Method for Detecting Surface Reflectivity of Photomultiplier Tube and Detection System

Abstract

The present invention relates to a method and a detection system for detecting the surface reflectivity of a photomultiplier tube, belonging to the technical field of weak light detection, and solves the problems that the existing detection method is not easy to operate, has low test efficiency, and the measured data is inaccurate. The detection method includes the following steps: Step 1: Perform spectral testing on a standard aluminum mirror to obtain the spectral data of the standard aluminum mirror; Step 2: Perform spectral testing on the surface of the photomultiplier tube to be tested to obtain the spectral data of the surface of the photomultiplier tube to be tested; Step 3: Substitute the spectral data of the standard aluminum mirror and the spectral data of the surface of the photomultiplier tube to be tested into the reflectivity calculation formula to obtain the reflectivity of the surface of the photomultiplier tube. The present invention realizes the rapid and non-destructive detection of the surface reflectivity of the photomultiplier tube.

Description

Technical Field

[0001] The present invention relates to the technical field of weak light detection, and particularly to a method and a system for detecting the surface reflectivity of a photomultiplier tube. Background Art

[0002] A photomultiplier tube is a vacuum electronic device that converts a weak light signal into an electrical signal. The photomultiplier tube is used in optical measuring instruments and spectroscopic analysis instruments, and it can measure the extremely weak radiation power with wavelengths of 200-1200 nanometers in low-level photometry and spectroscopy.

[0003] The surface reflectivity of the photomultiplier tube is used as an important quality control link for batch production and factory acceptance. In order to obtain the reflectivity data, optoelectronic devices are usually used to obtain the corresponding data at the wavelengths of interest. In the prior art, a photodiode (PD) is used to achieve this, but there are problems such as difficult operation, low test efficiency, and inaccurate measured data. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a method and a system for detecting the surface reflectivity of a photomultiplier tube, which can at least solve one of the following technical problems: (1) The existing detection method is difficult to operate and has low test efficiency; (2) The measured data is inaccurate.

[0005] The object of the present invention is mainly achieved by the following technical solutions:

[0006] On the one hand, the present invention provides a method for detecting the surface reflectivity of a photomultiplier tube, including the following steps:

[0007] Step 1: Perform a spectral test on a standard aluminum mirror to obtain the spectral data of the standard aluminum mirror;

[0008] Step 2: Perform a spectral test on the surface of the photomultiplier tube to be tested to obtain the spectral data of the surface of the photomultiplier tube to be tested;

[0009] Step 3: Substitute the spectral data of the standard aluminum mirror and the spectral data of the surface of the photomultiplier tube to be tested into the reflectivity calculation formula to obtain the surface reflectivity of the photomultiplier tube.

[0010] Optionally, the Step 1 includes the following steps:

[0011] Step 11: Fix the integrating sphere on the fixed support part of the standard aluminum mirror test device to ensure that the integrating sphere remains fixed during the spectral test of the standard aluminum mirror;

[0012] Step 12: Use optical fibers to connect the light source interface on the integrating sphere to the light source, the spectrometer interface on the integrating sphere to the spectrometer, and the spectrometer to the data acquisition and processing system respectively;

[0013] Step 13: Cover the center hole of the integrating sphere with the standard aluminum mirror test surface;

[0014] Step 14: Start the light source, observe the spectrum through the data acquisition and processing system, and save the spectrum data file to obtain the spectrum data of the standard aluminum mirror.

[0015] Optionally, obtaining the environmental background spectrum is included between Step 13 and Step 14.

[0016] Optionally, the obtaining of the environmental background spectrum includes the following steps: Keep the light source in the off state, turn on the spectrometer, observe the real-time spectrum through the data acquisition and processing system, and save the spectrum data file to obtain the environmental background spectrum data.

[0017] Optionally, the reflectivity calculation formula is:

[0018]

[0019] where R PMT (λ) is the reflectivity of the photomultiplier tube surface; P PMT (λ) is the spectrum at the position to be measured on the photomultiplier tube surface; P L (λ) is the light source intensity spectrum, P AL (λ) is the spectrum of the standard aluminum mirror; r(λ) is the reflectivity of the standard aluminum mirror at different wavelengths; P BG (λ) is the environmental background spectrum during detection.

[0020] Optionally, Step 2 includes the following steps:

[0021] Step 21: Place the photomultiplier tube to be measured in the fixing ring on the column, and install the test tooling on the surface of the photomultiplier tube to be measured, waiting for testing;

[0022] Step 22: Transfer the integrating sphere from the standard aluminum mirror test device to the detection device;

[0023] Step 23: Observe the spectrum through the data acquisition and processing system, and save the spectrum data file to obtain the spectrum data at the detection position on the surface of the photomultiplier tube to be measured.

[0024] Optionally, Step 22 includes the following steps:

[0025] Step 221: Keep the states of the light source and the spectrometer in the standard aluminum mirror spectrum test, and remove the standard aluminum mirror;

[0026] Step 222: Loosen the connecting piece and remove the integrating sphere from the clamping piece;

[0027] Step 223: Insert the integrating sphere into the positioning ring or detection hole of the test tooling.

[0028] Optionally, the light source used in step 14 is a monochromatic light source or a non-monochromatic light source.

[0029] Optionally, the wavelength of the monochromatic light source is 415 nm.

[0030] On the other hand, the present invention also provides a surface reflectivity detection system for a photomultiplier tube to complete the above detection method. The detection system includes a detection device for testing and obtaining the surface spectral data of the photomultiplier tube and a test device for testing and obtaining the spectral data of a standard aluminum mirror.

[0031] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0032] (1) The detection method of the present invention can quickly and accurately obtain test data. On the one hand, it is manifested that when used in cooperation with the test tooling, it can ensure that the integrating sphere is fixed during the test and reduce the influence caused by the shaking of the integrating sphere. On the other hand, the detection method of the present invention is simple and easy to implement, can be completed in a relatively short time, and the working state of the test instrument does not change significantly in a relatively short time, which also reduces the influence caused by the change of the working state of the test instrument.

[0033] (2) The detection method of the present invention takes into account the environmental background during detection, collects the environmental background spectrum, obtains the environmental background data, and can obtain a more accurate reflectivity detection result.

[0034] (3) In order to obtain reflectivity data, optoelectronic devices are usually used to obtain the corresponding data at the wavelength of interest. In the prior art, a photodiode (PD) is used to achieve this, which has problems such as difficult operation to implement, low test efficiency, and inaccurate measured data. Under the technical concept of using a spectrometer, the detection system of the present invention is provided with a detection device and a standard aluminum mirror test device. By setting the detection device and the test device to include specific components, that is, the detection device includes a light source, a spectrometer, an integrating sphere, a photomultiplier tube to be measured, a test tooling, a test bracket, and a data acquisition and processing system, and the test device includes a light source, a spectrometer, an integrating sphere, a standard aluminum mirror, a fixed support part, and a data acquisition and processing system, it can achieve rapid, accurate, and non-destructive quantitative detection of the surface reflectivity of the photomultiplier tube.

[0035] (4) By sharing the light source, spectrometer, integrating sphere, and data acquisition and processing system between the detection device and the standard aluminum mirror test device in the present invention, and by using the same operating states of the light source and spectrometer in the spectral test of the standard aluminum mirror and the spectral test of the surface of the photomultiplier tube to be measured, the consistency of the devices during the spectral test of the standard aluminum mirror and the spectral test of the photomultiplier tube to be measured can be maintained. Thus, the accuracy of the detection results can be ensured. The more accurate the obtained reflectivity results are, the more reference significance they have for establishing an optical model, and thus the more beneficial it is for physical research work.

[0036] (5) By providing a specific test tooling (i.e., including a positioning ring and a detection hole) in the present invention, the fixing of the integrating sphere during the test can be ensured, and the influence caused by the shaking of the integrating sphere can be reduced, thereby ensuring the accuracy of the test data. In addition, by setting the test tooling as a specific multi-branch structure (a plurality of connecting arms radially extending outward with the positioning ring as the center), the stability of the test tooling when installed on the surface of the photomultiplier tube to be measured is improved.

[0037] (6) By adopting the structural setting of detection holes on the connecting arms in the present invention, not only the structure of the test tooling is simplified, the fixed installation of the integrating sphere is realized, but also the material used for the test tooling is reduced and the weight is lightened.

[0038] (7) By setting at least partial overlap between adjacent detection holes on the same connecting arm in the present invention, the number of detection holes in the same length is increased, thereby increasing the number of test points, which is beneficial to studying the overall distribution characteristics of the surface reflectivity of the photomultiplier tube.

[0039] (8) By adopting a multi-branch structure (a plurality of connecting arms) and the repeated appearance of detection holes at corresponding positions on each branch in the present invention, multi-point testing of several "latitude line" positions is realized. Multi-point testing and statistical analysis can help obtain the reflectivity information at different positions of the same "latitude line" and different "latitude line" positions on the surface of the photomultiplier tube to be measured, and can more accurately know the distribution characteristics of the surface reflectivity of the photomultiplier tube.

[0040] (9) By setting the connecting arms to have a certain curvature in the present invention, the connecting arms can fit the surface of the photomultiplier tube to be measured, enhancing the firmness of the connection between the test tooling and the photomultiplier tube to be measured.

[0041] (10) By using an elastic material for the test tooling in the present invention, on the one hand, it is not easy to damage the surface of the photomultiplier tube and plays a role in protecting the surface of the photomultiplier tube to be measured; on the other hand, it is convenient for the installation and removal of the test tooling during the spectral test.

[0042] (11) By providing a boss at the free end of the connecting arm, the present invention increases the contact area between the connecting arm and the fixing ring, further enhancing the firmness of the connection between the test tooling and the surface of the photomultiplier tube to be tested.

[0043] (12) By setting the locking section and the second side to be movably connected, the present invention facilitates the installation and removal of the integrating sphere.

[0044] (13) By setting the connection line between the light source interface and the central hole to be not on the same axis as the axis of the integrating sphere but deflected by a certain angle, the present invention greatly ensures that the light emitted by the light source can directly irradiate the geometric center position of the end face central hole after entering the integrating sphere; and when the central hole contacts the surface to be tested, reflected light will enter the integrating sphere again.

[0045] (14) The detection system of the present invention has a simple structure, a small volume, and is easy to operate, thereby enabling rapid detection of the surface reflectivity of the photomultiplier tube.

[0046] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be obvious from the specification or understood by implementing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings are only for the purpose of illustrating specific embodiments and are not considered to be a limitation of the present invention. Throughout the drawings, the same reference signs represent the same components.

[0048] Figure 1 Schematic diagram of the structure of the photomultiplier tube;

[0049] Figure 2 Schematic diagram of the structure of the detection device for testing and obtaining the spectral data of the surface of the photomultiplier tube according to an embodiment of the present invention;

[0050] Figure 3 Schematic diagram of the connection relationship between the integrating sphere, the light source, and the spectrometer;

[0051] Figure 4 Schematic diagram of the structure of the test tooling according to an embodiment of the present invention;

[0052] Figure 5 Schematic diagram of the structure of the test device for testing and obtaining the spectral data of the standard aluminum mirror according to an embodiment of the present invention;

[0053] Figure 6 Ambient background spectrum according to an embodiment of the present invention;

[0054] Figure 7 Standard aluminum mirror spectrum according to an embodiment of the present invention;

[0055] Figure 8 Surface spectrum of the photomultiplier tube to be measured according to an embodiment of the present invention

[0056] Figure 9 Schematic diagram of the positional relationship between the central hole and the light source interface on the integrating sphere according to an embodiment of the present invention

[0057] Reference numerals:

[0058] 1 - incident window; 2 - photocathode; 3 - multiplier system; 4 - anode; 5 - light source; 6 - spectrometer; 7 - integrating sphere; 8 - photomultiplier tube to be measured; 9 - optical fiber; 10 - test fixture; 11 - data acquisition and processing system; 12 - light source interface; 13 - spectrometer interface; 14 - central hole; 15 - positioning ring; 16 - connecting arm; 17 - detection hole; 18 - base; 19 - column; 20 - fixing ring; 21 - weight reduction structure; 22 - boss; 23 - standard aluminum mirror; 24 - base; 25 - bracket; 26 - workbench; 27 - first side; 28 - second side; 29 - third side; 30 - connecting section; 31 - locking section; 32 - connecting piece; α - included angle; 33 - latitude line Detailed implementation manners

[0059] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention

[0060] The structure of the photomultiplier tube and the calculation formula for the reflectivity of the surface of the photomultiplier tube will be briefly described below

[0061] As Figure 1 shown, the photomultiplier tube mainly consists of an incident window 1, a photocathode 2, a multiplier system 3, an anode 4, etc

[0062] The front end of the photomultiplier tube includes an incident window 1 and a photocathode 2, which are combined together by a special process and regarded as a "whole", called the surface of the photomultiplier tube. The incident window 1 has a certain thickness, while the photocathode 2 is very thin and usually exists in the form of a thin film. The light incident on the photomultiplier tube is excited by the incident window 1, causing electrons on the photocathode 2 to be emitted into the vacuum, called photoelectrons. The photoelectrons are collected by the focusing electrode onto the first dynode, and after secondary electron multiplication, secondary electrons are successively emitted by each dynode, and finally the secondary electrons emitted by the last dynode are output through the anode 4

[0063] The materials of the incident window 1 in a photomultiplier tube are usually MgF2 crystals, sapphire (Al2O3), synthetic quartz, UV glass, borosilicate glass, etc. The short-wavelength limit of the incident window 1 depends on the ultraviolet absorption characteristics of the window material used. The photocathode 2 is a semiconductor compound, and its main component is generally an alkali metal with a low work function. For example, it can be double-alkali and multi-alkali such as Cs-I, Cs-Te, Sb-Cs, etc.

[0064] The value obtained by dividing the number of photoelectrons emitted from the photocathode 2 by the number of incident photons is used as an important performance index of the photomultiplier tube, which is called the quantum efficiency. On the one hand, the quantum efficiency of the photomultiplier tube is related to the material selected for the photocathode 2; on the other hand, the number of photoelectrons emitted from the photocathode 2 is also related to the number of photons reaching the photocathode 2. The value obtained by dividing the number of photons reaching the photocathode 2 by the number of incident photons can be used to represent the transmittance T (i.e., the surface transmittance of the photomultiplier tube) when the incident window 1 and the photocathode 2 of the photomultiplier tube are regarded as a whole, that is

[0065] T = N1 / N0 or T = P1 / P0 (1)

[0066] where N1 and N0 represent the number of photons reaching the photocathode 2 and the number of incident photons respectively; while P1 and P0 represent the power forms corresponding to N1 and N0 respectively.

[0067] The transmittance when the incident window 1 and the photocathode 2 of the photomultiplier tube are regarded as a whole is very important. A full understanding of it can help to deeply understand the functional characteristics of the photomultiplier tube. In the field of particle physics, the method of creating an optical model is used to carry out relevant physical research, and the above transmittance is used as an important optical parameter to guide the establishment and analysis of the optical model. The more accurate the result of the transmittance measurement, the more reference significance the established optical model has, and thus the more beneficial it is to the physical research work.

[0068] Since a photomultiplier tube is essentially a vacuum electron device, it is very difficult to detect the transmittance when the incident window 1 and the photocathode 2 are regarded as a whole by means of transmission after the photomultiplier tube is manufactured, because it is very difficult to place a probe inside the photomultiplier tube to receive the transmitted light; instead, the reflectance quantitative result when the incident window and the photocathode are regarded as a whole is detected to indirectly estimate the corresponding transmittance level. Numerically, the two satisfy the following expression:

[0069] T = 1 - R (2)

[0070] where R is the reflectance when the incident window and the photocathode of the photomultiplier tube are regarded as a whole, that is, the surface reflectance of the photomultiplier tube. The transmittance T and the reflectance R are functions of the wavelength λ, that is, T(λ) and R(λ). Specifically, it depends on the type of light source used in the detection and the working wavelength of interest.

[0071] The surface reflectivity R of the photomultiplier tube of the present invention PMT (λ) can be expressed as:

[0072]

[0073] Among them, P PMT (λ) is the spectrum of the position to be measured on the surface of the photomultiplier tube; P L (λ) is the light source intensity spectrum, and P AL (λ) is the standard aluminum mirror spectrum; r(λ) is the reflectivity of the standard aluminum mirror at different wavelengths.

[0074] In order to obtain more accurate reflectivity detection results, the environmental background spectrum P BG (λ) during detection is also considered and collected. Then, the surface reflectivity R PMT (λ) of the photomultiplier tube can be further expressed as:

[0075]

[0076] Among them, P PMT (λ) is the spectrum of the position to be measured on the surface of the photomultiplier tube; P L (λ) is the light source intensity spectrum, and P AL (λ) is the standard aluminum mirror spectrum; r(λ) is the reflectivity of the standard aluminum mirror at different wavelengths; P BG (λ) is the environmental background spectrum during detection.

[0077] Example 1

[0078] A specific embodiment of the present invention discloses a non-destructive quantitative detection method for the surface reflectivity of a photomultiplier tube, aiming to test and obtain the data required in formula (4), and then calculate the reflectivity data on the surface of the photomultiplier tube.

[0079] The detection method of this embodiment mainly includes two major steps: spectral testing of the standard aluminum mirror (step 1) and spectral testing of the surface of the photomultiplier tube to be measured (step 2). The above two steps are introduced separately below.

[0080] Step 1: Perform spectral testing on the standard aluminum mirror to obtain the spectral data of the standard aluminum mirror.

[0081] Performing spectral testing on the standard aluminum mirror includes the following steps:

[0082] Step 11: Fix the integrating sphere 7 on the fixed support part of the standard aluminum mirror test device to ensure that the integrating sphere 7 remains fixed during the spectral test of the standard aluminum mirror. Specifically: Loosen the connecting piece 32 on the locking section 31, pass one end of the integrating sphere 7 with the central hole 14 through the through hole on the clamping piece, make the end face of the integrating sphere 7 with the central hole 14 slightly higher than the surface of the clamping piece, and then tighten the connecting piece 32 to install the integrating sphere 7 on the clamping piece.

[0083] Step 12: Connect the light source interface 12 on the integrating sphere 7 to the light source 5, the spectrometer interface 13 on the integrating sphere 7 to the spectrometer 6, and the spectrometer 6 to the data acquisition and processing system 11 respectively by using the optical fiber 9.

[0084] Step 13: Cover the standard aluminum mirror test surface (i.e., the standard aluminum mirror reflection surface) on the central hole 14 of the integrating sphere, make the center of the standard aluminum mirror test surface as aligned as possible with the center of the central hole of the integrating sphere. At this time, the standard aluminum mirror test surface will also completely block the central hole of the integrating sphere.

[0085] Step 14: Test and obtain the environmental background spectral data.

[0086] Keep the light source 5 in the off state, turn on the spectrometer 6, and observe the real-time spectrum through the data acquisition and processing system 11. After the spectrum is stable, save the spectral data file to the specified path, name the file BG, and obtain the environmental background spectrum P BG (λ) corresponding to that in formula (4). The environmental background spectrum is as Figure 6 shown.

[0087] Step 15: Start the light source, observe the real-time spectrum through the data acquisition and processing system 11. After the spectrum is stable, save the spectral data file to the specified path, name the file AL, and obtain the standard aluminum mirror spectrum P AL (λ) corresponding to that in formula (4). The standard aluminum mirror spectrum is as Figure 7 shown.

[0088] So far, the spectral test of the standard aluminum mirror has been completed. Next, introduce Step 2: Perform a spectral test on the surface of the photomultiplier tube to be tested to obtain the spectral data of the surface of the photomultiplier tube to be tested. The specific steps are as follows:

[0089] Step 21: Place the photomultiplier tube 8 to be tested in the fixed ring 20 on the column 19, and install the test tooling 10 on the surface of the photomultiplier tube to be tested and wait for the test.

[0090] It should be noted that since the spectral test on the surface of the photomultiplier tube and the spectral test of the standard aluminum mirror are two relatively independent test processes, therefore, Step 21 can be carried out before the spectral test of the standard aluminum mirror.

[0091] Step 22: Transfer the integrating sphere 7 from the standard aluminum mirror testing device to the detection device, which specifically includes the following steps:

[0092] Step 221: Keep the states of the light source and the spectrometer in the standard aluminum mirror spectral test, and remove the standard aluminum mirror 23;

[0093] Step 222: Loosen the connecting piece 32 and remove the integrating sphere 7 from the clamping piece;

[0094] Step 223: Insert the integrating sphere 7 into the positioning ring 15 or the detection hole 17 of the test fixture.

[0095] It should be noted that the aperture of the positioning ring 15 and the aperture of the detection hole 17 on the test fixture are both matched with the diameter of the integrating sphere cylinder, so as to ensure that after the integrating sphere 7 is inserted into the positioning ring 15 or the detection hole 17, it can not only achieve good contact with the surface of the photomultiplier tube to be measured, but also play a fixing role for the integrating sphere 7.

[0096] Step 23: Observe the real-time spectrum through the data acquisition and processing system. After the spectrum is stable, save the spectrum data file to the specified path, and name the file PMT to obtain the spectrum P PMT (λ) at the detection position on the surface of the photomultiplier tube to be measured corresponding to the expression (4). The spectrum of the surface of the photomultiplier tube to be measured is as Figure 8 shown.

[0097] So far, the data used to calculate the reflectivity of the photomultiplier tube surface has been tested. Then proceed with the following Step 3: Substitute the spectral data of the standard aluminum mirror and the spectral data of the surface of the photomultiplier tube to be measured into the formula to obtain the reflectivity of the photomultiplier tube surface.

[0098] In a specific embodiment, the working wavelength of the monochromatic light source used in the actual measurement is 415 nm, and the calibrated reflectivity value of the standard aluminum mirror at 415 nm is 80.7%; at 415 nm, the measured environmental background spectrometer value is 8657, the standard aluminum mirror spectrometer value is 29326, and the spectrometer value at the detection position on the surface of the photomultiplier tube to be measured is 11087. Substitute the above values into the formula (4), and the calculated corresponding reflectivity result is:

[0099]

[0100] That is, the reflectivity at the detection position on the surface of the photomultiplier tube to be measured at 415 nm is about 9.5%.

[0101] Embodiment 2

[0102] Another specific embodiment of the present invention discloses a non-destructive quantitative detection system for the surface reflectivity of a photomultiplier tube, which is used to complete the detection method of Embodiment 1. The detection system includes a detection device and a standard aluminum mirror test device. The detection device is used to test and obtain the spectral data of the surface of the photomultiplier tube to be measured, and the standard aluminum mirror test device is used to test and obtain the spectral data of the standard aluminum mirror.

[0103] As Figure 2 shown, the detection device includes a light source 5, a spectrometer 6, an integrating sphere 7, a photomultiplier tube 8 to be measured, an optical fiber 9, a test fixture 10, a test bracket, and a data acquisition and processing system 11.

[0104] The light source 5 is used to provide light for detection, the integrating sphere 7 realizes the reflection of light, the spectrometer 6 forms spectral data from the light reflected from the integrating sphere 7, and the data acquisition and processing system 11 is used to realize the real-time acquisition of spectral data. The test fixture 10 is used to fix the integrating sphere 7 on the surface of the photomultiplier tube 8 to be measured. The test bracket is used to fix the photomultiplier tube 8 to be measured.

[0105] Specifically, the photomultiplier tube 8 to be measured is fixed on the test bracket, the integrating sphere 7 is fixed on the surface of the photomultiplier tube 8 to be measured through the test fixture 10, the light source 5 and the spectrometer 6 are respectively connected to the integrating sphere 7 through the optical fiber 9, and the data acquisition and processing system 11 is connected to the spectrometer 6. Continuing to refer to Figure 2 , the integrating sphere 7 is in the shape of a hollow cylinder, and it is provided with two interfaces, namely a light source interface 12 and a spectrometer interface 13. The light source interface 12 is connected to the light source 5 through the optical fiber 9, so that the light emitted by the light source 5 enters the interior of the integrating sphere 7 through the optical fiber 9. The spectrometer interface 13 is connected to the spectrometer 6 through the optical fiber 9, and the spectrometer 6 is connected to the data acquisition and processing system 11 through the optical fiber 9, and the data acquisition of the light reflected from the integrating sphere 7 is realized by using computer software.

[0106] Specifically, as Figure 2 shown, the light source interface 12 is provided on one end face of the integrating sphere 7, and the spectrometer interface 13 is provided on the side face of the integrating sphere 7. Exemplarily, both the light source interface 12 and the spectrometer interface 13 are SMA905 standard interfaces.

[0107] As Figure 3 shown, a central hole 14 communicating with the interior of the integrating sphere 7 is provided on the other end face of the integrating sphere 7. The central hole 14 is located at the center of the end face, and the light spot of the light beam transmitted from the interior of the integrating sphere 7 falls within the opening range of the central hole 14.

[0108] During the test, the central hole 14 is in contact with the surface of the photomultiplier tube 8 to be tested, so that the surface of the photomultiplier tube 8 to be tested reflects the light beam transmitted from inside the integrating sphere 7, making it return to the inside of the integrating sphere 7 again. Then, it is reflected by the inner wall of the integrating sphere 7 and finally enters the spectrometer 6 through the optical fiber connected to the side of the cylinder to form spectral data, and the acquisition of the spectral data is completed by the data acquisition and processing system 11.

[0109] It should be noted that, referring to Figure 9 , the light source interface 12 on one end face of the integrating sphere 7 and the central hole 14 on the other end face are not on the same axis, but are deflected by a certain angle, which greatly ensures that the light emitted by the light source 5 can directly shoot towards the geometric center position of the central hole on the end face after entering the inside of the integrating sphere 7; and when the central hole is in contact with the surface to be tested, reflected light will enter the inside of the integrating sphere 7 again.

[0110] Specifically, there is an angle α between the connecting line of the light source interface 12 and the central hole 14 and the axis of the integrating sphere 7, and α is 7° - 10°.

[0111] In an embodiment, α can be 7°, 8°, 9° or 10°.

[0112] In a specific embodiment, the aperture of the central hole 14 is 6 - 10 mm. For example, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

[0113] It should be noted that the inner wall of the integrating sphere 7 is coated with polytetrafluoroethylene (PTFE). Polytetrafluoroethylene can provide ultra-high reflectivity in the 200 - 2500 nm band.

[0114] Next, the test fixture is introduced. Referring to Figure 4 , the test fixture 10 includes a positioning ring 15 and a plurality of connecting arms 16 radially extending outward with the positioning ring as the center, that is, the test fixture has a multi-branch structure. Specifically, the positioning ring and the plurality of connecting arms are integrally formed.

[0115] After the test fixture 10 is buckled on the surface of the photomultiplier tube 8 to be tested, the positioning ring 15 is located at the highest point of the arc surface of the photomultiplier tube 8 to be tested, and one end of the integrating sphere 7 provided with the central hole 14 is placed in the opening of the positioning ring 15, so that the integrating sphere 7 can measure the highest point of the arc surface of the photomultiplier tube. The plurality of connecting arms 16 are respectively in contact with the surface of the photomultiplier tube 8 to be tested.

[0116] Specifically, the connecting arm 16 has a certain curvature, so as to ensure that the connecting arm 16 can fit with the surface of the photomultiplier tube 8 to be tested, enhancing the firmness of the connection between the test fixture and the photomultiplier tube to be tested.

[0117] Furthermore, a plurality of detection holes 17 are provided on the connecting arm 16. The detection holes 17 are arranged along the length direction of the connecting arm 16, and the detection holes 17 are through holes penetrating along the thickness direction of the connecting arm 16. The lower end of the integrating sphere can be placed in the detection holes 17, so as to realize the measurement of a certain latitude position on the surface of the photomultiplier tube to be measured by the integrating sphere. Preferably, at least part of the adjacent detection holes 17 on the same connecting arm 16 overlap. The above setting increases the number of detection holes in the same length, thereby increasing the number of test points, which is beneficial to studying the overall distribution characteristics of the reflectivity on the surface of the photomultiplier tube. In this embodiment, by adopting the structural setting of detection holes on the connecting arm, the structure of the test tooling is simplified, the fixed installation of the integrating sphere is realized, the material used for the test tooling is reduced, and the weight is reduced.

[0118] In addition, by setting the test tooling to have a multi-branch structure in this embodiment, the stability of the test tooling when installed on the surface of the photomultiplier tube to be measured is improved.

[0119] Furthermore, in this embodiment, by adopting a multi-branch structure and the detection holes repeating at corresponding positions of each branch, multi-point testing of several "latitude" positions is realized.

[0120] It should be noted that the concept of "latitude" 33 is proposed for the multi-branch, and it is a statement describing the integrity of the multi-branch. As Figure 4 shown, the "latitude" refers to the circle formed by the connection lines of the center points of the detection holes at corresponding positions of each branch.

[0121] Multi-point testing and statistical analysis can help obtain the reflectivity information of different positions on the same "latitude" and different "latitude" positions on the surface of the photomultiplier tube to be measured, and can more accurately know the distribution characteristics of the reflectivity on the surface of the photomultiplier tube.

[0122] In a preferred embodiment, the test tooling 10 is made of an elastic material. The elastic material can be nylon, for example. The test tooling of this embodiment adopts an elastic material, and the advantages of its certain elasticity can be fully utilized. On the one hand, it is not easy to scratch the surface of the photomultiplier tube and plays a role in protecting the surface of the photomultiplier tube to be measured; on the other hand, it is convenient for the installation and removal of the test tooling during spectral testing.

[0123] The following introduces the test bracket that fixes the photomultiplier tube 8 to be tested. The test bracket includes a base 18 and a column 19 vertically arranged with respect to the base. One end of the column 19 is connected to the base 18, and the other end is provided with a fixing ring 20 for fixing the photomultiplier tube 8 to be tested. The opening size of the fixing ring 20 is slightly smaller than the maximum diameter size corresponding to the projection of the arc surface of the photomultiplier tube 8 to be tested onto the base, so that the fixing ring 20 can clamp the photomultiplier tube 8 to be tested. During the test, the fixing ring 20 is sleeved on the outer surface of the photomultiplier tube 8 to be tested, such that the surface of the photomultiplier tube 8 to be tested is above the fixing ring 20, facilitating the installation and fixation of the integrating sphere 7.

[0124] Specifically, both the base 18 and the column 19 are in the shape of a cuboid. One end of the column 19 is connected to the base 18 in the width direction of the base 18. The fixing ring 20 is arranged parallel to the base 18, and both are on the same side of the column 19.

[0125] Preferably, the base 18 is provided with a weight reduction structure 21 for reducing the weight of the base 18. Exemplarily, the weight reduction structure 21 is a groove with an opening facing the fixing ring.

[0126] In addition, as Figure 4 shown, a boss 22 is provided at the free end of the connecting arm 16. The boss 22 contacts the fixing ring 20, increasing the contact area between the connecting arm 16 and the fixing ring 20, and further improving the firmness of the connection between the test tooling and the surface of the photomultiplier tube to be tested.

[0127] The following details the standard aluminum mirror test device.

[0128] As Figure 5 shown, the standard aluminum mirror test device includes a light source 5, a spectrometer 6, an integrating sphere 7, a standard aluminum mirror 23, an optical fiber 9, a fixed support portion, and a data acquisition and processing system (not shown in the figure). Among them, the light source 5, the spectrometer 6, the integrating sphere 7, the optical fiber 9, and the data acquisition and processing system are shared with the detection device, aiming to: maintain the consistency of the devices during the spectral test of the standard aluminum mirror and the spectral test of the photomultiplier tube to be tested, thereby ensuring the accuracy of the detection results.

[0129] The light source 5 is used to provide light for the detection. The light source 5 can be a monochromatic light source or a non-monochromatic light source. The integrating sphere 7 realizes the reflection of light. The spectrometer 6 forms spectral data from the light reflected from the integrating sphere 7. The data acquisition and processing system 11 is used to realize the real-time acquisition of spectral data. The fixed support portion is used to fix the integrating sphere 7.

[0130] Specifically, the integrating sphere 7 is fixed on the fixed support portion and keeps the central hole 14 facing upward; the standard aluminum mirror 23 is placed on the end face of the integrating sphere 7 and covers the central hole 14.

[0131] The light source 5 and the spectrometer 6 are respectively connected to the integrating sphere 7 through optical fibers 9, and the data acquisition and processing system 11 is connected to the spectrometer 6.

[0132] See Figure 5 , the fixed support part includes a base 24, a bracket 25 and a clamping member for clamping the integrating sphere 7. One end of the bracket 25 is fixedly connected to the base 24, the other end is fixedly connected to the clamping member, and the base 24 is fixedly connected to the workbench 26.

[0133] In a specific embodiment, both the base 24 and the clamping member are flat and thin, the base 24 and the clamping member are arranged in parallel and are located on the same side of the bracket 25. The bracket 25 is arranged vertically with respect to the base 24 and the clamping member.

[0134] Specifically, the clamping member is provided with a through hole for the integrating sphere 7 to pass through, which includes opposite first side 27 and second side 28, and third side 29 and fourth side connecting the first side 27 and the second side 28. The first side 27, the second side 28 and the third side 29 are all straight lines, and the length of the first side 27 is less than the length of the second side 28. The fourth side includes a connecting section 30 and a locking section 31, the connecting section 30 is arc-shaped,

[0135] The first side 27, the second side 28, the third side 29 and the connecting section 30 are integrally formed in structure. After the integrating sphere 7 (with the central hole 14 facing upwards) is inserted into the through hole of the formed part, by tightening the connecting member 32, the formed part can be tightened around the integrating sphere. Subsequently, the test surface of the standard aluminum mirror is covered on the central hole 14 of the integrating sphere for testing.

[0136] The connecting section 30 is connected to the first side 27, and the locking section 31 is movably connected to the second side 28. In this embodiment, by setting the locking section and the second side to be movably connected, it is convenient to install and remove the integrating sphere.

[0137] In a preferred embodiment, the end of the locking section 31 connected to the second side 28 is provided with a mounting hole for the connecting member 32 to pass through, and the installation and removal of the integrating sphere 7 are realized by tightening or loosening the connecting member 32.

[0138] Regarding the connection positions of the bracket 25 with the base 24 and the clamping member, for example, the connection position of the bracket 25 with the base 24 is located at the edge of one side of the base 24, specifically the edge along the length direction. The connection position of the bracket 25 with the clamping member is located near the second side 28 of the clamping member.

[0139] In addition, the bracket 25 is provided with a weight reduction structure 21. Specifically, the weight reduction structure 21 is a through hole penetrating along the thickness direction of the bracket 25. According to the shape of the bracket, the shape of the through hole can be, for example, a long strip along the length direction of the bracket.

[0140] The present invention adopts optical elements such as integrating spheres and standard aluminum mirrors, combines spectral methods, and designs a special test tooling, so as to achieve non-destructive, quantitative and rapid detection of the surface reflectivity of photomultiplier tubes.

[0141] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for detecting the surface reflectivity of a photomultiplier tube, characterized in that, It includes the following steps: Step 1: Conduct a spectral test on the standard aluminum mirror to obtain the spectral data of the standard aluminum mirror; Step 2: Conduct a spectral test on the surface of the photomultiplier tube to be measured to obtain the spectral data of the surface of the photomultiplier tube to be measured; Step 3: Substitute the spectral data of the standard aluminum mirror and the spectral data of the surface of the photomultiplier tube to be measured into the reflectivity calculation formula to obtain the reflectivity of the surface of the photomultiplier tube; The said Step 1 includes the following steps: Step 11: Fix the integrating sphere on the fixed support part of the standard aluminum mirror test device to ensure that the integrating sphere remains fixed during the spectral test of the standard aluminum mirror; Step 12: Use optical fibers to connect the light source interface on the integrating sphere with the light source, the spectrometer interface on the integrating sphere with the spectrometer, and the spectrometer with the data acquisition and processing system respectively; Step 13: Cover the test surface of the standard aluminum mirror on the central hole of the integrating sphere; Step 14: Start the light source, observe the spectrum through the data acquisition and processing system, and save the spectral data file to obtain the spectral data of the standard aluminum mirror; The said Step 2 includes the following steps: Step 21: Place the photomultiplier tube to be measured in the fixed ring on the column, and install the test tooling on the surface of the photomultiplier tube to be measured and wait for the test; Step 22: Transfer the integrating sphere from the standard aluminum mirror test device to the detection device; Step 23: Observe the spectrum through the data acquisition and processing system, and save the spectral data file to obtain the spectral data at the detection position on the surface of the photomultiplier tube to be measured; The said Step 22 includes the following steps: Step 221: Keep the states of the light source and the spectrometer during the spectral test of the standard aluminum mirror, and remove the standard aluminum mirror; Step 222: Loosen the connecting piece and remove the integrating sphere from the clamping piece; Step 223: Insert the integrating sphere into the positioning ring or detection hole of the test tooling; The reflectivity calculation formula is: where R PMT (λ) is the reflectivity of the surface of the photomultiplier tube; P PMT (λ) is the spectrum of the position to be measured on the surface of the photomultiplier tube; P L (λ) is the spectrum of the light source intensity, P AL (λ) is the spectrum of the standard aluminum mirror; r(λ) is the reflectivity of the standard aluminum mirror at different wavelengths; P BG (λ) is the environmental background spectrum during detection.

2. The detection method according to claim 1, wherein Between the said Step 13 and Step 14, it includes testing to obtain the environmental background spectrum.

3. The detection method according to claim 2, wherein, The said testing to obtain the environmental background spectrum includes the following steps: Turn off the light source, turn on the spectrometer, observe the real-time spectrum through the data acquisition and processing system, and save the spectral data file to obtain the environmental background spectral data.

4. The detection method according to claim 1, characterized in that The light source used in the said Step 14 is a monochromatic light source or a non-monochromatic light source.

5. The detection method according to claim 4, characterized in that The wavelength of the said monochromatic light source is 415 nm.

6. A surface reflectivity detection system for a photomultiplier tube, characterized in that, For completing the detection method described in any one of claims 1-5, the said detection system includes a detection device for testing and obtaining the spectral data of the surface of the photomultiplier tube and a test device for testing and obtaining the spectral data of the standard aluminum mirror.

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