Deep sea optical detection equipment, spherical cabin and assembling method thereof

Abstract

The invention discloses an optical detection ball cabin, the surface of the ball cabin is provided with a plurality of PMTs, the surface of each PMT is provided with a polygonal structure, and the surface of the ball cabin is formed by splicing the plurality of PMTs with the polygonal structures. The spherical cabin is formed as a truncated icosahedron. The surface of the PMT is a plane, and the surface of the PMT is a plane polygon. Or, the surface of the PMT is a curved surface, and the surface of the PMT is a curved polygon. The spherical cabin is provided with a spherical transparent shell. And a spherical bracket is arranged in the spherical cabin and is used for mounting and supporting the PMT.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and in particular relates to a deep-sea optical detection device, a spherical cabin and an assembly method thereof. Background Art

[0002] Optical detectors are a kind of precision instruments commonly used in high-energy physics experiments. They can be used to detect weak ambient light in fluid environments such as seawater, pure water or liquid scintillators. For example, the detection unit of the deep-sea neutrino detection telescope and the optical detection spherical cabin of the neutrino detection station. Due to the complexity and changeability of the deep-sea environment, and the high pressure, low temperature and low light conditions of the deep sea, the requirements for detection equipment are extremely harsh. Deep-sea optical detection, by capturing and processing weak light signals in seawater, can achieve long-term monitoring and data collection of the deep-sea environment. The photomultiplier tube (PMT) in these detection devices is the core component, which is used to realize photon collection and photoelectric signal conversion. It has high sensitivity in the deep-sea low-light environment and is a key component of deep-sea optical detection.

[0003] Among them, spherical deep-sea optical detectors have become an ideal configuration for deep-sea detectors due to their uniform coverage characteristics, good structural strength, high stability and high space utilization, and are particularly suitable for long-term high-pressure deployment. However, existing spherical detectors still have some technical bottlenecks in terms of effective detection area coverage. Current spherical detectors all use mature circular or cylindrical PMT units to splice inside the sphere to form a detection unit, but because there are inevitable gaps between circular PMTs, the effective detection area is usually only about 60%, which greatly wastes basic components such as deep-sea optical detection spherical shells, watertight connectors, and electronic devices inside the sphere, resulting in low detection efficiency. Summary of the invention

[0004] One aspect of the present disclosure is a high-coverage deep-sea optical detection spherical cabin configuration, the surface of the spherical cabin has a plurality of PMTs, and is characterized in that the surface of the PMT has a polygonal structure, and the surface of the spherical cabin is spliced ​​together by the plurality of PMTs with polygonal structures.

[0005] The spherical cabin is formed as a truncated icosahedron.

[0006] Preferably, the PMT surface is a plane, and the PMT surface is a planar polygon.

[0007] Preferably, the PMT surface is a curved surface, and the PMT surface is a curved polygon.

[0008] Preferably, the spherical cabin has a spherical transparent shell. A spherical bracket is provided inside the spherical cabin for mounting and supporting the PMT.

[0009] One aspect of the present disclosure is a deep-sea optical detection device, comprising at least one optical detection spherical cabin as described above.

[0010] In one aspect of the present disclosure, a method for assembling an optical detection spherical cabin is provided, wherein a plurality of PMTs having polygonal structures are spliced ​​on the surface of the optical detection spherical cabin, so that the spherical cabin is formed into a regular polyhedron. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, in which:

[0012] Figure 1 A schematic diagram of a spliced ​​structure of pentagons and hexagons with 60 vertices according to one embodiment of the present invention.

[0013] Figure 2 A schematic diagram of the surface of a pentagonal PMT-hexagonal PMT container according to one embodiment of the present invention.

[0014] Figure 3 A view of a pentagonal PMT-hexagonal PMT container according to one embodiment of the present invention, viewed downward from the S0 plane.

[0015] Figure 4 A side view of a pentagonal PMT and a hexagonal PMT container according to one embodiment of the present invention.

[0016] Figure 5 yes Figure 4 Side view of.

[0017] Figure 6 A diagram illustrating the geometric relationship of the distance D according to one embodiment of the present invention.

[0018] Figure 7 A schematic diagram of the structure of a pentagonal PMT-hexagonal PMT container according to one embodiment of the present invention.

[0019] Figure 8 A schematic diagram of a half portion of a spliced ​​closed polyhedron according to one embodiment of the present invention.

[0020] Fig. 9 A schematic diagram of a closed polyhedron splicing process according to one embodiment of the present invention.

[0021] Fig.10 Schematic diagram of a polyhedron structure obtained by splicing planar polygons with rounded corners according to one embodiment of the present invention.

[0022] Fig.11 A schematic diagram of the structure of a pentagonal pyramid-hexagonal pyramid plane combination according to one embodiment of the present invention.

[0023] Fig.12 A schematic structural diagram of a pentagonal pyramid-hexagonal pyramid curved surface combination according to one embodiment of the present invention.

[0024] Fig.13 A schematic diagram of a polyhedron obtained by splicing curved polygons with rounded corners according to one embodiment of the present invention.

[0025] Fig.14 A schematic diagram of the structure of a curved pentagonal-hexagonal PMT combination according to one embodiment of the present invention.

[0026] Fig.15 Schematic diagram of a curved five-sided and six-sided PMT splicing structure according to one embodiment of the present invention.

[0027] Fig.16 A schematic diagram of the appearance of a deep-sea optical detection spherical cabin based on planar polygons according to one embodiment of the present invention.

[0028] Fig.17 A schematic diagram of the appearance of a deep-sea optical detection spherical cabin based on curved polygons according to one embodiment of the present invention.

[0029] Fig.18 A schematic diagram of the internal and external structures of a deep-sea optical detection spherical cabin based on curved polygons according to one embodiment of the present invention.

[0030] Fig.19 Schematic diagram of PMT disassembly and assembly according to one embodiment of the present invention.

[0031] Fig. 20 A schematic diagram of the appearance of a planar regular icosahedron according to one embodiment of the present invention.

[0032] Fig.21 A schematic diagram of the appearance of a plane truncated octahedron according to one embodiment of the present invention.

[0033] Fig. 22 A schematic diagram of the appearance of a planar regular dodecahedron according to one embodiment of the present invention.

[0034] Fig.23 A schematic diagram of a PMT structure based on a regular dodecahedron according to one embodiment of the present invention.

[0035] Fig.24 Schematic diagram of the internal and external structure of a PMT spliced ​​based on a regular dodecahedron according to one embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to solve the problems existing in the above-mentioned spherical deep-sea optical detector, the idea of ​​the present invention is to innovate the PMT configuration and transform the circular PMT structure into a polygonal structure. The polygonal PMT module can achieve a close fit from a plane to a spherical surface through polygonal splicing. In this way, the PMT on the surface of the detector can be seamlessly spliced, effectively improving the surface coverage of the optical detector. In this way, the effective detection area of ​​the surface of the photosensitive element has been significantly improved, which can not only capture more photon signals, but also improve the overall detection efficiency of the detector. In addition, the polygonal structure can also maintain the detection efficiency of each PMT, thereby improving the performance of the optical detector without sacrificing sensitivity. This design structure optimization will greatly enhance the application prospects of deep-sea optical detection equipment in large-scale detection tasks, and is expected to play a greater role in deep-sea data collection, marine ecological monitoring and environmental protection.

[0037] According to one or more embodiments, generally, a typical configuration of completely covering the surface of a sphere with stitched polygons is, for example, a structure with 60 vertices, each vertex has 3 edges of the same length, and the number of edges is:

[0038] (60 vertices) × (3 edges) / (each edge has 2 vertices) = 90

[0039] Each vertex is shared by a regular pentagon and two regular hexagons, so the number of pentagons is:

[0040] (60 vertices) x (1 pentagon per vertex) / (5 vertices per pentagon) = 12

[0041] The number of hexagons is:

[0042] (60 vertices) x (2 hexagons per vertex) / (6 vertices per pentagon) = 20

[0043] Such a configuration is also called a truncated icosahedron.

[0044] A deep-sea optical detection spherical cabin configuration, considering the difficulty of realizing the PMT configuration, first consider connecting the plane pentagons and hexagons with the center of the polyhedron one by one to form a cone to obtain a pentagonal PMT-hexagonal PMT container. The splicing can start from one of the pentagons, and draw five hexagons at appropriate angles on its five sides to obtain a pentagonal PMT-hexagonal PMT container. Then, according to the angle matching relationship, the pentagons and hexagons are filled into the convex polyhedron surface until it is closed. Therefore, each pentagon will have five hexagons around it, and each hexagon will have three pentagons and three hexagons around it, such as Figure 1 shown.

[0045] In order to achieve seamless splicing while meeting the requirements of geometric dimensions, it is necessary to derive the necessary geometric relationships. Assuming the edge length is L, starting from the pentagon, if five hexagons are spliced ​​on the five sides of the pentagon and placed in the same plane, since the vertex angles of the regular pentagon and regular hexagon are 108° and 120° respectively, there will be 1 pentagon and 2 hexagons at each vertex after splicing, 108°+120°+120°=348°<360°, and there will be gaps between the hexagons. At this time, you only need to rotate the hexagon downward with the side of the pentagon as the axis until the hexagons are just connected, so that you get a pentagonal PMT-hexagonal PMT container, such as Figure 2 shown.

[0046] In order to obtain a pentagonal PMT-hexagonal PMT container that can be properly spliced, looking down from the plane S0 where the pentagon is located, the projection n of the adjacent side n of each hexagon on this plane s0 It needs to coincide with the extension line p of the pentagon vertex in the radial direction of its circumscribed circle. In addition, the extension length l p It needs to be equal to the radius R5 of the pentagon's circumscribed circle, such as Figure 3 As shown. This is because during the rotation of the hexagon along one side, the midline m is always parallel to its rotation axis, which is also parallel to the S0 plane. Therefore, the length of the projection of m on the S0 plane remains unchanged during the rotation process, and the length is 2L (the length of the midline of a regular hexagon is twice the length of the side). When the five hexagons are rotated until the adjacent sides n coincide with each other, the vertices at both ends of their midlines also coincide with each other. Connecting the projections of these vertices on S0 can result in a large pentagon similar to the pentagon. The side length of this large pentagon is the projection m of the hexagon's midline m on S0. s0 , which is equal to 2L, so the projection of the adjacent side n of each hexagon on S0 needs to coincide with the extended line p, and l p =R5.

[0047] From the side view of a pentagon and a hexagon (such as Figure 4 ) from the perspective of the right triangle POA, there is an angle α between them. To find α, first calculate the distance d from the median of the hexagon to the S0 plane. In the right triangle POA, PO = l p =R5, AO=L. According to the geometric relationship of the regular pentagon,

[0048]

[0049] So the distance d is

[0050]

[0051] Draw the perpendicular bisector a of one side OO1 of the pentagon on the hexagon and intersect the median m at A0 in the center of the hexagon. Since the length of a perpendicular line drawn from a straight line parallel to a plane to a plane at any point is equal to the distance from the straight line to the plane, the distance from A0 to the S0 plane is also d. Based on the perpendicular bisector a perpendicular to the intersection of the two planes, the dihedral angle α can be calculated.

[0052]

[0053] From the radius of the inscribed circle of the regular hexagon, we can get:

[0054]

[0055] So the dihedral angle is:

[0056]

[0057] Furthermore, according to the dihedral angle α, the distance D from the center Z of the entire convex polyhedron to each vertex can be obtained, which can be used as the minimum constraint of the radius of the spherical shell. Figure 4 Side view of Figure 5 ), since the center of the polyhedron can be obtained by drawing perpendicular lines from the centers of each polygon and intersecting them, ∠COZ = ∠CAZ = 90°, so the four points ACOZ are in the same circle, and CZ is the diameter of the circle. In addition, the dihedral angle α = 180°-∠ACO, then:

[0058] AO 2 =AC 2 +OC 2 -2AC·OC·cos(∠ACO)

[0059] =AC 2 +OC 2 +2AC·OC·cosα (6)

[0060] Where AC and OC are equal to the inscribed circle radii of the pentagon and hexagon respectively, that is:

[0061]

[0062] OC=r6=Lcos30° (8)

[0063] From the four points ACOZ and the trigonometric sine theorem, we can get:

[0064]

[0065] According to Figure 6 The geometric relationship can be obtained:

[0066]

[0067] When the spliced ​​pentagonal PMT-hexagonal PMT container is obtained, no additional geometric relationship is required to fill it into a closed polyhedron, and the polyhedron can be filled according to the angle matching relationship until it is closed. Figure 7 ), first embed the same pentagonal pyramid in the gap of the hexagonal pyramid, and then splice the hexagonal pyramid under the newly added pentagonal pyramid, so that half of the closed polyhedron is obtained (such as Figure 8 Finally, mirror it up and down and rotate one part of it 180° vertically to form a complete closed polyhedron (such as Fig. 9 ).

[0068] According to one or more embodiments, for deep-sea optical detectors, a commonly used specification size is a sphere with a diameter of 432 mm, and in order to meet the requirement of withstanding deep-sea pressure, the thickness needs to be 14 mm, that is, this type of detector requires a spherical shell with an outer diameter of 432 mm and a thickness of 14 mm, an inner diameter of 432 mm-2×14 mm=404 mm, and an inner radius of 202 mm, which needs to meet the following requirements:

[0069] D≤202mm

[0070] In this way, the seamless convex polyhedron formed by the above-designed planar pentagons and hexagons can be placed in the outer shell of the spherical shell. According to the relationship between the minimum constraint of the radius of the spherical shell and the edge length derived above, the edge length L can be set to 81mm, D=2.478L=200.72mm, and the convex polyhedron can be placed exactly in the outer shell of the spherical shell with a certain processing error tolerance. In order to better splice the surfaces of each photosensitive element, a certain fillet can be added to the bottom edges of the pentagonal pyramid and the hexagonal pyramid. According to the overall configuration size, the fillet radius is initially set to 2mm. In this way, the final convex polyhedron formed by seamless splicing of planar pentagons and hexagons is obtained (such as Fig.10 ), where the corresponding pentagonal pyramid and hexagonal pyramid reflect the maximum space that each PMT photosensitive element can occupy (such as Fig.11 ). Compared with the optical detection spherical cabin composed of circular PMT elements, this polyhedral configuration can effectively improve the surface coverage rate and effectively improve the detection efficiency while ensuring the detection efficiency of each polygonal photosensitive element.

[0071] This is because, when using planar polygons as components, each pentagon and hexagon is in a plane with a fixed side length. These planar polygons can be stitched together to form a sphere, and when all faces are fully spliced, 100% light absorption can be achieved. However, since planar polygons are easier to manufacture and combine, the convex polyhedron structure they form has a greater advantage in implementation.

[0072] Although, if curved polygons are used as components, the surface of the polyhedron can be made closer to an ideal sphere. Although this can make the overall shape smoother and make it easier to match and fix with the spherical shell, the production and splicing of PMT elements with curved polygons is technically challenging, so it is necessary to make a trade-off between the feasibility of mechanical combination and the quality differences of PMTs of different shapes. In general, polyhedrons composed of planar polygons have more advantages in implementation difficulty and manufacturing cost, while curved polygons may bring higher manufacturing difficulty, but are easier to match and fix with the spherical shell.

[0073] Furthermore, under the premise of being able to achieve the processing of PMT elements with curved polygons of a certain precision, based on the geometric constraints and similarities of the soccer-like polyhedron structure discussed above, the polyhedron can be appropriately enlarged according to the edge length L, and then the spherical surface formed by the required radius is intersected with the pentagonal pyramid and the hexagonal pyramid in the polyhedron and the external part is cut off, and the surface part is the polyhedron obtained by splicing the curved polygons (here, the pentagonal PMT-hexagonal PMT container can also be cut off first to obtain the pentagonal PMT-hexagonal PMT curved container and then spliced ​​to facilitate the addition of fillets. The pentagonal pyramid-hexagonal pyramid curved surface combination after the cut is as shown in FIG. Fig.12 As shown in the figure, here the edge length L is set to 100 mm, and then a spherical surface with a radius of 200 mm is used for cutting. The final curved polyhedron is as follows: Fig.13 As shown. Obviously, the curved pyramids corresponding to these curved polygons have less space available than the flat pyramids mentioned above. The PMT components are initially designed based on the limited space of the curved pentagonal pyramid and hexagonal pyramid as shown below. Fig.14 As shown, the internal and external structure diagram of the PMT components after splicing is as follows Fig.15 .

[0074] For the detectors with the assembled plane and curved polyhedron configurations, the common size of the deep-sea optical detector is 432mm in diameter and 14mm in thickness, that is, the spherical shell of the light-transmitting glass material with an inner diameter of 432mm, which is divided into two parts as the shell cover, and its appearance structure diagrams are as follows Fig.16 and Fig.17 In addition, a spherical shell can be used as a bracket at the cylindrical part at the lower end of the PMT element to fix the PMT element, and at the same time facilitate the insertion and replacement of the PMT original part, such as Fig.18 and 19 shown.

[0075] According to one or more embodiments, a deep-sea optical detection spherical cabin configuration is provided.

[0076] In addition to the truncated icosahedron, there are other polyhedral configurations with full coverage. These configurations can be mainly divided into two categories. One is to increase the number of faces to obtain a higher-order polyhedron. For example, further truncating the top on the basis of the truncated icosahedron increases the number of polygons that make up the polyhedron and reduces the size of a single face. By increasing the number of faces, the surface of the polyhedron becomes closer to a sphere, and as the number of faces increases and the surface becomes curved, the smoothness of the surface becomes higher. However, the increase in the number of faces will cause the size of each PMT photosensitive element to need to be further reduced. At the cost of limiting the size of the PMT photosensitive element, it is closer to a sphere and closer to the outer shell of the sphere, so that it can be matched and fixed with the inner and outer shells of the spherical body. Here, we take the regular icosahedron as an example. It is composed of twenty equilateral triangles. Its planar polyhedral structure is as follows: Fig. 20 As shown in the figure, it can be seen that the area of ​​each face is reduced, which requires a smaller size for each PMT photosensitive element, and higher-order polyhedrons are even smaller, so they can be used in larger optical detection spherical cabins.

[0077] The other type is the opposite, by reducing the number of faces to obtain a low-order polyhedron, such as a truncated octahedron (such as Fig.21 ), regular dodecahedron (such as Fig. 22 ), etc., their polygon number is reduced and the size of a single face is increased. By reducing the number of faces, the available surface area of ​​each PMT photosensitive element is increased. However, as the number of faces decreases, the surface smoothness decreases, and the surface curvature increases after the spherical surface is cut off. The relative available space inside each PMT photosensitive element will be reduced accordingly. Taking the regular dodecahedron as an example, the preliminary designed PMT and splicing structure are as follows Fig.23 , 24 As shown, it can be seen that there is less space in the radial direction, and the PMT element is similar to being "flattened", which is not conducive to the laying of its internal circuit.

[0078] In short, it is necessary to select a suitable polyhedron structure based on the various limitations of the PMT element (surface area, internal space, etc.), taking into account both the high coverage of optical detection and the lower difficulty of processing. At present, the truncated icosahedron similar to a football is used as the main design configuration. Here, because the truncated polyhedron generates polygonal faces by truncating vertices, it is not completely symmetrical in the case of a plane surface. The truncated polyhedron generates alternating polygonal faces by twisting (or rotating), which has stronger symmetry. In terms of configuration, the truncated icosahedron has 12 pentagonal and 20 hexagonal faces, a total of 32 faces, which is the commonly understood football structure. The truncated regular icosahedron, then Fig. 20 As shown, it consists of 20 equilateral triangle planes.

[0079] In summary, the technical effect of the present disclosure is that the existing spherical cabin detector uses a circular PMT to cover the surface of the spherical cabin, which makes the PMT surface coverage rate not high, usually only about 60% of the detection area can be achieved, thus greatly affecting the detection efficiency. The solution of the present disclosure is to change the existing PMT circular structure and design a PMT polygonal structure that can be fully spliced, so as to improve the coverage rate of the photosensitive element on the detector surface from the plane to the curved surface. Since the fully spliced ​​polygonal structure can improve the surface coverage rate, theoretically up to 100% effective detection area coverage can be achieved. The solution of the present disclosure improves the coverage rate of the photosensitive element on the surface of the optical detection equipment, thereby increasing its surface effective detection area, and can effectively increase the overall detection efficiency of the equipment while ensuring the detection efficiency of each PMT.

[0080] It should be understood that in the embodiments of the present invention, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0081] It is worth noting that, although the foregoing content has described the spirit and principle of the invention with reference to several specific embodiments, it should be understood that the invention is not limited to the disclosed specific embodiments, and the division of various aspects does not mean that the features in these aspects cannot be combined, and such division is only for the convenience of expression. The invention is intended to cover various modifications and equivalent arrangements included in the spirit and scope of the appended claims.

Claims

1. An optical detection spherical cabin, the surface of which has a plurality of PMTs, characterized in that: The surface of the PMT has a polygonal structure, and the surface of the spherical cabin is formed by splicing a plurality of PMTs with polygonal structures.

2. The optical detection spherical cabin according to claim 1, characterized in that: The spherical cabin is formed as a regular polyhedron.

3. The optical detection spherical cabin according to claim 2, characterized in that: The spherical cabin is a truncated icosahedron.

4. The optical detection spherical cabin according to claim 1, characterized in that: The PMT surface is a plane, and the PMT surface is a plane polygon.

5. The optical detection spherical cabin according to claim 1, characterized in that: The PMT surface is a curved surface, and the PMT surface is a curved polygon.

6. The optical detection spherical cabin according to claim 1, characterized in that: The ball cabin has a spherical transparent shell.

7. The optical detection spherical cabin according to claim 1, characterized in that: The spherical cabin is provided with a spherical bracket for installing and supporting the PMT.

8. A deep-sea optical detection device, characterized in that: It comprises at least one optical detection spherical cabin as claimed in any one of claims 1 to 7.

9. An optical detection spherical cabin assembly method, characterized in that: A plurality of PMTs with polygonal structures are spliced ​​on the surface of the optical detection spherical cabin.

10. The method according to claim 9, characterized in that The spherical cabin is formed as a regular polyhedron.

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