Laser radar detection system and method

Abstract

The invention discloses a laser radar detection system and method, and belongs to the technical field of detection, and the method specifically comprises the steps that a laser source emits a pulse type detection laser sequence; the counting type photoelectric detector receives a return light signal reflected by a detected object in a field of view through two different modulation phases, and the delay between the two different modulation phases is 180 degrees. Two digital domain counting signals with different phases can be obtained, the common noise problem in an analog signal chain in the prior art is eliminated, and therefore better signal-to-noise ratio performance is shown when narrow pulse optical signals are processed.

Description

Technical Field

[0001] The present invention belongs to the field of detection technology, and in particular relates to a laser radar detection system and method. Background Art

[0002] Time of Flight ("TOF") Light Detection and Ranging ("LIDAR") is a technology used for long-range distance measurement. A TOF LIDAR sensor determines the distance between an instrument including the sensor and an object by measuring the time it takes for a laser pulse to travel between the instrument and the object.

[0003] Currently, the most widely used detection methods include indirect time-of-flight (ITOF) measurement and direct time-of-flight (DTOF) measurement. Most indirect time-of-flight measurement schemes use the method of measuring phase shift, that is, the phase difference between the transmitted wave and the received wave. The horizontal coordinates of the transmitted and received waves are time t, and the vertical coordinates are light intensity. The flight time t can be obtained based on the phase difference between the two, and the distance of the detected object can be calculated based on d=ct / 2.

[0004] The detection system used in the related technology basically includes: a light source module, a processing module, and a light receiving module. The light source module includes but is not limited to semiconductor lasers, solid lasers, and may also include other types of lasers. When a semiconductor laser is used as a light source, a vertical cavity surface emitting laser (VCSEL) or an edge emitting semiconductor laser (EEL) may be used. Laser), which is only an exemplary description and is not specifically limited here. The light source module emits a sine wave, a square wave, a triangle wave, or a pulse wave, etc. In the distance measurement application, it is mostly a laser with a certain wavelength, such as an infrared laser of 950nm or the like (preferably a near-infrared laser). The emitted light is projected into the field of view. The detected object in the field of view can reflect the projected laser to form a return light. The return light enters the detection system and is captured by the light receiving module. The light receiving module may include a photoelectric conversion unit, wherein in ITOF ranging, it can obtain delayed receiving signals of 0°, 90°, 180° and 270° by the most commonly used four-phase delayed reception. The distance calculation scheme using the four-phase is described here using the sine wave method as an example, and the amplitude of the received signal is measured at four equidistant points (for example, at intervals of 90° or 1 / 4λ): (1) The ratio of the difference between A1 and A3 to the difference between A2 and A4 is equal to the tangent of the phase angle. ArcTan is actually a two-variable inverse tangent function that maps to the appropriate quadrant, defined as 0° or 180° when A2=A4 and A1>A3 or A3>A1, respectively.

[0005] The distance to the target object is determined by the following formula: (2) At this point, we need to determine the frequency of the emitted laser to measure the distance, where c is the speed of light and φ is the phase angle (measured in radians). f The above scheme can achieve the effect of distance detection for the detected object in the field of view. This scheme is called a four-phase delay scheme to obtain the detection result. Of course, the receiving module generates different information through photoelectric conversion. In some cases, the two-phase scheme of 0° and 180° is also used to obtain the information of the detected object. There are also documents that disclose the three-phase scheme of 0°, 120° and 240° to obtain target information. There are even documents that disclose the five-phase delay scheme, which is not specifically limited by the present invention.

[0006] Current ranging technology widely uses integral photodetectors as front-end signal capture devices. This method converts optical signals modulated with different phases into integrated charge quantities through an integration process. However, the core problem of this conversion process is that the conversion process from the integrated charge quantity to the digital signal relies on the analog-to-digital converter (ADC) to operate, which inevitably introduces noise in the analog signal chain. The noise in the analog signal chain, including but not limited to thermal noise, quantization noise, and circuit noise, will be superimposed on the original signal during the signal conversion process, thereby reducing the purity and signal-to-noise ratio of the signal. The presence of noise will directly affect the accuracy of subsequent digital processing and calculation, thereby limiting the overall accuracy and stability of the ranging system. In order to compensate for the impact of the analog signal chain noise to a certain extent, it is often necessary to add additional filtering, calibration, or compensation circuits, which increases the complexity and cost of the system.

[0007] In summary, the existing technology mainly relies on integral photodetectors to capture light signals under different phase modulations and convert them into integrated charge. The integrated charge generated by this process is then converted into a digital signal through an analog-to-digital converter (ADC) for subsequent digital processing and calculation to determine the distance of the detected object. However, this method has a significant limitation: since the integral photodetector initially captures an analog signal, and in the process of converting the analog signal into a digital signal, noise in the analog signal chain is inevitably introduced. The presence of this noise will directly affect the accuracy of subsequent processing and the accuracy of the final distance measurement. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a laser radar detection system and method to address the deficiencies in the above-mentioned prior art, so as to solve the technical problem of noise in the existing analog signal chain.

[0009] The present invention adopts the following technical solutions: A laser radar detection system, comprising: A laser source, used for emitting a pulsed detection laser sequence; The counting photodetector is used to receive the return light signal reflected by the detected object in the field of view at two different modulation phases, and the delay between the two different modulation phases is 180°.

[0010] Preferably, it also includes a signal processing module, which calculates the distance of the detected object based on the counting result obtained by the counting photoelectric detector receiving the return light signal reflected by the detected object in the field of view at a phase of 0° and 180° in the first time, and the counting result obtained by the counting photoelectric detector receiving the return light signal reflected by the detected object in the field of view at a phase of 90° and 270° in the second time.

[0011] Preferably, the counting photodetector includes a control module, which uses a high duty cycle gating timing to control the counting photodetector to receive a return light signal under low photon flux conditions; and uses a low duty cycle gating timing to control the counting photodetector to receive a return light signal under high photon flux conditions.

[0012] Preferably, the restored photon counting coefficient is obtained based on the counting result of the counting photodetector under high photon flux conditions and the duty cycle of the corresponding control signal; when the count exceeds the counter depth, the counting result is obtained based on the restored photon counting coefficient.

[0013] Preferably, two counters are used to count the triggering effects of the counting photodetector, wherein counter A has no phase delay relative to the emission light detection sequence; and counter B has a phase delay of 180° relative to the emission light detection sequence.

[0014] Preferably, the counting type photodetector adopts a probability counting type photodetector device with gain.

[0015] Another technical solution of the present invention is a laser radar detection method, characterized in that it includes the following steps: The laser source emits a pulsed detection laser sequence; The counting photodetector receives the return light signal reflected by the detected object in the field of view at two different modulation phases, and the delay between the two different modulation phases is 180°.

[0016] Preferably, a control signal is used to control the timing of the counting photodetector receiving the return light signal, and the restored photon counting coefficient is obtained based on the counting result of the counting photodetector under high photon flux conditions and the corresponding duty cycle of the control signal; when the count exceeds the counter depth, the counting result is obtained based on the restored photon counting coefficient.

[0017] Preferably, the control signal uses a high duty cycle gating timing to control the counting photodetector to receive the returned light signal under low photon flux conditions; the control signal uses a low duty cycle gating timing to control the counting photodetector to receive the returned light signal under high photon flux conditions.

[0018] Preferably, the counting photoelectric detector receives the return light signal reflected by the detected object in the field of view at a phase of 0° and a phase of 180° within the first time, and obtains the counting result within the first time; the counting photoelectric detector receives the return light signal reflected by the detected object in the field of view at a phase of 90° and a phase of 270° within the second time, and obtains the counting result within the second time; the distance of the detected object is obtained according to the counting result within the first time and the counting result within the second time.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: A laser radar detection system, by introducing a probability counting photoelectric detector with a gain function, is used to perform phase modulation and counting operations, and can obtain digital domain counting results of two different phases (such as 0° and 180°, or 90° and 270°). Compared with the traditional technology that relies on non-gain integration photoelectric detectors to demodulate the phase difference of reflected light signals, the detection system of the present invention significantly eliminates the common noise problems in the analog signal chain, thereby showing better signal-to-noise ratio performance when processing narrow pulse light signals; secondly, the emitting laser system can effectively reduce the pulse width while maintaining the stability of the average power, thereby greatly increasing the peak power; this feature is particularly critical for medium and long-distance detection and demodulation applications, because it not only enhances the signal penetration and detection distance, but also improves the overall performance and reliability of the system.

[0020] Furthermore, the signal processing module is used to count and calculate the four-phase photon counting results and calculate the distance and intensity information of the detected object.

[0021] Furthermore, the control module uses a high duty cycle gated timing control counting photodetector to receive the return light signal under low photon flux conditions, and can collect all counting information that can be used to calculate distance and intensity information; Furthermore, the restored photon counting coefficient is obtained based on the counting result of the counting photodetector under high photon flux conditions and the duty cycle of the corresponding control signal; when the count exceeds the counter depth, the counting result is obtained based on the restored photon counting coefficient, which can avoid saturation of the computing module, increase the dynamic range, and save power consumption.

[0022] Furthermore, two counters are used to count the triggering effects of the counting photodetector, wherein counter A has no phase delay relative to the emission light detection sequence; counter B has a phase delay of 180° relative to the emission light detection sequence, and is used to obtain counting information of the phase information capable of calculating the distance.

[0023] Furthermore, the counting photoelectric detector uses a probability counting photoelectric detector device with gain, which can improve the sensitivity of photoelectric detection and improve the ability to detect weak light.

[0024] A laser radar detection method that abandons the TDC+TCSPC method used by traditional single-photon laser radars and performs multiple statistics based on histograms to recalculate target depth information, and uses the common-mode counting and differential-mode counting triggered by the photons of the phase-controlled counting SPAD to extract depth information and intensity information. This method directly performs phase demodulation on single-photon counting, greatly reducing the hardware and algorithm consumption required to complete a 2D / 3D information extraction, and expanding the applicability of scenarios.

[0025] Furthermore, the counting photoelectric detector receives the return light signal reflected by the detected object in the field of view at a phase of 0° and a phase of 180° within the first time, and obtains the counting result within the first time; the counting photoelectric detector receives the return light signal reflected by the detected object in the field of view at a phase of 90° and a phase of 270° within the second time, and obtains the counting result within the second time; based on the counting result within the first time and the counting result within the second time, the distance information and intensity information of the detected object can be efficiently obtained at the same time.

[0026] In summary, by using SPAD and other probability counting photodetector devices with gain to perform phase modulation counting, two integral counting signals with different phases (0, 180 or 90, 270) are obtained. Compared with the prior art that uses a non-gain integral photodetector to demodulate the phase difference of the reflected optical signal, the noise problem of the analog signal chain can be eliminated. It has a better signal-to-noise ratio for narrow pulse light. Therefore, the emitted laser can reduce the pulse width while keeping the average power unchanged, thereby increasing the peak power. Therefore, this detection demodulation technology is used in medium and long-distance applications.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic diagram of a laser radar detection method flow chart provided in an embodiment of the present application; Figure 2 A schematic diagram of the timing principle in a laser radar detection method provided in an embodiment of the present application; Figure 3 A schematic diagram of a laser radar detection circuit provided in an embodiment of the present application; FIG4 is a timing diagram, wherein (a) is the first subframe, and (b) is the second subframe; Figure 5 A schematic diagram of the geometric scaling implementation principle provided in an embodiment of the present application; Figure 6 A schematic diagram of a laser radar detection system provided in an embodiment of the present application.

[0030] Wherein: 601. Laser source; 602. Counting photoelectric detector; 6021. Control module; 603. Processing module. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0035] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0036] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0037] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0038] The present invention provides a laser radar detection system and method, which introduces a probability counting photoelectric detector with a gain function to perform phase modulation and counting operations, and can obtain digital domain counting results of two different phases (such as 0° and 180°, or 90° and 270°). Compared with the traditional technology that relies on non-gain integration photoelectric detectors to demodulate the phase difference of the reflected light signal, it solves the common noise problem in the analog signal chain in the prior art, thereby showing better signal-to-noise ratio performance when processing narrow pulse light signals.

[0039] See also Figure 1 The present invention provides a laser radar detection method, comprising the following steps: S1, the laser source emits a pulsed detection laser sequence; Specifically, as the core component of ranging, the laser source can accurately control and emit a pulsed detection laser sequence. This pulsed laser sequence consists of a series of short and high-intensity light pulses, and the duration of each pulse (i.e., pulse width) and the time interval between adjacent pulses (i.e., pulse repetition frequency) can be precisely adjusted according to specific application requirements.

[0040] These pulsed lasers are collimated and focused by optical systems (such as lenses, mirrors, etc.) to ensure that they can be emitted to the target object with high energy density, high directivity and high speed.

[0041] The advantage of a pulsed detection laser sequence is that it can provide precise time markers, allowing the receiver to accurately measure the time it takes for a laser pulse to be reflected by the target and return; this time difference, combined with the known value of the speed of light, can be used to calculate the distance to the target object.

[0042] S2. The counting photoelectric detector receives the return light signal reflected by the detected object in the field of view at two different modulation phases, and the delay between the two different modulation phases is 180°.

[0043] Specifically, the counting photodetector is used to receive and process the reflected light signal. In the ranging or detection system, the detector is configured to receive the return light signal reflected from the detected object in the field of view with two different modulation phases that are delayed by 180° (for example, 0° and 180° or 90° and 270°). The laser source first emits a pulsed laser modulated by a specific frequency. When these laser pulses hit the target object and reflect back, they carry the distance information of the target object and produce a phase delay due to the path difference. The counting photodetector receives these two return light signals with a phase difference of 180° through its two internal receiving channels.

[0044] During the reception process, the circuit inside the detector will synchronously sample and compare the two signals with different phases. Since there is a fixed phase difference (180°) between the two signals, the detector can use this feature to distinguish and calculate the phase delay caused by the target object. By accurately measuring this phase delay and combining it with the known laser modulation frequency and speed of light, the system can calculate the distance between the target object and the detector.

[0045] See also Figure 2, is a schematic diagram of the timing principle in a laser radar detection method provided in an embodiment of the present application. The laser light source emits a pulsed detection laser sequence, and the detection laser sequence passes through the field of view and generates a return light signal reflected by the detection object. The return light signal is delayed α relative to the detection laser sequence. The counting detector receives the return light signal and triggers a response, generating a trigger pulse, and the counter counts the response pulses triggered by the return light signal.

[0046] It should be noted that when the reflected light signal has not yet reached the counting photodetector or the return light signal corresponding to the emitted light has not reached the counting photodetector, the background light or DCR (Dynamic Contrast Ratio) may also cause the counting detector to trigger a response. The counter counts the noise counts triggered by it, and finally removes the noise counts through post-processing. The process of removing the noise counts will not be described in detail here.

[0047] The triggering effects of the counting photodetector are counted using two counters, one of which has no phase delay relative to the emission light detection sequence, such as Figure 2 The other counter is delayed by 180° relative to the emission light detection sequence, as shown in Figure 2 The technology in B. That is to say, the phase delay between the two counters is 180°, for example, 0° and 180° or 90° and 270°.

[0048] It should be noted that the counting photodetector in the embodiment of the present application is a probability counting photodetector device with gain, such as SPAD (single photon avalanche diode), APD (avalanche diode), photomultiplier tube (PMT), multi-pixel photon counter (MPPC / SiPM), etc., and the embodiment of the present application does not make specific restrictions.

[0049] In some embodiments, a control signal may be used to control the timing of the counting photodetector receiving the return light signal, see Figure 3 , Figure 3 A schematic diagram of a laser radar detection circuit provided in an embodiment of the present application. Figure 3 As shown, CK is a control port, and the control signal controls the timing of the counting photodetector receiving the returning light signal through CK. CK can be turned on or through a pulse sequence to control the timing of the counting photodetector receiving the returning light signal. TX-A is the control switch of counter A, and TX-B is the control switch of counter B. The counting results of counter A and counter B are read out through column line A and column line B respectively for subsequent detection distance calculation. Figure 3 SPAD is used as an example for illustration, but the embodiments of the present application are not specifically limited.

[0050] In some embodiments, CK is always turned on, and in the first subframe, a return light signal reflected by a detected object in the field of view is received at a phase of 0° and a phase of 180° to obtain a counting result; In the second subframe, the return light signal reflected by the detected object in the field of view is received at a phase of 90° and a phase of 270° to obtain a counting result. See Figures 4A and 4B. Figure 4A is a timing diagram of the first subframe provided in an embodiment of the present application, and Figure 4B is a timing diagram of the second subframe provided in an embodiment of the present application. As shown in Figure 4A, the phase delay between TX-A and the pulsed detection laser sequence (transmitted light) is 0°, and the phase delay between TX-B and the transmitted light is 180°. TX-A and TX-B are the same pulse sequences as the pulsed detection laser sequence. When TX-A is turned on and TX-B is turned off, counter A counts to obtain a counting result with a phase delay of 0°; when TX-B is turned on and TX-A is turned off, counter B counts to obtain a counting result with a phase delay of 180°. Among them, the counting result includes the count caused by the reflected return light signal and the noise count caused by the background light and DCR.

[0051] As shown in Figure 4B, the phase delay between TX-A and the pulsed detection laser sequence (transmitted light) is 90°, and the phase delay between TX-B and the transmitted light is 270°. TX-A and TX-B are the same pulse sequence as the pulsed detection laser sequence. When TX-A is turned on and TX-B is turned off, counter A counts to obtain a count result with a phase delay of 90°; when TX-B is turned on and TX-A is turned off, counter B counts to obtain a count result with a phase delay of 270°. The count result includes the count caused by the reflected return light signal and the noise count caused by the background light and DCR.

[0052] By reading out the counting results of the four phases obtained by statistics, the distance of the detected object can be obtained according to the four phases, and the detailed process of obtaining the distance of the detected object will not be repeated here.

[0053] In some embodiments, the CK port integrates gated timing control technology to achieve pulse signal processing by dynamically adjusting the duty cycle of the control logic. The duty cycle of the gated signal is adjusted according to the received photon flux level to achieve the purpose of optimizing signal processing and expanding the dynamic range.

[0054] When the photon flux is low, the CK port switches to a high duty cycle gating sequence. The high duty cycle allows the gating signal to remain on for a greater proportion of the time, thereby improving the ability to capture weak signals. By extending the signal detection window, the system can capture every pulse event, ensuring measurement accuracy under low flux conditions.

[0055] On the contrary, in an environment with high photon flux, in order to avoid signal overload or bottleneck of processing capacity, the CK port adopts low duty cycle gating timing. Low duty cycle means that the gate signal is turned on for a relatively short time and turned off for a long time. This reduces the number of pulses processed per unit time, thereby avoiding signal congestion and ensuring the accuracy and stability of the signal. At the same time, through subsequent algorithm processing, the total number of pulses in the entire time period can be calculated based on the counting results of the low duty cycle period, achieving geometric scaling, and then expanding the dynamic range measurement capability.

[0056] For more information, see Figure 5 , which is a schematic diagram of the geometric scaling implementation principle provided in an embodiment of the present application; when the photon flux is low (low flux), the actual counting result of the counter will not exceed the counter depth, and the counter counting result can be obtained directly; however, in an environment with high photon flux (high flux), the statistical result of the counter will exceed the counter depth (N), causing the counter to be unable to work normally.

[0057] The embodiment of the present application obtains the restored photon counting coefficient (N1 / M) by adjusting the duty cycle M of the gating timing of the duty cycle of the CK port control signal and the actual counting result (N1) of the counter. When the count exceeds the depth of the counter, the counting result is obtained according to the restored photon counting coefficient.

[0058] For example, when the duty cycle of the CK port control signal is M1, the counting result exceeds the counter depth. Then, according to the restored photon counting coefficient (N1 / M), the counting result at the duty cycle M1 is: N1*M1 / M; thereby, the dynamic range of the counter can be expanded.

[0059] See also Figure 6 , a laser radar detection system, comprising: A laser source 601 is used to emit a pulsed detection laser sequence; The counting photodetector 602 is used to receive the return light signal reflected by the detected object in the field of view at two different modulation phases, and the two different modulation phases are delayed by 180°.

[0060] The counting photodetector 602 includes a control module 6021 for controlling the timing of the counting photodetector 602 receiving the return light signal.

[0061] Furthermore, the control module 6021 uses a high duty cycle gated timing control to control the counting photodetector 602 to receive the return light signal under low photon flux conditions; the control module 6021 uses a low duty cycle gated timing control to control the counting photodetector 602 to receive the return light signal under high photon flux conditions.

[0062] The detection system obtains the restored photon counting coefficient according to the counting result of the counting photodetector 602 under high photon flux conditions and the duty cycle of the corresponding control signal; when the count exceeds the counter depth, the detection system obtains the counting result according to the restored photon counting coefficient.

[0063] The detection system also includes a signal processing module 603, which calculates the distance of the detected object based on the counting result obtained by the counting photoelectric detector 602 receiving the return light signal reflected by the detected object in the field of view at a phase of 0° and a phase of 180° in the first time, and the counting result obtained by the counting photoelectric detector 602 receiving the return light signal reflected by the detected object in the field of view at a phase of 90° and a phase of 270° in the second time.

[0064] The transmitting laser system can effectively reduce the pulse width while maintaining the average power stable, thereby significantly increasing the peak power. This feature is particularly critical for medium and long-distance detection and demodulation applications, because it not only enhances the signal penetration and detection distance, but also improves the overall performance and reliability of the system.

[0065] In summary, the present invention provides a laser radar detection system and method, which can obtain digital domain counting signals of two different phases (such as 0° and 180°, or 90° and 270°) by introducing a probability counting photoelectric detector with a gain function to perform phase modulation and counting operations. Compared with the conventional technology that relies on a non-gain integrating photoelectric detector to demodulate the phase difference of the reflected light signal, the embodiment of the present application significantly eliminates the common noise problem in the analog signal chain, thereby showing a better signal-to-noise ratio performance when processing narrow pulse light signals.

[0066] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A laser radar detection system, characterized in that: include: A laser source (601) for emitting a pulsed detection laser sequence; The counting type photoelectric detector (602) is used to receive the return light signal reflected by the detected object in the field of view at two different modulation phases, and the delay between the two different modulation phases is 180 degrees.

2. The laser radar detection system according to claim 1, characterized in that: The device also includes a signal processing module (603) that calculates the distance of the detected object based on a counting result obtained by the counting photoelectric detector (602) receiving a return light signal reflected by the detected object in the field of view at a phase of 0° and a phase of 180° within a first time, and a counting result obtained by the counting photoelectric detector (602) receiving a return light signal reflected by the detected object in the field of view at a phase of 90° and a phase of 270° within a second time.

3. The laser radar detection system according to claim 1, characterized in that: The counting photoelectric detector (602) comprises a control module (6021), wherein the control module (6021) uses a high duty cycle gated timing control to control the counting photoelectric detector (602) to receive a return light signal under low photon flux conditions; and the control module (6021) uses a low duty cycle gated timing control to control the counting photoelectric detector (602) to receive a return light signal under high photon flux conditions.

4. The laser radar detection system according to claim 3, characterized in that: A restored photon counting coefficient is obtained based on the counting result of the counting photoelectric detector (602) under high photon flux conditions and the duty cycle of the corresponding control signal; when the count exceeds the counter depth, the counting result is obtained based on the restored photon counting coefficient.

5. The laser radar detection system according to claim 1, characterized in that: Two counters are used to count the triggering effects of the counting photoelectric detector (602), wherein counter A has no phase delay relative to the emission light detection sequence, and counter B has a phase delay of 180° relative to the emission light detection sequence.

6. The laser radar detection system according to any one of claims 1 to 5, characterized in that: The counting type photodetector (602) adopts a probability counting type photodetector device with gain.

7. A laser radar detection method, characterized in that: The following steps are involved: The laser source emits a pulsed detection laser sequence; The counting photodetector receives the return light signal reflected by the detected object in the field of view at two different modulation phases, and the delay between the two different modulation phases is 180°.

8. The laser radar detection method according to claim 7, characterized in that: A control signal is used to control the timing of the counting photodetector receiving the returned light signal, and the restored photon counting coefficient is obtained according to the counting result of the counting photodetector under high photon flux conditions and the corresponding duty cycle of the control signal; when the count exceeds the counter depth, the counting result is obtained according to the restored photon counting coefficient.

9. The laser radar detection method according to claim 8, characterized in that: The control signal uses a high duty cycle gate timing to control the counting photodetector to receive the returned light signal under low photon flux conditions; the control signal uses a low duty cycle gate timing to control the counting photodetector to receive the returned light signal under high photon flux conditions.

10. The laser radar detection method according to claim 8, characterized in that: The counting photoelectric detector receives the return light signal reflected by the detected object in the field of view at a 0° phase and a 180° phase in the first time, and obtains the counting result in the first time; The counting photoelectric detector receives the return light signal reflected by the detected object in the field of view at a 90° phase and a 270° phase in the second time, and obtains the counting result in the second time; the distance of the detected object is obtained according to the counting result in the first time and the counting result in the second time.

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