High-precision weak light detection or communication test system and test method

Abstract

The invention discloses a high-precision weak light detection or communication test system, which comprises a laser power controller, a function generator, a transmitting end microcontroller, a shielding box, a source meter, an oscilloscope, a trans-impedance amplifier, a receiving end microcontroller and a computer, a laser light source, an attenuator, a standard device, a test device, a spectroscope, a screw rod, a first sliding table, a second sliding table and a stepping motor are arranged in the shielding box; the laser light source and the attenuator are fixed on the first sliding table, the spectroscope is fixed on the second sliding table, the first sliding table and the second sliding table are arranged on the lead screw, the lead screw is connected with the stepping motor, the attenuator and the stepping motor are connected with the transmitting end microcontroller, the standard device and the testing device are arranged on the side wall of the shielding box, and the attenuator is located between the laser light source and the spectroscope. The standard device is connected with the source meter, and the trans-impedance amplifier is connected with the receiving end microcontroller; the spectroscope is used for irradiating the laser beam on the test device and the standard device, and the shielding box is used for shielding electromagnetic interference and providing a darkroom environment.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic detection, and particularly to a high-precision low-light detection or communication test system and test method based on an optoelectronic detector. Background Art

[0002] The rapid development of information science and technology, especially artificial intelligence technology, is driving the acceleration of human society on the road to realizing an intelligent life. As an important bridge connecting the physical space and the bit space, optoelectronic detectors are showing vigorous vitality. At present, the application requirements of optoelectronic detectors in scenarios such as near-infrared detection, low-light detection, and high-speed communication are continuously increasing. In the related R & D fields, the accurate quantitative evaluation of the low-light detection performance and communication efficiency of optoelectronic devices has become a key technical indicator for measuring the progress of device R & D.

[0003] For an optoelectronic detector, the recognition accuracy of the minimum detectable optical power by the system directly determines the evaluation accuracy of the low-light detection ability of the device and the accuracy of the LDR (Linear Dynamic Range) test. Although existing test systems generally provide LDR test methods, most of them adopt an incident optical power control scheme that combines adjusting the laser source power with the attenuation of a filter. However, due to the discreteness of the filter models and the adjustment accuracy of the laser power, it is difficult to continuously adjust the incident optical power, resulting in the inability to accurately determine the minimum detectable optical power (i.e., the noise equivalent power) of the optoelectronic detector.

[0004] Currently, there is still a lack of standardized test procedures and quantitative evaluation indicators for the low-light detection ability and low-light communication ability of optoelectronic detectors. Most test systems are only limited to LDR map testing, with the problem of single indicators. Existing systems mostly use a uniform light field for testing and can only evaluate the low-light detection performance under ideal conditions. In actual application scenarios, low-light detection mainly focuses on point light source environments. In addition, existing systems cannot effectively simulate the real low-light communication process, and the obtained performance parameters are too idealized to effectively guide the application of optoelectronic detectors in actual scenarios. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects and deficiencies of the prior art and provide a high-precision low-light detection or communication test system and test method, which controls the distance between the laser light source and the test device to facilitate high-precision low-light detection or communication testing.

[0006] In order to achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0007] A high-precision low-light detection or communication test system, comprising a laser power controller, a function generator, a transmitting-end microcontroller, a shielding box, a source meter, an oscilloscope, a transimpedance amplifier, a receiving-end microcontroller, and a computer. Inside the shielding box, there are a laser light source, an attenuator, a standard device, a test device, a beam splitter, a lead screw, a first slide table, a second slide table, and a stepping motor;

[0008] The laser light source and the attenuator are fixed on the first slide table, the beam splitter is fixed on the second slide table, the first slide table and the second slide table are arranged on the lead screw, the lead screw is connected to the stepping motor, the attenuator and the stepping motor are connected to the transmitting-end microcontroller, the standard device and the test device are arranged on the side wall of the shielding box, the attenuator is located between the laser light source and the beam splitter, the standard device is connected to the source meter, and the transimpedance amplifier is connected to the receiving-end microcontroller;

[0009] The laser light source is used to emit a laser beam, the attenuator is used to attenuate the laser light intensity, the transmitting-end microcontroller is used to control the attenuator and the stepping motor, the beam splitter is used to split the laser beam and irradiate it on the test device and the standard device, the test device is used to perform low-light detection or communication tests, the standard device is used to calibrate and calculate the corresponding light intensity, the source meter is used to read the current of the standard device, and the shielding box is used to shield electromagnetic interference and provide a darkroom environment;

[0010] When performing a low-light detection test, the laser light source is connected to the laser power controller and the function generator, the test device is connected to the oscilloscope, the function generator is used to control the laser light source to emit an optical signal, the laser power controller is used to cooperate with the attenuator to attenuate the laser light intensity, the oscilloscope is used to capture the pulsed optical signal diagram under the corresponding light intensity, and the stepping motor is used to control the movement of the first slide table and the second slide table to control the distance between the laser light source and the test device to achieve light intensity control;

[0011] When performing a low-light communication test, the laser light source is connected to the transmitting-end microcontroller, the test device is connected to the transimpedance amplifier, the transmitting-end microcontroller and the receiving-end microcontroller are respectively connected to the computer, the transimpedance amplifier is used to convert the current change of the test device into a voltage change, the receiving-end microcontroller is used to detect the voltage change converted by the test device, and the computer is used to write programs for the transmitting-end microcontroller and the receiving-end microcontroller to achieve low-light communication tests.

[0012] Furthermore, the laser light source adopts a laser with TTL modulation function and has the following two control methods: one is to connect the function generator and the laser power controller to realize the conversion and emission of optical signals with specific waveforms; the other is to connect to the IO port of the transmitting-end microcontroller to support the control of the laser light source to emit optical signals in the OOK modulation mode.

[0013] Further, the standard device uses a silicon-based standard device, the beam splitter uses a 45-degree beam splitter, the standard device and the test device are respectively fixed to the side wall of the shielding box by a strong magnetic fixture, and the beam splitter is located between the test device and the attenuator;

[0014] The beam splitter is used to equally divide the attenuated laser beam into two laser beams with equal light intensities. One beam is irradiated on the test device along the direct light path, and the other beam is irradiated on the standard device along the reflected light path.

[0015] Further, the attenuator is internally provided with a combined filter, which is controlled by the microcontroller at the transmitting end to achieve a specific percentage of light intensity attenuation.

[0016] Further, the stepping motor is controlled by the microcontroller at the transmitting end, and the forward and backward movement of the first sliding table and the second sliding table is realized by the rotational movement of the lead screw, so as to accurately control the dynamic change of the distance between the laser light source and the test device. In cooperation with the laser power controller and the attenuator, by using the effect of light intensity attenuation with distance and combining the current data of the standard device feedback by the source meter in real time, the directional dynamic precision change of the weak light intensity is realized.

[0017] A high-precision weak light detection or communication test method is applied to the high-precision weak light detection or communication test system described in any one of the above, and includes the following steps:

[0018] S1: Control the distance between the laser light source and the test device through the laser power controller, the attenuator and the stepping motor, and realize the directional precision dynamic change of the weak light intensity with reference to the numerical change of the source meter connected to the standard device;

[0019] S2: Connect the test device to the source meter as well, synchronously read the current values of the standard device and the test device on the source meter, convert the current value of the standard device into light intensity, and obtain the linear dynamic range diagram of the test device;

[0020] S3: With reference to the linear dynamic range diagram of the test device, determine the range of the starting point of the linear dynamic range of the test device, conduct a weak light detection ability test, and obtain the relationship diagram between the pulse signal waveform and the light intensity near the starting point;

[0021] S4: According to the relationship diagram between the pulse signal waveform and the light intensity near the starting point, introduce an arbitrary waveform distortion evaluation index D T , compare the pulse signal waveforms received by the test device and modulated by the function generator, and obtain the relationship diagram between the waveform distortion D T and the light intensity;

[0022] S5: According to the light intensity in a specific light source scenario, calculate the corresponding limit detection distance based on the relationship between the light intensity and the distance, obtain the conversion diagram of the limit weak light detection distance of the test device in the specific light source scenario, and compare the weak light detection capabilities of different test devices;

[0023] S6: Conduct weak light communication tests. Based on the test results of weak light communication under different light intensities, provide a reference for the weak light detection or communication capabilities of the test device under the same light intensity in an actual scenario.

[0024] Furthermore, conduct weak light detection capability tests, specifically as follows:

[0025] Connect the function generator to the laser light source, output pulsed signal light through TTL modulation, and connect the test device to the oscilloscope.

[0026] Referring to the change in the current value of the standard device on the source meter, control the distance between the laser light source and the test device according to the light intensity at the starting point of the linear dynamic range of the test device, and achieve the dynamic change of the laser light intensity near the starting point.

[0027] Record the waveform diagram of the pulsed signal on the oscilloscope and the corresponding average current value of the source meter. Through data processing, convert the current value into light intensity to obtain the relationship diagram between the pulsed signal waveform and light intensity near the starting point.

[0028] Furthermore, conduct weak light communication tests, specifically as follows:

[0029] Connect the laser light source to the microcontroller at the transmitting end, and connect the test device to the microcontroller at the receiving end after passing through a transimpedance amplifier.

[0030] Burn the control program for weak light communication tests into the microcontrollers at the transmitting end and the receiving end respectively through a computer, and configure relevant test parameters to achieve weak light communication tests.

[0031] By adjusting the attenuator and the distance between the laser light source and the test device, achieve weak light communication tests under different light intensities near the starting point of the linear dynamic range or at the specified light intensity in a specific light source scenario.

[0032] Furthermore, the definition of the total distortion of an arbitrary waveform is: the ratio of the root mean square of the residual between the actual waveform of a periodic signal and its optimal expected waveform to the root mean square of the AC component of the optimal expected waveform. That is, for a known signal x(t) with a period of T, its actual waveform function is y(t), and there exist G, Q, t0 ∈ R, and

[0033] f(t) = G · x(t - t0) + Q

[0034] such that

[0035]

[0036] If

[0037]

[0038] then the total distortion D of y(t) with respect to its optimal expected waveformT Defined as

[0039] D T = ρ / f r

[0040] Wherein, t0 is the time delay between y(t) and x(t); G is the waveform (amplitude) scaling factor; Q is the waveform (amplitude) position offset; x(t) is the desired waveform; f(t) is the optimal desired waveform; is the mean value of the optimal desired waveform; f r is the effective value of the AC component of the optimal desired waveform; ρ is the effective value of the residual between y(t) and f(t), representing waveform distortion.

[0041] Furthermore, the light intensity and distance dependence are as follows:

[0042] For a point light source:

[0043]

[0044] Wherein, I is the light intensity at a distance r from the light source, and I0 is the light intensity of the light source when r = 0.

[0045] Compared with the prior art, the present invention can achieve the measurement of the high-precision LDR starting point for the weak light detection ability of a photodetector, and innovatively establish a test process and test indexes for the weak light detection ability, which can quantitatively describe the weak light detection ability of the photodetector. The present invention also integrally builds a weak light communication test system for the photodetector. By observing the performance of the photodetector in a simulated weak light communication scenario, the potential of the photodetector in an actual application scenario can be effectively evaluated, providing a scientific guiding basis for device research and development and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic structural diagram of the high-precision weak light detection or communication test system of the present invention.

[0047] Figure 2 is a schematic flow diagram of the high-precision weak light detection or communication test method of the present invention.

[0048] Figure 3 is a graph of the light intensity and distance attenuation relationship of the test device.

[0049] Figure 4 is an LDR graph of the test device.

[0050] Figure 5 is a graph of the pulse signal waveform and light intensity near the LDR starting point of the test device.

[0051] Figure 6 is the waveform distortion degree D of the test device TRelationship diagram with light intensity.

[0052] Explanation of the reference numerals in the attached drawings:

[0053] 1 - Laser power controller; 2 - Function generator; 3 - Transmitting end microcontroller; 4 - Shielding box; 5 - Source meter; 6 - Oscilloscope; 7 - Transimpedance amplifier; 8 - Receiving end microcontroller; 9 - Computer; 10 - Laser light source; 11 - Attenuator; 12 - Standard device; 13 - Test device; 14 - 45° beam splitter; 15 - Lead screw; 16 - First slide; 17 - Second slide; 18 - Stepper motor; 19 - Clamp sleeve. Specific implementation mode

[0054] The high-precision weak light detection or communication test system and test method of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0055] Please refer to Figure 1 , the present invention discloses a high-precision weak light detection or communication test system, including a laser power controller 1, a function generator 2, a transmitting end microcontroller 3, a shielding box 4, a source meter 5, an oscilloscope 6, a transimpedance amplifier 7, a receiving end microcontroller 8 and a computer 9. A laser light source 10, an attenuator 11, a standard device 12, a test device 13, a beam splitter 14, a lead screw 15, a first slide 16, a second slide 17 and a stepper motor 18 are arranged in the shielding box 4.

[0056] The laser light source 10 and the attenuator 11 are fixed on the first slide 16, the beam splitter 14 is fixed on the second slide 17, the first slide 16 and the second slide 17 are arranged on the lead screw 15, the lead screw 15 is connected to the stepper motor 18, and the attenuator 11 and the stepper motor 18 are connected to the transmitting end microcontroller 3. The standard device 12 and the test device 13 are arranged on the side wall of the shielding box 4, the attenuator 11 is located between the laser light source 10 and the beam splitter 14, the standard device 12 is connected to the source meter 5, and the transimpedance amplifier 7 is connected to the receiving end microcontroller 8.

[0057] The laser light source 10 is used to emit a laser beam, the attenuator 11 is used to attenuate the laser light intensity, and the transmitting end microcontroller 3 is used to control the attenuator 11 and the stepper motor 18. The beam splitter 14 is used to split the laser beam and irradiate it on the test device 13 and the standard device 12. The test device 13 is used for weak light detection or communication test, and the standard device 12 is used for calibration and calculation of the corresponding light intensity. The source meter 5 is used to read the current of the standard device 12, and the shielding box 4 is used to shield electromagnetic interference and provide a dark room environment. Clamp sleeves 19 are provided on both side walls of the shielding box 4, and the clamp sleeves 19 are used for wires to pass through the shielding box 4 for relevant hardware connections.

[0058] When performing low-light detection tests, the laser light source 10 is connected to the laser power controller 1 and the function generator 2, and the test device 13 is connected to the oscilloscope 6. The function generator 2 is used to control the laser light source 10 to emit optical signals. The laser power controller 1 is used to cooperate with the attenuator 11 to attenuate the laser light intensity. The oscilloscope 6 is used to capture the pulsed optical signal diagram corresponding to the light intensity. The stepper motor 18 is used to control the movement of the first slide 16 and the second slide 17, control the distance between the laser light source 10 and the test device 13, and achieve light intensity control.

[0059] When performing low-light communication tests, the laser light source 10 is connected to the microcontroller 3 at the transmitting end, the test device 13 is connected to the transimpedance amplifier 7, and the microcontroller 3 at the transmitting end and the microcontroller 8 at the receiving end are respectively connected to the computer 9. The transimpedance amplifier 7 is used to convert the current change of the test device 13 into a voltage change. The microcontroller 8 at the receiving end is used to detect the voltage change converted by the test device 13. The computer 9 is used to write programs for the microcontroller 3 at the transmitting end and the microcontroller 8 at the receiving end to implement low-light communication tests.

[0060] The laser light source uses a laser with TTL (Transistor-Transistor Logic) modulation function and adopts the following two control methods: one is to connect the function generator and the laser power controller to realize the conversion and emission of optical signals with specific waveforms; the other is to connect the IO port of the microcontroller at the transmitting end and support the method of OOK modulation to control the laser light source to emit optical signals.

[0061] The standard device uses a silicon-based standard device, the beam splitter uses a 45-degree beam splitter, and the standard device and the test device are respectively fixed to the side wall of the shielding box by strong magnetic clamps. The beam splitter is located between the test device and the attenuator. The beam splitter is used to equally divide the attenuated laser beam into two laser beams with equal light intensities. One beam keeps the direct light path and irradiates on the test device, and the other beam irradiates on the standard device according to the reflected light path.

[0062] In this embodiment, the attenuator is built-in with a combined filter and is controlled by the microcontroller at the transmitting end, which can automatically achieve a specific percentage of light intensity attenuation. Without manually combining the filter, the attenuator cooperates with the laser power controller to effectively attenuate the laser light intensity.

[0063] The stepper motor is controlled by the microcontroller at the transmitting end. The forward and backward movement of the first slide and the second slide is realized by the rotational movement of the lead screw, and the dynamic change of the distance between the laser light source and the test device is accurately controlled. In cooperation with the laser power controller and the attenuator, using the effect of light intensity attenuation with distance, combined with the current data of the standard device feedback by the source meter in real time, the directional dynamic precision change of the low-light intensity is realized.

[0064] The present invention provides a test process for the weak light detection ability when the test device is a photodetector, as well as test indicators for quantitatively describing the weak light detection ability of the test device. By combining and coordinating a laser power controller, an attenuator, and a stepper motor, utilizing the effect of light intensity attenuation with distance, and combining the source meter current data feedback of a standard device, the directional dynamic precision change of extremely weak light intensity can be achieved, thereby realizing the high-precision test of the weak light detection ability of the test device.

[0065] By gradually obtaining the LDR graph, the relationship graph between the pulse signal waveform and the light intensity, the relationship graph between the waveform distortion degree D T and the light intensity graph, the conversion graph of the limit weak light detection distance of the test device under a specified light source scenario, etc., can intuitively reflect the weak light detection ability of the test device, and innovate the test process and test indicators for the weak light detection of the test device.

[0066] On the basis of not changing the core system structure, the present invention integrates an integrated test system for the weak light communication of the test device, which can perform the weak light communication test of the test device under a specific weak light intensity, thereby providing a scientific guiding basis for the weak light communication potential of the test device under a specific light intensity in the actual application scenario.

[0067] The present invention uses a common laser light source with TTL modulation function on the market, which is more in line with the actual application scenario of the device. Moreover, it supports two control methods, namely, a function generator and a transmitter microcontroller. When performing the weak light communication test later, there is no need to replace the laser light source. Compared with the homogenized laser used in the prior art, the laser beam is more convergent, the cost is lower, and the degree of freedom of the optical path design and the system integration degree are higher. The whole set of system is applicable to the weak light detection ability test of the device and the weak light communication test of the integrated device, with low cost, simple structure, and low construction difficulty.

[0068] Please refer to Figure 2 , the present invention also discloses a high-precision weak light detection or communication test method, which is applied to the high-precision weak light detection or communication test system described in any one of the above, and includes the following steps:

[0069] S1: Control the distance between the laser light source and the test device through a laser power controller, an attenuator, and a stepper motor, and realize the directional precision dynamic change of the weak light intensity with reference to the numerical change of the source meter connected to the standard device;

[0070] S2: Connect the test device to the source meter as well, synchronously read the current values of the standard device and the test device on the source meter, convert the current value of the standard device into light intensity, and obtain the linear dynamic range graph of the test device;

[0071] S3: With reference to the linear dynamic range graph of the test device, determine the range of the starting point of the linear dynamic range of the test device, perform the weak light detection ability test, and obtain the relationship graph between the pulse signal waveform and the light intensity near the starting point;

[0072] S4: According to the relationship diagram of the pulse signal waveform near the starting point and the light intensity, introduce an evaluation index D for any waveform distortion T , compare the pulse signal waveforms received by the test device and modulated by the function generator, and obtain the waveform distortion D T and the relationship diagram with the light intensity;

[0073] S5: According to the light intensity in a specific light source scenario, calculate the corresponding limit detection distance based on the relationship between the light intensity and the distance, obtain the conversion diagram of the limit weak light detection distance of the test device in the specific light source scenario, and compare the weak light detection capabilities of different test devices;

[0074] S6: Conduct weak light communication tests, and provide a reference for the weak light detection or communication capabilities of the test device at the same light intensity in the actual scenario through the weak light communication test results at different light intensities.

[0075] Among them, for the weak light detection ability test, specifically:

[0076] Connect the function generator to the laser light source, output pulsed signal light through TTL modulation, and connect the test device to the oscilloscope;

[0077] Refer to the change in the current value of the standard device on the source meter, and control the distance between the laser light source and the test device according to the light intensity at the starting point of the linear dynamic range of the test device, so as to achieve the dynamic change of the laser light intensity near the starting point;

[0078] Record the oscilloscope pulse signal waveform diagram and the corresponding average source meter current value, convert the current value into light intensity through data processing, and obtain the relationship diagram of the pulse signal waveform near the starting point and the light intensity.

[0079] Among them, for the weak light communication test, specifically:

[0080] Connect the laser light source to the microcontroller at the transmitting end, and connect the test device to the microcontroller at the receiving end after passing through a transimpedance amplifier;

[0081] Burn the control program for weak light communication test into the microcontroller at the transmitting end and the microcontroller at the receiving end respectively through the computer, and configure relevant test parameters to achieve the weak light communication test;

[0082] By adjusting the attenuator and the distance between the laser light source and the test device, achieve weak light communication tests at different light intensities near the starting point of the linear dynamic range or at the specified light intensity in a specific light source scenario.

[0083] In this embodiment, the relevant specific test steps are as follows:

[0084] Step 1: Prepare the test device and the standard device. Open the shielding box and place the test device and the standard device on the corresponding fixtures. The test device is fixed at a designated position on the left side wall of the shielding box by a strong magnetic fixture, while the standard device is fixed on the rear wall of the shielding box by a strong magnetic fixture.

[0085] Step 2: Set up the LDR test environment. Connect the laser light source to the laser power controller and the test device to the 2nd port of the source meter. Here, it describes the part of the hardware connection that needs to be changed when performing weak light detection tests on the test device to obtain the LDR graph of the test device.

[0086] During the weak light detection test and weak light communication test of the device, the stepper motor is always connected to the microcontroller at the transmitting end. By controlling the rotation of the lead screw, the distance between the laser light source and the test device can be precisely controlled. The attenuator is also connected to the microcontroller at the transmitting end. The microcontroller at the transmitting end controls the internal moving joints of the attenuator, enabling the automatic combination of up to five filter plates on the same optical path, thereby achieving a percentage attenuation of the specified light intensity. A transimpedance amplifier that supports three feedback adjustment ranges of pA - nA - uA is connected to the microcontroller at the receiving end, which can realize the conversion from the small current change under extremely weak light intensity to the voltage change that can be read by the analog pin of the microcontroller at the receiving end. The standard device is always connected to the source meter and the current data is displayed in real time. The above hardware connection part remains unchanged throughout the test.

[0087] During the weak light detection test and weak light communication test of the device, the centers of the laser light source, the attenuator, the 45° beam splitter, the test device, and the standard device always remain at the same horizontal height to avoid introducing systematic errors caused by optical path deviation. The optical path difference between the test device and the standard device and the 45° beam splitter remains the same throughout. Therefore, after fixing the test device and the standard device, the position of the 45° beam splitter needs to be adjusted and fixed.

[0088] When the optical path difference is the same, when the laser beam from the laser light source after passing through the attenuator irradiates on the 45° beam splitter, it is equally divided into two laser beams with the same light intensity. This not only further equally divides the attenuated light intensity but also ensures that the light intensities irradiating on the test device and the standard device are equal. Thus, the light intensity can be converted and calibrated by reading the current of the standard device through the source meter. Compared with the existing test system, it can directly read and convert the light intensity under the same test conditions without repeating the condition calibration again, effectively eliminating systematic errors and accidental errors.

[0089] Through the current reading value of the standard device connected to the source meter, the magnitude and change direction of the light intensity can be reflected in real time, thereby providing information feedback for the directional dynamic high-precision regulation of the light intensity.

[0090] Step 3: By controlling the distance between the laser power controller, the laser light source and the test device, and referring to the source meter current value corresponding to the standard device, the directional dynamic precision change of the light intensity can be achieved, such as Figure 3 shown. By synchronously measuring the current values of the test device and the standard device, and converting the current value of the standard device into light intensity, a high-precision LDR graph of the test device can be obtained, such as Figure 4 shown.

[0091] The calculation formula of LDR (Linear Dynamic Range) is as follows:

[0092]

[0093] In the formula, Pmax and Pmin respectively refer to the maximum optical power and the minimum optical power in the linear range.

[0094] Step 4: Build a test environment for the relationship between the pulse waveform and the light intensity. Connect the laser light source to the function generator and the laser power controller, and output a pulsed square wave signal through TTL modulation. The test device is connected to the oscilloscope. Referring to the numerical change of the source meter connected to the standard device, according to the light intensity at the starting point in the high-precision LDR graph of the test device obtained above, by re-controlling the laser power controller, the attenuator, and the distance between the laser light source and the test device, the directional dynamic precision change of the laser light intensity from small to large near the starting point is realized. Use the oscilloscope to record the waveform of the oscilloscope pulse signal, and at the same time record the corresponding source meter current reading. Through subsequent data processing, the relationship graph between the pulse signal waveform and the light intensity near the starting point can be obtained, such as Figure 5 shown.

[0095] Step 5: Calculate the waveform distortion degree D T and the relationship graph with the light intensity. According to the relationship graph between the pulse signal waveform and the light intensity near the starting point, introduce an arbitrary waveform distortion evaluation index D T , by importing the waveform data of the pulse signal received by the test device and the original pulse signal waveform modulated by the function generator, the waveform distortion degree D T can be quantitatively calculated, and thus the relationship graph between the waveform distortion degree D T and the light intensity can be obtained, such as Figure 6 shown.

[0096] The definition of the total distortion degree of an arbitrary waveform is: the ratio of the effective value of the residual between the actual waveform of the periodic signal and its optimal expected waveform to the effective value of the AC component of the optimal expected waveform. That is, for a known signal x(t) with a period of T, its actual waveform function is y(t), there exist G, Q, t0 ∈ R, and

[0097] f(t) = G·x(t - t0) + Q

[0098] such that

[0099]

[0100] If

[0101]

[0102] then the total distortion D of y(t) relative to its optimal desired waveform T is defined as

[0103] D T = ρ / f r

[0104] where t0 is the time delay between y(t) and x(t); G is the waveform (amplitude) scale factor; Q is the waveform (amplitude) position offset; x(t) is the desired waveform; f(t) is the optimal desired waveform; is the mean value of the optimal desired waveform; f r is the effective value of the AC component of the optimal desired waveform; ρ is the effective value of the residual between y(t) and f(t), representing waveform distortion.

[0105] For different low-light detection scenario requirements, different thresholds of waveform distortion can be defined. And according to different thresholds of waveform distortion, the corresponding starting light intensity for low-light detection can be obtained, as Figure 5 shown. The relationship diagrams of the waveform distortion D T versus the light intensity for different test devices are not the same. Due to reducing test errors, in the actual application process, the relationship diagram of the waveform distortion D T averaged over multiple measurements should be used. The above-mentioned starting light intensity for low-light detection is applicable to a specific scenario and is determined by the tolerance of the specific scenario to signal distortion, and is not necessarily equal to the starting point light intensity of the LDR.

[0106] Step 6: Conversion diagram of the limit low-light detection distance of the detector under a specific light source scenario. According to the light intensity of the light source in a specific application scenario, the corresponding limit detection distance can be calculated based on the relationship between the light intensity and the distance, so as to effectively and intuitively quantify the low-light detection ability of the detector in a specific scenario and facilitate the comparison of the low-light detection abilities of different detectors.

[0107] For a point light source:

[0108]

[0109] where I is the light intensity at a distance r from the light source, and I0 is the light intensity of the light source at r = 0.

[0110] For an actual complex low-light detection scenario, due to the presence of the medium and the interference of ambient light, the attenuation relationship between light intensity and distance may not strictly follow the above formula. It may be necessary to fully consider the exponential relationship of Lambert-Beer's law. However, the theoretical limit of the low-light detection distance in the specific scenario of the device here is still converted based on this relationship.

[0111] Step 7: Low-light communication test. To effectively evaluate the application potential of the test device in an actual low-light detection scenario, an integrated low-light communication test is conducted. First, the laser light source is connected to the microcontroller at the transmitting end, and the original information is encoded into the laser light source signal through OOK (on-off keying) modulation. The test device is then connected to the microcontroller at the receiving end after passing through a transimpedance amplifier. The corresponding transmitting-end and receiving-end programs for low-light communication testing are burned into the two microcontrollers through a computer, and relevant parameters are configured to achieve the low-light communication test.

[0112] The entire low-light communication test process is as follows: First, the original information is transmitted to the microcontroller at the transmitting end through serial communication. The microcontroller at the transmitting end encodes the original information using a custom communication protocol similar to Morse code and controls the laser light source through OOK (on-off keying) modulation to convert the encoded information into an optical signal and transmit it. The specific waveform is similar to an irregular pulse signal. The optical signal passes through an attenuator and a stepper motor controlled by the microcontroller at the transmitting end, and with reference to the current value feedback of the standard device, it can achieve directional dynamic high-precision light intensity control.

[0113] At the set light intensity, the optical signal is detected by the test device, and then the small current change of the test device is connected to the microcontroller at the receiving end for detection through a transimpedance amplifier. After the microcontroller at the receiving end detects the corresponding voltage change, it decodes the signal according to the transmitting-end protocol and finally obtains the original information. For the low-light communication test system to successfully achieve communication demonstration, it not only requires the test device to perfectly capture the light intensity change signal but also requires relevant parameters to be configured in the microcontroller program at the receiving end.

[0114] The present invention can achieve low-light communication testing at different light intensities near the LDR starting point or at the light intensity specified for a specific application scenario by adjusting the attenuator and the distance between the laser light source and the test device. The low-light communication test results at different light intensities, including the original voltage change signal captured during communication, whether the communication is successful, the communication rate, the bit error rate, etc., can provide a scientific guiding basis for the low-light detection ability and communication ability of the test device at the same light intensity in an actual scenario.

[0115] The above description is a detailed description of the preferred feasible embodiment of the present invention. However, the embodiment is not intended to limit the patent application scope of the present invention. Any equivalent changes or modifications completed under the technical spirit disclosed by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A high-precision weak light detection or communication test system, characterized in that: It includes a laser power controller, a function generator, a transmitting end microcontroller, a shielding box, a source meter, an oscilloscope, a transimpedance amplifier, a receiving end microcontroller and a computer. The shielding box is provided with a laser light source, an attenuator, a standard device, a test device, a spectroscope, a lead screw, a first slide, a second slide and a stepping motor; The laser light source and the attenuator are fixed on the first slide, the spectroscope is fixed on the second slide, the first slide and the second slide are arranged on the lead screw, the lead screw is connected to the stepper motor, the attenuator and the stepper motor are connected to the transmitting end microcontroller, the standard device and the test device are arranged on the side wall of the shielding box, the attenuator is located between the laser light source and the spectroscope, the standard device is connected to the source meter, and the transimpedance amplifier is connected to the receiving end microcontroller; The laser light source is used to emit a laser beam, the attenuator is used to attenuate the laser light intensity, the transmitting end microcontroller is used to control the attenuator and the stepper motor, the spectroscope is used to split the laser beam and irradiate it on the test device and the standard device, the test device is used to perform weak light detection or communication testing, the standard device is used to calibrate and calculate the corresponding light intensity, the source meter is used to read the current of the standard device, and the shielding box is used to shield electromagnetic interference and provide a darkroom environment; When performing a weak light detection test, the laser light source is connected to the laser power controller and the function generator, and the test device is connected to the oscilloscope. The function generator is used to control the laser light source to emit an optical signal. The laser power controller is used to cooperate with the attenuator to attenuate the laser light intensity. The oscilloscope is used to capture the pulse light signal diagram under the corresponding light intensity. The stepper motor is used to control the movement of the first slide and the second slide, and control the distance between the laser light source and the test device to achieve light intensity control. When conducting a weak light communication test, the laser light source is connected to a transmitting microcontroller, the test device is connected to a transimpedance amplifier, the transmitting microcontroller and the receiving microcontroller are respectively connected to a computer, the transimpedance amplifier is used to convert the current change of the test device into a voltage change, the receiving microcontroller is used to detect the voltage change after the test device is converted, and the computer is used to write programs for the transmitting microcontroller and the receiving microcontroller to implement a weak light communication test.

2. The high-precision weak light detection or communication test system according to claim 1, characterized in that: The laser light source uses a laser with TTL modulation function and adopts the following two control methods: one is to connect the function generator and the laser power controller to realize the conversion and emission of optical signals with specific waveforms; the other is to connect to the IO port of the microcontroller at the transmitting end and support OOK modulation to control the laser light source to emit optical signals.

3. The high-precision weak light detection or communication test system according to claim 1, characterized in that: The standard device uses a silicon-based standard device, the spectroscope uses a 45-degree spectroscope, the standard device and the test device are fixed to the side wall of the shielding box by strong magnetic clamps, and the spectroscope is located between the test device and the attenuator; The beam splitter is used to split the attenuated laser beam into two laser beams with equal light intensity. One beam maintains a direct light path to irradiate the test device, and the other beam follows a reflected light path to irradiate the standard device.

4. The high-precision weak light detection or communication test system according to claim 1, characterized in that: The attenuator has a built-in combined filter, which is controlled by the microcontroller at the transmitting end to achieve a specific percentage of light intensity attenuation.

5. The high-precision weak light detection or communication test system according to claim 1, characterized in that: The stepper motor is controlled by the transmitting end microcontroller, and the rotational motion of the lead screw is used to realize the forward and backward movement of the first slide and the second slide, and the dynamic change of the distance between the laser light source and the test device is accurately controlled. In conjunction with the laser power controller and attenuator, the attenuation effect of light intensity with distance is utilized, combined with the current data of the standard device fed back by the source meter in real time, the directional dynamic precision change of weak light intensity is realized.

6. A high-precision weak light detection or communication test method, applied to the high-precision weak light detection or communication test system according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: The distance between the laser light source and the test device is controlled by a laser power controller, attenuator and stepper motor, and the value change of the source meter connected to the standard device is referred to to achieve directional and precise dynamic change of weak light intensity; S2: Connect the test device to the source meter, synchronously read the current values ​​of the standard device and the test device on the source meter, convert the current value of the standard device into light intensity, and obtain the linear dynamic range diagram of the test device; S3: referring to the linear dynamic range diagram of the test device, determining the range of the starting point of the linear dynamic range of the test device, performing a weak light detection capability test, and obtaining a pulse signal waveform and light intensity relationship diagram near the starting point; S4: Based on the relationship between the pulse signal waveform and light intensity near the starting point, the arbitrary waveform distortion evaluation index D is introduced T , compare the pulse signal waveform received by the test device and modulated by the function generator, and get the waveform distortion D T Relationship diagram with light intensity; S5: According to the light intensity in a specific light source scene, the corresponding limit detection distance is calculated based on the relationship between light intensity and distance, and a conversion chart of the limit weak light detection distance of the test device in a specific light source scene is obtained to compare the weak light detection capabilities of different test devices; S6: Conduct weak light communication test. Through the weak light communication test results under different light intensities, provide a reference for the weak light detection capability or communication capability of the test device under the same light intensity in actual scenes.

7. The high-precision weak light detection or communication test method according to claim 6, characterized in that: Conduct weak light detection capability test, specifically: Connect the function generator to the laser light source, output the pulse signal light through TTL modulation, and connect the test device to the oscilloscope; Referring to the current value change of the standard device on the source meter, according to the light intensity at the starting point of the linear dynamic range of the test device, the distance between the laser light source and the test device is controlled to achieve dynamic changes in the laser light intensity near the starting point; The oscilloscope pulse signal waveform and the corresponding average value of the source meter current are recorded, and the current value is converted into light intensity through data processing to obtain the relationship diagram between the pulse signal waveform and light intensity near the starting point.

8. The high-precision weak light detection or communication test method according to claim 6, characterized in that: Conduct weak light communication test, specifically: The laser light source is connected to the transmitting end microcontroller, and the test device is connected to the receiving end microcontroller after passing through the transimpedance amplifier; The control program for weak light communication test is burned into the transmitting end microcontroller and the receiving end microcontroller through a computer, and relevant test parameters are configured to realize the weak light communication test; By adjusting the distance between the attenuator and the laser light source and the test device, weak light communication testing at different light intensities near the starting point of the linear dynamic range or at specified light intensities in a specific light source scenario can be achieved.

9. The high-precision weak light detection or communication test method according to claim 6, characterized in that: The total distortion of an arbitrary waveform is defined as the ratio of the effective value of the residual between the actual waveform of a periodic signal and its optimal expected waveform to the effective value of the AC component of the optimal expected waveform. That is, for a known signal x(t) with a period of T, its actual waveform function is y(t), and there exist G, Q, t0∈R, and f(t)=G·x(t-t0)+Q Make like Then the total distortion of y(t) relative to its optimal expected waveform is D T Defined as D T =ρ / f r Where t0 is the time delay between y(t) and x(t); G is the waveform (amplitude) scale factor; Q is the waveform (amplitude) position offset; x(t) is the desired waveform; f(t) is the optimal desired waveform; is the mean value of the optimal expected waveform; f r is the effective value of the AC component of the optimal expected waveform; ρ is the effective value of the residual between y(t) and f(t), which describes the waveform distortion.

10. The high-precision weak light detection or communication test method according to claim 6, characterized in that: The dependence of light intensity on distance is as follows: For point light sources: Where I is the light intensity at a distance r from the light source, and I0 is the light intensity when the light source is at a distance r = 0.

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