Device and method for detecting dToF performance of a light source

Abstract

The application discloses a kind of DToF performance detection device and method of light source, wherein detection device includes: light source;Capacitor charging and discharging driving power supply, with light source electric connection, for power supply for light source, and with preset frequency driving light source light emitting;High-speed detector, in the light emission direction of light source, for detecting the light pulse signal of light source, and the light pulse signal that light source outputs is converted into electric pulse signal;Oscilloscope, for displaying voltage signal input light source;Also for displaying electric pulse signal;Optical power meter, in the light emission direction of light source, for detecting the average optical power of light source;Construction module, according to electric pulse signal, voltage signal and average optical power constructs optical power-current curve and power conversion efficiency-current curve, to detect the DToF performance of light source.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of laser, in particular to a kind of DToF performance detection device and method of light source. BACKGROUND

[0002] Time of Flight (ToF) technology, i.e. light source transmitter sends modulated near-infrared light, reflects after encountering object, sensor calculates time difference or phase difference of light emission and reflection, to convert the distance of the photographed scene, to produce depth information, in addition, combined with traditional camera shooting, can the three-dimensional profile of object be presented in different colors representing different distance topographic map, so it is widely used in 3D image acquisition and 3D sensing field. Time of flight technology has two types, namely indirect time of flight technology (Indirect Time of Flight, iTOF) and direct time of flight technology (Direct Time of Flight, dToF), iToF indirectly measures the time of flight of light by measuring phase shift, and DToF directly measures the time of flight of light.

[0003] Direct time of flight technology includes two different driving modes, respectively capacitive charging and discharging driving mode and transistor switch control driving mode, but its problem is that when driving light source by capacitive charging and discharging driving mode, due to unstable power supply signal and other factors, it is difficult to directly measure the performance of laser by measuring source table, such as driving current, signal pulse width, output optical power, energy conversion efficiency and other performance parameters cannot be directly obtained by measuring source table. In the process of product research and development and use, the performance of laser under the condition of capacitive charging and discharging driving needs to be accurately evaluated, so as to facilitate product performance iteration and give accurate performance specification, thus, the present application provides a kind of DToF performance detection device and method of light source. SUMMARY

[0004] The present application provides a kind of DToF performance detection device and method of light source, to realize in the process of product research and development and use, the performance of laser under the condition of capacitive charging and discharging driving can be accurately evaluated.

[0005] To achieve the above object, an embodiment of the present application provides a kind of DToF performance detection device of light source, comprising:

[0006] Light source

[0007] Capacitive charging and discharging driving power supply, electrically connected with the light source, for powering the light source, and driving the light source to emit light at a preset frequency

[0008] A high-speed detector is located in the light emission direction of the light source, used for detecting the light pulse signal of the light source and converting the light pulse signal output by the light source into an electric pulse signal;

[0009] An oscilloscope is electrically connected with the output end of the capacitor charging and discharging driving power supply, used for displaying the voltage signal input into the light source, and is also electrically connected with the output end of the high-speed detector, used for displaying the electric pulse signal;

[0010] A power meter is located in the light emission direction of the light source, used for detecting the average light power of the light source;

[0011] A construction module is used for constructing a light power-current curve and a power conversion efficiency-current curve according to the electric pulse signal, the voltage signal and the average light power.

[0012] Optionally, the capacitor charging and discharging driving power supply comprises a capacitor charging and discharging circuit, and the capacitor charging and discharging circuit comprises:

[0013] A charging resistor;

[0014] A charging and discharging capacitor;

[0015] A power supply, a negative electrode of the power supply is grounded, a positive electrode of the power supply is electrically connected with one end of the charging resistor, the other end of the charging resistor is electrically connected with one end of the charging and discharging capacitor, the other end of the charging and discharging capacitor is grounded, and the other end of the charging resistor and the connecting end of the charging and discharging capacitor are also electrically connected with one end of the light source.

[0016] Optionally, the capacitor charging and discharging driving power supply further comprises a capacitor charging and discharging driving circuit, and the capacitor charging and discharging driving circuit comprises:

[0017] A switch tube;

[0018] A switch tube driving circuit, one end of the switch tube driving circuit is grounded, the other end is electrically connected with the first end of the switch tube, the second end of the switch tube is grounded, and the third end of the switch tube is electrically connected with the other end of the light source.

[0019] To achieve the above object, another aspect of the present application provides a DToF performance detection method of a light source, which uses the DToF performance detection device of the light source as described above, and comprises the following steps:

[0020] Obtaining the electric pulse signal output by the high-speed detector, the voltage signal input into the light source and the average light power output by the power meter;

[0021] Constructing a light power-current curve and a power conversion efficiency-current curve according to the electric pulse signal, the voltage signal and the average light power.

[0022] Optionally, the constructing the optical power-current curve and the power conversion efficiency-current curve according to the electrical pulse signal, the voltage signal and the average optical power comprises:

[0023] constructing the optical power-current curve according to the peak current and the peak power;

[0024] constructing the power conversion efficiency-current curve according to the power conversion efficiency and the peak current.

[0025] Optionally, the constructing the optical power-current curve according to the peak current and the peak power comprises:

[0026] obtaining the peak current and the peak power.

[0027] Optionally, the constructing the power conversion efficiency-current curve according to the power conversion efficiency and the peak current comprises:

[0028] obtaining the power conversion efficiency and the peak current.

[0029] Optionally, the obtaining the peak current comprises:

[0030] obtaining the maximum output voltage and the minimum output voltage of the capacitor charging and discharging driving power supply according to the voltage signal;

[0031] obtaining the pulse width of the electrical pulse signal according to the electrical pulse signal;

[0032] obtaining the capacitance value of the charging and discharging capacitor in the capacitor charging and discharging driving power supply;

[0033] calculating the peak current according to the maximum output voltage, the minimum output voltage, the pulse width of the electrical pulse signal and the capacitance value.

[0034] Optionally, the obtaining the peak power comprises:

[0035] obtaining the average optical power output by the power meter;

[0036] obtaining the capacitor charging and discharging frequency in the capacitor charging and discharging driving power supply;

[0037] calculating the peak power according to the average optical power, the capacitor charging and discharging frequency and the pulse width of the electrical pulse signal.

[0038] Optionally, the obtaining the power conversion efficiency comprises:

[0039] calculating the average input power according to the capacitance value, the maximum output voltage, the minimum output voltage and the capacitor charging and discharging frequency;

[0040] A power conversion efficiency is calculated according to the average input power and the output optical power.

[0041] The DToF performance detection device and method for the light source according to the embodiments of the present application can directly and accurately measure the performance of the laser, such as the driving current, the signal pulse width, the output optical power, the energy conversion efficiency and the like, according to the optical power-current curve and the power conversion efficiency-current curve when the light source is driven in the capacitive charging and discharging mode, and further facilitate the performance iteration of the product in the product research and development and use processes. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a structural schematic diagram of the DToF performance detection device for the light source according to an embodiment of the present application;

[0043] Figure 2 is a structural schematic diagram of the DToF performance detection device for the light source according to an embodiment of the present application;

[0044] Figure 3 is a circuit principle diagram of the capacitive charging and discharging driving power supply in the DToF performance detection device for the light source according to an embodiment of the present application;

[0045] Figure 4 is a flowchart of the DToF performance detection method for the light source according to an embodiment of the present application;

[0046] Figure 5 is a flowchart of the DToF performance detection method for the light source according to an embodiment of the present application;

[0047] Figure 6 is a flowchart of the DToF performance detection method for the light source according to another embodiment of the present application;

[0048] Figure 7 is a flowchart of the DToF performance detection method for the light source according to another embodiment of the present application;

[0049] Figure 8 is a flowchart of the DToF performance detection method for the light source according to another embodiment of the present application;

[0050] Figure 9 is a voltage signal input into the light source in the DToF performance detection method for the light source according to an embodiment of the present application;

[0051] Figure 10 is an electrical pulse signal output by the high-speed detector in the DToF performance detection method for the light source according to an embodiment of the present application;

[0052] Figure 11 is a flowchart of the DToF performance detection method for the light source according to another embodiment of the present application;

[0053] Figure 12 is a flow chart of a DToF performance detection method of a light source according to another embodiment of the present application;

[0054] Figure 13 is a light power-current curve constructed in a DToF performance detection method of a light source according to an embodiment of the present application;

[0055] Figure 14 is a power conversion efficiency-current curve constructed in a DToF performance detection method of a light source according to an embodiment of the present application. DETAILED DESCRIPTION

[0056] The present application will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are intended to be merely illustrative of the present application and not in limitation thereof. It should also be noted that, for the purpose of description, only the parts related to the present application are shown in the drawings rather than all the parts.

[0057] Figure 1 is a structural schematic diagram of a DToF performance detection device of a light source according to an embodiment of the present application. In combination with Figures 1-2 shown, the DToF performance detection device 100 of the light source comprises:

[0058] a light source 102;

[0059] a capacitor charging and discharging driving power supply 101, electrically connected with the light source 102, for supplying power to the light source 102 and driving the light source 102 to emit light at a preset frequency;

[0060] a high-speed detector 103, located in the light emission direction of the light source 102, for detecting the light pulse signal of the light source 102 and converting the light pulse signal c output by the light source 102 into an electric pulse signal b;

[0061] an oscilloscope 104, electrically connected with the output end of the capacitor charging and discharging driving power supply 101, for displaying the voltage signal a input to the light source 102, and also electrically connected with the output end of the high-speed detector 103, for displaying the electric pulse signal b;

[0062] a light power meter 105, located in the light emission direction of the light source 102, for detecting the average light power of the light source 102;

[0063] a construction module (not shown in the figure), for constructing a light power-current curve and a power conversion efficiency-current curve according to the electric pulse signal b, the voltage signal a and the average light power.

[0064] It should be noted that the high-speed detector 103 can be a CCD photodetector or a CMOS photodetector. The optical power meter 105 can be an integrating sphere. The construction module can be a processor. After obtaining the voltage signal a, the electrical pulse signal b through the oscilloscope 104, and the average optical power through the optical power meter 105, the light power-current curve and the power conversion efficiency-current curve can be constructed according to the voltage signal a, the electrical pulse signal b and the average optical power. After constructing the light power-current curve and the power conversion efficiency-current curve, the DToF performance of the light source can be detected according to the two curves.

[0065] The response time of the high-speed detector 103 is less than 1 nanosecond. The voltage signal a includes maximum voltage information and minimum voltage information. The electrical pulse signal b includes pulse width information and peak value information.

[0066] It should be noted that for the light power-current curve, the slope (also known as slope efficiency) of the curve and the intercept (threshold current) of the curve and the x-axis can be compared, wherein the larger the slope efficiency, the better the DToF performance of the light source; the smaller the threshold current, the better the DToF performance of the light source.

[0067] For the power conversion efficiency-current curve, the peak value (i.e. the maximum PCE value) of the curve can be compared. The larger the maximum PCE value, the better the DToF performance of the light source.

[0068] Optionally, as shown in Figure 3 The capacitor charging and discharging driving power supply 101 includes a capacitor charging and discharging circuit 1011, which includes:

[0069] a charging resistor R1;

[0070] a charging and discharging capacitor C1;

[0071] a power supply 1012, the negative electrode of the power supply 1012 is grounded, the positive electrode of the power supply 1012 is electrically connected to one end of the charging resistor R1, the other end of the charging resistor R1 is electrically connected to one end of the charging and discharging capacitor C1, the other end of the charging and discharging capacitor C1 is grounded; the other end of the charging resistor R1 and the connection end of the charging and discharging capacitor C1 are also electrically connected to one end of the light source 102.

[0072] The range of the charging and discharging capacitor C1 is between 1 pF and 1 uF. The range of the charging resistor R1 is between 1 Ω and 1 MΩ. The charging and discharging frequency is between 1 kHz and 1 GHz.

[0073] Optionally, as shown in Figure 3As shown, the capacitor charging and discharging drive power supply 101 also includes a capacitor charging and discharging drive circuit 1013, which includes:

[0074] Switching transistor Q1;

[0075] The switching transistor drive circuit 1014 has one end grounded, the other end electrically connected to the first end of the switching transistor Q1, the second end of the switching transistor Q1 grounded, and the third end of the switching transistor Q1 electrically connected to the other end of the light source 102.

[0076] It should be noted that the switching transistor drive circuit 1014 drives the switching transistor Q1 to close and close at a preset frequency. Therefore, when the switching transistor Q1 is off, the light source 102 and the capacitor charging / discharging circuit 1011 do not form a closed loop. At this time, the charging / discharging capacitor C1 does not discharge; instead, the power supply 1012 charges the charging / discharging capacitor C1 through the charging resistor R1. When the switching transistor Q1 is closed, the light source 102 and the capacitor charging / discharging circuit 1011 form a closed loop. At this time, the charging / discharging capacitor C1 discharges, supplying power to the light source 102. Thus, the frequency at which the switching transistor drive circuit 1014 drives the switching transistor Q1 to close and close is the charging / discharging frequency of the charging / discharging capacitor C1, which is also the light emission frequency of the light source 102.

[0077] It is understood that the light source 102 can be an edge-emitting laser (EEL), a vertical-cavity surface-emitting laser (VCSEL), or a light-emitting diode (LED).

[0078] The following section explains in detail how to construct optical power-current curves and power conversion efficiency-current curves using the aforementioned device.

[0079] Figure 4 This is a flowchart of a dTOF performance testing method for a light source according to an embodiment of the present invention. It is implemented using the dTOF performance testing device for the light source as described above. Figure 4 As shown, it includes the following steps:

[0080] S101, acquire the electrical pulse signal output by the high-speed detector, the voltage signal of the input light source, and the average optical power output by the power meter;

[0081] Among them, according to such Figure 3 As shown in the circuit diagram for driving the laser to emit light, the voltage signal input to the light source is... Figure 3 The voltage at terminal V1.

[0082] The electrical pulse signal output by the high-speed detector is the electrical pulse signal converted from the light pulse signal emitted by the light source.

[0083] The average optical power output by the power meter is the average optical power of the light emitted from the light source that is detected.

[0084] S102, constructing a light power-current curve and a power conversion efficiency-current curve according to the electrical pulse signal, the voltage signal and the average light power.

[0085] Optionally, as shown in Figure 5 constructing a light power-current curve and a power conversion efficiency-current curve according to the electrical pulse signal, the voltage signal and the average light power includes:

[0086] S201, constructing a light power-current curve according to the peak current and the peak power;

[0087] It should be noted that in actual application, the sensor receiving end (such as a high-speed detector, a photodetector, a photodiode (PD), an avalanche photodiode (APD), a single-photon avalanche diode (SPAD), a silicon photomultiplier (SiPM) and the like) usually records the peak power as a measurement value; in other words, the high-speed detector receiving end measures the peak power, so the peak power is used when constructing the laser performance curve. Because the peak power can be reached only at the peak current, the peak current and the peak power are used to construct the light power-current curve.

[0088] S202, constructing a power conversion efficiency-current curve according to the power conversion efficiency and the peak current.

[0089] Optionally, as shown in Figure 6 constructing a light power-current curve according to the peak current and the peak power includes:

[0090] S2011, obtaining the peak current and the peak power.

[0091] Optionally, as shown in Figure 7 constructing a power conversion efficiency-current curve according to the power conversion efficiency and the peak current includes:

[0092] S2021, obtaining the power conversion efficiency and the peak current.

[0093] Optionally, as shown in Figure 8 obtaining the peak current includes:

[0094] S301, obtaining the maximum output voltage and the minimum output voltage of the capacitance charging and discharging driving power supply according to the voltage signal; as shown in Figure 9As shown, the oscilloscope collects the input end voltage signal, the maximum output voltage is Vmax, and the minimum output voltage is Vmin.

[0095] S302, obtaining the pulse width of the electric pulse signal according to the electric pulse signal;

[0096] As shown, Figure 10 As shown, Figure 10 The electric pulse signal in the electric pulse signal is the electric pulse signal output by the high-speed detector. The oscilloscope can only read out the electric pulse signal, so the function of the high-speed detector is to convert the received optical pulse signal into an electric pulse signal, and the pulse width is usually selected by the "half-width" method, that is, the pulse width at the half position of the peak signal intensity. The pulse width is Figure 10 Δt in the electric pulse signal.

[0097] S303, obtaining the capacitance value of the charge-discharge capacitor in the capacitor charge-discharge driving power supply;

[0098] The capacitance value of the charge-discharge capacitor can be obtained when selecting the charge-discharge capacitor, and the capacitance value range is between 1 picofarad (1pF) and 1 microfarad (1μF), and the preferred value is 1nF.

[0099] S304, calculating the peak current according to the maximum output voltage, the minimum output voltage, the pulse width of the electric pulse signal, and the capacitance value.

[0100] It can be understood that since the definition formula of the current is I=Cdu / dt, wherein C is the capacitance value of the charge-discharge capacitor, du is the voltage change, and dt is the time change, and then after obtaining the maximum output voltage Vmax and the minimum output voltage Vmin of the capacitor charge-discharge driving power supply, the pulse width Δt of the electric pulse signal is obtained, and the expression of the peak current is as follows:

[0101] I=C(Vmax-Vmin) / Δt

[0102] Optionally, as shown, obtaining the peak power includes: Figure 11

[0103] S401, obtaining the average optical power output by the power meter;

[0104] That is, the average optical power Lavg can be directly read out by the power meter.

[0105] S402, obtaining the capacitance charge-discharge frequency in the capacitor charge-discharge driving power supply;

[0106] The capacitance charge-discharge frequency f can be set in advance, and the charge-discharge frequency f is preferably in the range of 1kHz to 1GHz, and the preferred value is 1MHz.

[0107] ​S403, calculate the peak power according to the average optical power, the capacitance charging and discharging frequency and the pulse width of the electric pulse signal.

[0108] It can be understood that the peak power L=Lavg / (Δt*f), wherein the capacitance charging and discharging frequency f can be a preset frequency, i.e. can be set according to actual conditions, Lavg is the average optical power output by the power meter; and Δt is the pulse of the electric pulse signal.

[0109] Further, the peak current and the peak power can be transformed according to the equation to obtain the curve between the peak current and the peak power. That is:

[0110] Figure 13 For the constructed optical power-current curve, the slope efficiency is 3.1 W / A, and thus the DToF performance of the light source can be judged according to the slope efficiency.

[0111] Optionally, as shown in Figure 12 , the power conversion efficiency comprises:

[0112] S501, calculate the average input power according to the capacitance value, the maximum output voltage, the minimum output voltage and the capacitance charging and discharging frequency;

[0113] Wherein, the average input power Pin=E*f, Pin is the average input power, E is the energy, and f is the frequency. In addition, E=0.5*C*U 2 , Pin=(Emax-Emin)*f, and further, Pin=0.5*C*(Vmax 2 -Vmin 2 )*f.

[0114] S502, calculate the power conversion efficiency according to the average input power and the output optical power.

[0115] The power conversion efficiency PCE=Lavg / Pin.

[0116] Further, the peak current and the power conversion efficiency can be obtained according to the equation between the peak current and the power conversion efficiency, i.e. PCE=L / [0.5I(Vmax+Vmin)].

[0117] Figure 14 For the constructed power conversion efficiency-current curve, when the power conversion efficiency is close to 45%, the DToF performance of the light source is the best.

[0118] In summary, the DToF performance detection device and method of the light source according to the embodiments of the present application can directly and accurately measure the performance of the laser, such as the driving current, signal pulse width, output optical power, energy conversion efficiency and the like, according to the optical power-current curve and the power conversion efficiency-current curve when the light source is driven in the capacitor charging and discharging driving mode, and further facilitate product performance iteration in the product research and development and use process.

[0119] It should be noted that the above only describes the preferred embodiments of the present application and the technical principles applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A device for detecting DToF performance of a light source, characterized in that, include: light source; A capacitor charging and discharging driving power supply is electrically connected to the light source, used to supply power to the light source and drive the light source to emit light at a preset frequency; A high-speed detector, located in the light emission direction of the light source, is used to detect the light pulse signal of the light source and convert the light pulse signal output by the light source into an electrical pulse signal; An oscilloscope, electrically connected to the output terminal of the capacitor charging and discharging drive power supply, is used to display the voltage signal input to the light source; it is also electrically connected to the output terminal of the high-speed detector, used to display the electrical pulse signal. An optical power meter, located in the light emission direction of the light source, is used to detect the average optical power of the light source; The module constructs optical power-current curves and power conversion efficiency-current curves based on the electrical pulse signal, the voltage signal, and the average optical power. The build module calculates the peak current according to the formula Peak current = (V * I) / (V * I) 2. The DToF performance detection device of the light source according to claim 1, wherein, The capacitor charging and discharging drive power supply includes a capacitor charging and discharging circuit, which includes: Charging resistor; Charging and discharging capacitors; The power supply has its negative terminal grounded, its positive terminal electrically connected to one end of the charging resistor, and its other end electrically connected to one end of the charging / discharging capacitor, the other end of which is grounded; the connection between the other end of the charging resistor and the charging / discharging capacitor is also electrically connected to one end of the light source.

3. The DToF performance detection device of the light source according to claim 2, wherein, The capacitor charging and discharging driving power supply further includes a capacitor charging and discharging driving circuit, which includes: Switching transistor; A switching transistor driving circuit, wherein one end of the switching transistor driving circuit is grounded, the other end is electrically connected to the first end of the switching transistor, the second end of the switching transistor is grounded, and the third end of the switching transistor is electrically connected to the other end of the light source.

4. A method for detecting the DToF performance of a light source, using the device for detecting the DToF performance of a light source according to any one of claims 1-3, characterized in that, Includes the following steps: The system acquires the electrical pulse signal output by the high-speed detector, the voltage signal input to the light source, and the average optical power output by the power meter. Optical power-current curves and power conversion efficiency-current curves are constructed based on the electrical pulse signal, the voltage signal, and the average optical power.

5. The method of claim 4, wherein the method further comprises: The construction of the optical power-current curve and the power conversion efficiency-current curve based on the electrical pulse signal, the voltage signal, and the average optical power includes: Construct an optical power-current curve based on peak current and peak power; A power conversion efficiency-current curve is constructed based on the power conversion efficiency and peak current.

6. The method of claim 5, wherein the method further comprises: The construction of the optical power-current curve based on peak current and peak power includes: Obtain the peak current and the peak power.

7. The method of claim 5, wherein the method further comprises: The construction of the power conversion efficiency-current curve based on power conversion efficiency and peak current includes: Obtain the power conversion efficiency and the peak current.

8. The method of claim 6 or 7, wherein the method further comprises: The process of obtaining the peak current includes: The maximum and minimum output voltages of the capacitor charging and discharging drive power supply are obtained based on the voltage signal. The pulse width of the electrical pulse signal is obtained based on the electrical pulse signal; Obtain the capacitance value of the charging and discharging capacitor in the capacitor charging and discharging drive power supply; The peak current is calculated based on the maximum output voltage, the minimum output voltage, the pulse width of the electrical pulse signal, and the capacitance value.

9. The method of claim 6, wherein the obtaining the peak power comprises: obtaining an average optical power output by the power meter; obtaining a capacitance charging and discharging frequency of the capacitance charging and discharging power supply; and calculating the peak power based on the average optical power, the capacitance charging and discharging frequency, and a pulse width of the electrical pulse signal.

10. The method of claim 8, wherein the obtaining the power conversion efficiency comprises: calculating an average input power based on the capacitance value, the maximum output voltage, the minimum output voltage, and the capacitance charging and discharging frequency; and calculating the power conversion efficiency based on the average input power and the output optical power. ​ ​ ​ ​ ​ ​ ​

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