These have generally employed a flat glass faceplate into one end of which light was injected at an angle to cause total internal reflection. A flat photoemissive layer on a surface of the glass provided increased electron emission due to the multiple reflections of the light beam.
  • One such device is illustrated in US. Patent No. 3, 040,976, issued July 10, 1962. There is need, however, for tubes having even greater sensitivities and for a configuration that is capable of adaption to a variety of systems utilizing light detection devices.
  • a novel cylindrical phototube structure wherein light is injected into the glass envelope for total internal reflection around the cylinder.
  • the characteristics of a photosensitive layer on the inner surface of the glass change in accordance with the intensity of light projected thereon to provide an output signal.
  • a photocathode layer emitting electrons in response to the light intensity may be utilized in conjunction with a centrally positioned anode or an electron multiplier to provide a varying output current, or a photoconductive layer having a resistance which changes with light intensity may similarly be employed.
  • FIG. 1 is a top cross-sectional view of one form of the novel cylindrical pho-totube structure.
  • FIG. 2 shows a side view of the structure
  • FIG. 3 shows an electron multiplier used in conjunction with the phototube.
  • a source of light 10 is directed at a prism or stepped window 12 on the outer surface of a cylindrical glass envelope 14 of a photosensitive tube 16.
  • the light or radiation enters the envelope at normal incidence to the prism faceplate.
  • the prism is designed so that the angle of incidence of the beam entering the prism at the glass-air interface on the outer surface and at the glass-vacuum interface on the inner surface, is greater than the critical angle. This is a known relationship which causes the light to be trapped within the glass envelope so that the light is reflected in multiple bounces, shown by dashed lines, between the inner and outer surfaces as it continues around the cylindrical envelope.
  • the critical angle is a function of the index of refraction of the particular transparent material and is usually about 42-45.
  • a relatively thin photoemissive layer or coating 18 is deposited around the inner surface of the glass so that electrons, shown by dotted lines and arrows, are emitted at each point as the light strikes the inner surface and photons penetrate the emissive layer.
  • the multiple passes permit increased absorption of energy for any particular desired wavelength region and are particularly useful with long infrared wavelengths which require absorption by the photosensitive material.
  • a longitudinal anode or collector electrode 20 is centrally positioned within the tube to collect the electrons.
  • a suitable source of potential 22 is connected between the anode and photoemissive cathode to cause electrons to be attracted to the anode which is also connected to an output circuit or utilization device 2'4, as shown in FIG. 2.
  • the cathode may typically be at ground potential while the anode may be at volts.
  • Suitable photoemissive materials such as a standard S11 type coating which includes cesium and antimony, or an S20 coating including antimony, potassium, sodium and cesium may be used. If a poor conductor is employed as the cathode material, it is necessary to apply a nonabsorptive transparent conductive coating 30 such as NESA or tin oxide material to the glass before applying the photoemissive layer. The potential source will then be connected between the conductive coating and the anode.
  • the present invention thus provides an improved phototube of greater sensitivity having a novel multirefiecting cylindrical structure which is useful in a variety of applications. While several embodiments have been illustrated, it is apparent that the invention is not limited to the exact forms or uses shown and that many other variations may be made in the particular design and configuration without departing from the scope of the invention as set forth in the appended claims.
  • said photosensitive coating includes a photoemissive layer emitting electrons in response to said light impinging thereon and a centrally positioned anode arranged to collect said electrons, said potential being applied between said layer and said anode.
  • said photosensitive coating includes a photoconductive layer having a resistance which changes in accordance with said light intensity, said potential being applied between opposite ends of said layer.
  • said photosensitive coating includes a photoemissive layer emitting electrons in response to said light impinging thereon and an electron multiplier arranged to collect said electrons, said potential being applied between said layer and said electron multiplier.
  • said electron multiplier includes an accelerating electrode arranged to attract said electrons into said multiplier.
  • said accelerating electrode is a coaxial ring positioned adjacent said layer and including a plurality of successive longitudinally positioned dynodes, said potential being applied between said layer and said accelerating electrode.

Landscapes

  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US648459A 1967-06-23 1967-06-23 Cylinder with internal photosensitive coating and prism on outer surface for admitting light at an angle to be totally internally reflected Expired - Lifetime US3445709A (en)

Applications Claiming Priority (1)

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US64845967A 1967-06-23 1967-06-23

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US3445709A true US3445709A (en) 1969-05-20

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US (1) US3445709A (forum.php)
BE (1) BE717840A (forum.php)
DE (1) DE1764538A1 (forum.php)
FR (1) FR1580311A (forum.php)
GB (1) GB1220736A (forum.php)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59120983A (ja) * 1982-12-28 1984-07-12 Matsushita Electric Works Ltd 太陽電池時計

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2254422A (en) * 1936-05-27 1941-09-02 Gabor Dennis Electron multiplier
US2538588A (en) * 1948-06-23 1951-01-16 Continental Electric Company Photocell
US2544261A (en) * 1948-11-11 1951-03-06 Alan F Gibson Infrared sensitive cell
US2678400A (en) * 1950-12-30 1954-05-11 Bell Telephone Labor Inc Photomultiplier utilizing bombardment induced conductivity
US3043976A (en) * 1958-01-18 1962-07-10 Leitz Ernst Gmbh Photocathode for photocells, photoelectric quadrupler and the like
US3060338A (en) * 1959-10-20 1962-10-23 Philco Corp Photoconductor device
US3082342A (en) * 1959-02-11 1963-03-19 Philips Corp Photo-electric tube
US3099764A (en) * 1960-05-05 1963-07-30 Rca Corp Photomultiplier tube
US3239709A (en) * 1962-06-26 1966-03-08 Rca Corp Electron multiplier having electrostatic field shaping electrodes
US3299306A (en) * 1964-07-23 1967-01-17 Optics Technology Inc Phototube having a photocathode adapted to absorb substantially all the light energyreceived
US3317738A (en) * 1963-12-12 1967-05-02 Licentia Gmbh Photoelectric scanning arrangement using light conducting rod with fluorescent portion

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2254422A (en) * 1936-05-27 1941-09-02 Gabor Dennis Electron multiplier
US2538588A (en) * 1948-06-23 1951-01-16 Continental Electric Company Photocell
US2544261A (en) * 1948-11-11 1951-03-06 Alan F Gibson Infrared sensitive cell
US2678400A (en) * 1950-12-30 1954-05-11 Bell Telephone Labor Inc Photomultiplier utilizing bombardment induced conductivity
US3043976A (en) * 1958-01-18 1962-07-10 Leitz Ernst Gmbh Photocathode for photocells, photoelectric quadrupler and the like
US3082342A (en) * 1959-02-11 1963-03-19 Philips Corp Photo-electric tube
US3060338A (en) * 1959-10-20 1962-10-23 Philco Corp Photoconductor device
US3099764A (en) * 1960-05-05 1963-07-30 Rca Corp Photomultiplier tube
US3239709A (en) * 1962-06-26 1966-03-08 Rca Corp Electron multiplier having electrostatic field shaping electrodes
US3317738A (en) * 1963-12-12 1967-05-02 Licentia Gmbh Photoelectric scanning arrangement using light conducting rod with fluorescent portion
US3299306A (en) * 1964-07-23 1967-01-17 Optics Technology Inc Phototube having a photocathode adapted to absorb substantially all the light energyreceived

Also Published As

Publication number Publication date
DE1764538A1 (de) 1971-08-05
BE717840A (forum.php) 1969-01-10
FR1580311A (forum.php) 1969-09-05
GB1220736A (en) 1971-01-27

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Owner name: ITT CORPORATION

Free format text: CHANGE OF NAME;ASSIGNOR:INTERNATIONAL TELEPHONE AND TELEGRAPH CORPORATION;REEL/FRAME:004389/0606

Effective date: 19831122