Integrating sphere detector, spectral responsivity calibration device and calibration method

Abstract

This invention relates to the field of photoelectric detection technology, providing an integrating sphere detector, a spectral responsivity calibration device, and a calibration method. The integrating sphere detector includes a hollow sphere and multiple photodetectors. The hollow sphere has a spherical cavity, a light inlet, and multiple light outlets. The inner wall of the spherical cavity is coated with a diffuse reflection layer. The light inlet is located on one side of a first reference surface passing through the center of the sphere. The multiple light outlets are evenly distributed circumferentially on a second reference surface. The second reference surface is parallel to a third reference surface passing through the center of the sphere, on the side opposite to the light inlet. The third reference surface is perpendicular to the first reference surface. The multiple photodetectors and multiple light outlets are arranged one-to-one. A light beam enters the spherical cavity through the light inlet, with the incident direction deviating from the center of the sphere and incident on the inner wall of the spherical cavity on the side of the second reference surface opposite to the light inlet. The integrating sphere detector of this invention has a simple structure, good uniformity, and facilitates accurate spectral responsivity calibration in the 1200-2300 nm range.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, and in particular to an integrating sphere detector, a spectral responsivity calibration device, and a calibration method. Background Technology

[0002] Currently, integrating sphere detectors are widely used in the field of photoelectric detection, and the structure of the integrating sphere directly affects its uniformity. The uniformity of an integrating sphere detector refers to the consistency of the light intensity / spectral distribution within the integrating sphere on the detector's receiving surface, and is a core indicator for evaluating the reliability of the final output signal.

[0003] In practical applications, existing integrating sphere detectors typically employ a design where a single photodetector is connected to the integrating sphere, with a baffle placed between the light inlet of the integrating sphere and the photodetector. This combination design of a single photodetector and a baffle based on the integrating sphere is complex. It is not only limited by the viewing angle of the single photodetector, which can only capture reflected light within a local angular range within the integrating sphere, resulting in uneven light field detection, but also introduces additional light loss while attempting to block stray light, causing uneven light reflection and affecting the uniformity of the integrating sphere detector. Summary of the Invention

[0004] This invention provides an integrating sphere detector, a spectral responsivity calibration device, and a calibration method, which at least solve or improve the problems of complex structure and poor uniformity of existing integrating sphere detectors.

[0005] In a first aspect, the present invention provides an integrating sphere detector, comprising: A hollow sphere has a spherical cavity and a light inlet and multiple light outlets communicating with the spherical cavity. The inner wall of the spherical cavity is provided with a diffuse reflection coating. The light inlet is located on one side of a first reference surface passing through the center of the sphere. The multiple light outlets are evenly distributed along the circumference on a second reference surface. The second reference surface is parallel to a third reference surface passing through the center of the sphere on the side opposite to the light inlet. The third reference surface is perpendicular to the first reference surface. Multiple photodetectors are connected in parallel and are respectively arranged opposite to the multiple light output ports; The light beam enters the spherical cavity through the light inlet and is then reflected by the diffuse reflection coating within the spherical cavity. The incident direction of the light beam is deviated from the center of the sphere, and the light beam is configured to enter the inner wall of the spherical cavity on the side of the second reference surface opposite to the light inlet.

[0006] According to an integrating sphere detector provided by the present invention, the angle between the incident direction of the light beam and the direction of the line connecting the light inlet and the center of the sphere is 0° to 25°, and the angle between the direction of the line connecting the light outlet and the center of the sphere and the third reference plane is 10° to 30°.

[0007] According to an integrating sphere detector provided by the present invention, the diffuse reflection coating has a reflectivity of not less than 98% for the light beam.

[0008] According to the present invention, an integrating sphere detector is an extended indium gallium arsenide photodiode; And / or, the photodetector is provided in two, and the two photodetectors are symmetrically arranged with respect to the first reference plane.

[0009] In a second aspect, the present invention also provides a spectral responsivity calibration apparatus, comprising: Laser light source, used to emit laser beams of different wavelengths; A displacement stage is used to set the integrating sphere detector as described above, so as to drive the integrating sphere detector to switch between a first position and a second position. A pyroelectric power meter, wherein the pyroelectric power meter is disposed on one side of the displacement stage; A current detection component, wherein the current detection component and the photodetector are electrically connected; When the integrating sphere detector is in the first position, the laser beam emitted by the laser source illuminates the pyroelectric power meter, and the pyroelectric power meter detects the optical radiation power of the laser beam; When the integrating sphere detector is in the second position, the laser beam emitted by the laser source illuminates the light inlet of the integrating sphere detector, and the current detection component detects the current of the photodetector.

[0010] According to the present invention, a spectral responsivity calibration device is provided, wherein the laser source includes: a tunable laser, a power stabilizer, and an aperture; the tunable laser, the power stabilizer, and the aperture are arranged sequentially along the transmission direction of the laser beam.

[0011] According to the spectral responsivity calibration device provided by the present invention, the laser source further includes: at least one first reflector and at least one second reflector; At least one of the first reflectors is disposed between the tunable laser and the power stabilizer for reflecting the laser beam emitted by the tunable laser to the power stabilizer; At least one of the second reflectors is disposed between the power stabilizer and the aperture to reflect the laser beam output by the power stabilizer to the aperture.

[0012] According to the spectral responsivity calibration device provided by the present invention, the current detection component includes: a transimpedance amplifier and a voltmeter; The transimpedance amplifier is electrically connected to the photodetector to convert the current signal of the photodetector into a voltage signal; The voltmeter is electrically connected to the transimpedance amplifier to collect the voltage signal generated on the transimpedance amplifier.

[0013] According to the spectral responsivity calibration device provided by the present invention, a chopper is further included, wherein the chopper is disposed between the displacement stage and the pyroelectric power meter, and is used to modulate the laser beam emitted by the laser source into a pulsed laser.

[0014] In a third aspect, the present invention also provides a calibration method for the spectral responsivity calibration device as described above, comprising: The displacement stage is controlled to move to the first position so that the laser beam emitted by the laser source illuminates the pyroelectric power meter, and the optical radiation power detected by the pyroelectric power meter is obtained; The displacement stage is controlled to move to the second position so that the laser beam emitted by the laser source illuminates the light inlet of the integrating sphere detector, and the current detected by the current detection component is obtained. The spectral responsivity of the integrating sphere detector is calculated based on the current detected by the current detection component and the optical radiation power detected by the pyroelectric power meter. The laser source is configured to emit laser beams of different wavelengths.

[0015] This invention provides an integrating sphere detector, a spectral responsivity calibration device, and a calibration method. By configuring the integrating sphere detector with a hollow sphere and multiple photodetectors, the incident direction of the light beam passing through the inlet is deflected from the center of the sphere. This increases the number of reflections of the incident light beam by the diffuse reflection coating, preventing the light beam incident at the center of the sphere from being directly reflected from the outlet, thus avoiding significant light loss. Since each outlet is uniformly distributed on a second reference surface opposite to the inlet of the third reference surface, by incidenting the light beam onto the inner wall of the second reference surface opposite to the inlet, direct illumination of the incident light beam to the photodetectors located at each outlet can be avoided. This design ensures that the incident beam, after being reflected once by the diffuse reflection coating, is not directly received by the photodetector. Instead, it undergoes multiple diffuse reflections before being received by the photodetector. This ensures that the light within the spherical cavity tends to be spatially uniform, while also covering a wider range of reflected light based on multiple photodetectors at different positions. This expands the detection range of reflected light and significantly reduces the non-uniformity caused by "insufficient sampling of local light." In principle, this optimizes the comprehensiveness of light field detection. Compared to the traditional integrating sphere detector design using baffles, this design is not only simpler in structure but also effectively improves the uniformity of the integrating sphere detector. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a cross-sectional structural schematic diagram of the integrating sphere detector provided by the present invention.

[0018] Figure 2 This is a schematic diagram showing the curves illustrating the uniformity of the integrating sphere detector based on two photodetectors and one photodetector, as a function of the incident angle of the light beam, provided by the present invention.

[0019] Figure 3 This is a three-dimensional simulation diagram of the uniformity of an integrating sphere detector based on a photodetector provided by the present invention.

[0020] Figure 4 This is a three-dimensional simulation diagram of the uniformity of an integrating sphere detector based on two photodetectors provided by the present invention.

[0021] Figure 5 This is a schematic diagram of the spectral response calibration device provided by the present invention.

[0022] Figure 6This is a schematic flowchart of the calibration method for the spectral response calibration device provided by the present invention.

[0023] Figure label: 1. Integrating sphere detector; 11. Hollow sphere; 111. Spherical cavity; 112. Light inlet; 113. Light outlet; 1101. Diffuse reflection coating; 12. Photodetector; 2. Laser source; 21. Tunable laser; 22. Power stabilizer; 23. Aperture; 24. First reflecting mirror; 25. Second reflecting mirror; 3. Displacement stage; 4. Pyroelectric power meter; 5. Chopper; 6. Current sensing component; 61. Transimpedance amplifier; 62. Voltmeter. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] The following is combined Figures 1 to 6 The present invention describes the integrating sphere detector, spectral responsivity calibration device, and calibration method.

[0026] In the first aspect, such as Figure 1 As shown, an embodiment of the present invention provides an integrating sphere detector 1, comprising: a hollow sphere 11 and a plurality of photodetectors 12; The hollow sphere 11 has a spherical cavity 111, a light inlet 112 communicating with the spherical cavity 111, and multiple light outlets 113. The inner wall of the spherical cavity 111 is provided with a diffuse reflection coating 1101. The light inlet 112 is located on one side of a first reference surface J1 passing through the center o of the sphere 111. The multiple light outlets 113 are evenly distributed along the circumference on a second reference surface J2. The second reference surface J2 is parallel to the side of a third reference surface J3 passing through the center o that is away from the light inlet 112. The third reference surface J3 is perpendicular to the first reference surface J1. Multiple photodetectors 12 are connected in parallel and are respectively arranged opposite to the multiple light outlets 113. The light beam is incident into the spherical cavity 111 through the light inlet 112, and then reflected in the spherical cavity 111 by the diffuse reflection coating 1101. The incident direction of the light beam is deviated from the center of the sphere o, and the light beam is configured to be incident on the inner wall of the spherical cavity 111 on the side of the second reference surface J2 away from the light inlet 112.

[0027] Understandably, the diameter of the hollow sphere 11 can be 45-55mm, and the hollow sphere 11 can be made of metal materials, such as anodized aluminum, brass, or stainless steel.

[0028] The diffuse reflection coating 1101 is used to diffusely reflect the light beam incident into the spherical cavity 111 through the light inlet 112, so as to reduce the light loss when the light beam is reflected in the spherical cavity 111; wherein, the reflectivity of the diffuse reflection coating 1101 to the light beam is not less than 98%, for example, the reflectivity of the diffuse reflection coating 1101 to the light beam reaches 98%-99.5%, and the material of the diffuse reflection coating 1101 can be barium sulfate, ceramic or polytetrafluoroethylene, etc., without specific limitation.

[0029] like Figure 1 As shown, the light inlet 112 and each light outlet 113 are opened on the shell wall of the hollow sphere 11. The diameter of the light inlet 112 is larger than the diameter of each light outlet 113. The diameter of the light outlet 113 is adapted to the diameter of the photodetector 12. The diameter of the light inlet 112 can be 4.5-5.5mm. The multiple light outlets 113 are evenly distributed in a circle relative to the axis passing through the center of the sphere o and the third reference plane J3.

[0030] The first reference plane J1 can be a horizontal reference plane, the third reference plane J3 can be a vertical reference plane, and the distance between the second reference plane J2 and the third reference plane J3 can be 30%-60% of the radius of the hollow sphere 11.

[0031] The formula for calculating the uniformity U of integrating sphere detector 1 is as follows: U = 1 - σ / µ; Where µ is the average value of the optical signal received when the beam is incident on different positions of the photodetector 12, and σ is the standard deviation of the optical signal received when the beam is incident on different positions of the photodetector 12.

[0032] like Figure 1 As shown, the incident angle of the beam is represented by the angle α between the incident direction of the beam and the line connecting the light inlet 112 and the center of the sphere. The light inlet 112 of the integrating sphere detector 1 is scanned by moving the position of the light source. The photosensitive area of ​​the scan can be 5 mm. As the position of the light source changes, the position where different beams first contact the inner wall of the spherical cavity 111 is different. Different beams are parallel to each other, and the light flux absorbed by the detector surface under different incident conditions can be obtained. The uniformity of the integrating sphere detector 1 under the incident angle can be obtained by calculation.

[0033] In practical applications, by setting the incident direction of the beam to deviate from the center of the sphere, the number of times the incident beam is reflected by the diffuse reflection coating 1101 can be increased, and the beam incident through the center of the sphere can be prevented from being directly reflected out of the light outlet 113, which would result in greater light loss.

[0034] Meanwhile, since each light exit port 113 is uniformly distributed on the second reference plane J2 on the side of the third reference plane J3 away from the light inlet port 112, by configuring the light beam to be incident on the inner wall of the spherical cavity 111 on the side of the second reference plane J2 away from the light inlet port 112, it can both prevent the incident light beam from directly irradiating the photodetector 12 located at each light exit port 113, and ensure that the light beam reflected by the diffuse reflection coating 1101 is not directly received by the photodetector 12, but is received by the photodetector 12 after multiple diffuse reflections by the diffuse reflection coating 1101. This design ensures that the light in the spherical cavity 111 tends to be spatially uniform, and can also cover a wider range of reflected light based on multiple photodetectors 12 at different positions, thus expanding the detection range of reflected light. For example, it ensures that the light in multiple regions such as "top-side-bottom" in the integrating sphere can be effectively detected, greatly reducing the non-uniformity caused by "insufficient sampling of local light", and optimizing the comprehensiveness of light field detection in principle, thereby improving the uniformity of the integrating sphere detector 1.

[0035] In some embodiments, such as Figure 1 As shown, the angle α between the incident direction of the light beam and the line connecting the light inlet 112 and the center of the sphere is 0° to 25°; exemplaryly, the angle α can further be 10° to 25°, for example, the angle α is specifically 10°, 15°, 20°, 25° and other suitable angles. Wherein, since the incident direction of the light beam deviates from the center of the sphere o, the angle α is greater than 0°.

[0036] In some embodiments, such as Figure 1 As shown, the angle β between the line connecting the light outlet 113 and the center of the sphere and the third reference plane is 10° to 30°. For example, the angle β is specifically 10°, 15°, 20°, 25°, 30° and other suitable angles.

[0037] It should be noted that the uniformity of the integrating sphere detector 1 is optimal when the included angle α is 15° and the included angle β is 20°.

[0038] The following is combined Figures 2 to 4 The uniformity of the integrating sphere detector shown in the embodiments of the present invention will be described in detail below. Figure 2 This is a schematic diagram showing the uniformity of the integrating sphere detector based on two photodetectors and one photodetector as a function of the incident angle α of the light beam, provided by the present invention. Figure 3 This is a three-dimensional simulation diagram of the uniformity of an integrating sphere detector based on a photodetector provided by the present invention. Figure 4 This is a three-dimensional simulation diagram of the uniformity of an integrating sphere detector based on two photodetectors provided by the present invention.

[0039] like Figure 1 and Figure 2 It can be seen that for integrating sphere detectors with either photodetector 1 or photodetector 2 configured alone, the uniformity of these two types of integrating sphere detectors does not exhibit a clear regularity with the change of the incident angle α. In some cases, when the uniformity of the integrating sphere detector based on photodetector 1 increases with the increase of the incident angle α, the uniformity of the integrating sphere detector based on photodetector 2 decreases with the increase of the incident angle α; the uniformity of the two types changes in opposite directions with the change of the incident angle α.

[0040] Within the range of 0° to 25° of the incident angle α of the beam, the uniformity of the integrating sphere detector based on a single photodetector is between 99% and 99.6%, that is, the minimum non-uniformity of the integrating sphere detector based on a single photodetector is 0.4% and the maximum non-uniformity is 1%.

[0041] like Figure 2 As shown, the integrating sphere detector 1 of this invention is configured with two photodetectors (i.e., photodetector 1 and photodetector 2). When the incident angle α of the light beam increases, the uniformity of the integrating sphere detector with two photodetectors is significantly improved compared to that with a single photodetector, reaching 99.6%-99.9%. Compared to the non-uniformity of 0.4%-1% for an integrating sphere detector with a single photodetector, the non-uniformity of the integrating sphere detector with two photodetectors is reduced to 0.1%-0.4%.

[0042] like Figure 2 As shown, for an integrating sphere detector based on two photodetectors, when the incident angle α of the beam is 0°, the spatial uniformity of integrating sphere detector 1 is poor. At this time, the beam is incident perpendicularly to the center of the integrating sphere. This perpendicular incident causes most of the beam to reflect back along its original path after the first contact with the inner wall of the integrating sphere, thus escaping outside the integrating sphere. This significantly reduces the number of rays actually participating in diffuse reflection within the integrating sphere. Therefore, the uniformity of integrating sphere detector 1 is poor when the beam is incident perpendicularly to the center of the sphere. When the incident angle α is gradually increased in 2.5° intervals, it can be seen that the uniformity of integrating sphere detector 1 does not change significantly within the range of incident angle α from 0° to 5°. This is because a large portion of the incident beam still escapes directly from the integrating sphere through the light inlet 112 after the first reflection, which does not significantly improve the uniformity of integrating sphere detector 1.

[0043] However, when the incident angle α increases to 10°, according to Figure 2It is evident that the uniformity of integrating sphere detector 1 exhibits a clear increasing trend. When the incident angle α increases to 15°, the uniformity of integrating sphere detector 1 reaches its optimal level (99.9%). However, when the incident angle α increases to above 25°, the uniformity of integrating sphere detector 1 shows a decreasing trend. This indicates that changing the incident angle α can reduce the escape of reflected light within the integrating sphere, thus helping to improve the uniformity of integrating sphere detector 1. Specifically, when the incident angle α is within the range of 10° to 25°, the integrating sphere detector based on two photodetectors exhibits relatively good uniformity.

[0044] like Figure 3 As shown in the figure, according to the three-dimensional simulation diagram of the uniformity of the integrating sphere detector based on a single photodetector, the center of the sensitive surface of the integrating sphere detector 1 is approximately a circular area with a diameter of 5 mm. The horizontal coordinate of the center of the sensitive surface is X = 7.71 mm, and the vertical coordinate of the center of the sensitive surface is Y = 4.82 mm. The non-uniformity of the integrating sphere detector 1 in the sensitive surface area is approximately 0.4%.

[0045] like Figure 4 As shown in the three-dimensional simulation diagram of the uniformity of the integrating sphere detector based on two photodetectors, the center of the sensitive surface of the integrating sphere detector 1 is approximately a circular area with a diameter of 5 mm. The horizontal coordinate of the center of the sensitive surface is approximately X = 7.5 mm, and the vertical coordinate is approximately Y = 7.5 mm. The non-uniformity of the integrating sphere detector 1 in the sensitive surface area is approximately 0.2%. Compared to the non-uniformity of 0.4% for an integrating sphere detector based on a single photodetector, the non-uniformity of the integrating sphere detector based on two photodetectors shown in this embodiment is significantly reduced, which also verifies the reliability of the integrating sphere detector design structure shown in this embodiment.

[0046] In some embodiments, such as Figure 1 As shown, the photodetector 12 of this invention can be an extended indium gallium arsenide photodiode. Specifically, the integrating sphere detector 1 can be configured with two photodetectors 12, which are symmetrically arranged with respect to the first reference plane J1. Both photodetectors 12 can be extended indium gallium arsenide photodiodes.

[0047] In related technologies, the spectral responsivity calibration of photodetectors is of great significance for their wide application. However, in the near-infrared band, especially for photodetectors in the (1600~2300) nm band, such as extended indium gallium arsenide photodiodes, the small photosensitive area (Φ≤3mm) and non-uniform response of extended indium gallium arsenide photodiodes make it impossible to perform high-precision spectral responsivity calibration.

[0048] However, based on the above embodiments, it can be seen that when each photodetector 12 of the integrating sphere detector 1 adopts an extended indium gallium arsenide photodiode, the design of the light inlet 112, the light outlet 113, and the incident angle of the beam based on the integrating sphere ensures that the overall light receiving area of ​​the integrating sphere detector 1 is increased, while also significantly improving the overall uniformity and responsivity of the integrating sphere detector 1. Thus, the integrating sphere detector 1 shown in this invention can be used to accurately calibrate the spectral responsivity of 1200-2300nm.

[0049] In the second aspect, such as Figure 5 As shown, this embodiment of the invention also provides a spectral responsivity calibration device, including: a laser source 2, a displacement stage 3, a pyroelectric power meter 4, and a current detection component 6; Laser source 2 is used to emit laser beams of different wavelengths; displacement stage 3 is used to set the integrating sphere detector 1 as described above, so as to drive the integrating sphere detector 1 to switch between the first position and the second position; pyroelectric power meter 4 is set on one side of displacement stage 3; current detection component 6 and photodetector 12 are electrically connected. When the integrating sphere detector 1 is in the first position, the laser beam emitted by the laser source 2 illuminates the pyroelectric power meter 4, and the pyroelectric power meter 4 detects the optical radiation power of the laser beam. When the integrating sphere detector 1 is in the second position, the laser beam emitted by the laser source 2 illuminates the light inlet 112 of the integrating sphere detector 1, and the current detection component 6 detects the current of the photodetector 12.

[0050] Understandably, the laser source 2 is used to emit laser beams with wavelengths of 1200-2300nm. The laser source 2 can be controlled to emit laser beams of different wavelengths according to a preset wavelength interval (e.g., 50nm) in order to calibrate the spectral responsivity of the integrating sphere detector 1 based on the extended indium gallium arsenide photodiode.

[0051] For example, such as Figure 5 As shown, the laser source 2 includes a tunable laser 21, a power stabilizer 22, and an aperture 23; the tunable laser 21, the power stabilizer 22, and the aperture 23 are arranged sequentially along the transmission direction of the laser beam.

[0052] It is understandable that the tunable laser 21 is also called a parametric oscillating tunable laser (OPO laser for short). Based on the tunable laser 21, laser beams of different wavelengths can be output.

[0053] In practical applications, after the laser beam output by the tunable laser 21 reaches the power stabilizer 22, the optical power is continuously and stably output through the power stabilizer 22 to improve the accuracy of the measurement results. Then, the laser beam output by the power stabilizer 22 is output through the aperture 23; wherein, the aperture 23 is used to filter stray light around the laser beam to improve the quality of the laser beam.

[0054] In some embodiments, such as Figure 5 As shown, the laser source 2 further includes: at least one first reflector 24 and at least one second reflector 25; At least one first reflector 24 is disposed between the tunable laser 21 and the power stabilizer 22 for reflecting the laser beam emitted by the tunable laser 21 to the power stabilizer 22; wherein, one first reflector 24 may be provided, for example Figure 5 M1 in the diagram represents the first reflecting mirror 24; At least one second reflector 25 is disposed between the power stabilizer 22 and the aperture 23 to reflect the laser beam output from the power stabilizer 22 to the aperture 23; wherein, two second reflectors 25 may be provided, for example Figure 5 M2 and M3 in the diagram represent the second reflector 25, respectively. The laser beam output by the power stabilizer 22 is reflected by M3 and M2 in sequence before reaching the aperture 23.

[0055] In practical applications, the displacement stage 3 can adopt a movable platform structure driven by a linear motor module. When the displacement stage 3 drives the integrating sphere detector 1 to move to the first position, it can ensure that the integrating sphere detector 1 leaves the optical path between the laser source 2 and the pyroelectric power meter 4, and ensure that the laser beam emitted by the laser source 2 directly illuminates the pyroelectric power meter 4 so that the pyroelectric power meter 4 can collect the optical radiation power of the laser beam in the current band.

[0056] Correspondingly, when the displacement stage 3 drives the integrating sphere detector 1 to move to the second position, it can be ensured that the integrating sphere detector 1 is in the optical path between the laser source 2 and the pyroelectric power meter 4. The laser beam emitted by the laser source 2 will not irradiate the pyroelectric power meter 4, but will enter the spherical cavity 111 through the light inlet 112 of the integrating sphere detector 1. After multiple diffuse reflections by the diffuse reflection coating 1101 set on the inner wall of the spherical cavity 111, it will be received by the photodetectors 12 set at each light outlet 113. Each parallel photodetector 12 converts the received optical signal into an electrical signal. At this time, the current of the photodetector 12 can be detected based on the current detection component 6.

[0057] Spectral responsivity of integrating sphere detector 1 R (λ0)= I (λ0) / P (λ0); where,I (λ0) is the current signal detected by the current detection component 6. P (λ0) represents the optical radiation power of the incident laser beam.

[0058] In some embodiments, such as Figure 5 As shown, the current detection component 6 includes: a transimpedance amplifier 61 and a voltmeter 62; the transimpedance amplifier 61 is electrically connected to the photodetector 12 to convert the current signal of the photodetector 12 into a voltage signal; the voltmeter 62 is electrically connected to the transimpedance amplifier 61 to collect the voltage signal formed on the transimpedance amplifier 61.

[0059] It is understood that the transimpedance amplifier 61 is a current-voltage amplifier known in the art, and the voltmeter 62 can be a digital voltmeter known in the art.

[0060] Considering that when photodetector 12 receives light, it will generate photogenerated carriers accordingly, producing a weak current at the microampere or even nanoampere level, which is difficult to detect by ordinary multimeters or ammeters, a transimpedance amplifier 61 is used to amplify the current signal of photodetector 12 and convert it into a voltage signal that can be recognized by voltmeter 62. Then, voltmeter 62 is used to collect the voltage signal generated on transimpedance amplifier 61.

[0061] Obviously, based on the voltage signal collected by voltmeter 62 and combined with the resistance information of transimpedance amplifier 61, the current of photodetector 12 can be obtained.

[0062] In some embodiments, such as Figure 5 As shown, the spectral responsivity calibration device also includes a chopper 5, which is disposed between the displacement stage 3 and the pyroelectric power meter 4, and is used to modulate the laser beam emitted by the laser source 2 into a pulsed laser.

[0063] Understandably, a chopper is a device that periodically blocks / transmits a beam of light, used to convert a continuous optical signal into a frequency-modulated pulsed optical signal.

[0064] In practical applications, when the integrating sphere detector 1 moves out of the optical path, the laser beam is modulated by the chopper 5 and then incident on the pyroelectric power meter. During this process, the chopper 5 modulates the continuous laser beam into a pulsed laser. The pyroelectric power meter 4 receives the frequency-modulated pulsed laser signal. Subsequently, the pulsed laser can be amplified and acquired through synchronous detection technology (such as a lock-in amplifier), which greatly suppresses low-frequency noise such as ambient stray light, thereby improving the accuracy of power measurement.

[0065] In the third aspect, such as Figure 6As shown, this embodiment of the invention also provides a calibration method for the spectral responsivity calibration device described above, comprising the following steps: Step S610: Control the displacement stage to move to the first position so that the laser beam emitted by the laser source illuminates the pyroelectric power meter and obtains the optical radiation power detected by the pyroelectric power meter. Step S620: Control the displacement stage to move to the second position so that the laser beam emitted by the laser source illuminates the light inlet of the integrating sphere detector and obtains the current detected by the current detection component. Step S630: Calculate the spectral responsivity of the integrating sphere detector based on the current detected by the current detection component and the optical radiation power detected by the pyroelectric power meter. The laser source is configured to emit laser beams of different wavelengths.

[0066] It is understandable that the laser source, displacement stage, pyroelectric power meter, and current detection component are electrically connected to the controller, and the controller is electrically connected to the human-machine interface module (e.g., touch screen). The testing personnel can input control commands through the human-machine interface module, and the controller controls the working state of the laser source and displacement stage according to the control commands. For example, the controller can control the laser source to output laser beams of different wavelengths according to the control commands, and the controller can control the displacement stage to move between the first position and the second position according to the control commands.

[0067] In a calibration test, the spectral responsivity of the integrating sphere detector can be tested based on a laser beam of a specific wavelength (e.g., the wavelength of the laser beam is λ0) according to steps S610 to S630. The specific operation is as follows: When the integrating sphere detector moves out of the optical path via the displacement stage, the laser beam emitted by the laser source passes through a chopper and is incident on the pyroelectric power meter. The optical radiation power of the currently incident laser beam can be obtained by the pyroelectric power meter. P (λ0); When the integrating sphere detector is moved into the optical path by the displacement stage, the laser beam emitted by the laser source is incident on the integrating sphere detector. After multiple diffuse reflections within the spherical cavity of the integrating sphere detector, the light signal is uniformly distributed and then absorbed by each photodetector to complete the conversion from light signal to electrical signal. The electrical signal is then amplified by a transimpedance amplifier, and a voltmeter is used to read the data. Based on the voltage signal collected by the voltmeter and the resistance information of the transimpedance amplifier, the current of the photodetector can be obtained. I (λ0), spectral responsivity formula R (λ0)= I (λ0) / P (λ0) can be used to obtain the spectral responsivity of the integrating sphere detector in the λ0 band.

[0068] After the spectral responsivity test of the integrating sphere detector is completed using a laser beam in a specific wavelength band, the laser source can be controlled to output laser beams of different wavelengths according to a preset interval wavelength (e.g., 50 nm). Steps S610 to S630 can be repeated to obtain the spectral responsivity of the integrating sphere detector in each wavelength band. This allows for convenient calibration of the spectral responsivity of the integrating sphere detector in the 1200-2300 nm range.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integrating sphere detector, characterized in that, include: A hollow sphere has a spherical cavity and a light inlet and multiple light outlets communicating with the spherical cavity. The inner wall of the spherical cavity is provided with a diffuse reflection coating. The light inlet is located on one side of a first reference surface passing through the center of the sphere. The multiple light outlets are evenly distributed along the circumference on a second reference surface. The second reference surface is parallel to a third reference surface passing through the center of the sphere on the side opposite to the light inlet. The third reference surface is perpendicular to the first reference surface. Multiple photodetectors are connected in parallel and are respectively arranged opposite to the multiple light output ports; The light beam enters the spherical cavity through the light inlet and is then reflected by the diffuse reflection coating within the spherical cavity. The incident direction of the light beam is deviated from the center of the sphere, and the light beam is configured to enter the inner wall of the spherical cavity on the side of the second reference surface opposite to the light inlet.

2. The integrating sphere detector of claim 1, wherein, The angle between the incident direction of the light beam and the line connecting the light inlet and the center of the sphere is 0° to 25°, and the angle between the line connecting the light outlet and the center of the sphere and the third reference plane is 10° to 30°.

3. The integrating sphere detector of claim 1, wherein, The diffuse reflective coating has a reflectivity of not less than 98% for the light beam.

4. The integrating sphere detector according to any one of claims 1 to 3, characterized in that The photodetector is an extended indium gallium arsenide photodiode; And / or, the photodetector is provided in two, and the two photodetectors are symmetrically arranged with respect to the first reference plane.

5. A spectral responsivity calibration apparatus, characterized by, include: Laser light source, used to emit laser beams of different wavelengths; A displacement stage is used to set the integrating sphere detector as described in any one of claims 1 to 4, so as to drive the integrating sphere detector to switch between a first position and a second position; A pyroelectric power meter, wherein the pyroelectric power meter is disposed on one side of the displacement stage; A current detection component, wherein the current detection component and the photodetector are electrically connected; When the integrating sphere detector is in the first position, the laser beam emitted by the laser source illuminates the pyroelectric power meter, and the pyroelectric power meter detects the optical radiation power of the laser beam; When the integrating sphere detector is in the second position, the laser beam emitted by the laser source illuminates the light inlet of the integrating sphere detector, and the current detection component detects the current of the photodetector.

6. The spectral responsivity calibration apparatus of claim 5, wherein, The laser source includes a tunable laser, a power stabilizer, and an aperture; the tunable laser, the power stabilizer, and the aperture are arranged sequentially along the transmission direction of the laser beam.

7. The spectral responsivity calibration device according to claim 6, characterized in that, The laser source further includes: at least one first reflector and at least one second reflector; At least one of the first reflectors is disposed between the tunable laser and the power stabilizer for reflecting the laser beam emitted by the tunable laser to the power stabilizer; At least one of the second reflectors is disposed between the power stabilizer and the aperture to reflect the laser beam output by the power stabilizer to the aperture.

8. The spectral responsivity calibration device according to claim 5, characterized in that, The current detection component includes: a transimpedance amplifier and a voltmeter; The transimpedance amplifier is electrically connected to the photodetector to convert the current signal of the photodetector into a voltage signal; The voltmeter is electrically connected to the transimpedance amplifier to collect the voltage signal generated on the transimpedance amplifier.

9. The spectral responsivity calibration apparatus according to any one of claims 5 to 8, characterized in that, Also includes: A chopper, disposed between the displacement stage and the pyroelectric power meter, is used to modulate the laser beam emitted by the laser source into a pulsed laser.

10. A calibration method for a spectral responsivity calibration device as described in any one of claims 5 to 9, characterized in that, include: The displacement stage is controlled to move to the first position so that the laser beam emitted by the laser source illuminates the pyroelectric power meter, and the optical radiation power detected by the pyroelectric power meter is obtained; The displacement stage is controlled to move to the second position so that the laser beam emitted by the laser source illuminates the light inlet of the integrating sphere detector, and the current detected by the current detection component is obtained. The spectral responsivity of the integrating sphere detector is calculated based on the current detected by the current detection component and the optical radiation power detected by the pyroelectric power meter. The laser source is configured to emit laser beams of different wavelengths.

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