JP2021051035A - Light detector and method for manufacturing the same - Google Patents

Abstract

To provide a light detector that can be assembled easily and has a high cooling performance, and a method for manufacturing the light detector.SOLUTION: A light detector 100 according to an embodiment includes: an outer sleeve 1 with a tapered inner surface inclined to an axis center line OX; an inner sleeve 2 in the outer sleeve 1, the inner sleeve having a tapered outer periphery surface inclined to the center axis line OX; a light reception element in the inner sleeve 2; and a Peltier element 13 between the inner sleeve 2 and the outer sleeve 1, the element being inclined to the center axis line OX.SELECTED DRAWING: Figure 1

Description

The present invention relates to a photodetector and a method for manufacturing the same.

In a photodetector using a light receiving element such as a photomultiplier tube or a photodiode, there is a demand for cooling the light receiving element. In the past, the entire light receiving element was cooled, but recently, some have intensively cooled the photoelectric surface. In this case, a perforated electronic cooling element (Peltier element) is often used.

However, in a light receiving element having a large photoelectric surface, the inflow of heat from the photoelectric surface becomes large. For this reason, the Peltier element cannot be cooled to the same extent unless a larger amount of heat is transferred, as compared with the case of a light receiving element having a small photoelectric surface. Therefore, the amount of heat generated by the Peltier element increases. It is generally known that a Peltier element generates heat about three times the amount of heat absorbed.

Further, since the body (outer diameter) of the photodetector becomes thick, the amount of heat feedback from the outer peripheral case to the light receiving element also increases, and it is difficult to efficiently perform cooling. Therefore, in a light receiving element having a large photoelectric surface, it is necessary to cool not only the photoelectric surface but also the entire element.

Patent Document 1 discloses an apparatus having a photocathode. In FIG. 6 of Patent Document 1, a Peltier element is arranged between the side surface of the image multiplying tube and the cooling box. A plurality of Peltier elements are arranged so as to hit the side surface of the image multiplying tube.

Japanese Unexamined Patent Publication No. 62-180930

It is desired to efficiently arrange the Peltier element in order to cool the entire light receiving element. In FIG. 6 of Patent Document 1, the light receiving element, the Peltier element, and the cooling box (radiator) are aligned in the same direction. Therefore, considering the outer shape tolerance of the light receiving element, the thickness tolerance of the Peltier element, the inner diameter tolerance of the radiator, and the like, a gap (gap) is required between the elements.

Further, since the heat medium (thermal grease, etc.) has a high "concentration", it is difficult to slide the light receiving element during assembly unless the interval is widened. From the above, the thickness of the thermal grease must be allowed. The thicker the thermal paste, the greater the thermal resistance.

Non-Patent Document 1 is a document of a general commercially available thermal grease. According to this, the thermal conductivity of the heat-dissipating grease is 0.8 W / mK, which is considerably lower than that of copper (401 W / mK) and aluminum (250 W / mK), which are often used in radiators and the like. In general, thermal paste having high thermal conductivity has high consistency. It is difficult to prepare thermal paste that is easy to assemble and has high thermal conductivity.

The present disclosure has been made against the background of such circumstances, and an object of the present invention is to provide a photodetector having high cooling performance and easy to assemble, and a method for manufacturing the same.

The photodetector according to one aspect of the present embodiment has an outer peripheral device having a tapered inner peripheral surface inclined with respect to the axis center line, and an outer peripheral device arranged inside the outer peripheral device and inclined with respect to the axis center line. An inner peripheral device having a tapered outer peripheral surface, a light receiving element arranged inside the inner peripheral device, and arranged between the inner peripheral device and the outer peripheral device, and inclined with respect to the axis center line. It is provided with a heat radiating element arranged in a row.

In the above-mentioned photodetector, grease may be provided between the outer peripheral device and the heat radiating element.

In the above-mentioned photodetector, grease may be provided between the inner peripheral device and the heat radiating element.

In the above-mentioned photodetector, the heat radiating element may be fixed to the inner peripheral device or the outer peripheral device by an adhesive.

The method for manufacturing a photodetector according to one aspect of the present embodiment is a peripheral device having a tapered inner peripheral surface inclined with respect to the axis center line, and an outer peripheral device arranged inside the outer peripheral device with respect to the axis center line. An inner peripheral device having a tapered outer peripheral surface that is inclined, a light receiving element arranged inside the inner peripheral device, and an inner peripheral device arranged between the inner peripheral device and the outer peripheral device, with respect to the axis center line. A step of inserting the inner peripheral device into the outer peripheral device and a step of attaching a front plate to one end of the outer peripheral device after inserting the inner peripheral device. , A step of purging or exhausting the internal space of the inner circumference to which the front plate is attached.

The method for manufacturing a photodetector according to claim 5, wherein in the above manufacturing method, grease is provided between the inner peripheral device and the heat radiating element.

In the above manufacturing method, grease may be provided between the outer peripheral device and the heat radiating element.

In the above manufacturing method, the inner peripheral device to which the heat radiating element is fixed may be inserted into the outer peripheral device. Alternatively, the inner peripheral device may be inserted into the outer peripheral device to which the heat radiating element is fixed.

According to the present disclosure, it is possible to provide a photodetector having high cooling performance and easy to assemble, and a method for manufacturing the same.

It is a side sectional view which shows the structure of the photodetector. It is XY sectional view of the photodetector. It is a front view which shows the structure of the photodetector. It is a side sectional view which shows typically the main part of the photodetector at the time of assembly.

Hereinafter, embodiments to which the present invention can be applied will be described. The following description describes embodiments of the present invention, and the present invention is not limited to the following embodiments. In order to clarify the explanation, the following description has been omitted or simplified as appropriate. Further, those skilled in the art will be able to easily change, add, and convert each element of the following embodiments within the scope of the present invention. In each figure, those having the same reference numerals indicate the same elements, and the description thereof will be omitted as appropriate.

The configuration of the photodetector 100 according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a side sectional view showing a configuration of a photodetector. FIG. 2 is an XY cross-sectional view showing the configuration of the photodetector. FIG. 3 is a front view showing the configuration of the photodetector 100. FIG. 2 is a view of the configuration on the incident surface side where the light of the photodetector 100 is incident, observed from the incident light direction with the front plate of 3 removed, and shows the configuration on the light receiving side. FIG. 3 shows the front plate of 3.

In the figure, the XYZ three-dimensional Cartesian coordinate system is shown for the sake of clarity. The photodetector 100 has a cylindrical shape, and its axial direction is the Z direction. The plane orthogonal to the axial direction is the XY plane. The light receiving surface of the photodetector 100 is parallel to the XY plane. Further, the −Z side is the light receiving side of the photodetector 100. The −Z side of the photodetector 100 is the front side, and the + Z side is the back side.

Further, the machine center line of the photodetector 100 is set as the axis center line OX. The axis center line OX is a straight line parallel to the Z direction. The axis center line OX passes through the center of the light receiving surface of the light receiving element 14, which will be described later. The basic configuration of the photodetector 100 is axisymmetric. Therefore, in the following description, in the XY plane, the circumferential direction of the circle whose origin is the position of the axis center line OX is the circumferential direction, and the radial direction of the circle is the radial direction.

The photodetector 100 includes an outer sleeve 1, an inner sleeve 2, a front plate 3, a rear plate 4, a Peltier element 13, a light receiving element 14, and the like. The outer sleeve 1 is an outer peripheral device located on the outermost peripheral side of the photodetector 100, and a light receiving element 14 or the like is arranged inside the outer peripheral sleeve 1. Specifically, the inner sleeve 2, the Peltier element 13, and the light receiving element 14 are arranged in the hollow portion of the outer sleeve 1. The outer sleeve 1 is a cylinder that serves as a radiator, and serves as a case for accommodating each element. The outer sleeve 1 is a metal cylinder. The outer sleeve 1 is made of, for example, copper. The surface of the outer sleeve 1 may be chrome-plated or the like.

A rear plate 4 is provided on the bottom surface of the outer sleeve 1 on the + Z side, and a front plate 3 is provided on the bottom surface on the −Z side. That is, both end faces of the cylindrical outer sleeve 1 are covered with the front plate 3 and the rear plate 4. The front plate 3 and the rear plate 4 are fixed to the outer sleeve 1 with bolts or the like. Further, an O-ring 11 is arranged between the front plate 3 and the outer sleeve 1. Insulating felts 12 and 21 for suppressing heat sneaking are provided on the back side of the front plate 3 and the front side of the rear plate 4. The heat insulating felts 12 and 21 are made of wool having a thickness of 3 mm. Acrylic or the like may be used instead of the heat insulating felts 12 and 21.

The front plate 3 is provided with an outer window 5. The outer window 5 is made of a transparent material so as to transmit the detection light. The outer window 5 is formed of, for example, PMMA (Polymethylcrylic). Further, the surface of the outer window 5 may be coated with an antireflection coating or the like.

The front plate 3 and the rear plate 4 are made of, for example, copper. The surfaces of the front plate 3 and the rear plate 4 may be plated with chrome or the like. The space surrounded by the outer sleeve 1, the front plate 3, the rear plate 4, the outer window 5, etc. is a purge space. The purge space is purged with a purge gas such as Kr gas, Ar gas, or Xe gas. By substituting the purge space with the purge gas, the heat transfer from the outer peripheral device to the inner peripheral device can be reduced and discharge can be prevented. A Peltier element 13, a light receiving element 14, an inner sleeve 2, and the like are arranged in the purge space.

The inner sleeve 2 is an inner peripheral device smaller than the outer sleeve 1. The inner sleeve 2 is a metal cylinder. The inner sleeve 2 may be made of iron, copper, or the like. By using iron as the material of the inner sleeve 2, it is possible to have a magnetic shielding action. For example, electromagnetic soft iron can be used as the inner sleeve 2. The thermal conductivity of soft iron is 73 W / mK. The surface of the inner sleeve 2 may be chrome-plated or the like.

The inner sleeve 2 holds the light receiving element 14. That is, the light receiving element 14 is arranged in the hollow portion of the inner sleeve 2. The light receiving element 14 is a photomultiplier tube, but may be a photodiode or an image intensifier. Thermal grease may be applied between the inner sleeve 2 and the light receiving element 14. As a result, the light receiving element 14 can be slid into the inner sleeve 2.

More specifically, a convex portion 2a is provided on the inner peripheral surface of the inner sleeve 2. The convex portion 2a is a protrusion protruding toward the center of the shaft on the inner peripheral surface of the inner sleeve 2. The light receiving element 14 is fixed when the light receiving element 14 comes into contact with the convex portion 2a from the back surface side. The light receiving element 14 is inserted in the inner sleeve 2. It is sufficient that at least a part of the light receiving element 14 is arranged in the inner sleeve 2.

The light receiving element 14 is, for example, a cylindrical photomultiplier tube. The light receiving element 14 outputs a detection signal according to the amount of light received. The light receiving surface of the light receiving element 14 is arranged on the inner window 6 side. The light receiving surface of the light receiving element 14 has a circular shape having a diameter of several mm to several tens of mm. The outer shape of the light receiving element 14 on the XY plane may be circular or square. That is, the shape of the light receiving element 14 is not limited to a cylindrical shape, and may be a rectangular parallelepiped shape. The inner peripheral surface of the inner sleeve 2 may be processed so as to accommodate the light receiving element 14. A thermistor 22 for detecting the temperature on the light receiving surface side is attached to the light receiving element 14. The heat dissipation of the Peltier element 13 may be controlled according to the temperature detected by the thermistor 22.

An inner window 6 is attached to the front surface side of the inner sleeve 2. The inner window 6 is arranged in front of the light receiving element 14 with a gap. The inner window 6 is made of a transparent material so as to transmit the detection light. The inner window 6 is formed in PMMA, for example. Further, the surface of the inner window 6 may be provided with an antireflection coating or the like.

A Peltier element 13 is arranged between the inner sleeve 2 and the outer sleeve 1. As shown in FIG. 2, a plurality of Peltier elements 13 are arranged along the circumferential direction. Here, the eight Peltier elements 13 have the same size. The Peltier element 13 has a rectangular thin plate shape. For example, the size of the Peltier element 13 is 22 mm × 11 mm × 3.27 mm. The intersection of thickness is 3.27 mm ± 0.01 mm.

As shown in FIG. 2, eight Peltier elements 13 are arranged at equal intervals in the circumferential direction. Eight Peltier elements 13 are arranged at a constant angle in the circumferential direction. In the XY plane, eight Peltier elements 13 are arranged concentrically. The Peltier element 13 may be fixed to the outer peripheral surface of the inner sleeve 2 with an adhesive or the like. The adjacent Peltier elements 13 may be fixed to each other with a wire or the like.

The Peltier element 13 is a heat radiating element, and transfers heat absorbed on one surface to the other surface. The endothermic surface of the Peltier element 13 is a surface facing the inner sleeve 2, and the heat radiating surface is a surface on the outer sleeve 1 side. That is, the Peltier element 13 dissipates the heat of the inner sleeve 2 to the outer sleeve 1. As a result, the heat of the light receiving element 14 can be dissipated to the outside, and the temperature of the light receiving element 14 can be lowered.

The rear plate 4 is provided with a port 16. A connector for taking out a signal is connected to the port 16. Further, a gas lid 19 is attached to the rear plate 4. The gas lid 19 closes a gas hole (not shown) for purging the purge space. That is, after purging the purge space, the gas lid 19 is attached to the rear plate 4. An O-ring 20 is provided between the gas lid 19 and the rear plate.

A printed circuit board 15 is provided on the back side of the light receiving element 14. The thickness of the printed circuit board 15 is 1.6 mm, and wiring is formed on both sides thereof. Wiring such as signal lines and power supply lines is formed on the printed circuit board 15. A pin 14a projecting from the back surface side of the light receiving element 14 is inserted into the printed circuit board 15. As a result, the wiring between the light receiving element 14 and the printed circuit board 15 is electrically connected. Further, the printed circuit board 15 is formed with wiring connected to the Peltier element 13 and the thermistor 22. Similarly, the wiring of the printed circuit board 15 is connected to the Peltier element 13 and the thermistor 22 via a pin or the like.

Further, a spacer ring 7 is interposed between the printed circuit board 15 and the inner sleeve 2. Therefore, a gap corresponding to the thickness of the spacer ring 7 is provided between the light receiving element 14 and the printed circuit board 15.

A gap ring 8, a heat shield 9, and a gap ring 10 are provided on the back side of the printed circuit board 15. The heat shield 9 is a plate-shaped member along the XY plane. The gap ring 8 and the gap ring 10 are ring-shaped members having a hollow portion. The gap ring 8, the heat shield 9, and the gap ring 10 are formed of, for example, PMMA.
Further, a heat insulating felt 21 is arranged on the back surface side of the gap ring 10. Although not shown, the heat insulating felt 21 may be provided with a through hole for passing a cable or a connector.

The heat shield 9 is provided to prevent heat from sneaking in from the back surface side. The gap ring 8 and the gap ring 10 are provided to form a gap. A gap corresponding to the thickness of the gap ring 8 is formed between the heat shield 9 and the printed circuit board 15. A gap corresponding to the thickness of the gap ring 10 is formed between the heat shield 9 and the heat insulating felt 12.

A connector 25 is attached to the back side of the printed circuit board 15. The connector 25 is connected to the wiring provided on the printed circuit board 15. Further, a cable (not shown) is pulled out from the connector 25 to the port 16. The detection signal from the light receiving element 14 can be taken out of the photodetector 100 via the port 16. Further, an external power source can be supplied to the light receiving element 14 via the connector 25. Although only one connector 25 is shown in FIG. 1, a connector for connecting to the thermistor 22 or the Peltier element 13 may be provided separately. As the connector, an SHV connector or an SMA connector can be used.

The configuration and elements in the purge space shown in FIG. 1 show an example of the photodetector 100, and are not limited to the configuration shown in the figure.

Hereinafter, the configuration of the main part of the photodetector 100 will be described with reference to FIG. FIG. 4 schematically shows the configuration of the main part of the photodetector 100 at the time of assembly. Here, the Peltier element 13, the light receiving element 14, the inner sleeve 2, the outer sleeve 1, the inner window 6, and the like are shown as the main parts, and other configurations are omitted as appropriate.

In FIG. 4, the side surface of the outer sleeve 1 facing the Peltier element 13 is defined as the inner peripheral surface 1i. Further, the side surface of the inner sleeve 2 facing the Peltier element 13 is defined as the outer peripheral surface 2o. The inner peripheral surface 1i and the outer peripheral surface 2o are inclined with respect to the axis center line. Since the inner peripheral surface 1i is tapered, the inner diameter of the cylindrical outer sleeve 1 gradually decreases toward the −Z direction. Therefore, the outer diameter of the outer sleeve 1 is the largest on the + Z side end surface of the outer sleeve 1. Similarly, since the outer peripheral surface 2o is tapered, the outer diameter of the cylindrical inner sleeve 2 gradually decreases toward the −Z direction.

The inclination angle θ of the inner peripheral surface 1i with respect to the axis center line OX is, for example, 5 °. Similarly, the inclination angle of the outer peripheral surface 2o with respect to the axis center line OX is 5 °. That is, the inner peripheral surface 1i and the outer peripheral surface 2o are parallel to each other. The inner peripheral surface 1i and the outer peripheral surface 2o have the same inclination angle. Therefore, when the inner sleeve 2 is inserted into the outer sleeve 1, the inner peripheral surface 1i and the outer peripheral surface 2o face each other in a parallel state. A Peltier element 13 having a constant thickness can be interposed between the outer sleeve 1 and the inner sleeve 2.

Further, the inner peripheral surface 1i of the outer sleeve 1 is coated with thermal grease 31. The thermal grease 31 is, for example, a silicone resin. For example, SCH-20 manufactured by Sanhayato Co., Ltd. can be used as the heat radiating grease 31. In this case, the thermal conductivity of the heat-dissipating grease 31 is 0.84 W / m · K, and the consistency is 290. The thermal grease 31 may be applied to the Peltier element 13 instead of the inner peripheral surface 1i of the outer sleeve 1.

As described above, the Peltier element 13 is fixed to the outer peripheral surface 2o of the inner sleeve 2 with an adhesive or the like. Further, a light receiving element 14 is attached to the inside of the inner sleeve 2. The insertion unit 30 has a configuration in which the light receiving element 14 and the Peltier element 13 are attached to the inner sleeve 2. In FIG. 4, the insertion unit 30 is provided with an inner window 6, a spacer ring 7, a printed circuit board 15, and a connector 25, but these may be attached after insertion.

When assembling the photodetector 100, the insertion unit 30 is inserted inside the outer sleeve 1. That is, the insertion unit 30 is pushed into the outer sleeve 1 in the −Z direction with the + Z side end surface of the outer sleeve 1 as the insertion port. Since the inner peripheral surface 1i is coated with the heat radiating grease 31, the insertion unit 30 can be slid along the inner peripheral surface 1i. Then, the insertion unit 30 is pushed in the −Z direction until the insertion unit 30 does not move. That is, since the insertion unit 30 moves in the direction in which the diameter of the inner peripheral surface 1i becomes smaller, the insertion unit 30 is fitted into the outer sleeve 1 inside.

As described above, since the inner peripheral surface 1i and the outer peripheral surface 2o are tapered surfaces, they can be assembled even if there is an outer diameter tolerance of the outer sleeve 1, an inner diameter tolerance of the inner sleeve 2, and a thickness tolerance of the Peltier element 13. Can be easily performed. Further, since the thickness of the heat radiating grease 31 can be reduced, the heat radiating characteristics can be improved.

Since the inner peripheral surface 1i and the outer peripheral surface 2o are parallel tapered surfaces, the Peltier element 13 having a constant thickness can be used. That is, the Peltier element 13 having a constant thickness is arranged so as to be tilted from the axis center line OX. Since the Peltier element 13 having a constant thickness is inexpensive and easily available, the component cost can be reduced. Therefore, the manufacturing cost can be reduced. The inner peripheral surface 1i and the outer peripheral surface 2o do not have to be parallel to each other.

Further, the outer sleeve 1 serving as a radiator is separated from the insertion unit 30 including the Peltier element 13, the inner sleeve 2, and the like. That is, the photodetector 100 can be assembled by inserting the insertion unit 30 along the axis center line OX. Therefore, assembly can be easily performed. Further, since the outer sleeve 1 is separated, gas replacement can be easily performed.

Thermal grease may be applied between the inner sleeve 2 and the light receiving element 14. That is, when the light receiving element 14 is inserted into the inner sleeve 2, the light receiving element 14 may be slid sideways. Since the amount of heat transferred between the inner sleeve 2 and the light receiving element 14 is small, there is no problem even if the gap is set wide so that the inner sleeve 2 can be easily inserted. For the same reason, since electromagnetic soft iron having a low thermal conductivity can be used for the inner sleeve 2, it is also possible to give it a magnetic shielding action.

In the above description, the thermal paste 31 is provided between the outer sleeve 1 and the Peltier element 13, but the thermal grease 31 may be provided between the inner sleeve 2 and the Peltier element 13. In this case, the inner sleeve 2 may be slid sideways with the Peltier element 13 fixed to the inner peripheral surface 1i of the outer sleeve 1 using an adhesive or the like. In this case, the insertion unit 30 does not include the Peltier element 13. That is, the insertion unit 30 including the inner sleeve 2 may be inserted into the outer sleeve 1 to which the Peltier element 13 is attached.

Alternatively, the heat-dissipating grease 31 may be provided on both the heat-dissipating surface and the heat-absorbing surface of the Peltier element 13. That is, the thermal grease 31 may be arranged between the outer sleeve 1 and the Peltier element 13 and between the Peltier element 13 and the outer sleeve 1. For example, a plurality of Peltier elements 13 are integrated and inserted into the outer sleeve 1. Then, the inner sleeve 2 is inserted into the plurality of Peltier elements 13.

Further, as the heat radiating element, a flexible thermoelectric conversion module can be used instead of the Peltier element 13. As a result, the heat radiating element can be arranged along the outer peripheral surface 2o.

In the method of manufacturing the photodetector 100 according to the present embodiment, the inner sleeve 2 is inserted into the outer sleeve 1. For example, as shown in FIG. 4, the insertion unit 30 including the inner sleeve 2 is inserted into the outer sleeve 1. Then, after inserting the inner sleeve 2 (insertion unit 30), the gap ring 8, the heat shield 9, the gap ring 10, and the heat insulating felt 21 are sequentially inserted into the outer sleeve 1. After that, the rear plate 4 is attached to one end of the outer sleeve 1. Then, after attaching the rear plate 4, the internal space of the outer sleeve 1 is purged or exhausted. As a result, the photodetector 100 having high heat dissipation characteristics can be easily assembled.

Further, when the inner sleeve 2 is inserted into the outer sleeve 1, the inner sleeve 2 to which the Peltier element 13 is fixed by an adhesive may be inserted into the outer sleeve 1. That is, the insertion unit 30 in which the Peltier element 13 and the inner sleeve 2 are integrated may be inserted into the outer sleeve 1 along the axis center line OX.

The inner peripheral surface 1i and the outer peripheral surface 2o do not have to have a tapered shape as a whole. That is, at least a part of the inner peripheral surface 1i and the outer peripheral surface 2o may have a tapered shape. In other words, the inner peripheral surface 1i and the outer peripheral surface 2o may have a portion parallel to the axis center line OX. The tapered portion of the inner peripheral surface 1i and the tapered portion of the outer peripheral surface 2o may be arranged to face each other.

Although the invention made by the present inventor has been specifically described above based on the embodiments, the present invention is not limited to the embodiments already described, and various changes can be made without departing from the gist thereof. It goes without saying that it is possible.

100 Light detector 1 Outer sleeve 2 Inner sleeve 3 Front plate 4 Rear plate 5 Outer window 6 Inner window 7 Spacer ring 8 Gap ring 9 Heat shield 10 Gap ring 11 O-ring 12 Thermal insulation felt 13 Connector element 14 Light receiving element 15 Printed board 16 Port 19 Gas lid 20 O-ring 21 Insulation felt 22 Thermistor 25 Connector 30 Insertion unit 31 Thermal paste

Claims (9)

An outer peripheral device having a tapered inner peripheral surface inclined with respect to the axis center line,
An inner peripheral device that is arranged inside the outer peripheral device and has a tapered outer peripheral surface that is inclined with respect to the axis center line.
A light receiving element arranged inside the inner peripheral device and
A photodetector comprising a heat radiating element arranged between the inner peripheral device and the outer peripheral device and arranged at an angle with respect to the axis center line. The photodetector according to claim 1, wherein grease is provided between the outer peripheral device and the heat radiating element. The photodetector according to claim 1 or 2, wherein grease is provided between the inner peripheral device and the heat radiating element. The photodetector according to claim 2 or 3, wherein the heat radiating element is fixed to the inner peripheral device or the outer peripheral device by an adhesive. An outer peripheral device having a tapered inner peripheral surface inclined with respect to the axis center line,
An inner peripheral device that is arranged inside the outer peripheral device and has a tapered outer peripheral surface that is inclined with respect to the axis center line.
A light receiving element arranged inside the inner peripheral device and
A heat radiating element arranged between the inner peripheral device and the outer peripheral device and arranged at an angle with respect to the axis center line is provided.
The step of inserting the inner peripheral device into the outer peripheral device,
After inserting the inner peripheral device, the step of attaching the front plate to one end of the outer peripheral device,
A method of manufacturing a photodetector comprising a step of purging or exhausting the internal space of an inner peripheral to which the front plate is attached. The method for manufacturing a photodetector according to claim 5, wherein grease is provided between the outer peripheral device and the heat radiating element. The method for manufacturing a photodetector according to claim 5 or 6, wherein grease is provided between the inner peripheral device and the heat radiating element. The method for manufacturing a photodetector according to claim 6, wherein the inner peripheral device to which the heat radiating element is fixed is inserted into the outer peripheral device. The method for manufacturing a photodetector according to claim 7, wherein the inner peripheral device is inserted into the outer peripheral device to which the heat radiating element is fixed.

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