JP2009170171A - Image tube unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an S/N ratio by enhancing cooling efficiency of a vicinal space of a photoelectric surface of an image tube. <P>SOLUTION: This image tube unit 1 has the image tube 10 for arranging the photoelectric surface 6 inside a light receiving surface plate 5, and a cooling mechanism 20 cooling the vicinity of the image tube 10. In the image tube unit, the cooling mechanism 20 has a metal flange 21 arranged adjacent to a side surface of the light receiving surface plate 5 of the image tube 10, and four Peltier elements 23a-23d arranged adjacent to the metal flange 21. In the four Peltier elements 23a-23d, respective four heat absorbing surfaces 29 are arranged so as to surround the sides of the light receiving surface plate 5 from the four directions along the direction guiding the heat absorbing surfaces 29 to intersect with a light incident surface 4a of the light receiving surface plate 5. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an image tube unit including an image tube that reproduces an optical image received at an entrance window as an optical image at an exit window, and more particularly to a cooling structure in the image tube unit.

  The image tube has a photocathode formed inside the entrance window, and an optical image incident on the entrance window is converted into a photoelectron image by the external photoelectric effect of the photocathode. The photoelectron image is multiplied by the electron multiplier, and is incident on the fluorescent screen formed inside the emission window to be reproduced as an optical image.

In such an image tube, depending on the photocathode used, photoelectrons may be emitted by heat even when no measurement target light is incident. This photoelectron becomes thermal noise and causes the S / N ratio of the image tube to deteriorate. In order to suppress such noise caused by heat, a conventional image tube uses a cooling means using a cooling element such as a Peltier element (see Patent Document 1 below). By using such a cooling means, the photocathode arranged inside the entrance window is cooled.
Japanese Patent No. 3276418

  However, in recent years, there has been a demand for an image tube with a higher S / N ratio. For this reason, it is required to suppress noise caused by heat more than a conventional image tube. In order to further suppress noise due to heat, it is required to further increase the cooling efficiency of the space near the image tube.

  Accordingly, the present invention has been made in view of such problems, and an image tube unit capable of improving the S / N ratio by increasing the cooling efficiency of the space near the photocathode of the image tube. The purpose is to provide.

  In order to solve the above problems, an image tube unit of the present invention is an image tube unit including an image tube having a photocathode disposed inside a face plate, and a cooling unit that cools the vicinity of the image tube. A cooling plate provided adjacent to the side surface of the face plate of the image tube, and a plurality of Peltier elements provided in contact with the cooling plate, the plurality of Peltier elements each having a plurality of endothermic surfaces, It is arrange | positioned so that the side of a faceplate may be surrounded along the direction which cross | intersects a light-incidence surface.

  According to such an image tube unit, the vicinity of the side surface of the face plate is efficiently cooled by the plurality of Peltier elements via the cooling plate, and the heat absorption surface of the plurality of Peltier elements intersects with the light incident surface of the face plate. Accordingly, the space near the light incident surface of the face plate can be sufficiently cooled. As a result, the cooling efficiency of the space near the photocathode can be increased, the generation of noise due to heat from the photocathode is reduced, and the S / N ratio is improved.

  A container for accommodating the image tube is further provided, and the space between the side surface of the image tube and the container is potted by an insulating member and between the surface opposite to the cooling surface in contact with the Peltier element on the cooling plate and the container. It is preferable that a gap is formed. In this case, the space near the photocathode is due to the gap between the insulating member used for insulating the wiring member of the image tube and the surface opposite to the cooling surface in contact with the Peltier element of the cooling plate and the container. While cooling efficiently, excessive cooling of the side surface of the image tube by the cooling unit can be suppressed.

  In addition, an electron multiplier is disposed in the image tube so as to face the light exit surface of the photocathode, and between the face plate side surface of the electron multiplier between the cooling plate and the container. It is also preferable that a cavity is formed. With such a configuration, it is possible to improve the cooling efficiency by reducing the heat capacity of the space in the vicinity of the photocathode while ensuring the insulation of the electron multiplier to which a high voltage is applied.

  Further, the cooling plate is formed with a plurality of cooling surfaces in contact with each of the heat absorbing surfaces of the plurality of Peltier elements so as to surround the side surface of the face plate, and between the plurality of cooling surfaces, the cooling plate faces the side surface of the face plate. It is also preferable that a notched part that is notched is formed. With this configuration, the heat capacity of the region not in contact with the cooling surface directly cooled by the Peltier element is reduced, and the vicinity of the photocathode can be more efficiently cooled via the cooling plate.

  The cooling unit further includes a plurality of cooling blocks provided in contact with the heat radiation surfaces of the plurality of Peltier elements, and having a heat exchange function with the outside, along the side surfaces of the face plates of the plurality of cooling blocks. It is also preferable that the height in the horizontal direction is higher than the height in the direction along the side surface of the cooling plate. In this way, the cooling block partitions the cooling space located on the inner side on which the image tube is disposed and the heat radiation space located on the outer side, and increases the cooling efficiency in the vicinity of the photocathode while increasing the cooling efficiency from the heat radiation space to the face plate. It is possible to reliably prevent the transfer of heat toward.

  According to the present invention, the S / N ratio can be improved by increasing the cooling efficiency of the space near the photocathode of the image tube.

  Hereinafter, preferred embodiments of an electron multiplier according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  1 is an external perspective view of an image tube unit according to a preferred embodiment of the present invention, FIG. 2 is a perspective view showing an internal configuration of the image tube unit of FIG. 1, and FIG. 3 is an image tube unit of FIG. FIG. 4 is a partial enlarged cross-sectional view of FIG. 3.

  The image tube unit 1 is configured by housing an image tube 10 inside a rectangular parallelepiped housing 2 in a vacuum state and a cooling mechanism 20 that cools the vicinity of the image tube 10 inside the housing 2. A circular entrance window 3a is provided at one end of the housing 2, and an exit window 3b is provided at the other end. The image tube 10 is an image intensifier that is a kind of electron tube having a substantially cylindrical shape, and is mounted on a base plate 2 a constituting a part of the housing 2.

  As shown in FIGS. 3 and 4, the end of the image tube 10 on the incident window 3 a side is a light incident surface 4 a for an optical image (incident light), and is opposite to the end where the light incident surface 4 a is provided. That is, the end on the exit window 3b side is an exit window 4b. The light incident surface 4a is a surface on the light incident side of the light receiving surface plate 5 made of a translucent material such as a substantially disc-shaped borosilicate glass, and the light receiving surface plate 5 has a surface opposite to the light incident surface 4a. The rectangular flat photocathode 6 is disposed so as to be in contact with the center of the surface. The photocathode 6 emits photoelectrons from the light exit surface 6b in response to incident light that passes through the light receiving surface plate 5 and enters the light incident surface 6a. The photocathode 6 is a photocathode having a particularly high sensitivity to near-infrared light. For example, an InP / InGaAs or InP / InGaAsP layer is grown on a p + InP substrate. On the outside of the light receiving surface plate 5, a feeding electrode 11 made of Kovar metal for applying a bias voltage to the light incident surface 6a of the photocathode 6 and a kovar for applying a ground potential to the light emitting surface 6b of the photocathode 6 are provided. A feeding electrode 12 made of metal is provided so as to penetrate the light-receiving face plate 5 (FIG. 2).

  Further, an MCP (multichannel plate) 7 as an electron multiplier is provided on the light emitting surface 6b side of the photocathode 6 of the image tube 10 so as to face the light emitting surface 6b. The MCP 7 multiplies the photoelectrons emitted from the light exit surface 6 b of the photocathode 6 by secondary electrons. Further, a phosphor screen 9 for converting secondary electrons emitted from the MCP 7 into light is formed on the surface of the MCP 7 on the lower side of the exit window 4b side of the MCP 7, and the light from the phosphor screen 9 is transmitted to the exit window 4b. An FOP (fiber optic plate) 8 that is a light guide member that guides toward the surface is disposed.

  In such an image tube 10, the optical image incident on the light receiving surface plate 5 is photoelectrically converted in the photocathode 6 to become photoelectrons, is emitted from the photocathode 6 and enters the MCP 7. The photoelectrons incident on the MCP 7 are multiplied by the secondary electrons and enter the phosphor screen 9. The secondary electrons incident on the phosphor screen 9 are converted into light, which is transmitted through the FOP 8 and output to the outside from the exit window 4b. That is, the optical image incident from the light incident surface 4a is enhanced while retaining the two-dimensional information and is output from the exit window 4b.

  A cooling mechanism 20 is provided around the image tube 10. The cooling mechanism 20 includes a metal flange (cooling plate) 21, a container 22, Peltier elements 23a to 23d, and cooling blocks 24a to 24d (FIG. 2).

  The metal flange 21 is a copper metal member, and a flat flange body 25 disposed around the side surface of the light receiving face plate 5 of the image tube 10, and four rectangular cooling plates 26 a connected to the flange body 25. ~ 26d.

  Further, a copper flange portion 13 (FIG. 4) is provided between the side tube 14 of the image tube 10 and the light receiving face plate 5. The flange portion 13 is attached to the surface on the photoelectric surface 6 side of the light receiving surface plate 5 and has an extending portion 13a extending from the side surface of the light receiving surface plate 5 along the light incident surface 4a. And the flange main body 25 is arrange | positioned adjacent to the side surface of the light-receiving surface board 5 by connecting to the extension part 13a of the flange part 13. As shown in FIG. The flange main body 25 has a shape in which the center is cut out with substantially the same diameter as the outer edge (side surface) of the light receiving surface plate 5, and the center of each of the two sets of opposite sides is along the side surface of the light receiving surface plate 5. That is, the cooling plates 26a to 26d are connected along the incident direction of the optical image (FIGS. 2 and 3). These cooling plates 26a to 26d are provided so that the cooling plate 26a and the cooling plate 26c, and the cooling plate 26b and the cooling plate 26d are parallel to each other, so that the four cooling surfaces outside the cooling plates 26a to 26d are provided. 27, the light-receiving face plate 5 is surrounded from the side. Further, between the two cooling surfaces 27 orthogonal to each other at the outer edge portion of the flange body 25, that is, between two adjacent connection portions of the connection portions with the cooling plates 26 a to 26 d, the side surface of the light receiving surface plate 5 is provided. Four cutout portions 28 that are cut out in a circular arc shape are formed.

  Here, as for the metal flange 21, the flange main body 25 and the cooling plates 26a-26d may not be comprised with another member, and may be formed integrally.

  Peltier elements 23a-23d cool the heat absorption surface 29 side vicinity by moving the heat which generate | occur | produced in the heat absorption surface 29 located in one end surface toward the heat radiating surface 30 located in the other end surface (FIG. 3). ). These Peltier elements 23 a to 23 d have a four-layer structure from the heat absorption surface 29 to the heat dissipation surface 30, and the heat dissipation surface 30 has a larger area than the heat absorption surface 29, thereby enabling efficient heat exchange. Yes. The Peltier elements 23a to 23d are arranged so as to surround the light receiving surface plate 5 from the side of the light receiving surface plate 5 by fixing the respective heat absorbing surfaces 29 in contact with the cooling surfaces 27 of the cooling plates 26a to 26d. With such an arrangement, the heat radiation surfaces 30 of the Peltier elements 23 a to 23 d are arranged from the side of the light receiving surface plate 5 toward the outside.

The container 22 has side walls extending along the inner surfaces of the four cooling plates 26a to 26d and extending so as to form a gap with the inner surfaces of the four cooling plates 26a to 26d (opposite surfaces of the cooling surfaces 27). This is a resin cup-shaped member that is joined to the surface of the metal flange 21 on the photocathode 6 side and accommodates the image tube 10 in a portion on the exit window 4b side of the light receiving surface plate 5. One opening of the container 22 is connected to the lower surface of the flange body 25, and the exit window 4b is exposed from the other opening. The space between the image tube 10 and the side tube 14 in the container 22 is potted by a heat insulating member. More specifically, between the bottom surface of the container 22 on the exit window 4b side and the level L ₁ (see FIG. 4) of the boundary surface on the light receiving surface plate 5 side of the MCP 7, the container 22 and the side tube 14 of the image tube 10 are connected. The entire space between them is potted. On the other hand, only the side tube 14 and the flange portion 13 side are potted from the level L ₁ in the container 22 to the end surface on the MCP 7 side (level L _{2 in} FIG. 4) of the edge of the flange portion 13. A ring-shaped cavity 31 that is not potted is formed on the inner wall side. That is, between the flange main body 25 of the metal flange 21 and the container 22, there is a non-potting space located in the space between the boundary surface on the light receiving surface plate 5 side of the MCP 7 and the outer surface of the light receiving surface plate 5. The insulating member in the potting space is inclined from the light receiving face plate 5 side to the MCP 7 side from the image tube 10 side toward the container 22 side.

  The cooling blocks 24a to 24d are block-like members arranged in contact with the heat radiation surfaces 30 of the Peltier elements 23a to 23d, respectively. These cooling blocks 24a-24d have the pipe line 32 for circulating cooling water in the inside, and have a heat exchange function between the outside. As shown in FIG. 3, the cooling blocks 24 a to 24 d are arranged in the tube axis direction of the image tube 10 (the direction along the side surface of the light receiving surface plate 5) so as to cover the entire heat radiation surface 30 of the Peltier elements 23 a to 23 d. The height along the direction is provided to be higher than the flange main body 25 of the metal flange 21.

  FIG. 5 is a perspective view illustrating the flow of cooling water in the cooling blocks 24a to 24d. As shown in the figure, the cooling water introduced from the outside into the cooling block 24c through the base plate 2a is connected to a plurality of tubes provided in a direction parallel or perpendicular to the tube axis of the image tube 10. The flow passes through the pipe 32 and flows into the cooling block 24c. Thereafter, the cooling water discharged from the cooling block 24c sequentially flows through the conduits 32 in the cooling blocks 24d, 24a, and 24b via a relay pipe (not shown) provided in the base plate 2a, and then the base plate. It is discharged outside through 2a. Thereby, the heat from the heat radiating surface 30 of the Peltier elements 23a to 23d in contact with the cooling blocks 24a to 24d is transmitted to the outside.

  According to the image tube unit 1 described above, the plurality of Peltier elements 23a to 23d provided so as to surround the side surface of the light-receiving face plate 5 from four sides, through the metal flange 21 and the flange portion 13 that is in direct contact with the light-receiving face plate 5. Thus, the vicinity of the side surface of the light receiving face plate 5 is efficiently cooled. In addition, since the heat absorbing surfaces 29 of the plurality of Peltier elements 23a to 23d are provided so as to surround the side surfaces of the light receiving surface plate 5 from four directions along the direction intersecting the light incident surface 4a of the light receiving surface plate 5, the light receiving surface plate 5, especially the space near the light incident surface 4 a can be sufficiently cooled, and the light incident surface 4 a can also be indirectly cooled. Further, since the Peltier elements 23a to 23d are arranged so that the heat absorbing surface 29 faces the side surface of the light receiving surface plate 5, the heat radiating surface 30 of the Peltier elements 23a to 23d can be moved away from the light receiving surface plate 5, and the heat is dissipated. Heat from the surface 30 is prevented from being transmitted to the light receiving face plate 5 side. This is because the heat from the heat radiating surface 30 must pass through the cooling space surrounded by the heat absorbing surface 29 of the metal flange 21 and the Peltier elements 23a to 23d in order to transfer to the light receiving surface plate 5 side. As a result, the cooling efficiency of the space in the vicinity of the photocathode 6 can be increased so as to be maintained at −80 ° C. or less, and the generation of noise due to heat from the photocathode 6 is reduced and the S / N ratio is improved. Is done.

  The space between the side tube 14 of the image tube 10 and the container 22 is potted by an insulating member, and there is a gap between the container 22 and the opposing surface of the cooling surface 27 that contacts the Peltier elements 23a to 23d of the metal flange 21. Is formed. Accordingly, the insulating member used also for insulating the wiring member provided on the side tube 14 of the image tube 10 and the gap between the insulating member and the container 22 and the vicinity of the photocathode 6 are more efficiently cooled. Excessive cooling of the MCP 7 via the side tube 14 of the image tube 10 can be suppressed to prevent a decrease in electron multiplication efficiency.

  The cavity 31 is formed between the boundary surface of the MCP 7 on the light receiving surface plate 5 side and the outer surface of the light receiving surface plate 5. Since the potential difference between the light receiving surface plate 5 side of the MCP 7 and the photocathode 6 is smaller than the potential difference between the FOP 8 side surface of the MCP 7 and the photocathode 6, the surface of the MCP 7 on the light receiving surface plate 5 side and the photocathode 6 side. Insulation failure is unlikely to occur. As a result, the insulation between the flange 13 and the electrode for applying voltage to the MCP 7 provided on the side tube 14 of the image tube 10 is secured, and the cooling capacity is improved by reducing the heat capacity of the space near the photocathode 6. Can be made.

  The metal flange 21 includes cooling plates 26 a to 26 d in which a plurality of cooling surfaces 27 are formed, and a flange body 25, and a notch portion 28 is provided between two adjacent cooling surfaces 27 of the flange body 25. Is formed. As a result, the heat capacity of the region on the image tube 10 side that is not in contact with the cooling surface 27 that is directly cooled by the Peltier elements 23a to 23d is reduced, and the vicinity of the photocathode 6 is more efficiently cooled via the metal flange 21. be able to.

  Furthermore, the height in the direction along the side surface of the light receiving face plate 5 of the plurality of cooling blocks 24 a to 24 d is higher than the height of the metal flange 21. As a result, the cooling blocks 24a to 24d partition the cooling space located on the side (inner side) on which the image tube 10 is disposed and the heat radiation space located on the outer side, while increasing the cooling efficiency in the vicinity of the photocathode 6. Heat transfer from the heat radiation space toward the light receiving face plate 5 can be reliably prevented.

  In addition, this invention is not limited to embodiment mentioned above. For example, the Peltier element is not limited to a specific number as long as the side surface of the light receiving face plate is surrounded by the endothermic surface. However, in order to uniformly cool the periphery of the photocathode 6 and obtain a uniform output image, it is preferable that the photocathode 6 be arranged at equal intervals around the light receiving face plate.

  The metal flange 21 is in contact with the flange portion 13 of the image tube 10, but may be provided so as to be in contact with the light receiving face plate 5. However, it is more preferable to connect to the flange portion 13 from the viewpoint of securing insulation with the feeding electrode 11 for applying bias to the photocathode 6 provided on the light receiving face plate 5.

1 is an external perspective view of an image tube unit according to a preferred embodiment of the present invention. It is a perspective view which shows the internal structure of the image tube unit of FIG. It is sectional drawing along the III-III line of the image tube unit of FIG. It is a partially expanded sectional view of FIG. It is a perspective view explaining the flow of the cooling water in the cooling block of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image tube unit, 4a ... Light incident surface, 5 ... Light-receiving surface plate, 6 ... Photoelectric surface, 7 ... MCP (electron multiplication part), 10 ... Image tube, 14 ... Side tube, 20 ... Cooling mechanism (cooling part) 21 ... Metal flange (cooling plate), 22 ... Container, 23a-23d ... Peltier element, 24a-24d ... Cooling block, 27 ... Cooling surface, 28 ... Notch, 29 ... Heat absorbing surface, 30 ... Heat radiating surface, 31 ... Hollow part.

Claims (5)

In an image tube unit comprising an image tube having a photocathode disposed inside a face plate, and a cooling unit for cooling the vicinity of the image tube,
The cooling unit includes a cooling plate provided adjacent to a side surface of the face plate of the image tube, and a plurality of Peltier elements provided in contact with the cooling plate,
The plurality of Peltier elements are arranged such that each of the plurality of heat absorbing surfaces surrounds a side of the face plate along a direction intersecting a light incident surface of the face plate.
An image tube unit characterized by that. A container for accommodating the image tube;
Between the side surface of the image tube and the container, a gap is formed between the container and the surface opposite to the cooling surface in contact with the Peltier element on the cooling plate. ing,
The image tube unit according to claim 1. In the image tube, an electron multiplier is disposed so as to face the light exit surface of the photocathode,
A cavity is formed between the face plate and the face plate side surface of the electron multiplier between the cooling plate and the container.
The image tube unit according to claim 2. The cooling plate is formed with a plurality of cooling surfaces in contact with each of the heat absorbing surfaces of the plurality of Peltier elements so as to surround a side surface of the face plate, and between the plurality of cooling surfaces, A notch cut out to the side is formed,
The image tube unit according to claim 1, wherein the image tube unit is a unit. The cooling unit further includes a plurality of cooling blocks that are provided in contact with the heat dissipation surfaces of the plurality of Peltier elements and have a heat exchange function with the outside,
The height in the direction along the side surface of the face plate of the plurality of cooling blocks is higher than the height in the direction along the side surface of the cooling plate,
The image tube unit according to any one of claims 1 to 4, wherein the image tube unit is provided.

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