A PDE-based light flux adjustment structure

Abstract

The application provides a light flux adjusting structure based on PDE, which comprises a light source, a light adjusting group, an integrating sphere and an optical sleeve; the light adjusting group comprises a collimating lens and a converging lens; the light emitted by the light source is converted into parallel light through the light adjusting group, the parallel light is converged, and then enters an input end of the integrating sphere; an output end of the integrating sphere is connected with one end of the optical sleeve, light is emitted from the output end of the integrating sphere and enters the optical sleeve, a SiPM to be measured is arranged at the other end of the optical sleeve, and the light irradiates the SiPM to be measured through the optical sleeve. The application can realize PDE testing of photoelectric detectors, especially SiPM and the like, can realize the effect of adjusting the light flux input to the SiPM by adjusting the length of the optical sleeve under the condition that the light intensity is constant, and can meet the testing demand of PDE. The integrating sphere testing part is separated from the light source input part, which is beneficial to guarantee that the testing part is not disturbed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of PDE testing, and in particular to a light flux adjusting structure based on PDE. BACKGROUND

[0002] SiPM (Silicon Photomultipliers) is one of the indispensable photoelectric detectors of time-of-flight sensors at present. Its working principle is that after the external photon is incident, an electron-hole pair is excited. In the Geiger mode, the electron-hole pair is accelerated by the electric field to have enough energy to hit and generate a new multiple electron-hole pair, thereby triggering an avalanche. The avalanche is rapidly stopped under the additional quenching circuit to return to the state before the avalanche, and then waits for the next photon to be tested. It has high gain, high sensitivity and many other advantages.

[0003] The photo detection efficiency (PDE) is an important parameter for evaluating the performance of a SiPM and can be decomposed into three quantities:

[0004] , wherein represents the fill factor, i.e. the ratio of the actual effective light receiving area to the total area; is the quantum efficiency, which represents the probability of generating an electron-hole pair under optical / thermal excitation; is the probability of an electron-hole pair triggering an avalanche, which is affected by many factors such as operating voltage, incident light wavelength, light intensity, etc. In recent years, with the gradual development of the field of laser radar technology, PDE has become one of the most important evaluation parameters of RX (receiving end), directly affecting the detection sensitivity and detection efficiency of the laser radar. The present technical solution designs a light flux adjusting structure based on PDE, which is particularly suitable for PDE testing of SiPM, to meet the PDE testing requirements. SUMMARY

[0005] In view of the above prior art, the purpose of the present application is to provide a light flux adjusting structure based on PDE to meet the PDE testing requirements of photoelectric detectors.

[0006] Based on the above technical purpose, the present application adopts the following technical solution:

[0007] The application provides a PDE-based light flux adjusting structure, comprising a light source, a light adjusting group, an integrating sphere and an optical sleeve; the light adjusting group comprises a collimating lens and a condensing lens; light emitted by the light source is converted into parallel light through the light adjusting group, the parallel light is converged, and then enters an input end of the integrating sphere; an output end of the integrating sphere is connected with one end of the optical sleeve, light is emitted from the output end of the integrating sphere and enters the optical sleeve, and a to-be-tested SiPM is arranged at the other end of the optical sleeve, and light irradiates the to-be-tested SiPM through the optical sleeve.

[0008] In a preferred embodiment, the PDE-based light flux adjusting structure further comprises a light filtering mirror and a photodetector; light emitted by the light source is reflected by the light filtering mirror after passing through the collimating lens, and light of a to-be-tested wavelength is reflected; the light of the to-be-tested wavelength enters the input end of the integrating sphere through the condensing lens; light passing through the collimating lens is transmitted by the light filtering mirror, and light of a non-to-be-tested wavelength is transmitted; and the light of the non-to-be-tested wavelength is sensed by the photodetector.

[0009] In a preferred embodiment, the PDE-based light flux adjusting structure is provided with an optical fiber at the input end of the integrating sphere; light passing through the condensing lens enters the optical fiber, and then enters the input end of the integrating sphere through the optical fiber.

[0010] In a preferred embodiment, the PDE-based light flux adjusting structure further comprises a first optical attenuating sheet; the light of the to-be-tested wavelength is transmitted by the first optical attenuating sheet and then enters the input end of the integrating sphere through the condensing lens; and the first optical attenuating sheet is an adjustable attenuating sheet.

[0011] In a preferred embodiment, the PDE-based light flux adjusting structure further comprises a first mirror and a second mirror; light passing through the collimating lens sequentially passes through the first mirror and the second mirror and then irradiates the light filtering mirror.

[0012] In a preferred embodiment, the PDE-based light flux adjusting structure is provided with a first mirror and a second mirror; the first mirror and the second mirror are both right-angle mirrors; and the light filtering mirror is a right-angle mirror.

[0013] In a preferred embodiment, the PDE-based light flux adjusting structure is provided with a first mirror and a second mirror; the first mirror and the second mirror are both right-angle mirrors; and the light filtering mirror is a right-angle mirror.

[0014] In a preferred embodiment, the PDE-based light flux adjusting structure, a second optical attenuation sheet is arranged in the optical sleeve, and light passes through the second optical attenuation sheet in the optical sleeve to irradiate on the SiPM to be measured.

[0015] In a preferred embodiment, the PDE-based light flux adjusting structure, the optical sleeve is an optical sleeve with adjustable length.

[0016] In a preferred embodiment, the PDE-based light flux adjusting structure, the collimating lens and the condensing lens are both semi-convex lenses.

[0017] Compared with the prior art, the PDE-based light flux adjusting structure provided by the application comprises a light source, a light adjusting group, an integrating sphere and an optical sleeve. The light adjusting group comprises a collimating lens and a condensing lens. The light emitted by the light source is converted into parallel light through the light adjusting group, and the parallel light is converged to enter an input end of the integrating sphere. An output end of the integrating sphere is connected with one end of the optical sleeve. Light is emitted from the output end of the integrating sphere to enter the optical sleeve. A SiPM to be measured is arranged at the other end of the optical sleeve, and light passes through the optical sleeve to irradiate on the SiPM to be measured. The application can realize PDE testing of photoelectric detectors, especially SiPMs. In the case of a certain light intensity, the length of the optical sleeve can be adjusted to adjust the light flux input to the SiPM, so as to meet the testing requirements of PDE. The application separates the integrating sphere testing part from the light source input part. This design separates the optical path into input adjustment and testing two parts, which is beneficial to ensure that the testing part is not disturbed. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The structure diagram of the PDE-based light flux adjusting structure provided by the application.

[0019] Figure 2 The structure diagram of the output of the integrating sphere of the PDE-based light flux adjusting structure provided by the application.

[0020] Figure 3 The structure diagram of the testing part of the PDE-based light flux adjusting structure provided by the application.

[0021] BRIEF DESCRIPTION OF DRAWINGS: 101, light source; 102, light adjusting group; 103, integrating sphere; 104, optical sleeve; 105, collimating lens; 106, condensing lens; 107, SiPM to be measured; 108, light filtering mirror; 109, photoelectric detector; 110, first mirror; 111, second mirror; 112, first optical attenuation sheet; 113, optical fiber; 114, second optical attenuation sheet. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] It should be noted that when a component is referred to as being "mounted on," "fixed to," or "set on" another component, it can be directly on the other component or may have an intervening component present. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or may have an intervening component present.

[0024] It should also be noted that the directional terms such as left, right, up, and down in the embodiments of the present invention are only relative concepts or are based on the normal use state of the product, and should not be considered as restrictive.

[0025] like Figure 1 As shown, this invention provides a PDE-based luminous flux adjustment structure, including a light source 101, a light adjustment assembly 102, an integrating sphere 103, and an optical sleeve 104. The light adjustment assembly 102 includes a collimating lens 105 and a condensing lens 106. The light emitted from the light source 101 is converted into parallel light by the light adjustment assembly 102, and then converged before entering the input end of the integrating sphere 103. The output end of the integrating sphere 103 is connected to one end of the optical sleeve 104, and the light exits from the output end of the integrating sphere 103 and enters the optical sleeve 104. The SiPM 107 to be tested is placed at the other end of the optical sleeve 104, and the light shines on the SiPM 107 through the optical sleeve 104. Preferably, in this embodiment, the collimating lens 105 and the condensing lens 106 in the PDE-based luminous flux adjustment structure provided by this invention are both semi-convex lenses. This invention enables PDE testing of photoelectric detection electronic devices, especially SiPMs. This invention allows for the adjustment of the luminous flux input to the SiPM by adjusting the length of the optical sleeve 104 or by replacing it with optical sleeves of different lengths, under a constant light intensity, thus meeting the testing requirements of the PDE. This invention separates the testing section of the integrating sphere 103 from the input section of the light source 101. This design divides the optical path into two parts: input adjustment and testing, which helps ensure that the testing section is not disturbed. Furthermore, the optical sleeve 104 at the output end of the integrating sphere 103 provides dust protection and safeguards the optical coating inside the integrating sphere 103, thereby extending its service life.

[0026] SiPM is composed of multiple SPAD (Single Photon Avalanche Diode) arrays, and shares the same output, and whether avalanche occurs between each SPAD is a relatively independent event, if the number of SPADs that avalanche occurs under a fixed light condition is regarded as a discrete random variable, then it should be subject to Poisson distribution, and PDE should be equal to the ratio of the difference between the number of avalanches triggered only by photons minus the number of avalanches triggered by heat and the number of incident photons:

[0027]

[0028] Where npe is the number of SPADs that avalanche occurs, and nph is the number of incident photons of a single pulsed light. Generally, a SiPM can be composed of several hundred to several thousand SPADs, in order to ensure the accuracy of PDE testing, nph must be lower than npe, and accordingly nph must be controlled very low, at the same time, since it is necessary to capture the avalanche signal induced by the external light, it is necessary to measure the time of incident light, and therefore it is also necessary to output the synchronization signal of the light, which directly leads to the requirement of the light source 101 for PDE measurement being particularly harsh.

[0029] Preferably, the PDE-based light flux adjusting structure provided by the present application further comprises a light filtering mirror 108 and a photodetector 109, the light emitted by the light source 101 passes through the collimating lens 105, is reflected by the light filtering mirror 108 to reflect the light of the wavelength to be tested, the reflected light of the wavelength to be tested enters the input end of the integrating sphere 103 via the condensing lens 106, the light passing through the collimating lens 105 is transmitted by the light filtering mirror 108 to transmit the light of the non-wavelength to be tested, and the transmitted light of the non-wavelength to be tested is sensed by the photodetector 109. The present application sets the light filtering mirror 108 in the input part, which cleverly filters out the non-test light wavelength while intercepting the synchronization signal of the light source 101, without the need for the light source 101 to additionally design a synchronization signal output circuit, which is conducive to reducing the cost and simplifying the structure of the device.

[0030] Preferably, the PDE-based light flux adjusting structure provided by the present application further comprises a first mirror 110 and a second mirror 111, and the light passing through the collimating lens 105 passes through the first mirror 110 and the second mirror 111 in turn to irradiate on the light filtering mirror 108. These settings are based on the position adjustment between the corresponding components of the actual device structure, which can make the overall device space structure more compact. Preferably, the PDE-based light flux adjusting structure provided by the present application, the first mirror 110 and the second mirror 111 are both right-angle mirrors; and the light filtering mirror 108 is a right-angle mirror.

[0031] Preferably, the PDE-based light flux adjustment structure provided by the present application, the light adjustment group 102 further comprises a first optical attenuator 112, the reflected light of the wavelength to be tested passes through the first optical attenuator 112 to enter the input end of the integrating sphere 103 via the condenser lens 106; the first optical attenuator 112 is an adjustable attenuator. The first optical attenuator 112 is used to adjust the light intensity of the input light.

[0032] Preferably, the PDE-based light flux adjustment structure provided by the present application, the input end of the integrating sphere 103 is provided with an optical fiber 113, the light passing through the condenser lens 106 enters the optical fiber 113, and the light passing through the condenser lens 106 enters the input end of the integrating sphere 103 through the optical fiber 113 to guide the light into the integrating sphere 103. Preferably, the PDE-based light flux adjustment structure provided by the present application, the end face of the other end of the optical sleeve 104 is parallel to the light output face of the integrating sphere 103, so as to better ensure that the SiPM 107 to be tested receives a uniform light (which can control the light intensity variation within 8% in a range of 7mm). Preferably, the PDE-based light flux adjustment structure provided by the present application, the optical sleeve 104 is provided with a second optical attenuator 114, and the light passes through the second optical attenuator 114 in the optical sleeve 104 to irradiate on the SiPM 107 to be tested.

[0033] The present application has the advantages of simple structure, economic and effective realization of high attenuation requirement of the light path, guarantee of uniformity effect of the light received by the SiPM 107 to be tested, filtering out of the non-test required light wavelength without the output of the synchronous signal circuit of the light source 101 circuit, portability, simplicity, effectiveness, improvement of PDE test efficiency, and saving of test cost.

[0034] After the laser scattered by the light source 101, the light input part of the present embodiment is converted into parallel light through the semi-convex lens, enters the light filter mirror 108 after reflection, the remaining light of the non-test wavelength transmits through the light filter mirror 108 and enters the photodetector 109, converts the signal into a synchronous electrical signal, and the light of the test wavelength is reflected and passes through the adjustable first optical attenuator 112 and then converges to the end of the optical fiber 113 through the next semi-convex lens.

[0035] As Figure 2 , Figure 3As shown, the test part of the embodiment is after the light to be tested is input to the integrating sphere 103 by the optical fiber 113, the light is output from the output end after multiple reflections inside the integrating sphere 103, and the isotropic light enters the optical sleeve 104, and then the second optical attenuation piece 114 in the optical sleeve 104 is used for secondary attenuation, and the incident light angle to the SiPM 107 to be tested is limited, so that the solid angle is small enough to reduce the light flux. Preferably, the PDE-based light flux adjusting structure provided by the application is the optical sleeve 104 with adjustable length.

[0036] According to the relationship between light intensity and light flux:

[0037] Where I is the luminous intensity, Φ is the light flux, Ω is the solid angle, and the solid angle is equal to the infinitesimal area on the unit sphere:

[0038] Since the light output by the integrating sphere 103 is isotropic, when the input end is fixed, the light intensity (I) is constant, and the light receiving area (dA) of the SiPM to be tested is constant. In order to adjust the light flux to be small enough, the solid angle must be small enough, and the length of the optical sleeve can be increased ( ) to achieve this effect.

[0039] The application separates the test part from the input part, so that the test part can be tested in a better dark environment, which is beneficial to ensure the test effect. The optical sleeve 104 selected by the application is easy to assemble and can be used with the attenuation piece. The application is economical and practical, and can make the test efficient and reliable. The application selects a filter mirror 108 on the input end reflection path, which not only filters out light of different wavelengths, but also uses part of the light to output a synchronization signal for PDE test, which is beneficial to simplify the structure and reduce the cost. The application uses a simple optical sleeve 104 structure to complete the high attenuation requirement of PDE test, and also reduces the solid angle to a low enough level to ensure the uniformity of the light received by the chip to be tested.

[0040] In summary, the application can realize the PDE test of photoelectric detection electronic device, especially SiPM. The application uses simple optical sleeve structure, which not only meets the high attenuation requirement of PDE test, but also reduces the solid angle to a low enough level to ensure the uniformity of the light received by the tested chip. The application can adjust the light flux input to the SiPM by adjusting the length of the optical sleeve or replacing the optical sleeve with different length under the condition of certain light intensity, so as to meet the test requirement of PDE. The application selects a filter on the input end reflection light path, which not only filters out the light of miscellaneous wavelength, but also uses the light to output a synchronous signal to facilitate the PDE test, which is conducive to simplifying the structure and reducing the cost. The application separates the integrating sphere test part from the light source input part, which divides the light path into input adjustment and test two parts, so that the test part can be tested in a better dark environment, which is conducive to ensuring that the test part is not disturbed. Furthermore, the application sets the optical sleeve at the output end of the integrating sphere, which can realize dust prevention and protect the optical coating in the integrating sphere, which is conducive to prolonging the service life of the integrating sphere.

[0041] It can be understood that, for those skilled in the art, equivalent replacements or changes can be made according to the technical solutions and inventive concepts of the application, and all these changes or replacements shall belong to the protection scope of the appended claims of the application.

Claims

1. A light flux adjustment structure based on PDE, characterized in that, The system includes a light source, a light adjustment assembly, an integrating sphere, and an optical sleeve. The light adjustment assembly includes a collimating lens and a condensing lens. Light emitted from the light source is converted into parallel light by the light adjustment assembly, and then converged before entering the input end of the integrating sphere. The output end of the integrating sphere is connected to one end of the optical sleeve, and light exits from the output end of the integrating sphere and enters the optical sleeve. The SiPM to be tested is placed at the other end of the optical sleeve, and light shines on the SiPM through the optical sleeve. The light adjustment assembly also includes a filter mirror and a photodetector. Light emitted from the light source passes through the collimating lens and is reflected by the filter mirror to produce light of the wavelength to be tested. The reflected light of the wavelength to be tested enters the input end of the integrating sphere through the condensing lens. Light passing through the collimating lens is transmitted through the filter mirror to produce light of a wavelength other than the wavelength to be tested. The transmitted light of the wavelength other than the wavelength to be tested is sensed by the photodetector.

2. The PDE-based luminous flux adjustment structure according to claim 1, characterized in that, The input end of the integrating sphere is provided with an optical fiber. Light rays passing through the condenser lens enter the optical fiber and then pass through the optical fiber to enter the input end of the integrating sphere.

3. The PDE-based luminous flux adjustment structure according to claim 1, characterized in that, The light adjustment assembly further includes a first optical attenuator, through which the reflected light of the wavelength to be tested passes and enters the input end of the integrating sphere via the condenser lens; the first optical attenuator is an adjustable attenuator.

4. The PDE-based luminous flux adjustment structure according to claim 1, characterized in that, The light adjustment assembly also includes a first reflector and a second reflector. Light passing through the collimating lens passes sequentially through the first reflector and the second reflector to illuminate the filter reflector.

5. The PDE-based luminous flux adjustment structure according to claim 4, characterized in that, Both the first and second reflectors are right-angle reflectors; the filter reflector is a right-angle reflector.

6. The PDE-based luminous flux adjustment structure according to claim 1, characterized in that, The end face of the other end of the optical sleeve is parallel to the light-emitting surface of the integrating sphere.

7. The PDE-based luminous flux adjustment structure according to claim 1, characterized in that, A second optical attenuator is provided inside the optical sleeve, and light passes through the second optical attenuator inside the optical sleeve to illuminate the SiPM under test.

8. The PDE-based luminous flux adjustment structure according to any one of claims 1-5, characterized in that, The optical sleeve is an adjustable length optical sleeve.

9. The luminous flux adjustment structure based on PDE according to any one of claims 1-5, characterized in that, Both the collimating lens and the condensing lens are semi-convex lenses.

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