Electron tube and camera

Abstract

The electron tube of the present invention comprises: a shell, the interior of which is kept in vacuum and has a window for transmitting electromagnetic waves; an electron emission unit, which is arranged in the shell and has a metasurface for emitting electrons in response to the incidence of the electromagnetic waves; an electron multiplication unit, which is arranged in the shell and multiplies the electrons emitted from the electron emission unit, and an electron collection unit, which is arranged in the shell and collects the electrons multiplied by the electron multiplication unit. The window comprises at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide and calcium carbonate.

Description

Technical Field

[0001] The invention relates to an electron tube and a camera device. Background Art

[0002] A known terahertz wave detector includes a substrate having a metamaterial structure and a light sensor (for example, see Patent Document 1). A terahertz wave is incident on the substrate.

[0003] Patent Literature

[0004] Patent Document 1: U.S. Patent Application Publication No. 2016 / 0216201 Summary of the invention

[0005] Problem that the invention aims to solve

[0006] In the detector described in Patent Document 1, when a terahertz wave is incident on a substrate having a metamaterial structure, the substrate emits electrons. For example, the electrons emitted from the substrate excite molecules contained in the atmosphere. The excited molecules generate light. The generated light is detected by a light sensor. It is difficult for the detector to detect terahertz waves having a weak intensity.

[0007] One aspect of the present invention is to provide an electron tube that ensures detection accuracy of electromagnetic waves. Another aspect of the present invention is to provide an imaging device that ensures detection accuracy of electromagnetic waves.

[0008] Means for solving technical problems

[0009] An electron tube according to one aspect of the present invention includes: a housing, an electron emission unit and an electron multiplication unit. The interior of the housing is kept in vacuum and includes a window that transmits electromagnetic waves. The electron emission unit is arranged in the housing. The electron emission unit includes a metasurface that emits electrons in response to the incidence of electromagnetic waves. The electron multiplication unit is arranged in the housing. The electron multiplication unit multiplies the electrons emitted from the electron emission unit. The electron collection unit is arranged in the housing. The electron collection unit collects the electrons multiplied by the electron multiplication unit. The window includes at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide and calcium carbonate.

[0010] In one aspect, the window included in the housing includes at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide, and calcium carbonate. Therefore, the intensity of the electromagnetic wave (for example, an electromagnetic wave in a frequency band from terahertz waves to infrared light) guided into the housing can be ensured. When the electromagnetic wave passing through the window is incident on the metasurface of the electron emission unit, electrons are emitted from the electron emission unit. The emitted electrons are multiplied by the electron multiplying unit in the housing. In the electron collecting unit, the multiplied electrons are collected. Therefore, the detection accuracy of the above-mentioned electromagnetic waves is ensured.

[0011] In one aspect, the electron emission unit may include: a substrate including a first main surface provided with a metasurface and a second main surface opposite to the first main surface. The electron multiplying unit may include: an incident surface on which electrons emitted from the electron emission unit are incident. The substrate may be transmissive to electromagnetic waves passing through the window. The substrate may be arranged in such a way that the first main surface faces the incident surface of the electron multiplying unit and the second main surface faces the window. In this case, in a structure in which an electromagnetic wave is incident on the metasurface through the window and the substrate, electrons emitted from the metasurface in response to the incidence of the electromagnetic wave are guided to the electron multiplying unit through a simple structure.

[0012] In one aspect, the electron multiplying unit may include an incident surface on which the electrons emitted from the electron emitting unit are incident. Alternatively, the metasurface may be disposed on the window to face the incident surface of the electron multiplying unit. In this case, a substrate having a metasurface is not required to be disposed in the housing. Therefore, the size and weight of the electron tube may be reduced.

[0013] In one aspect, the electron emission unit may include: a substrate including a first main surface provided with a metasurface and a second main surface opposite to the first main surface. The electron multiplying unit may include: an incident surface on which electrons emitted from the electron emission unit are incident. The substrate may be arranged in such a way that the first main surface faces the window and the incident surface of the electron multiplying unit. In this case, in a structure in which an electromagnetic wave passing through the window is incident on the metasurface without passing through the substrate, the electrons emitted from the metasurface in response to the incidence of the electromagnetic wave are guided to the electron multiplying unit through a simple structure.

[0014] In one aspect, the metasurface may be comprised of a patterned oxide layer or a patterned metal layer. In this case, the electrons emitted from the metasurface in response to the incident electromagnetic wave increase.

[0015] In one aspect, the electron multiplying unit and the electron collecting unit may be diodes and may be integrally formed. In this case, the size of the electron tube can be further reduced.

[0016] In one aspect, the electron multiplication unit may include a plurality of dynodes spaced apart from one another. Alternatively, the electron collection unit may include an anode or a diode configured to collect electrons multiplied by the electron multiplication unit. In this case, the electrons emitted from the metasurface are multiplied by the plurality of dynodes. Thus, the multiplication factor of the electrons collected by the anode or the diode is increased.

[0017] In one aspect, the electron multiplying unit may include a microchannel plate. The electron collecting unit may include an anode or a diode configured to collect electrons multiplied by the electron multiplying unit. In this case, the size, weight, and power consumption are reduced and the response speed and gain are improved compared to the case where the electron multiplying unit includes a plurality of dynodes.

[0018] In one aspect, the electron multiplying unit may include a microchannel plate. Alternatively, the electron collecting unit may include a phosphor configured to receive electrons multiplied by the electron multiplying unit and emit light. In this case, the two-dimensional position of the electrons emitted from the metasurface may be detected by the light emitted from the phosphor.

[0019] An image pickup device according to another aspect of the present invention includes: an electron tube, and an image pickup unit configured to capture an image based on light from a fluorescent body. In another aspect, detection accuracy of electromagnetic waves is ensured.

[0020] Advantageous Effects of the Invention

[0021] According to one aspect of the present invention, an electron tube that ensures detection accuracy of electromagnetic waves can be provided. According to another aspect of the present invention, an imaging device that ensures detection accuracy of electromagnetic waves can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a cross-sectional view showing an electron tube according to an embodiment.

[0023] Figure 2 This is a partial enlarged view of the electron tube.

[0024] Figure 3 A local enlarged image of the metasurface.

[0025] Figure 4 A partial exploded view of the electron tube is shown.

[0026] Figure 5 It is a partially enlarged view showing an electron tube according to a modified example of the embodiment.

[0027] Figure 6 It is a partially enlarged view showing an electron tube according to a modified example of the embodiment.

[0028] Figure 7It is a partially enlarged view showing an electron tube according to a modified example of the embodiment.

[0029] Figure 8 2 is a cross-sectional view showing an electron tube according to a modification of the embodiment.

[0030] Fig. 9 2 is a cross-sectional view showing an electron tube according to a modification of the embodiment.

[0031] Fig.10 FIG. 4 is a perspective cross-sectional view showing a microchannel plate.

[0032] Fig.11 It is a partial cross-sectional view showing an electron tube according to a modification of the embodiment.

[0033] Fig.12 2 is a cross-sectional view showing an electron tube according to a modification of the embodiment.

[0034] Fig.13 It is a side view showing an image pickup device according to a modification of the embodiment.

[0035] Fig.14 2 is a cross-sectional view showing an electron tube according to a modification of the embodiment. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions are denoted by the same reference numerals, and redundant explanations are omitted.

[0037] First, refer to Figures 1 to 4 , describing the structure of an electron tube according to an embodiment of the present invention. Figure 1 is a cross-sectional view showing an example of an electron tube. Figure 2 It is a partial enlarged view showing an example of an electron tube.

[0038] The electron tube 1 is a photomultiplier tube that outputs an electrical signal in response to the incidence of electromagnetic waves. When electromagnetic waves are incident, the electron tube 1 emits electrons inside and multiplies the emitted electrons. In this specification, the "electromagnetic waves" incident on the electron tube are electromagnetic waves contained in the frequency band from so-called millimeter waves to infrared light. Figure 1 As shown, the electron tube 1 includes: a housing 10 , an electron emission unit 20 , an electron multiplication unit 30 , and an electron collection unit 40 .

[0039] The housing 10 includes a valve 11 and a valve stem 12. The interior of the housing 10 is hermetically sealed by the valve 11 and the valve stem 12 and is kept in vacuum. Vacuum includes not only an absolute vacuum but also a state where the housing is filled with a gas having a pressure lower than the atmospheric pressure. For example, the interior of the housing 10 is kept at 1×10 -4 Up to 1×10-7 Pa. The valve 11 includes a window 11a that transmits electromagnetic waves. For example, the housing 10 has a cylindrical shape. In this embodiment, the housing 10 has a cylindrical shape. The valve stem 12 constitutes the bottom surface of the housing 10. The valve 11 constitutes the side surface of the housing 10 and the bottom surface facing the valve stem 12.

[0040] The window 11a constitutes the bottom surface facing the valve stem 12. For example, the window 11a has a circular shape in a top view. The window 11a includes at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide and calcium carbonate. In the present embodiment, the window 11a is made of quartz. The frequency characteristics of the transmittance of electromagnetic waves vary depending on the material. Therefore, the material of the window 11a can be selected according to the frequency band of the electromagnetic wave passing through the window 11a. For example, quartz can be selected as the material of a component that transmits electromagnetic waves with a frequency band of 0.1 to 5 THz, silicon can be selected as the material of a component that transmits electromagnetic waves with a frequency band of 0.04 to 11 THz and above 46 THz, magnesium fluoride can be selected as the material of a component that transmits electromagnetic waves with a frequency band of 40 THz or above, germanium can be selected as the material of a component that transmits electromagnetic waves with a frequency band of 13 THz or above, and zinc selenide can be selected as the material of a component that transmits electromagnetic waves with a frequency band of 14 THz or above.

[0041] The electron tube 1 includes a plurality of wires 13 for achieving electrical connection between the outside and the inside of the housing 10. The plurality of wires 13 are, for example, leads or pins. In the present embodiment, the plurality of wires 13 are pins that penetrate the valve stem 12 and extend from the inside of the housing 10 to the outside thereof. At least one of the plurality of wires 13 is connected to various components disposed inside the housing 10.

[0042] The electron emission unit 20 is disposed in the housing 10, and emits electrons in response to the incidence of electromagnetic waves in the housing 10. The electron emission unit 20 includes a meta-surface 50 and a substrate 21 provided with the meta-surface 50. The substrate 21 has transmittance to electromagnetic waves passing through the window 11a. In this specification, "transmittance" refers to the performance of transmitting at least a portion of the frequency band of the incident electromagnetic wave. That is, the substrate 21 transmits at least a portion of the frequency band of the electromagnetic wave passing through the window 11a. The substrate 21 is composed of silicon, for example. The substrate 21 has a rectangular shape in a top view. The substrate 21 is separated from the window 11a and the electron multiplying unit 30.

[0043] like Figure 2 As shown, the substrate 21 includes a pair of main surfaces 21a and 21b facing each other. The super surface 50 is provided on the main surface 21a. For example, when the main surface 21a constitutes the first main surface, the main surface 21b constitutes the second main surface. The main surface 21a and the main surface 21b are arranged to be parallel to the window 11a.

[0044] The metasurface 50 includes a patterned oxide layer or metal layer on the main surface 21a of the substrate 21. The oxide layer is, for example, titanium oxide. The metal layer is, for example, gold. The metasurface 50 has a rectangular shape in a top view. Figure 3 is a partial enlarged view showing an example of a metasurface. Figure 3 As shown, the metal layer included in the passive meta-surface 50 forms a plurality of antennas 51 on the main surface 21 a .

[0045] The antenna 51 with a smaller size is sensitive to electromagnetic waves with a shorter wavelength, that is, with a higher frequency. According to the change of the structure of the antenna 51, the metasurface 50 corresponds to a frequency band of about 0.01 to 150 THz, that is, a frequency band from so-called millimeter waves to near-infrared light. For example, the metasurface 50 can be configured to correspond to a frequency band of 0.01 to 10 THz, which is equivalent to a frequency band from so-called millimeter waves to terahertz waves. For example, the metasurface 50 can be configured to correspond to a frequency band of 10 to 150 THz, which is equivalent to a frequency band from terahertz waves to near-infrared light. In the present embodiment, the size of the metasurface 50 in the top view is 10×10 mm. The spacing between the antennas 51 is about 70 μm to 100 μm. The metasurface 50 corresponds to an electromagnetic wave with a frequency of 0.5 THz.

[0046] In this embodiment, the metasurface 50 is a transmission-type metasurface. In a transmission-type metasurface, when an electromagnetic wave is incident, electrons are emitted from the opposite side of the electromagnetic wave incident surface. In the electron tube 1, the electromagnetic wave passing through the window 11a is incident on the main surface 21b of the substrate 21. The electromagnetic wave passing through the substrate 21 is incident on the metasurface 50 provided on the main surface 21a. After passing through the window 11a and the substrate 21, the metasurface 50 emits electrons in response to the electromagnetic wave incident thereon.

[0047] The electron multiplying unit 30 is disposed in the housing 10, and includes an incident surface 35 to which the electrons emitted from the electron emitting unit 20 are incident. The electron multiplying unit 30 multiplies the electrons incident on the incident surface 35. In the present embodiment, the main surface 21a of the substrate 21 faces the incident surface 35 of the electron multiplying unit 30. That is, the metasurface 50 faces the incident surface 35 of the electron multiplying unit 30, and the electrons emitted from the metasurface 50 are incident on the incident surface 35. The main surface 21b of the substrate 21 faces the window 11a of the housing 10.

[0048] In this specification, "α faces β" means that β is located in a normal direction closer to α than the plane in contact with α. In other words, "α faces β" means that when the space is divided into two by the surface in contact with α, β is located on the α side, not on the back side of α. For example, in the electron tube 1, as described above, the metasurface 50 faces the incident surface 35 of the electron multiplying unit 30. This means that the incident surface 35 of the electron multiplying unit 30 is located in a normal direction closer to the metasurface 50 than the plane in contact with the metasurface 50.

[0049] In this embodiment, if Figure 1 and Figure 4 As shown, the electron multiplying unit 30 comprises a so-called linear-focused multistage dynode. Figure 4 A partial exploded view of the electron multiplying unit 30 and the electron collecting unit 40 is shown.

[0050] In the present embodiment, the electron multiplying unit 30 includes: a focusing electrode 31 configured to gather electrons, and multistage dynodes 32a, 32b, 32c, 32d, 32e, 32f, 32g, 32h, 32i and 32j spaced from each other. The dynode 32a includes the above-mentioned incident surface 35. In the present embodiment, the electron multiplying unit 30 includes ten stages of dynodes 32a to 32j. A circular incident opening 31a is provided in the central portion of the focusing electrode 31. The dynodes 32a to 32j are arranged at the rear stage of the incident opening 31a. One of the plurality of wires 13 is connected to each of the dynodes 32a to 32j. A predetermined potential is applied to each of the dynodes 32a to 32j through the wire 13. The dynodes 32a to 32j multiply the electrons passing through the incident opening 31a according to the applied potential.

[0051] The electron collecting unit 40 is arranged in the housing 10, and collects electrons multiplied by the electron multiplying unit 30. In the present embodiment, the electron collecting unit 40 includes a mesh anode 41. The anode 41 is opposite to the main surface 21b of the substrate 21. One of the plurality of wires 13 is connected to the anode 41. A predetermined potential is applied to the anode 41 through the wire 13. The anode 41 captures the electrons multiplied by the multiplier electrodes 32a to 32j. The electron collecting unit 40 may include a diode instead of the anode 41.

[0052] In the present embodiment, the electron tube 1 includes insulating substrates 52, 53. The dynodes 32a to 32j are fixed to the substrates 52 and 53 in the housing 10. The insulating substrates 52, 53 are made of aluminum oxide. The insulating substrates 52, 53 are opposite to each other. The dynodes 32a to 32j include a pair of end portions 32k extending in the direction in which the insulating substrates 52, 53 are opposite to each other. The anode 41 includes a pair of end portions 41k extending in the direction in which the insulating substrates 52, 53 are opposite to each other. The end portions 32k and 41k of the dynodes 32a to 32j and the anode 41 are inserted into slit-shaped through holes 52a, 53a provided in the insulating substrates 52, 53.

[0053] The electron tube 1 includes a shielding plate 36. The shielding plate 36 surrounds the dynodes 32a to 32j and a portion of the anode 41. The shielding plate 36 prevents light and ions generated by collision of electrons multiplied by the dynodes 32a to 32j from scattering in the housing 10. The shielding plate 36 is connected to one of the plurality of wires 13. A predetermined potential is applied to the shielding plate 36 through the wire 13.

[0054] Next, the operation of the electron tube 1 when an electromagnetic wave is incident is described. After passing through the window 11a of the housing 10, the electromagnetic wave is incident on the main surface 21b of the substrate 21. The electromagnetic wave incident on the main surface 21b passes through the substrate 21 and is incident on the metasurface 50 provided on the main surface 21a of the substrate 21. The metasurface 50 emits electrons in response to the incidence of the electromagnetic wave. The electrons are emitted to the incident surface 35 of the electron multiplying unit 30.

[0055] The electrons emitted from the metasurface 50 are gathered by the focusing electrode 31 and sent to the first-stage dynode 32a. When the electrons are incident on the first-stage dynode 32a, the secondary electrons are emitted from the dynode 32a to the second-stage dynode 32b. When the electrons are incident on the second-stage dynode 32b, the secondary electrons are emitted from the dynode 32b to the third-stage dynode 32c. In this way, the electrons are multiplied from the first-stage dynode 32a to the tenth-stage dynode 32j and sent in sequence. That is, for the electrons emitted from the metasurface 50, cascade multiplication is performed by the electron multiplication unit 30. The electrons multiplied by the electron multiplication unit 30 are collected by the anode 41 and output from the anode 41 as an output signal through the wire 13. For example, the first-stage dynode 32a constitutes the incident surface 35.

[0056] Next, refer to Figure 5 and Figure 6 , an electron tube according to a modified example of the embodiment is described. Figure 5 and Figure 6 A partially enlarged view of an electron tube according to a modified example is shown.

[0057] Figure 5The modification shown is substantially similar to or the same as the above-described embodiment. However, the modification differs from the embodiment in that the substrate 21 is provided on the window 11a. The differences between the embodiment and the modification are mainly described below.

[0058] exist Figure 5 In the electron tube 1A shown, the metasurface 50 is indirectly provided on the window 11a in such a manner that the substrate 21 is located between the window 11a and the metasurface 50 in the housing 10. The substrate 21 is provided on the window 11a in the housing 10. The substrate 21 has transmissivity to electromagnetic waves passing through the window 11a. That is, the substrate 21 transmits at least a portion of the frequency band of the electromagnetic waves passing through the window 11a. The substrate 21 is made of silicon, for example. The substrate 21 has a rectangular shape in a top view. The substrate 21 is separated from the window 11a and the electron multiplying unit 30.

[0059] The substrate 21 includes: a main surface 21a provided with a metasurface 50, and a main surface 21b opposite to the main surface 21a. The main surface 21a faces the incident surface 35 of the electron multiplying unit 30. That is, the metasurface 50 faces the electron multiplying unit 30. The main surface 21b faces the window 11a of the housing 10. The main surface 21a and the main surface 21b are arranged parallel to the window 11a. The main surface 21b and the window 11a of the substrate 21 are bonded by a vacuum adhesive L. The adhesive L is transmissive to electromagnetic waves passing through the window 11a. The vacuum adhesive L is, for example, a polyethylene resin or an epoxy resin adhesive. For example, when the main surface 21a constitutes the first main surface, the main surface 21b constitutes the second main surface.

[0060] exist Figure 5 In the electron tube 1A shown, the electromagnetic wave passing through the window 11a is incident on the main surface 21b of the substrate 21. The electromagnetic wave incident on the main surface 21b of the substrate 21 passes through the substrate 21 and is incident on the metasurface 50 provided on the main surface 21a. When the terahertz wave is incident on the metasurface 50, the metasurface 50 emits electrons. The electrons are emitted from the metasurface 50 to the incident surface 35 of the electron multiplying unit 30.

[0061] Figure 6 The variation shown is substantially similar or identical to the above-described embodiment. However, the variation differs from the embodiment in that, in the housing 10, the metasurface 50 is directly disposed on the window 11a, without positioning the substrate between the metasurface and the window 11a. The following mainly describes the differences between the embodiment and the variation.

[0062] exist Figure 6 In the electron tube 1B shown, the metasurface 50 faces the incident surface 35 of the electron multiplying unit 30. Figure 6 In the electron tube 1B shown, the electromagnetic wave passing through the window 11a is incident on the metasurface 50 provided on the window 11a, and electrons are emitted from the metasurface 50. The electrons are emitted from the metasurface 50 to the incident surface 35 of the electron multiplying unit 30.

[0063] Next, refer to Figure 7 , an electron tube according to a modified example of the embodiment is described. Figure 7 A cross-sectional view showing an example of an electron tube. Figure 7 The variation shown is substantially similar or identical to the above-described embodiment. However, the variation differs from the embodiment in that the window 11a is disposed on the side of the housing 10, the incident direction of the electromagnetic wave to the metasurface 50 is different, and the electron multiplying unit 30 includes a so-called circular-cage multistage dynode. The following mainly describes the differences between the embodiment and the variation.

[0064] exist Figure 7 In the electron tube 1C shown, the window 11a is provided on the side surface of the cylindrical housing 10. In the electron tube 1C, the main surface 21a of the substrate 21 faces the window 11a and the incident surface 35 of the electron multiplying unit 30. That is, the metasurface 50 provided on the main surface 21a faces the window 11a and the incident surface 35 of the electron multiplying unit 30.

[0065] In the electron tube 1C, the metasurface 50 of the electron emission unit 20 is a reflective metasurface. In the reflective metasurface, when an electromagnetic wave is incident, electrons are emitted on the surface side where the electromagnetic wave is incident. In the electron tube 1C, the electromagnetic wave passing through the window 11a does not pass through the substrate 21 but is incident on the metasurface 50 provided on the main surface 21a of the substrate 21. After passing through the window 11a, the metasurface 50 emits electrons in response to the electromagnetic wave incident on the metasurface 50.

[0066] The electron tube 1C includes a grid 55 between the metasurface 50 and the window 11a. The electromagnetic wave passing through the window 11a passes through the grid 55 and is incident on the metasurface 50. A voltage is applied to the grid 55 through the wire 13. Due to the influence of the electric field caused by the grid 55, the electrons emitted from the metasurface 50 are guided to the incident surface 35 of the electron multiplying unit 30.

[0067] The electron multiplying unit 30 of the electron tube 1C includes so-called circular cage-type multistage dynodes 32a, 32b, 32c, 32d, 32e, 32f, 32g, 32h and 32i. The dynode 32a includes an incident surface 35. In this modification, the electron multiplying unit 30 includes nine stages of dynodes 32a to 32i. The dynodes 32a to 32i are arranged along the side of the housing 10 and around the electron emission unit 20. A predetermined potential is applied to each of the dynodes 32a to 32i through the wire 13. The dynodes 32a to 32i multiply the incident electrons according to the applied potential.

[0068] The electron collecting unit 40 of the electron tube 1C is surrounded by the bent dynode 32i. In this modification, the electron collecting unit 40 is an anode 41. One of the plurality of wires 13 is connected to the anode 41. A predetermined potential is applied to the anode through the wire 13. The anode 41 captures electrons multiplied by the dynodes 32a to 32i.

[0069] exist Figure 7 In the electron tube 1C shown, if an electromagnetic wave passes through the window 11a of the housing 10, the electromagnetic wave passes through the grid 55 and is incident on the metasurface 50 provided on the main surface 21a of the substrate 21. The metasurface 50 emits electrons in response to the incidence of the electromagnetic wave. The electrons emitted from the metasurface 50 are emitted to the incident surface 35 of the electron multiplying unit 30 by the influence of the electric field caused by the grid 55.

[0070] The electrons emitted from the metasurface 50 are sent to the first-stage dynode 32a. When the electrons are incident on the first-stage dynode 32a (incident surface 35), secondary electrons are emitted from the dynode 32a to the second-stage dynode 32b. When the electrons are incident on the second-stage dynode 32b, secondary electrons are emitted from the dynode 32b to the third-stage dynode 32c. In this way, the electrons are multiplied from the first-stage dynode 32a to the ninth-stage dynode 32i, and are sent sequentially in a manner around the substrate 21. The electrons multiplied by the electron multiplier unit 30 are collected by the anode 41 and output from the anode 41 as an output signal through the wire 13.

[0071] Next, refer to Figure 8 , an electron tube according to a modified example of the present embodiment is described. Figure 8 is a cross-sectional view showing an example of an electron tube. Figure 8 The modification shown is substantially similar or identical to the above-described embodiment. However, the modification differs from the embodiment in that the electron multiplying unit 30 and the electron collecting unit 40 are integrally formed into a diode 60. The differences between the embodiment and the modification are mainly described below.

[0072] exist Figure 8 In the electron tube 1D shown, the electron multiplying unit 30 and the electron collecting unit 40 are diodes 60. In the electron tube 1D, the electron multiplying unit 30 and the electron collecting unit 40 are integrally formed. In the electron tube 1D, the metasurface 50 faces the window 11a.

[0073] In this modification, the diode 60 is an avalanche diode. The diode 60 has a rectangular shape in a top view and includes a pair of main surfaces 61, 62 facing each other. The main surface 61 includes an electron incident surface 61a. The main surface 61 faces the window 11a of the housing 10. The main surface 62 faces the valve stem 12 of the housing 10. The main surfaces 61, 62 are arranged parallel to the window 11a, the substrate 21 and the metasurface 50.

[0074] The main surface 62 of the diode 60 is provided with an insulating layer 65. The diode 60 is connected to the valve stem 12 in such a manner that the insulating layer 65 is located between the diode 60 and the valve stem 12. One of the plurality of wires 13 is connected to each of the main surface 61 and the main surface 62.

[0075] A reverse bias voltage is applied to the diode 60 through the wire 13. In this modification, a reverse bias voltage higher than the breakdown voltage is applied between the main surface 61 side of the diode 60 and the main surface 62 side of the diode 60. In the electron tube 1D, when electrons emitted from the metasurface 50 of the substrate 21 are incident on the electron incident surface 61a of the diode 60, the incident electrons are multiplied in the diode 60 by the avalanche multiplication effect. The multiplied electrons are output as an output signal through the wire 13. For example, the main surface 61 constitutes the electron incident surface 61a

[0076] Next, refer to Fig. 9 and Fig.10 , an electron tube according to a modified example of the embodiment is described. Fig. 9 is a cross-sectional view showing an example of an electron tube. Fig. 9 The variation shown is substantially similar or identical to the above-described embodiment. However, the variation differs from the embodiment in that the electron multiplying unit 30 includes a microchannel plate 70 instead of the focusing electrode 31 and the dynodes 32a to 32j. The following mainly describes the differences between the embodiment and the variation.

[0077] exist Fig. 9 In the electron tube 1E shown, the microchannel plate 70 is supported by the inner edges of the attachment members 71, 72 fixed to the inner wall of the valve 11. The microchannel plate 70 is arranged between the electron emission unit 20 and the electron collection unit 40. The microchannel plate 70 is arranged between the substrate 21 provided with the metasurface 50 and the anode 41. The microchannel plate 70 is separated from the substrate 21 and the anode 41. Even in the electron tube 1E, the electron collection unit 40 may include a diode instead of the anode 41.

[0078] Fig.10 is a perspective cross-sectional view of an example of a microchannel plate. In this variant, as Fig.10 As shown, the microchannel plate 70 includes: a substrate 73, a plurality of channels 74, a partition wall portion 75 and a frame member 76. The substrate 73 includes: an input surface 73a and an output surface 73b opposite to the input surface 73a. The substrate 73 is formed in a disc shape. The input surface 73a faces the substrate 21. The output surface 73b faces the anode 41. The input surface 73a and the output surface 73b are configured to be parallel to the window 11a, the substrate 21 and the metasurface 50. The anode 41 has a flat plate shape and is configured to be parallel to the output surface 73b of the microchannel plate 70.

[0079] A plurality of channels 74 are formed in the substrate 73 from the input surface 73a to the output surface 73b. Specifically, each channel 74 extends from the input surface 73a to the output surface 73b in a direction orthogonal to the input surface 73a and the output surface 73b. The plurality of channels 74 are arranged in a matrix shape in a top view. Each channel 74 has a circular cross-sectional shape. A partition wall portion 75 is provided between the plurality of channels 74. In order to function as an electron multiplier, the microchannel plate 70 includes a resistance layer and an electron emission layer (not shown) on the surface of the partition wall portion 75 in the channel 74. A frame member 76 is provided at the peripheral portion of the input surface 73a and the output surface 73b of the substrate 73.

[0080] In the electron tube 1E, one of the plurality of wires 13 is connected to each of the attachment members 71, 72. At the microchannel plate 70, a voltage is applied to the input face 73a and the output face 73b through the wire 13 and the attachment members 71, 72. Specifically, a potential is applied to the input face 73a and the output face 73b so that the output face 73b has a higher potential than the input face 73a. When the electrons emitted from the metasurface 50 are incident on the input face 73a, the electrons are multiplied by the channel 74 and emitted from the output face 73b. The electrons multiplied by the microchannel plate 70 are collected by the anode 41 and output from the anode 41 as an output signal through the wire 13.

[0081] Next, refer to Fig.11 and Fig.12 , an electron tube according to a modified example of the embodiment is described. Fig.11 is a partial cross-sectional view showing an example of an electron tube. Fig.12 It is shown Fig.11 A cross-sectional view of a portion of an electron tube is shown. Fig.11 and Fig.12 The embodiment described above is substantially similar or identical to the embodiment described above. However, the difference between the embodiment and the modified example is that the electron tube is a so-called image intensifier. The following mainly describes the difference between the embodiment and the modified example.

[0082] exist Fig.11 In the electron tube 1F shown in FIG. 1 , the electron emission unit 20, the electron multiplication unit 30 and the electron collection unit 40 are arranged in a housing 80. Fig. 9 Similar to the electron tube 1E shown, in the electron tube 1F, the electron multiplying unit 30 includes a microchannel plate 70 instead of the focusing electrode 31 and the dynodes 32a to 32j. In the electron tube 1F, the electron collecting unit 40 includes a phosphor 81 instead of the anode 41. In the electron tube 1F, the metasurface 50, the microchannel plate 70 and the phosphor 81 are close to each other in the housing 80.

[0083] The housing 80 includes a side wall 82, an incident window 83 (window 11a), and an emission window 84. The side wall 82 has a hollow cylindrical shape. The incident window 83 and the emission window 84 each have a disk shape. By hermetically sealing both ends of the side wall 82 by the incident window 83 and the emission window 84, the interior of the housing 80 is kept in a vacuum. For example, the interior of the housing 80 maintains a 1×10 -5 to 1×10 -7 Pa.

[0084] For example, the side wall 82 includes: a side tube 85, a mold member 86 covering the side of the side tube 85, and a shell member 87 covering the side and bottom of the mold member 86. Each of the side tube 85, the mold member 86, and the shell member 87 has a hollow cylindrical shape. The side tube 85 is made of, for example, ceramic. The mold member 86 is made of, for example, silicone rubber. The shell member 87 is made of, for example, ceramic.

[0085] Through holes are formed at both ends of the mold member 86. One end of the shell member 87 is opened. The other end of the shell member 87 is provided with a through hole. The through hole of the shell member 87 includes an edge positioned to coincide with the edge position of one through hole of the mold member 86. At one end of the mold member 86, the incident window 83 is bonded to the surface of the periphery of the through hole of the mold member 86. Similar to the window 11a of the electron tube 1, the incident window 83 transmits electromagnetic waves. Similar to the window 11a of the electron tube 1, the incident window 83 includes at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide and calcium carbonate.

[0086] In the electron tube 1F, the metasurface 50 is directly disposed on the incident window 83 in the housing 80. The metasurface 50 faces the microchannel plate 70. The microchannel plate 70 is disposed between the metasurface 50 and the phosphor 81. The microchannel plate 70 is separated from the metasurface 50 and the phosphor 81.

[0087] At the other end side of the mold member 86, an emission window 84 is fitted into another through hole of the mold member 86. The emission window 84 is, for example, a fiberboard formed by gathering a large number of optical fibers into a plate shape. Each optical fiber of the fiberboard is arranged so that the end surface 84a on the inner side of the housing 80 is flush with each optical fiber. The end surface 84a is arranged parallel to the metasurface 50.

[0088] The phosphor 81 is arranged on the end face 84a. For example, the phosphor 81 is formed by applying a fluorescent material to the end face 84a. The fluorescent material is, for example, (ZnCd)S:Ag (silver-doped zinc cadmium sulfide). On the surface of the phosphor 81, a metal back layer and a low electron reflectivity layer are stacked in sequence. For example, the metal back layer is formed by Al evaporation, has a relatively high reflectivity for light passing through the microchannel plate 70, and has a relatively high transmittance for electrons emitted from the microchannel plate 70. The low electron reflectivity layer is formed by, for example, evaporation of C (carbon), Be (beryllium), etc., and has a relatively low reflectivity for electrons emitted from the microchannel plate 70.

[0089] Similar to the electron tube 1E, in the electron tube 1F, one of the plurality of wires 13 extending to the outside of the housing 80 is connected to each of the attachment members 71, 72 holding the microchannel plate 70. At the microchannel plate 70, voltage is applied to the input face 73a side and the output face 73b side through the attachment members 71, 72.

[0090] When the electrons emitted from the metasurface 50 are incident on the input surface 73a, the electrons are multiplied by the channel 74 and emitted from the output surface 73b. In the electron tube 1F, the electrons multiplied by the microchannel plate 70 are collected in the phosphor 81. The phosphor 81 receives the electrons multiplied by the microchannel plate 70 and emits light. The light emitted from the phosphor 81 passes through the fiber plate and is emitted from the emission window 84 to the outside of the housing 80.

[0091] Next, refer to Fig.13 , an imaging device including an electron tube according to a modified example of the embodiment is described. Fig.13 It is a side view of the camera device. Fig.13 The illustrated imaging device 90 acquires an image based on electromagnetic waves emitted from an observation target or electromagnetic waves reflected or scattered by an observation target. The imaging device 90 includes an electron tube 1F as an image intensifier, an objective lens 91, a relay lens 92, and an imaging unit 93 as components. In the imaging device 90, the components are connected in the order of the objective lens 91, the electron tube 1F, the relay lens 92, and the imaging unit 93.

[0092] The objective lens 91 includes a lens having a refractive index for the electromagnetic wave incident on the electron tube 1F. The objective lens 91 guides the electromagnetic wave T from the observation object to the incident window 83 of the electron tube 1F. The relay lens 92 guides the light emitted from the emission window 84 of the electron tube 1F to the imaging unit 93. The imaging unit 93 captures an image based on the light guided from the relay lens 92, that is, the light emitted from the fluorescent body 81. The imaging unit 93 is, for example, a CCD camera.

[0093] Next, refer to Fig.14 , an electron tube according to a modified example of the present embodiment is described. Fig.14is a partial cross-sectional view showing an example of an electron tube. Fig.14 The variation shown is substantially similar or identical to the above-described embodiment. However, the variation differs from the embodiment in that the electron multiplying unit 30 includes an electron multiplier 95 instead of the focusing electrode 31 and the dynodes 32a to 32j. The following mainly describes the differences between the embodiment and the variation. The electron multiplier 95 is a so-called channel electron multiplier (CEM).

[0094] exist Fig.14 In the electron tube 1G shown, the electron multiplier 95 is supported by a holding member 96 fixed to the inner wall of the valve 11. The electron multiplier 95 is arranged between the electron emission unit 20 and the electron collection unit 40. Specifically, the microchannel plate 70 is arranged between the window 11a provided with the metasurface 50 and the anode 41. The electron multiplier 95 is separated from the window 11a and the anode 41. Even in the electron tube 1G, the electron collection unit 40 may include a diode instead of the anode 41.

[0095] In this modification, the electron multiplier 95 includes: an input surface 95a and an output surface 95b opposite to the input surface 95a. The input surface 95a faces the window 11a. The output surface 95b faces the anode 41 configured to constitute the electron collecting unit 40. The input surface 95a and the output surface 95b are configured to be parallel to the window 11a and the metasurface 50. The anode 41 has a flat plate shape and is configured to be parallel to the output surface 95b of the electron multiplier 95. In an embodiment, in a direction orthogonal to the input surface 95a, the distance S between the input surface 95a and the metasurface 50 is, for example, 0.615 mm.

[0096] The electron multiplier 95 includes a main body 97 and a plurality of channels 98. The main body 97 has a rectangular parallelepiped shape. The plurality of channels 98 are defined by the main body 97. Each channel 98 is formed from the input surface 95a to the output surface 95b. Specifically, each channel 98 extends from the input surface 95a to the output surface 95b in a direction orthogonal to the input surface 95a and the output surface 95b. Fig.14 In the illustrated structure, three channels 98 are arranged in a direction parallel to the input surface 95a.

[0097] Each channel 98 includes an electron incident portion 98a and a multiplication portion 98b. The electron incident portion 98a of each channel 98 has an opening provided at the input surface 95a. When viewed from a direction orthogonal to the input surface 95a, the opening of the electron incident portion 98a has a rectangular shape. The electron incident portion 98a gradually narrows from the input surface 95a to the output surface 95b in the arrangement direction of the plurality of channels 98. That is, the electron incident portion 98a has a tapered shape whose diameter decreases along a direction orthogonal to the input surface 95a.

[0098] The multiplier 98b of each channel 98 is formed in a zigzag or wavy shape when viewed from a direction parallel to the input surface 95a and perpendicular to the arrangement direction of the plurality of channels 98. In other words, the multiplier 98b has a repeatedly curved shape in the arrangement direction of the plurality of channels 98.

[0099] In the electron tube 1G, two of the plurality of wires 13 are connected to the holding member 96. A voltage is applied to the electron multiplier 95 through the wires 13 and the holding member 96. Specifically, a potential is applied to the input face 95a and the output face 95b so that the output face 95b has a higher potential than the input face 95a. A wire 13 different from the wire 13 connected to the holding member 96 is connected to the anode 41. The holding member 96 and the anode 41 are electrically insulated from each other by the insulating member 99.

[0100] The electrons emitted from the metasurface 50 enter the opening of the input face 95a of any channel 98, and then enter the multiplication portion 98b through the electron incident portion 98a. As a result, the electrons emitted from the metasurface 50 are multiplied by the channel 98 and emitted from the output face 95b. The electrons multiplied by the electron multiplier 95 are collected by the anode 41 configured to constitute the electron collecting unit 40, and are output from the anode 41 as an output signal through the wire 13.

[0101] As described above, in the electron tubes 1, 1A, 1B, 1C, 1D, 1E, 1F, a window 11a for transmitting electromagnetic waves is provided in the housing 10. The window 11a includes at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide, and calcium carbonate. Therefore, the intensity of the electromagnetic waves (for example, electromagnetic waves in a frequency band from terahertz waves to infrared light) guided into the housing 10, 80 can be ensured. When the electromagnetic waves passing through the window 11a are incident on the metasurface 50 of the electron emission unit 20, electrons are emitted. The emitted electrons are multiplied by the electron multiplying unit 30 in the housing 10, 80, and then collected by the electron collecting unit 40. Therefore, for electromagnetic waves with weak intensity, detection accuracy can be ensured.

[0102] In the electron tube 1, 1A, 1B, 1D, 1E, 1F, the electron emission unit 20 includes a substrate 21, and the substrate 21 includes a main surface 21a provided with a metasurface 50 and a main surface 21b opposite to the main surface 21a. The electron multiplying unit 30 includes an incident surface 35 on which electrons emitted from the electron emission unit 20 are incident. The substrate 21 has transmissivity to electromagnetic waves passing through the window 11a. The substrate 21 is configured in such a manner that the main surface 21a is opposite to the incident surface 35 of the electron multiplying unit 30 and the main surface 21b is opposite to the window 11a. In this case, in a structure in which an electromagnetic wave is incident on the metasurface 50 through the window 11a and the substrate 21, the electrons emitted from the metasurface 50 in response to the incidence of the electromagnetic wave are guided to the electron multiplying unit 30 by a simple structure.

[0103] In the electron tubes 1B and 1F, the metasurface 50 is provided on the window 11a to face the incident surface 35 of the electron multiplying unit 30. According to this structure, a substrate provided with the metasurface 50 is not required in the housing 10 and 80. Therefore, the size and weight of the electron tube can be reduced.

[0104] In the electron tube 1C, the substrate 21 is configured so that the main surface 21a faces the window 11a and the incident surface 35 of the electron multiplying unit 30. In this case, in a structure in which the electromagnetic wave passing through the window 11a is incident on the metasurface 50 without passing through the substrate, the electrons emitted from the metasurface 50 in response to the incidence of the electromagnetic wave are guided to the electron multiplying unit 30 by a simple structure.

[0105] The metasurface 50 is included in a patterned oxide layer or a patterned metal layer. According to this structure, the electrons emitted from the metasurface 50 in response to the incidence of electromagnetic waves increase.

[0106] In the electron tube 1D, the electron multiplying unit 30 and the electron collecting unit 40 are integrally formed as a diode 60. According to this structure, the size of the electron tube can be further reduced.

[0107] In the electron tube 1, 1A, 1B, the electron multiplying unit 30 includes a plurality of dynodes 32a to 32j spaced apart from each other. The electron collecting unit 40 includes an anode 41 or a diode configured to collect electrons multiplied by the electron multiplying unit 30. According to this structure, the electrons emitted from the metasurface 50 are multiplied by the plurality of dynodes 32a to 32j. Therefore, the multiplication factor of the electrons collected by the anode 41 or the diode is increased.

[0108] In the electron tube 1E, the electron multiplying unit 30 includes a microchannel plate 70. The electron collecting unit 40 includes an anode 41 or a diode configured to collect electrons multiplied by the electron multiplying unit 30. According to this structure, compared with the case where a plurality of dynodes are used for the electron multiplying unit 30, the size, weight, and power consumption are reduced and the response speed and gain are improved.

[0109] In electron tube 1F, electron multiplying unit 30 includes microchannel plate 70. Electron collecting unit 40 includes phosphor 81 that receives electrons multiplied by electron multiplying unit 30 and emits light. According to this structure, the two-dimensional position of electrons emitted from metasurface 50 can be detected by light emitted from phosphor 81.

[0110] The imaging device 90 includes an electron tube 1F and an imaging unit 93. The imaging unit 93 captures an image based on light from the fluorescent body 81. According to this structure, the detection accuracy of electromagnetic waves is ensured. An image showing the two-dimensional position of electrons emitted from the metasurface 50 can be obtained.

[0111] Although the embodiment and the modified example of the present invention have been described, the present invention is not necessarily limited to the embodiment and the modified example, and various changes can be made within the scope not departing from the gist thereof.

[0112] In the electron tubes 1 , 1A, 1B, 1C, 1E, 1F, 1G, the metasurface 50 may be a passive metasurface or may be an active metasurface. Figure 3 A passive metasurface 50 is shown. The electron emission unit 20 including the passive metasurface 50 is configured to operate without a bias voltage applied to each antenna 51 of the metasurface 50. That is, the passive metasurface 50 is a metasurface configured to emit electrons in response to the incidence of electromagnetic waves in a state where each antenna 51 has the same potential.

[0113] The electron emission unit 20 including the active metasurface is configured to operate in a state where a bias voltage is applied to each antenna 51 of the metasurface 50. That is, the active metasurface 50 is a metasurface configured to emit electrons in response to the incidence of electromagnetic waves in a state where a bias voltage is applied to each antenna. In this case, a voltage from any one of the plurality of wires 13 is applied to the metasurface 50.

[0114] In the electron tubes 1, 1A, 1B, 1C, 1E, 1G, the electron collecting unit 40 may include a diode instead of the anode 41. In this case, the electrons multiplied by the electron multiplying unit 30 are collected by the diode.

[0115] In the electron tubes 1, 1A, 1B, as in the electron tube 1C, the window 11a may be provided on the side of the housing 10, 80. In this case, for example, the configuration of the dynodes of the electron multiplying unit 30 is changed so that electrons based on electromagnetic waves incident from the window 11a can be collected by the electron collecting unit 40.

[0116] In the electron tubes 1, 1A, 1B, 1D, 1E, 1F, 1G, as in the electron tube 1C, the metasurface 50 of the electron emission unit 20 may be a so-called reflective metasurface. In the case of using a reflective metasurface, the electron tube is configured such that the metasurface 50 faces the window 11a and faces the incident surface 35 of the electron multiplying unit 30.

[0117] The shape of each of the housings 10 and 80 is not limited to a cylindrical shape. For example, each of the housings 10 and 80 may include a tubular shape having a polygonal cross section.

[0118] In the electron tube 1F, a sweep electrode may be provided between the metasurface 50 and the microchannel plate 70. As a result, a so-called streak tube may be formed. In this case, a slit configured to allow the measurement light to be incident and a lens system configured to capture the slit image may be provided outside the window 11a of the electron tube 1F functioning as a streak tube. As a result, a so-called streak camera may be formed.

[0119] In the imaging device 90, the electrons multiplied by the microchannel plate 70 in the electron tube 1F are collected in the phosphor 81, and the light emitted from the phosphor 81 is photographed by the imaging unit 93 provided outside the electron tube 1F. At this point, by providing an electron bombardment solid-state image sensor instead of the phosphor 81 as the electron collecting unit 40 in the electron tube, the electron tube can be configured to function as an imaging device. In this case, the electrons multiplied by the microchannel plate 70 are photographed by the electron bombardment solid-state image sensor, without providing the imaging unit 93 outside the electron tube. The electron bombardment solid-state image sensor is, for example, an electron-bombarded charge-coupled device (EBCCD).

[0120] Explanation of symbols:

[0121] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G tube

[0122] 10, 80 shell

[0123] 11a Window

[0124] 20 Electron emission unit

[0125] 21 substrate

[0126] 21a, 21b Main surface

[0127] 30 Electron Multiplication Unit

[0128] 35 Incident surface

[0129] 40 electron collection unit

[0130] 41 Anode

[0131] 50 Super Surface

[0132] 60 diode

[0133] 70 Microchannel Plate

[0134] 81 Phosphor

[0135] 90 Camera Device

[0136] 93 Camera unit.

Claims

1. An electron tube, comprising: a housing, the interior of which maintains a vacuum and includes a window that transmits electromagnetic waves; an electron emission unit disposed in the housing and comprising a metasurface that emits electrons in response to incidence of the electromagnetic wave; an electron multiplying unit disposed in the housing and configured to multiply electrons emitted from the electron emitting unit; as well as an electron collecting unit, which is disposed in the housing and is configured to collect electrons multiplied by the electron multiplying unit, wherein the metasurface forms a plurality of antennas and emits electrons in response to the incidence of the electromagnetic wave, each of the plurality of antennas having a size corresponding to the wavelength of the electromagnetic wave, The window includes at least one selected from quartz, silicon, germanium, sapphire, zinc selenide, zinc sulfide, magnesium fluoride, lithium fluoride, barium fluoride, calcium fluoride, magnesium oxide and calcium carbonate.

2. The electron tube according to claim 1, wherein: The electron emission unit comprises: a substrate including a first main surface provided with the super surface and a second main surface opposite to the first main surface, The electron multiplying unit includes: an incident surface to which the electrons emitted from the electron emitting unit are incident, and The substrate has a transmittance to electromagnetic waves passing through a window, and is disposed such that the first principal surface faces the incident surface of the electron multiplying unit and the second principal surface faces the window.

3. The electron tube according to claim 1, wherein: The electron multiplying unit includes: an incident surface to which the electrons emitted from the electron emitting unit are incident, and The metasurface is arranged on the window to face the incident surface of the electron multiplying unit.

4. The electron tube according to claim 1, wherein: The electron emission unit comprises: a substrate including a first main surface provided with the super surface and a second main surface opposite to the first main surface, The electron multiplying unit includes: an incident surface to which the electrons emitted from the electron emitting unit are incident, and The substrate is disposed in such a manner that the first main surface faces the window and the incident surface of the electron multiplying unit.

5. The electron tube according to any one of claims 1 to 4, wherein: The metasurface is formed to emit electrons in response to incidence of the electromagnetic wave in a state where the plurality of antennas are at the same potential without being applied with a bias voltage.

6. The electron tube according to any one of claims 1 to 5, wherein: The metasurface is comprised of a patterned oxide layer or a patterned metal layer.

7. The electron tube according to any one of claims 1 to 6, wherein: The electron multiplying unit and the electron collecting unit are diodes and are integrally constructed.

8. The electron tube according to any one of claims 1 to 6, wherein: The electron multiplying unit comprises a plurality of dynodes spaced apart from each other, and The electron collecting unit includes an anode or a diode configured to collect the electrons multiplied by the electron multiplying unit.

9. The electron tube according to any one of claims 1 to 6, wherein: The electron multiplying unit comprises a microchannel plate, and The electron collecting unit includes an anode or a diode configured to collect the electrons multiplied by the electron multiplying unit.

10. The electron tube according to any one of claims 1 to 6, wherein: The electron multiplying unit comprises a microchannel plate, and The electron collecting unit includes a phosphor configured to receive the electrons multiplied by the electron multiplying unit and emit light.

11. A camera device, comprising: The electron tube according to claim 10, and An imaging unit is configured to capture an image based on the light from the phosphor.

Images