JP2010245677A - Holding device of image intensifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holding device of an image intensifier, which prevents damage on a housing even if an impact or vibration is applied to a lens barrel and stably holds the image intensifier while preventing misalignment between a photoelectric surface of the image intensifier and an image formation surface of an optical system, when connecting the image intensifier having the housing made of ceramic to a rear end of the lens barrel housing the optical system. <P>SOLUTION: A holding cylinder 7 is fixed to a coupling ring 6 fixed to the rear end of the lens barrel 3. The inner diameter of the holding cylinder 7 is made larger than the outer diameter of the housing 8a of the image intensifier 8. The holding cylinder 7 is provided with a plurality of through-holes 7b reaching the inner circumferential surface from the outer circumferential surface of the holding cylinder 7. A silicone resin 15 is filled through each of the through-holes 7b to fill a gap between the inner circumferential surface of the holding cylinder 7 and the outer circumferential surface of the housing 8a. The silicone resin 15 adheres the inner circumferential surface of the holding cylinder 7 to the outer circumferential surface of the housing 8a, and also functions as an elastic body for absorbing a mechanical impact between both surfaces. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a holding device that holds an image intensifier connected to a lens barrel of an optical system. More specifically, the present invention relates to an image intensifier mounted on a spacecraft such as an artificial satellite or a space probe together with an optical system. The present invention relates to a holding device.

  The photomultiplier tube accelerates and collides the photoelectrons emitted from the photocathode by the incidence of light onto the secondary electron emission surface, and the secondary electrons emitted from the secondary electron emission surface are further brought into the secondary electrons of the next stage. By making it incident on the emission surface, it has the effect of increasing the number of electrons one after another. Depending on the number of steps of the secondary electron emission surface, the signal level of the first-stage photoelectron can be increased several hundred thousand times or more, and even a very weak incident light can be detected with a high SN ratio.

  In principle, a microchannel plate (hereinafter referred to as “MCP”) is a plate formed by bundling a large number of miniaturized photomultiplier tubes so that each photomultiplier tube functions as a photosensor corresponding to one pixel. It is used for an image intensifier that converts a dark, low-contrast image into a bright, high-contrast image. MCPs are connected in multiple stages to obtain a higher level of signal output, and the spectral sensitivity of the first stage photocathode is changed so that infrared images and X-ray images can be clearly visualized. Fire is used in various fields.

  Such image intensifiers are also used in space navigation objects such as artificial satellites and space probes in combination with optical systems for the purpose of observing hoshino and various astronomical objects. As is well known, the environmental temperature of a spacecraft greatly changes depending on whether or not sunlight is irradiated. In the case of an artificial satellite, a difference in temperature between about −30 ° C. and 80 ° C. occurs even inside the spacecraft. . Such a temperature change also has an adverse effect on the optical system inside the satellite, such as deterioration of imaging performance. For example, as known in Patent Documents 1 to 3, the optical system holding method, temperature control method, and holding part material Etc. are devised.

JP 2007-188010 A Japanese Patent Application Laid-Open No. 11-249039 Japanese Patent Laid-Open No. 2002-202187

  By the way, since an image intensifier generally requires a voltage of several hundred volts or more when driven, a ceramic material having a high insulating property is used for a casing serving as an exterior. Until now, this ceramic case has been firmly bolted to the rear end of the lens barrel that houses the optical system, and the photoelectric surface of the image intensifier matches the image plane of the optical system. So that it is positioned. Therefore, by keeping the imaging surface of the optical system stable by the method described in the above-mentioned patent document, it becomes possible to obtain a clear image regardless of the temperature change.

  However, it is inevitable that the spacecraft will be subjected to an excessive impact at the time of launch, and that the impact will also be exerted on various observation devices installed inside. The ceramic used in the image intensifier case is a material that is highly hard but easily brittle and breaks, so impact and vibration during launch are applied to the connection between the rear end of the lens barrel and the image intensifier. When added, there is a risk of cracks and chipping in the ceramic housing.

If the housing is elastically pressure-bonded to the rear end of the optical lens barrel by using a spring piece together instead of being firmly fixed mechanically, the spring piece and the case are When they are rubbed, there is a concern that ceramic powder is generated, which adversely affects the optical system and the image intensifier. In addition, metal parts such as bolts and spring pieces used to fix the housing will repeatedly expand and contract with changes in temperature, so the tightening load on the housing will change without interruption and brittle fracture will occur. It is promoted or the rubbing is repeated at the contact portion with the casing, which causes more powder generation.

  The present invention has been made in consideration of the above-mentioned background. When the image intensifier casing is connected to the lens barrel of the optical system, the image input from the imaging plane of the optical system can be performed even if the environmental temperature changes greatly. The image intensifier is fixed so that the photocathode of the tensiifier is stable so that it does not shift, and the casing is not cracked or chipped against excessive shock or vibration when launching the spacecraft. It aims to provide a method.

  The device of the present invention connects an image intensifier comprising a cylindrical casing made of ceramic and a photomultiplier housed in a hollow portion of the casing to the rear end of the lens barrel containing the optical system. And holding a connecting ring in which the position of the optical system is adjusted and fixed in the optical axis direction of the optical system at the rear end of the lens barrel, and a photographing opening is formed in the center, than the outer diameter of the casing. A hollow portion having a large inner diameter, and the image intensifier is accommodated in the hollow portion and fixed to the front surface of the connection ring so as to be accommodated in the lens barrel, and a plurality of penetrations reaching the hollow portion from the outer peripheral surface A holding cylinder in which a hole is formed, a regulating ring fixed to the front surface of the holding cylinder, regulating the front surface of the housing and exposing the front surface of the photomultiplier, and the plurality of through holes Injected through the hole , Composed of an elastic filler filling discretely for each position of the through-hole gap between the outer peripheral surface of the housing and the inner peripheral surface of the holding cylinder.

A small hole is formed in the restriction ring so as to penetrate from the front surface to the back surface and partially expose the case by forming in the upper part of the case. Through the small hole, the restriction ring and the case are formed. It is also effective to fill the elastic filler that fills the gaps for each small hole position.
In these cases, it is desirable that the through hole and the small hole are respectively provided at positions shifted with respect to the circumferential direction of the image intensifier. Furthermore, it is also effective to fix a photographing lens barrel incorporating a camera for photographing an image formed on the rear end surface of the photomultiplier on the back surface of the coupling ring. Moreover, a silicone resin can be effectively used for the elastic filler.

  According to the present invention, since the ceramic case of the image intensifier is not directly mechanically fixed to the lens barrel containing the optical system, it is assumed that excessive shock and vibration are applied to these connecting portions. There is no crack or chipping in the case. Even if the ambient temperature changes significantly, the image plane of the optical system and the photocathode of the image intensifier do not shift, and the tightening load on the case changes or the case changes. And the machine parts do not rub against each other, and the ceramic housing is not adversely affected.

It is principal part sectional drawing of the state which connected the image intensifier to the lens-barrel. It is a disassembled perspective view of 1st Embodiment which shows the outline of the holding | maintenance apparatus of an image intensifier. It is principal part sectional drawing of 1st Embodiment of the holding device of an image intensifier. It is a front view of 1st Embodiment of the holding device of an image intensifier. It is a disassembled perspective view of 2nd Embodiment of the holding device of an image intensifier. It is a front view of 2nd Embodiment of the holding device of an image intensifier.

[First Embodiment]
FIG. 1 shows a first embodiment in which the present invention is applied to an imaging device mounted on an artificial satellite. This photographing apparatus includes a lens barrel 3 that houses a telephoto lens 2 as an optical system, and a camera module 5 connected to the lens barrel 3. An optical system such as a wide-angle lens for photographing Hoshino can be used depending on the application. The lens barrel 3 is integrally provided with a flange 4 for installation. By fixing the flange 4 with a bolt, the photographing apparatus is fixed to a required portion in the artificial satellite. Although the temperature environment changes greatly inside the artificial satellite, the telephoto lens 2 and the lens barrel 3 are devised so that the imaging performance hardly changes by a known method.

  A screw ring 3a is formed on the inner peripheral surface of the rear end portion of the lens barrel 3, and a connecting ring 6 in which a photographing opening 6a (FIG. 2) is formed in the central portion and a screw thread is formed on the outer peripheral surface is screwed and fixed. Has been. An image intensifier 8 is attached to the front side of the connecting ring 6 via a holding cylinder 7. The image intensifier 8 includes a cylindrical ceramic casing 8a and a photomultiplier 8b provided in a vacuum chamber defined in a hollow portion of the casing 8a, and has a cylindrical shape as a whole. ing.

  The photomultiplier 8b is composed of, in order from the front side, a transparent incident window having a photocathode formed thereon, a known microchannel plate (MCP), and a fiber plate having a phosphor screen formed on the front surface. An acceleration electrode that accelerates photoelectrons emitted from the photocathode to enter the MCP, an electrode that applies a voltage gradient to the MCP, an acceleration electrode that collides secondary electrons emitted from the MCP with the phosphor screen of the fiber plate, and the like are provided. . A cord is drawn from the housing 8a to apply a voltage signal to each of the electrodes, but the illustration thereof is omitted.

  A regulating ring 9 is fixed to the front surface of the holding cylinder 7. The restriction ring 9 is positioned at the front surface of the housing 8a whose rear end is restricted by the front surface of the connecting ring 6, and restricts the image intensifier 8 from moving forward, and an opening formed at the center thereof. The front surface of the photomultiplier 8b is exposed through 9a. The photocathode 10 that emits the number of photoelectrons corresponding to the amount of incident light is formed on the back side of the transparent entrance window of the photomultiplier 8b. However, for convenience, here it is made to coincide with the front of the photomultiplier 8b. It is illustrated.

  2 and 3 showing the camera module 5, the holding cylinder 7 is firmly bolted to the front surface of the connection ring 6 by tightening the hexagonal bolt 12 in the screw hole 6 b formed on the front surface of the connection ring 6. The The bolt 12 is fastened to the screw hole 6b through the insertion holes 9b and 7a of the restriction ring 9 and the holding cylinder 7, and the mechanical tightening force by the bolt 12 is not directly applied to the image intensifier 8. It is like that.

  The inner diameter of the holding cylinder 7 is slightly larger than the outer diameter of the housing 8a (for example, about 0.5 mm to 1 mm), and there is a clearance between the inner peripheral surface of the holding cylinder 7 and the outer peripheral surface of the housing 8a. Therefore, the mechanical force is not exerted on the image intensifier 8, and the image intensifier 8 moves in the direction of the optical axis 2a of the telephoto lens 2 inside the holding cylinder 7 and rotates around the optical axis 2a. In some cases, an elastic filler is used for the fixing.

  In order to hold the image intensifier 8 on the holding cylinder 7 with an elastic filler, the holding cylinder 7 is formed with a through hole 7b reaching from the outer peripheral surface to the inner peripheral surface. These through-holes 7b are provided at three positions equally dividing the outer periphery of the holding cylinder 7 and at a position approximately in the middle in the optical axis direction. When assembling the image intensifier 8 to the connecting ring 6, the image intensifier 8 a is placed in the hollow portion of the holding cylinder 7, and the bolt 12 is tightened after the regulating ring 9 is put on the front surface. Then, a silicon resin 15 suitable as an elastic filler is injected from the through hole 7 b of the holding cylinder 7.

  As shown in FIGS. 3 and 4, at this time, the silicon resin 15 is partially held for each position of the through hole 7b by adjusting the injection amount using a silicone resin 15 having an appropriate viscosity. 7 is filled so as to fill a gap between the inner peripheral surface of the housing 7 and the outer peripheral surface of the housing 8a, and is hardened while leaving a space in the periphery in the circumferential direction and the optical axis direction. Since the silicon resin 15 has an appropriate elasticity even after being cured, the image intensifier 8 has three locations on the outer periphery thereof inside the holding cylinder 7 using the elasticity of the silicon resin 15. It will be supported stably. In FIG. 4, the holding cylinder 7 and the regulating ring 9 are partially broken to show the inside of the holding cylinder 7 filled with the silicon resin 15.

  On the other hand, a small hole 9c for partially exposing the housing 8a is formed in the restriction ring 9 so that the image intensifier 8 can be held with high accuracy in the optical axis direction. Since the front end surface of the holding cylinder 7 protrudes slightly forward from the front surface of the housing 8a, there is a gap between the regulating ring 9 and the front surface of the housing 8a. By filling the resin 15, the gap between the regulation ring 9 and the front surface of the housing 8 a can be partially filled. Since the small holes 9c are respectively provided at positions that divide the circumference of the regulating ring 9 into three equal parts, the image intensifier 8 is urged backward by the elasticity of the cured silicone resin 15, and the rear end thereof is The image intensifier 8 is pressed against the front surface of the connection ring 6 with respect to the optical axis 2a direction, and the image intensifier 8 is pressed against the front surface of the connection ring 6 with respect to the optical axis 2a direction. It will be positioned to the reference. The small hole 9c and the through hole 7b are preferably shifted in the circumferential direction, and in terms of balance, the through hole 7b and the small hole 9c are preferably shifted from each other by 30 ° with respect to the optical axis 2a.

  As shown in FIG. 3, the connection ring 6 is used to hold not only the image intensifier 8 but also the imaging barrel. An imaging unit 18 including a CCD-type or CMOS-type solid-state imaging device and a recording device for recording image data obtained by imaging with the solid-state imaging device is assembled at the rear end of the imaging barrel 17 to increase the photoelectron gain. The image transmitted to the rear end surface 20 of the magnification unit 8 b is imaged on the imaging surface of the solid-state imaging device by the imaging lens 22 through the imaging aperture 6 a of the connecting ring 6.

The photographing lens barrel 17 is fixed to the back surface of the connecting ring 6 by bolting the front end flange portion. Although not shown, the imaging unit 18 and the imaging lens 22 can be fixed after moving and adjusting in the optical axis direction for focusing, respectively, and the imaging unit 18 is an image obtained by imaging. It is desirable to be able to fix after adjusting the rotation around the optical axis so that the top and bottom of the lens are constant.

  The camera module 5 assembled as shown in FIG. 3 is integrally connected to the rear end of the lens barrel 3 by a connecting ring 6. The image intensifier 8 is moved together with the holding cylinder 7 in the direction of the optical axis 2a by adjusting the screwing amount of the connecting ring 6, and the photocathode of the image intensifier 8 is made to coincide with the imaging surface of the telephoto lens 2. Can do. For example, a light beam from a point light source may be incident on the telephoto lens 2 through a collimator, and the screwing amount of the connection ring 6 may be adjusted while confirming an image signal obtained from the solid-state imaging device. After matching the imaging surface of the telephoto lens 2 and the photocathode 10 of the image intensifier 8, the connecting ring 6 is fixed to the lens barrel 3 using an adhesive or a fixing screw.

  The photomultiplier 8b multiplies the image formed by the telephoto lens 2 and transmits it to the rear end face 20. Therefore, the image intensity is adjusted by adjusting the screwing amount of the connecting ring 6 as described above. Even if the fire 8 is positioned at an arbitrary rotational position, the posture of the image transmitted to the rear end face 20 does not change at all. However, since the solid-state imaging device incorporated in the imaging unit 18 has the vertical and horizontal directions on the screen, the rotational position adjustment described above may be performed after the coupling ring 6 is fixed.

  According to the above configuration, a large impact is applied to the lens barrel 3 when the artificial satellite is launched, and even if the impact or vibration is transmitted to the holding cylinder 7 as it is, the silicone resin 15 functions as a buffering agent, and the image intensifier 8 Shock and vibration are reduced. Since the silicon resin 15 is filled between the regulating ring 9 and the housing 8a, the position of the image intensifier 8 is maintained and the mechanical strength is not directly applied. ing. Therefore, the image intensifier 8 including the housing 8a is not damaged.

  The image intensifier 8 is fixed to the inner peripheral surface of the holding cylinder 7 with a silicon resin 15. Further, the image intensifier 8 has a rear end surface on the front surface of the connecting ring 6 and a front end surface on the small hole 9 c of the regulating ring 9. Therefore, the photocathode 10 of the image intensifier 8 is not deviated from the image plane of the telephoto lens 2. Even if an impact is applied from the direction crossing the optical axis 2a and the image intensifier 8 is shifted in a direction perpendicular to the optical axis 2a, no problem in image formation occurs.

[Second Embodiment]
In the embodiment shown in FIGS. 5 and 6, instead of the restriction ring 9 used in the first embodiment described above, a restriction ring 30 having a spring piece 9d protruding toward the inner peripheral side is used. The spring pieces 9d are formed at three locations that equally divide the inner periphery of the regulating ring 30, and are bent rearward so that the tips of the spring pieces 9d are in light contact with the front surface of the housing 8a. A small hole 9c is formed on the base side of each spring piece 9c, and silicon resin 15 is injected through the small hole 9c so that the gap between the spring piece 9c and the front surface of the housing 8a can be filled. In FIG. 6, the holding cylinder 7 and the regulating ring 30 are partially broken as in FIG.

  Since the urging force of the spring piece 9d is weakened, if the viscous silicone resin 15 is filled so as to fill the gap between the spring piece 9d and the front surface of the housing 8a through the small hole 9c, the spring piece 9d. Is pushed up by the silicon resin 15 and lifted from the front surface of the housing 8a. When the silicone resin 15 is cured, in addition to the elasticity of the silicone resin 15, the urging force of the spring piece 9 d also becomes the urging force that presses the image intensifier 8 toward the rear end side, as in the previous embodiment. The intensifier 8 is positioned with reference to the front surface of the connecting ring 6. Therefore, if the connecting ring 6 is correctly positioned with respect to the lens barrel 3 in the direction of the optical axis 2a, the photocathode of the image intensifier 8 is always connected to the telephoto lens 2 regardless of the impact or vibration when the satellite is launched. It can be in a state of being matched with the image plane.

  When the image of the telephoto lens 2 is formed on the photocathode 10 of the image intensifier 8, a number of photoelectrons corresponding to the two-dimensional light-dark distribution of the optical image are emitted from the photocathode 10, each of which is an acceleration electrode. It goes straight by the acceleration action and reaches the entrance surface of the MCP. The incident end of the fine photomultiplier tube is densely arranged on the incident surface of the MCP, and the individually incident photoelectrons collide with the secondary electron emission surface formed on the respective tube walls one after the other. Increase the number of electrons emitted. A large number of secondary electrons proportional to the number of incident photoelectrons are emitted from the exit end of the fine photomultiplier tube, and collide with the phosphor screen on the front surface of the fiber plate in which ultrafine optical fibers are bundled. The phosphor screen emits light with brightness corresponding to the number of secondary electrons that have collided, and is transmitted to the rear end surface of the fiber plate. Since the rear end face of the fiber plate is the rear end face of the photomultiplier 8b, the image is picked up and recorded by the image pickup unit 18.

  Even if the silicon resin 15 repeatedly expands and contracts slightly with changes in the temperature environment in the artificial satellite, the silicon resin 15 also has an action of an elastic filler. The image intensifier 8 is not moved in the direction of the optical axis 2a only by expanding and contracting within the gap between the surface and the housing 8a. Therefore, the image of the telephoto lens 2 can always be formed on the photocathode 10 of the image intensifier 8. Further, since the silicon resin 15 has a feature that a small amount of outgas is released in a vacuum, even if it is used in an artificial satellite, its surroundings are not contaminated with the emitted gas, and the optical surface and image of the telephoto lens 2 are not affected. There is no risk of fogging the surface of the transparent window of the intensifier 8.

  As described above, the image intensifier holding device suitable for the imaging device mounted on the artificial satellite has been described. However, the present invention is particularly suitable for an imaging device used in an environment where the temperature fluctuates greatly, such as daytime and nighttime. It can be effectively used when the image intensifier is used for monitoring at night in places where the temperature fluctuates greatly. Further, as the elastic filler having an effect of filling the space between the inner peripheral surface of the holding cylinder and the outer peripheral surface of the housing of the image intensifier, another material having elasticity can be used.

2 telephoto lens 3 lens barrel 5 camera module 6 connecting ring 7 holding cylinder 8 image intensifier 8a housing 8b photomultiplier 9, 30 regulating ring 10 photocathode 17 photographing barrel 18 imaging unit

Claims (5)

An image in which an image intensifier comprising a ceramic cylindrical housing and a photomultiplier housed in a hollow portion of the housing is connected to and held at the rear end of the lens barrel housing the optical system. In the intensifier holding device,
A connection ring that is fixed to the rear end portion of the lens barrel in the optical axis direction of the optical system, and has a photographing aperture at the center,
A hollow portion having an inner diameter larger than the outer diameter of the housing, and the image intensifier is accommodated in the hollow portion and fixed to the front surface of the coupling ring so as to be accommodated in the lens barrel, from the outer peripheral surface. A holding cylinder in which a plurality of through holes reaching the hollow portion are formed;
A regulating ring fixed to the front surface of the holding cylinder, which regulates the front surface of the housing and exposes the front surface of the photomultiplier, and
An elastic filler that is injected through the plurality of through holes and discretely fills the gap between the inner peripheral surface of the holding cylinder and the outer peripheral surface of the housing for each position of the through holes;
A device for holding an image intensifier, comprising:   A small hole that partially exposes the front surface of the housing is formed in the restriction ring, and the elastic filler that partially fills the space between the restriction ring and the housing at each small hole position through the small hole is filled. The image intensifier holding device according to claim 1, wherein   The image intensifier holding device according to claim 1, wherein the through hole and the small hole are formed at positions shifted with respect to a circumferential direction of the image intensifier.   4. A camera barrel is fixed to a back surface of the coupling ring, and a camera for taking an image formed on a rear end surface of the photomultiplier is incorporated in the camera barrel. One of the image intensifier holding devices.   5. The image intensifier holding device according to claim 1, wherein the elastic filler is a silicon resin.

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