JP3854723B2 - Phototube - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a phototube that converts photons incident on a photocathode (photocathode) into photoelectrons and takes it out of an anode, and more particularly to a phototube having a reflective photocathode.
[0002]
[Prior art]
As a photoelectron emission layer of this type of phototube, a phototube capable of responding to a broadband light wavelength has been developed, and a phototube having high photodetection sensitivity and a large S / N ratio has been realized. Therefore, this photoelectric tube is widely used in fields that require a light detection area that cannot be handled by other semiconductor photosensors.
[0003]
As such a conventional reflection type phototube, a phototube having a structure disclosed in Japanese Patent Laid-Open No. 7-105903 is generally used. That is, as shown in FIG. 4, a photocathode (cathode) 102 having a photoelectron emission layer is provided in the metal bulb 100, and a cathode voltage is applied to the photocathode 102 via lead wires 104 and 106. Has been. When photons enter the photocathode 102 via the light receiving face plate 108, photoelectrons corresponding to the amount of incident light are emitted from the photocathode 102. The photoelectrons are collected on the side wall of the metal bulb 100 that also serves as an anode, and incident light is detected as an electric signal.
[0004]
[Problems to be solved by the invention]
By the way, in the above-mentioned phototube, since the metal valve 100 which also serves as an anode is used, there is a problem that the output of the phototube is likely to include noise because it is easily influenced by an external electric field.
[0005]
An object of the present invention is to block the influence of an external electric field and prevent noise from being included in the output of a phototube.
[0006]
[Means for Solving the Problems]
2. The photoelectric tube according to claim 1, wherein a cathode and an anode are provided in a tube having a light receiving portion at one end face and the inside of which is vacuum-sealed, and light incident through the light receiving portion is photoelectrically converted at the cathode to form the cathode. in phototube be collected by the anode the photoelectrons emitted from the tube is constituted by welding a metal stem at the other end surface of the metal valve having a receiving portion on one end face, the anode of the anode has a cylindrical shape An anode lead-out line is connected to the lower end portion and is arranged so as to surround the axis of the tube. The cathode is supported in the tube by the cathode lead-out line, and the anode lead-out line and the cathode lead-out line have electrical insulation. It is fixed to the metal stem by glass, and the metal valve and the metal stem are at a ground potential.
[0007]
According to the photoelectric tube of the first aspect, since the electric potential of the conductive tube is set to the ground potential, the influence from the outside can be blocked by the conductive tube, and the output of the photoelectric tube is noisy. Can be prevented from being included.
[0008]
The photoelectric tube according to claim 2 is characterized in that the cathode has a disk shape and is arranged inside the cylinder of the anode. According to the photoelectric tube of the second aspect, photoelectrons emitted from the cathode can be efficiently collected by the anode.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing the photoelectric tube 2 according to the first embodiment. FIGS. 2A, 2B, and 2C are a plan view, a side sectional view, and a back view of the photoelectric tube 2, respectively. ing.
[0012]
The metal valve 10 has a cylindrical shape with both ends opened and constitutes a side tube of a metal container. An inward flange 10a projecting into the inside of the valve is formed on one opening surface of the metal valve 10, and a light receiving face plate (face plate) 12 is fused to the inward flange 10a. The light receiving surface plate 12 is made of a light-transmitting glass material, and one opening surface of the side tube is closed by the light receiving surface plate 12.
[0013]
In addition, an outward flange 10b that protrudes outside the valve is formed on the other opening surface of the metal valve 10, and a metal stem 14 is resistance-welded to the outward flange 10b. The metal valve 10 and the metal stem 14 are made of an alloy of iron, cobalt, and nickel (Kovar), and have a property of being easily fused with a glass material. The other opening surface of the side tube is closed by the metal stem 14, and the inside of the metal container is evacuated from the metal exhaust pipe 16 provided at the center of the metal stem 14. It is kept. The metal valve 10 and the metal stem 14 are in electrical contact and are set to the same potential, that is, the ground potential.
[0014]
A disc-shaped photocathode 18 is provided at a position facing the light-receiving face plate 12 inside the metal container. A photoelectron emission layer made of Cs-Te is formed on the surface of the photocathode 18 facing the light receiving face plate 12, and the photocathode 18 is supported in a metal container by a single cathode lead-out line 20. In addition, an anode 22 having a cylindrical shape is disposed inside the metal container so as to surround the side tube axis, that is, the light receiving face plate 12 is disposed inside. Three anode lead wires 24 are connected to the lower end of the anode 22. The cathode lead-out line 20 and the anode lead-out line 24 are made of a conductive material such as a copper wire, and are fixed to the metal stem 14 by a tapered hermetic glass 26 having electrical insulation.
[0015]
Specifically, the vacuum sealing of the photoelectric tube 2 is performed as follows. First, the metal valve 10 to which the light receiving face plate 12 is fused is prepared. Further, the metal stem 14 in which the cathode lead-out line 20 and the anode lead-out line 24 are arranged by the hermetic glass 26 is prepared. Each anode lead wire 24 is welded to the lower end portion of the anode 22. In addition, the photocathode 18 on which Te is vapor-deposited is welded to the cathode lead-out wire 20. Thereafter, the outward flange 10b of the metal valve 10 and the metal stem 14 are resistance welded using a resistance welding jig, and the vacuum tightness of the flange portion of the metal container is maintained.
[0016]
Next, the phototube 2 that has undergone the above steps is connected to a vacuum pump (not shown) through an exhaust pipe 16 provided in the phototube 2. In this state, the vacuum pump is driven, and the inside of the metal container of the phototube 2 is evacuated.
[0017]
When this evacuation is completed, the degree of vacuum inside the metal container is confirmed, and when the predetermined degree of vacuum is reached, an alkali activation process is started. That is, the cesium source is heated by the high frequency induction heater and cesium is introduced into the metal container. By this alkali activation process, a photoelectron emission layer made of Cs-Te is formed on the photocathode 18. Finally, the metal exhaust pipe 16 serving as the lower part of the metal container is sealed off leaving a certain length.
[0018]
The photoelectric tube 2 thus obtained is used as follows. That is, a cathode potential is applied to the cathode extraction line 20 and an anode potential higher than the cathode potential is applied to the anode extraction line 24. When light is incident on the photocathode 18 through the light receiving face plate 12 with the voltage applied between the electrodes in this way, photoelectrons are emitted from the photocathode 18. Photoelectrons emitted from the photocathode 18 are collected by the anode electrode 22 and incident light is extracted as an electric signal.
[0019]
According to the photoelectric tube 2 according to this embodiment, since the potential of the conductive metal valve 10 is the ground potential, the influence of the external electric field can be blocked by the metal valve 10, and the output of the photoelectric tube can be reduced. Including noise can be prevented. Therefore, a minute current as an electronic signal can be reliably output. In addition, since the metal valve 10 is set to the ground potential, it can be easily attached by using the metal valve 10 when the phototube 2 is attached.
[0020]
Next, a phototube 4 according to a second embodiment of the present invention will be described with reference to FIG. This phototube 4 is provided with a photocathode (cathode) 42 having a photoelectron emission layer formed in a glass bulb 40 and an anode 44 having a cylindrical shape, and an anode voltage is applied to the anode 44 by a lead wire 46. In addition, a cathode voltage is applied to the cathode 42. A conductive member 48 is provided on the outer peripheral wall of the glass bulb 40, and the potential of the conductive member 48 is set to the ground potential.
[0021]
Also in the photoelectric tube 4 according to the second embodiment, since the potential of the conductive member 48 is the ground potential, the conductive member 48 can block the influence of the external electric field, and the output of the photoelectric tube 4 It is possible to prevent noise from being included.
[0022]
【The invention's effect】
According to the first aspect of the present invention, since the potential of the conductive tube is the ground potential, the conductive tube can block the influence from the outside, and noise is generated in the output of the photoelectric tube. It can be prevented from being included.
[0023]
According to the second aspect of the present invention, photoelectrons emitted from the cathode can be efficiently collected by the anode.
[0024]
According to the invention described in claim 3, since the conductive member is provided on the outer wall portion of the tube and the conductive member is at the ground potential, the influence from the outside can be blocked by the conductive member. , It is possible to prevent noise from being included in the output of the phototube.
[Brief description of the drawings]
FIG. 1 is a perspective view of a phototube according to a first embodiment of the present invention.
FIG. 2 is a diagram showing three surfaces of the phototube according to the first embodiment of the present invention.
FIG. 3 is a side sectional view of a phototube according to a second embodiment of the present invention.
FIG. 4 is a side sectional view of a conventional photoelectric tube.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2,4 ... Photoelectric tube, 10 ... Metal valve (side tube), 12 ... Light-receiving surface plate, 14 ... Metal stem, 16 ... Metal exhaust pipe, 18 ... Photocathode (photocathode), 20 ... Cathode extraction line, 22 ... Anode, 24 ... Anode lead wire, 26 ... Tapered hermetic glass, 40 ... Glass bulb, 42 ... Photocathode (cathode), 44 ... Anode, 48 ... Conductive member.

Claims (2)

A cathode and an anode are provided in a tube having a light receiving portion on one end surface and vacuum-sealed inside, and photoelectrons emitted from the cathode are photoelectrically converted at the cathode by incident light through the light receiving portion. In the phototube collected by
The tube is configured by welding a metal stem to the other end surface of a metal bulb having a light receiving portion on one end surface,
The anode has a cylindrical shape , an anode lead wire is connected to the lower end of the anode, and is arranged so as to surround the axis of the tube,
The cathode is supported in the tube by a cathode lead-out line;
The anode lead-out line and the cathode lead-out line are fixed to the metal stem by electrically insulating glass,
A photoelectric tube, wherein the metal valve and the metal stem are at a ground potential.   2. The phototube according to claim 1, wherein the cathode has a disk shape and is arranged inside a cylinder of the anode.

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