A laser radar detection system and method

Abstract

A laser radar detection system, characterized in that, comprising a drive signal generation unit, the drive signal generation unit acts on a laser source through a laser modulation drive circuit, the laser source receives the drive signal to emit a pulse type detection laser sequence; array type return light receiving module, receiving the return light signal reflected by the detected object in the field of view, and generating a return signal; count sequence splicing module, according to the return signal, get copy splicing signal, processing module, the processing module generates modulation signal according to the drive signal generated by the drive signal generation unit, and the copy splicing signal is calculated according to the preset rule to obtain the distance related signal, the processing module outputs the distance information of the final detected object according to the distance related signal, through such design, smaller laser emission energy can be used to realize smaller ranging deviation.

Description

Technical Field

[0001] This application relates to the field of detection technology, and in particular to a lidar detection system and detection method. Background Technology

[0002] Distance detection, especially active detection systems that utilize laser sources, works by actively emitting detection light, such as near-infrared light, with wavelengths selectable within the range of 800-1200nm (though not limited to this range). Using near-infrared detection waves can ensure safety when there are human objects within the field of view. Therefore, near-infrared active detection systems are increasingly being used in various scenarios, such as subsequent autonomous driving, smart door locks, security cameras, and mobile phone 3D cameras.

[0003] Time-of-flight (“TOF”) optical detection and ranging (“LIDAR”) is a technology used for long-range distance measurement. A TOFLIDAR sensor determines the distance between an instrument and an object by measuring the time it takes for a laser pulse to travel between the instrument and the object.

[0004] Currently, widely used detection methods include indirect time-of-flight (ITOF) and direct time-of-flight (DTOF) measurement schemes. Most ITOF schemes use phase shift measurement, specifically the phase difference between the transmitted and received waves. The x-axis represents time (t), and the y-axis represents light intensity. The flight time (t) is obtained from the phase difference, and the distance to the detected object can be calculated using d = ct / 2. Direct time-of-flight (DTOF) schemes typically use picosecond-resolution measurement systems (often SPAD+TDC) to directly obtain the time difference between the transmission and the corresponding receiver trigger, which is the flight time (t), and then calculate the distance to the detected object. Of course, there is another type called coherent detection. When the coherent laser signal and the local laser oscillation signal meet the wavefront matching condition (i.e., maintain the same phase relationship on the entire photosensitive surface of the laser detector), they are incident together on the photosensitive surface of the detector, generating beat frequency or coherent superposition. The magnitude of the detector output electrical signal is proportional to the square of the sum of the laser signal wave to be measured and the local laser oscillation wave. Of course, the above detection methods have their own advantages, but they still have great shortcomings in terms of pixel-level, fast processing and efficient utilization of emission energy.

[0005] In recent years, some direct time-of-flight (incoherent) lidar principles have also been developed and have gradually become a detection technology that is known to more people. Patent application number CN202010604232.3 is entitled "A Novel Laser Ranging Method and Lidar System". It proposes a new type of detection mechanism. Instead of using the coherent light principle in the optical path, correlation calculation is performed in the electrical signal stage. The distance or other information of the detected object is obtained through the correlation calculation of the electrical signal. However, this method still has the following limitations: (1) As can be seen from the principle of noncoherent chirped signal amplitude-modulated continuous wave laser three-dimensional imaging, the difference frequency signal is generated by multiplying the delayed chirped signal with the local oscillator signal. From the perspective of energy utilization, the detection efficiency of the existing technology is low and the ranging range is small because the gain of the detector needs to be modulated at high speed. (2) The existing technology uses broadband amplifiers, mixers and A / D devices, the dynamic range of which limits the dynamic range of the received laser signal, thus limiting the dynamic receiving range of the existing technology. (3) The performance of the laser three-dimensional imaging system realized by the existing technology is greatly affected by the frequency modulation linearity and frequency modulation flatness of the chirped signal.

[0006] Patent application number 202111112299.6, entitled "A LiDAR Detection System," adds a counting sequence generation module compared to the aforementioned prior art. This module converts the photon counting sequence or the accumulated photon counting sequence into an adaptive photon counting sequence or an adaptive accumulated photon counting sequence, respectively. After processing by a digital multiplier and a preset rule operation module, an accumulated counting sequence is generated. Similarly, target information can be calculated by analyzing the spectral characteristics of the accumulated counting sequence.

[0007] The current method involves analyzing the spectrum of an accumulated counting sequence to determine the target distance. The number of elements in the accumulated counting sequence is equal to the number of pulses M contained in the laser pulse sequence. The larger M is, the higher the spectral signal-to-noise ratio and the smaller the spectral line spacing, thus enabling a smaller ranging error.

[0008] Therefore, in the aforementioned prior art, there is a contradiction between laser emission energy and ranging deviation.

[0009] Therefore, in order to overcome the aforementioned technical problems, it is urgent to develop a more efficient detection method and system that can utilize less laser emission energy to achieve a smaller ranging deviation. Summary of the Invention

[0010] The purpose of this application is to address the shortcomings of the prior art by providing a lidar detection system and method for obtaining distance, so as to achieve a smaller ranging deviation by using less laser emission energy.

[0011] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0012] In a first aspect, embodiments of this application provide a lidar detection system, characterized in that it includes a drive signal generator, which acts on a laser source through a laser modulation drive circuit, and the laser source receives the drive signal to drive the emission of a pulse-type detection laser sequence; an array-type return light receiving module, which receives return light signals reflected by the object being detected within the field of view and generates a return signal; a counting sequence splicing module, which obtains a copy splicing signal based on the return signal; and a processing module, which generates a modulation signal based on the drive signal generated by the drive signal generator, and calculates a distance-related signal with the copy splicing signal according to a preset rule, and outputs the final distance information of the object being detected according to the distance-related signal.

[0013] Optionally, the laser source emits a detection laser sequence within less than one detection period to obtain a return signal. The counting sequence splicing module copies the return signal of the detection laser sequence emitted within the less than one detection period and splices the return signals to obtain the copied spliced ​​signal.

[0014] Optionally, the laser source emits a detection laser sequence within one detection cycle to obtain a return signal. The counting sequence splicing module copies a portion of the return signal of the detection laser sequence emitted within the one detection cycle and performs a calculation with the return signal to obtain the copied spliced ​​signal.

[0015] Optionally, based on the most recently copied splicing signal, the counting sequence splicing module copies a portion of the most recently copied splicing signal and performs operations with it to obtain the copied splicing signal.

[0016] Optionally, the lidar detection system further includes a counting sequence generation module, which generates an adaptive counting sequence based on the returned signal.

[0017] Secondly, the present invention proposes a lidar detection system using the first aspect, comprising a drive signal generator that acts on a laser source through a laser modulation drive circuit, the laser source receiving the drive signal and driving it to emit a pulsed detection laser sequence; an array-type return light receiving module that receives return light signals reflected by the object being detected within the field of view and generates a return signal; a counting sequence splicing module that obtains a copy splicing signal based on the return signal; and a processing module that generates a modulation signal based on the drive signal generated by the drive signal generator and calculates a distance-related signal with the copy splicing signal according to a preset rule, and outputs the final distance information of the object being detected according to the distance-related signal.

[0018] Optionally, the laser source emits a detection laser sequence within less than one detection period to obtain a return signal. The counting sequence splicing module copies the return signal of the detection laser sequence emitted within the less than one detection period and splices the return signals to obtain the copied spliced ​​signal.

[0019] Optionally, the laser source emits a detection laser sequence within one detection cycle and obtains a return signal. The counting sequence splicing module copies a portion of the return signal of the detection laser sequence emitted within the one detection cycle and performs a calculation with the return signal to obtain the copied spliced ​​signal.

[0020] Optionally, based on the most recently copied splicing signal, the counting sequence splicing module copies a portion of the most recently copied splicing signal and performs operations with it to obtain the copied splicing signal.

[0021] Optionally, it may also include a counting sequence generation module, which generates an adaptive counting sequence based on the return signal.

[0022] The beneficial effects of this application are as follows: This invention provides a lidar detection system, characterized in that it includes a drive signal generator, which acts on a laser source through a laser modulation drive circuit, and the laser source receives the drive signal to drive the emission of a pulsed detection laser sequence; an array-type return light receiving module, which receives the return light signal reflected by the object being detected within the field of view and generates a return signal; a counting sequence splicing module, which obtains a copy splicing signal based on the return signal; and a processing module, which generates a modulation signal based on the drive signal generated by the drive signal generator, and calculates a distance-related signal with the copy splicing signal according to a preset rule; and outputs the final distance information of the object being detected according to the distance-related signal. Through this design, a smaller ranging deviation can be achieved with less laser emission energy. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram illustrating the modular working principle of a detection system provided in this application embodiment;

[0025] Figure 2 A schematic diagram of a detection scheme provided by existing technology;

[0026] Figure 3 This is a schematic diagram illustrating a pulsed detection scheme provided in an embodiment of this application.

[0027] Figure 4 This is a schematic diagram of an array-type receiving module provided in an embodiment of this application;

[0028] Figure 5 This application provides a schematic diagram of the counting sequence results of the return light statistics of an L-time laser emission sequence.

[0029] Figure 6 This is a schematic diagram of a preset rule calculation module provided in an embodiment of this application;

[0030] Figure 7 The embodiments of this application provide a schematic diagram of generating a discrete modulation sequence using a driving signal;

[0031] Figure 8 A schematic diagram illustrating the acquisition of distance-related signals using a preset rule calculation module, provided as an embodiment of this application;

[0032] Figure 9 A schematic diagram illustrating another method for obtaining distance-related signals using a preset rule calculation module, provided as an embodiment of this application;

[0033] Figure 10 A schematic diagram illustrating the acquisition of distance-related signals provided in an embodiment of this application;

[0034] Figure 11 A schematic diagram of a three-dimensional imaging system provided in an embodiment of this application;

[0035] Figure 12 A flowchart for generating an adaptive counting sequence provided in an embodiment of this application;

[0036] Figure 13 A flowchart for generating an adaptive accumulating count sequence provided in an embodiment of this application;

[0037] Figure 14 This is another flowchart for generating an adaptive counting sequence provided in an embodiment of this application;

[0038] Figure 15 A flowchart for generating an adaptive accumulator count sequence based on a pre-generated adaptive correction sequence is provided for embodiments of this application.

[0039] Figure 16 A schematic diagram of a detection system provided in an embodiment of this application;

[0040] Figure 17 A schematic diagram of a detection system provided in an embodiment of this application;

[0041] Figure 18 A schematic diagram illustrating the obtained copy splicing sequence provided in an embodiment of this application;

[0042] Figure 19 A schematic diagram illustrating another obtained copy splicing sequence provided in an embodiment of this application;

[0043] Figure 20 This is a waveform diagram of a three-dimensional imaging process provided in an embodiment of this application. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0046] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0047] The current detection system basically includes: a light source module 110, a processing module 120, and a light receiving module 130. The light source module 110 includes, but is not limited to, semiconductor lasers, solid-state lasers, and may also include other types of lasers. When a semiconductor laser is used as the light source, a vertical-cavity surface-emitting laser (VCSEL) or an edge-emitting semiconductor laser (EEL) can be used. (The term "laser" is used here for illustrative purposes only and is not intended to be specific.) The light source module 110 emits sine waves, square waves, triangular waves, or pulse waves, etc. In ranging applications, lasers with a certain wavelength are often used, such as infrared lasers (ideally near-infrared lasers) at 950nm. The emitted light is projected into the field of view. The object 140 present in the field of view can reflect the projected laser to form return light. The return light enters the detection system and is captured by the light receiving module 130. The light receiving module 130 may include a photoelectric conversion unit. In ITOF ranging, it can obtain delayed reception signals of 0°, 90°, 180°, and 270° using the most commonly used four-phase delay reception. The distance calculation scheme using the four-phase method is illustrated here using the sine wave method as an example. The amplitude of the received signal is measured at four equidistant points (e.g., 90° or 1 / 4λ intervals).

[0048]

[0049] 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 bivariate arctangent function that can be mapped to the appropriate quadrant, defined as 0° or 180° when A2 = A4 and A1 > A3 or A3 > A1, respectively.

[0050] The distance to the target object is determined by the following formula:

[0051]

[0052] At this point, it is necessary to determine the frequency of the emitted laser to calculate the distance, where c is the speed of light. Here, f is the phase angle (measured in radians), and f is the modulation frequency. The above scheme achieves distance detection of objects within the field of view. This scheme is called the four-phase delay scheme for obtaining detection results. Of course, the receiving module generates different information through photoelectric conversion. In some cases, a two-phase scheme of 0° and 180° is also used to acquire information about the detected object. Some literature discloses a three-phase scheme of 0°, 120°, and 240° to obtain target information, and some literature even discloses a five-phase difference delay scheme. This invention does not specifically limit this.

[0053] In DTOF ranging, since the pixel unit of the array sensor is a SPAD (single-photon avalanche photodiode) device, it operates in Geiger mode. In Geiger mode, the avalanche photodiode absorbs photons and generates electron-hole pairs. Under the action of the strong electric field generated by the high reverse bias voltage, the electron-hole pairs are accelerated, thereby gaining enough energy. Then they collide with the crystal lattice, forming a chain effect. As a result, a large number of electron-hole pairs are formed, triggering the avalanche phenomenon, and the current increases exponentially. Theoretically, the gain of a SPAD is infinite, and a single photon can saturate its photocurrent. Therefore, SPAD is the preferred choice for high-performance single-photon detection systems. The ranging principle is actually very simple: the light source emits pulsed laser light with a certain pulse width, such as a few nanoseconds. The pulsed laser light is reflected back from the target and returns to the array-type receiving module of the SPAD in an avalanche state. The detection unit in the avalanche state can receive the returned signal. After processing by the processing module, the distance between the detection system and the target can be output, thus completing the detection. In order to obtain a highly reliable result, tens of thousands of laser pulses can be emitted. The detection unit obtains a statistical result. By processing the statistical result, a more accurate distance can be obtained. Table 1 below shows the applicant's comparison of two commonly used ITOF ranging methods and DTOF ranging methods. As can be seen from the comparison in Table 1, these two commonly used time-of-flight ranging schemes have certain limitations, and a new detection method needs to be developed to obtain more accurate and interference-resistant results.

[0054] Table 1. Comparison of ITOF and DTOF ranging methods

[0055]

[0056]

[0057] Figure 2This invention discloses a scheme for acquiring information such as the distance to a detected object using an incoherent (direct detection) method. A drive signal generator produces a drive signal, which can be a signal with a marking function, such as a signal with a gradually increasing or decreasing period. Alternatively, a drive signal with certain characteristics and marking functions can be obtained through specific functions or internal algorithms. A chirped signal is used as an example here, but the actual implementation is not limited to this signal. The drive signal is applied to a laser emitter (here, a continuous wave laser) through a laser modulation circuit, emitting a detection laser with a similar pattern to the drive signal. After reflection from the detected object within the field of view, a returning laser signal is formed. Due to the difference in distance between the detected object and the target within the field of view, different areas of the optical receiving module can obtain delayed return optical signals. The delayed start signal obtained by photoelectric conversion in the receiving module is then amplified by a bandwidth amplifier. Subsequently, the output signal is correlated with the drive signal inside the mixer to obtain the mixed output signal. The signal processor processes the mixed output signal to obtain the difference frequency signal. The signal processor may include a low-pass filter circuit to filter out noise interference and obtain the truly useful difference frequency signal. The difference frequency amplifier can amplify the filtered difference frequency signal to obtain a difference frequency signal with strong anti-interference capability and more realistic signal. Finally, it is converted into a digital signal by an A / D converter. The converted digital difference frequency signal is transmitted to the time-frequency domain conversion module, which can obtain the spectrum of the difference frequency signal through time-frequency domain conversion. Finally, the detection result, such as the speed and distance of the detected object, is identified by the characteristics of the spectrum, such as peak characteristics. Of course, in order to ensure that the signal converted by the frequency domain meets the detection requirements, the time-frequency domain conversion module also includes a threshold detection unit and an information calculation unit, etc. Figure 2 In this example, we will further explain using a chirped signal generator as the driving signal generator. The chirped signal generator produces two chirped signals: one is used as the local oscillator signal of the mixer, and the other is sent to the laser modulation driving circuit, so that the laser power emitted by the continuous wave laser changes according to the following rule:

[0058] P t (t)=P t0 [1+m t cos(2πf0t+πkt 2 +θ0)],t∈[0,T] (3)

[0059] In the formula, P t0 m is the average emission power of the laser. t θ is the transmit modulation depth; f0 is the chirp signal start frequency; t is time; k is the frequency modulation slope and k = B / T (B is the chirp signal bandwidth and T is the chirp signal period), and θ0 is the initial phase.

[0060] The receiving optical system focuses the laser signal reflected from the target onto a photodetector. After photoelectric conversion, a delayed chirped signal is obtained. This signal is amplified and mixed with the local oscillator signal. After low-pass filtering, a difference frequency signal is obtained. The delayed chirped signal is as follows:

[0061] A r (t)=A r0 [1+m t cos(2πf0(t-τ)+πk(t-τ) 2 +θ0+φ0)], t∈[τ,T+τ] (4)

[0062] In the formula, A r0 φ is the average amplitude of the delayed chirped signal; φ0 is the additional phase introduced by the target reflection; τ = 2R / c (R is the relative distance to the target, c is the speed of light in vacuum) is the time it takes for the laser to travel to and from the target and the rangefinder.

[0063] The local oscillator signal is:

[0064] A LO (t)=A LO0 [1+m LO cos(2πf0t+πkt 2 +θ LO )],t∈[0,T] (5)

[0065] In the formula, A LO0 The average amplitude of the local oscillator signal is m. LO θ represents the modulation depth of the local oscillator signal. LO This is the initial phase of the local oscillator signal.

[0066] The difference frequency signal is:

[0067]

[0068] In the formula, A IF The difference frequency signal amplitude, This represents the phase of the difference frequency signal.

[0069] The difference frequency signal is amplified and then converted to digital value (A / D). Its spectrum is then obtained through Fast Fourier Transform (FFT). Threshold detection is performed on the spectrum to obtain the frequency of the difference frequency signal.

[0070]

[0071] Based on the relationship between the difference frequency signal frequency and the relative distance to the target, the relative distance to the target is obtained as follows:

[0072]

[0073] While this type of incoherent detection technique can, to some extent, compensate for some of the shortcomings of ITOF, DTOF, and even coherent detection methods, the aforementioned existing techniques still have the following limitations in detection:

[0074] (1) As can be seen from the principle of incoherent chirped signal amplitude-modulated continuous wave laser three-dimensional imaging, the difference frequency signal is generated by multiplying the delayed chirped signal with the local oscillator signal. From the perspective of energy utilization, since the difference frequency signal is converted from digital to digital (A / D), the energy of the difference frequency signal within the A / D sampling interval is not utilized. Furthermore, since the energy of the delayed chirped signal is proportional to the energy emitted by the continuous wave laser, the average laser emission power of the existing technology (incoherent chirped signal amplitude-modulated continuous wave laser three-dimensional imaging) is relatively high, and the ranging range is relatively small.

[0075] (2) By Figure 2 As can be seen from the description of the system's working principle, the existing technology uses devices such as broadband amplifiers, mixers, and A / D converters. The dynamic range of these devices limits the dynamic range of the received laser signal, thereby limiting the dynamic receiving range of the existing technology.

[0076] (3) The performance of laser three-dimensional imaging systems achieved using existing technologies is greatly affected by the frequency modulation linearity and frequency modulation flatness of the chirped signal.

[0077] Due to the technical problems and data processing complexities and large data volumes inherent in existing incoherent detection methods, the inventors of this invention propose an improved detection method and system, such as... Figure 3As shown, the system uses a pulsed laser, so the emitted active probe laser is a pulsed laser sequence segment composed of pulse sequences. The system's drive signal generator produces a drive signal, which can be a chirped signal similar to the previous example, or other types of drive signals. The essential characteristic of this drive signal is that it modulates the emitted laser to obtain an emitted light signal with identifiable characteristics. The drive signal acts on the pulsed laser through a laser modulation drive circuit. The laser can utilize at least some characteristics of the drive signal, such as the total period of the drive signal as the period of the pulse sequence segment. Individual pulses within the pulse segment can be selected with the same or similar peak values ​​and peak durations, or the amplitude information of the drive signal can be used as the peak value basis of the pulse sequence. In this case, the peak values ​​contained in the pulse sequence can be different. Furthermore, the decreasing or increasing pattern of small periods within the drive signal segment can be used as the basis for the pulse triggering probability within the emitted laser segment, thereby generating non-equidistant pulsed laser segments, etc. The specific implementation scheme of the pulsed laser segment emitted by the pulsed laser source is not limited here. The reflected light from the object within the field of view generates a return light signal, which is received by the photodetector to form a photon counting sequence. At this time, the preset rule operation module included in the processing module generates a discontinuous modulation sequence Y using the driving signal. On the other hand, it can obtain a distance-related signal by operating the photon counting sequence and the modulation sequence Y according to the preset rules. The distance-related signal is then processed by the time-frequency domain conversion module to obtain a spectrum signal converted from the distance-related signal. Then, using the characteristics of the spectrum signal, such as peak characteristics (including the highest peak information, the second highest peak information, or the peak information in the region of interest, etc.), the output includes distance information of the object being detected, and may also include velocity information, etc., without specific limitations. Similarly, for pulse-type discontinuous detection schemes, the time-frequency domain conversion module includes a unit that can perform time-frequency domain conversion processing, which can perform operations such as wavelet operation, piecewise FFT, FFT, chirp-Z operation, DFT, etc. Of course, the specific algorithm implementation will not be described in detail here, but is only exemplified. Of course, the time-frequency domain conversion module may also include a threshold detection unit and / or an information calculation unit, which is also not limited here.

[0078] The optical receiver module can be adopted as follows: Figure 4The array-type receiving module shown includes pixel units 410 composed of diodes. In actual implementation, the active region of the array-type receiving module can be composed of M*N pixel units, and the number of pixel units can be in the tens of thousands or even hundreds of thousands, etc., which is not limited here. The array-type receiving module can include a lens part 4301 and a detection unit substrate part 4302. The lens part 4301 includes multiple lens units, which can be composed of microlens units with a predetermined curvature. Of course, in order to ensure the maximum utilization of the returned light, the lens part can also include a structure with more than one layer. The specific implementation scheme is not limited here. In a more preferred case, the substrate part 4302 can be disposed on the lens part. The focal plane position corresponding to 4301 ensures that the detection pixel unit can acquire accurate return light information to the maximum extent. In this case, the lens of the lens part 4301 can construct an optical channel, so that the signal received by the photosensitive part of the detection unit is near the corresponding focal position. The base part 4302 of the detection unit contains an array of photosensitive pixels arranged in an array. In order to meet the requirements of discontinuous detection, the diodes of the photosensitive pixel units can be single-photon avalanche diode arrays (SPADs) with single-photon sensitivity, or Geiger mode detector unit arrays (APDs), or array detectors composed of photon counting detection pixel units with linear amplification factor, etc., which are not limited here. Since the signal directly output by the detector array of the present invention is a photon counting sequence, the direct output and transmission of digital signals are realized. The preset rule operation module uses the driving signal as the model to obtain the modulation sequence Y, which is also a discontinuous sequence signal, or even directly obtains the digitized modulation sequence Y. Neither of them are analog signals similar to those in the prior art. Therefore, there is no need to go through A / D analog-to-digital conversion and the relevant operations are directly performed in the preset rule operation module.

[0079] Here, we will still use a chirped signal generator as an example for illustration. On one hand, the chirped signal generator produces a chirped signal as a modulation sequence Y. This modulation sequence can be the discretization of the continuous signal in the example mentioned above, and finally converted into a digital modulation sequence signal. Here, the laser emission period is chosen to be the chirped signal period T (that is, the total duration within the emitted laser segment is chosen to be the periodic characteristic of the chirped signal). On the other hand, the chirped signal generator controls the laser modulation drive circuit to generate a pulsed laser drive signal. The pulsed laser drive signal controls the pulsed laser to emit a laser pulse sequence. The emitting optical system projects the laser pulse sequence onto the target area. The energy of each laser pulse in the laser pulse sequence is equal. This is just an example of one case. The receiving system includes a receiving optical system, a photodetector, a digital correlator, a digital integrator and accumulator, etc. The receiving optical system focuses the laser pulse sequence reflected back from the target onto the photodetector. The photodetector starts detecting when the laser pulse sequence is emitted, and obtains the laser pulse sequence. To minimize the computational load in subsequent calculations, the photon count results within the emission cycle are first obtained by illuminating the scene within the field of view using a sequence of L emitted pulses (where L is an integer greater than or equal to 1). More optimally, to obtain more accurate detection results, L can be in the hundreds or thousands, etc., without limitation. Of course, to ensure data accuracy or efficient and fast computation, it is not limited to statistically analyzing all L detection results. Instead, a statistically analyzed photon count sequence X can be generated using the excitation information from fewer than or equal to L returned light pulses. For example, the following scenario illustrates an exemplary scheme for generating and constructing the statistically analyzed photon sequence X: L (L is a positive integer and L≥1) cumulative detections are performed on the laser pulse sequence reflected back from the target. Each cumulative detection includes M (M is a positive integer and M≥1) detection pulses. The photon count result obtained from the i-th (i is a positive integer and 1≤i≤M) detection pulse in the d-th (d is a positive integer and 1≤d≤L) cumulative detection is x. di Thus, the basic counting sequence X, composed of the counting results of M probe pulses, is obtained as follows:

[0080]

[0081] First, perform L cumulative probes to obtain the basic counting sequence X (X consists of L X's) after L cumulative probes. d (The summation), then multiply X and Y to get Z (Z is L Z). d (Accumulate Z), and then perform segmented accumulation on Z to obtain S.

[0082] The above steps can be expressed in principle as follows: Figure 5The scheme, where the single-emission laser sequence is shown at the top, contains M probe pulses in each emission. The laser source outputs L pulse laser sequences in L times. The detection module obtains the trigger information of the return light from the probe light emitted no more than L times to obtain the statistical photon count sequence, as shown in Equation 9. The final constructed statistical photon count sequence is as follows. Figure 5 The result shown at the bottom.

[0083] The preset calculation module can include, for example: Figure 6 The structure includes a digital multiplier unit and a digital integrator-accumulator unit. Through the multiplier unit and digital integrator-accumulator unit included in the preset operation module, it can achieve self-adaptation to the scene within the detection field of view. Furthermore, it can adaptively adjust the maximum detection distance to achieve self-adjustment of detection accuracy as the scene changes. It can also perform correlation operations between signals through the multiplier unit, thereby improving the system's anti-interference capability. That is, it can be obtained according to the following example: the aforementioned statistical photon count sequence X of the returned light was obtained from L pulse light emissions. Figure 7 This diagram illustrates the generation of a discrete modulation sequence Y using a driving signal. The driving signal is expressed as a function f(x). A discrete modulation sequence Y, similar to the driving emitted laser pulse, is obtained using a discretization scheme. The single-emission laser sequence contains M pulsed laser excitation high-value units, and the modulation sequence also contains N pulsed high-value units. The modulation signal is a discontinuous modulation sequence generated by the driving signal generator according to a similar rule to the emitted light pulse sequence, as shown in Equation 10 below.

[0084] Y{y i |y i =f(i)i=1, 2,...,N} (10)

[0085] After obtaining the statistical photon count sequence and modulation sequence excited by the returned emitted light, the preset rule operation module can perform correlation operations on the two sets of sequences according to the units within the module, thereby obtaining the correlation operation results of the two sets of sequences. Figure 8 and Figure 9 Two different schemes are illustrated respectively, according to Figure 8 The computational scheme can perform multiplication operations on the statistical photon counting sequence and the modulation sequence, that is, it can use a digital multiplier to obtain the modulation counting sequence Z. d :

[0086] Z d ={z di |z di =x di ·y i ,i=1,2,...,N} (11)

[0087] After the multiplication unit completes its calculations, the digital integrator accumulator performs segmented accumulation on the modulation counting sequence. The accumulation interval is the segment within which the accumulation operation is performed. The processing module can set the actual size of the accumulation interval according to certain rules. Performing segmented accumulation of the multiplication result sequence within the effective superposition region within the accumulation interval can achieve signal enhancement while ensuring detection accuracy. The number of superposition units within the effective superposition region is K. Therefore, the final result after performing the segmented accumulation operation is the segmented accumulated counting sequence S. d :

[0088]

[0089] Finally, using a digital integrator accumulator, L segmented accumulator count sequences are accumulated within L (L is a positive integer and L≥d) laser pulse sequence emission cycles to obtain the accumulated count sequence S:

[0090]

[0091] certainly Figure 9 As an alternative approach, referring to the attached diagram, we can derive another scheme for the implementation of the relevant computation module. Each unit within this module first performs a segmented accumulation operation on the sequence. That is, the previously mentioned statistical photon counting sequence X and modulation sequence Y are first divided into effective superposition intervals within the accumulation interval, and then segmented accumulation operations are performed on them respectively. After completion, a multiplication operation is performed on the two sequences. The results produced by the two orders can be different, which is not limited here, but both can contain relevant information related to the physical characteristics of the detected object, such as distance and velocity. The signal processing system includes time-frequency domain transformation, threshold detection, and information decomposition. Time-frequency domain transformation converts the spectrum of the accumulated counting sequence S according to methods such as wavelet operation, segmented FFT, FFT, chirp-Z operation, DFT, etc. Threshold detection detects the peak characteristics of the spectrum of the accumulated counting sequence S, including the highest peak information, the second highest peak information, or peak information within the region of interest, etc. Information decomposition obtains information such as the target's relative distance, relative velocity, and three-dimensional image based on the spectral information of the accumulated counting sequence S.

[0092] Figure 10 This can also be interpreted as a detailed description of another solution for implementing the present invention, in conjunction with... Figure 10To illustrate, the laser source emits a sequence of L pulses. The reflected laser light from the object within the field of view is then received at the receiver, forming a photon statistical result X of the returned light. This X can be the result of L pulses. The modulation sequence is obtained by multiplying the output modulation sequence with the returned photon statistical sequence for each pulse to obtain a modulated statistical sequence Z. Finally, the results are accumulated in segments to obtain the final counting sequence S. This scheme is also one of the schemes protected by this invention. The execution steps are as follows: first, X is obtained using a single pulse sequence. d ,

[0093] X d ={x di |i=1,2,...,N} (14)

[0094] Similar to the aforementioned scheme, a discontinuous modulation sequence Y is obtained, and then X is... d Multiplying by Y gives Z d ,

[0095] Z d ={z di |z di =x di ·y i ,i=1,2,...,N} (15)

[0096] Then for Z d S is obtained by segmented accumulation. d This is similar to the segmented accumulation scheme shown in Equation 13. Of course, this is only an illustrative example of one scenario, and the actual implementation is not limited to this method. The difference from the previous one is that this scheme may require a larger amount of computation. Under the requirement of fast output, a more optimized scheme needs to be used to implement the detection, but this is not a limitation here.

[0097] The photon counting sequence or accumulated photon counting sequence in the above embodiments can be generated not only by the laser pulse sequence received by the photodetector array, but also by the ambient background light received by the photodetector array, including both natural and unnatural background light. Furthermore, when the detector array does not receive photons, the photon counting sequence or accumulated photon counting sequence can be generated solely by the detector array itself, such as dark counting in a Geiger-mode APD photodetector array or counting caused by readout circuit noise. Among these, the photon counting results generated by ambient background light, detector array-specific factors, etc., will reduce the signal-to-noise ratio of the detection system, causing a deterioration in detection performance.

[0098] Since natural background light, such as sunlight, and the counting results generated by the detector array itself usually follow certain statistical laws, these statistical laws can be determined based on the photon counting sequence or the accumulated photon counting sequence. On the other hand, since the generation rules of laser pulse sequences and the photon counting laws generated by them are known, the photon counting statistical laws generated by non-natural background light interference, such as interference light from other detection devices, can be distinguished from the photon counting sequence or the accumulated photon counting sequence. Based on the photon counting statistical laws generated by the ambient background light and the detector array itself, the photon counting sequence or the accumulated photon counting sequence generated by the photodetector array can be corrected, thereby improving the signal-to-noise ratio and detection performance of the detection system.

[0099] To mitigate the aforementioned problems, in some embodiments a counting sequence generation module is added to the receiving system. Its function is to acquire the statistical characteristics of the photon counting sequence or the accumulated photon counting sequence, and generate an adaptive counting sequence or an accumulated adaptive counting sequence according to a preset rule.

[0100] Figure 11 A schematic diagram of a three-dimensional imaging system provided in an embodiment of this application; Figure 11 Compared to Figure 3 An additional counting sequence generation module has been added; the functions of other modules are the same. Figure 3 As shown, it will not be repeated here. Figure 11 The middle counting sequence generation module generates an adaptive counting sequence based on the statistical characteristics of the photon counting sequence and preset rules.

[0101] Figure 12 This is a flowchart illustrating the generation of an adaptive counting sequence provided in an embodiment of this application. In some embodiments, the counting sequence generation module obtains natural background light, such as sunlight, and counting results generated by the detector array itself, based on the photon counting sequence, and generates an adaptive counting sequence accordingly. Specifically, the adaptive counting sequence module generates the adaptive counting sequence based on the photon counting sequence...

[0102] X d ={x di |i=1,2,...,N} (16)

[0103] For X as described in Formula 16 d Summing yields:

[0104]

[0105] Or, regarding X as shown in Formula 16 d The average value is:

[0106]

[0107] Formulas (16) and (17) are used to obtain the characteristics of the photon counting sequence. The summation in formula (16) and the averaging in formula (17) are for illustrative purposes only and are not subject to specific restrictions. Based on the characteristics of the photon counting sequence, an adaptive correction sequence conforming to a certain distribution is constructed, such as an adaptive correction sequence X with a boson distribution, a Poisson distribution, or a Gaussian distribution. dm Here, no restrictions are placed on the specific mathematical distribution. Adaptive correction sequence X dm The variance and mean of the photon counting sequence X d The sum of A d or arithmetic mean These properties exhibit certain specific relationships, such as positive or negative correlation, or certain specific values; no specific limitations are made here. The photon counting sequence X... d With adaptive correction sequence X dm ={x dmi The sequence |i=1,2,...,N} is processed according to a predefined set of rules, thereby changing the photon counting sequence X. d The number of high-value elements in the sequence is used to obtain the adaptive counting sequence X. da For example, calculations can be performed according to the preset rules of formula (19):

[0108]

[0109] The preset rule of formula (19) is equivalent to the adaptive correction sequence X. dm Inserted into photon counting sequence X d The adaptive counting sequence X is obtained. da Obtain X da The subsequent signal processing is the same as in the aforementioned embodiments, and will not be repeated here.

[0110] Figure 13 A flowchart illustrating the generation of an adaptive accumulating count sequence provided in an embodiment of this application. Figure 13 The counting sequence generation module generates an adaptive cumulative counting sequence based on the statistical characteristics of the cumulative photon counting sequence and preset rules.

[0111] In some embodiments, the counting sequence generation module obtains natural background light, such as sunlight, and counting results generated by the detector array itself, based on the photon counting sequence, and generates an adaptive counting sequence accordingly. Specifically, the adaptive counting sequence module calculates the count based on the accumulated photon counting sequence...

[0112]

[0113] Summing the sequence described in formula (20) yields:

[0114]

[0115] Alternatively, the average of the sequences described in Formula 20 can be obtained:

[0116]

[0117] Formulas (21) and (22) are used to obtain the characteristics of the accumulated photon counting sequence. The summation in formula (21) and the averaging in formula (22) are for illustrative purposes only and are not subject to specific restrictions here. Based on the characteristics of the photon counting sequence, a modified sequence conforming to a certain distribution is constructed, such as an adaptive modified sequence X with a mathematical distribution such as a binomial distribution, a Poisson distribution, or a Gaussian distribution. m Here, no restrictions are placed on the specific mathematical distribution. Adaptive correction sequence X m The variance and mean of the sum A or arithmetic mean of the accumulated photon count sequence X. These properties exhibit certain specific relationships, such as positive or negative correlation, or certain specific values; no specific limitations are made here. The accumulated photon counting sequence X and the adaptive correction sequence X... m ={x mi The sequence |i=1,2,...,N} is processed according to a predetermined rule, thereby changing the number of high-value elements in the accumulated photon counting sequence X, resulting in an adaptive accumulated counting sequence X. a For example, calculations can be performed according to the preset rules of formula (23).

[0118] X a ={x ai |x ai =x i +x mi ,i=1,2,...,N} (23)

[0119] The preset rule of formula (23) is equivalent to adding the adaptive correction sequence to the accumulated photon counting sequence X to obtain the adaptive accumulated counting sequence X. a .

[0120] In other embodiments, the variance of the series shown in formulas (20) to (22) and formula (20) can be obtained:

[0121]

[0122] The threshold X is obtained from the same characteristics. H To obtain the threshold X H For example, a threshold can be set. Where λ is a positive integer, without specific limitations. The sequence of accumulated photon counts X is selected based on values ​​greater than a threshold X. HBy analyzing the distribution characteristics of these high-value elements and combining them with the known emission frequency characteristics of the laser pulse sequence, high-value elements generated by non-natural background light interference are identified and eliminated, resulting in an adaptive accumulating counting sequence X. a .

[0123] An adaptive cumulative counting sequence can be obtained by performing calculations according to the preset rules in equation (25):

[0124]

[0125] Obtain the adaptive accumulator counting sequence X a The subsequent processing is the same as in the previous embodiments, and will not be repeated here.

[0126] In the above embodiments, generating adaptive counting sequences in real time enhances the anti-interference effect, but it also increases the implementation difficulty of the imaging system.

[0127] Figure 14 This is another flowchart for generating an adaptive counting sequence provided in this application embodiment. In some other embodiments, the counting sequence generation module can also pre-generate an adaptive correction sequence based on prior information about the counting statistics caused by factors such as natural background light interference (e.g., sunlight), detector array inherent issues, and non-natural background light interference (e.g., interference light from other detection devices). In this implementation, the counting sequence generation module stores the pre-generated adaptive correction sequence, instead of generating the adaptive correction sequence dynamically and in real-time based on the photon counting sequence or the accumulated photon counting sequence. The process for generating the adaptive counting sequence is as follows: Figure 14 As shown, the process for generating the adaptive accumulator counting sequence is as follows: Figure 15 As shown, in Figure 14 and Figure 15 The preset rules described herein may be the same as those in the above embodiments, and will not be repeated here. The subsequent signal processing is the same as in the aforementioned embodiments, and will not be repeated here either.

[0128] Figure 16 This is a schematic diagram of a detection system provided in an embodiment of this application. Figure 16 As shown, it is similar to Figure 3 The difference in the illustrated embodiment is that a counting sequence replication and splicing module is added between the photodetector and the digital multiplier in this detection system; the other modules are the same as... Figure 3 The embodiments shown are the same and will not be described again here.

[0129] Figure 17 This is a schematic diagram of another detection system provided in an embodiment of this application. For example... Figure 17 The illustrated embodiment is similar to Figure 11The difference in the illustrated embodiment is that a counting sequence replication and splicing module is added between the photodetector and the counting sequence generation module in this detection system; the other modules are the same as... Figure 11 The embodiments shown are the same and will not be described again here.

[0130] exist Figure 16 and Figure 17 In the embodiment shown, the counting sequence copying and splicing module copies the photon counting sequence X. d Transform into a copy splicing sequence X c :

[0131] X c ={x ci i = 1, 2, ..., N} (26)

[0132] The digital multiplier yields the modulated counting sequence Zd:

[0133] Z d ={z di z di =x ci ·y i ,i=1,2,...,N} (27)

[0134] The preset rule operation module performs operations on the modulation counting sequence Z. d Perform segmented accumulation to obtain the segmented accumulation counting sequence S. d :

[0135]

[0136] In the formula, N0 is the integer whose value is closest to N / M, and K is an integer and (R max (Maximum detectable distance).

[0137] The preset rule calculation module accumulates the L segmented cumulative count sequences obtained during the L laser pulse sequence emission process to obtain the cumulative count sequence S:

[0138]

[0139] exist Figure 16 and Figure 17 In the illustrated embodiment, the counting sequence copying and splicing module copies the photon counting sequence X. d One or more elements in the sequence, and compare them with the photon counting sequence X. d The concatenated sequence X is obtained by splicing. c . Figure 18 This is a schematic diagram illustrating the obtained copied and spliced ​​sequence provided in an embodiment of this application. Figure 18In the embodiment shown, the emission period of the laser pulse sequence is equal to the chirped signal period T, but each laser pulse sequence consists of... (M is a positive integer) laser pulses constitute ( Figure 7 Each laser pulse sequence consists of M0 = M / 2 = 4 laser pulses, meaning that laser pulses are emitted only during the first half of the chirped signal period. Therefore, during the first half of the chirped signal period, the photon counting sequence obtained by the photodetector when detecting the d-th (d is a positive integer and d ≤ L) laser pulse sequence is X. d Its number of elements is N0 = N / 2:

[0140]

[0141] At this time, the photon counting sequence X d All elements in the sequence are used as a copy concatenation sequence X. c The first N / 2 terms are extracted, and the photon counting sequence X is copied. d All elements in the sequence are used as a copy concatenation sequence X. c The last N / 2 terms in the formula are used to obtain the copy splicing sequence X represented by formula (26). c It has N elements. Figure 18 The illustrated embodiments are for illustrative purposes only and are not limited to emitting laser pulses only within half a cycle. Laser pulses can be emitted at 1 / 3 of a cycle, 1 / 4 of a cycle, and so on. Figure 18 The method of the illustrated embodiment obtains the copied spliced ​​signal.

[0142] Figure 19 This is another schematic diagram of obtaining a copied spliced ​​sequence provided for an embodiment of this application. Figure 16 and Figure 17 The counting sequence copying and splicing module described in the illustrated embodiment can be used to... Figure 19 The illustrated embodiment yields a replicated spliced ​​sequence. Figure 19 In the embodiment shown, the emission period of the laser pulse sequence is equal to the chirped signal period T, and each laser pulse sequence is composed of M = f s • T (M is a positive integer) laser pulses constitute ( Figure 19 Each laser pulse sequence consists of M = 4 laser pulses. The photon counting sequence obtained by the photodetector when detecting the d-th laser pulse sequence (d is a positive integer and d ≤ L) is X. d The number of elements is N. The photon counting sequence X is copied. d Take all elements in the set, and select the first N / 2M (assuming N is divisible by 2M = 8). Figure 19 The N=64 elements shown are related to X d The last N / 2M elements are superimposed; the last N / 2M elements are then combined with X. dThe first N / 2M elements are superimposed to obtain the copy splicing sequence X. c Its number of elements is also N, that is:

[0143]

[0144] In contrast, according to Figure 3 The illustrated embodiments and Figure 11 The method in the illustrated embodiment utilizes a laser pulse sequence containing M pulses to obtain an accumulation counting sequence S containing M elements. Figure 16 and Figure 17 The method of the illustrated embodiment utilizes an accumulated counting sequence S obtained from a laser pulse sequence containing M pulses, the number of which can be greater than M. Since target information is obtained by analyzing the spectral characteristics of the accumulated counting sequence S, if... Figure 3 and Figure 16 The target information obtained by solving the accumulated count sequence S obtained by the method in the illustrated embodiment is compared with the information obtained by using... Figure 16 and Figure 17 The target information obtained by solving the accumulated count sequence S obtained by the method in the illustrated embodiment is basically the same, so the method used... Figure 16 and Figure 17 The method in the illustrated embodiment requires less total laser emission energy and has higher detection efficiency.

[0145] Can be repeated Figure 19 The method in the illustrated embodiment, based on the previous execution result, again superimposes and concatenates some elements from the previous result to obtain a new sequence. This can further improve the ranging accuracy. Figure 19 The embodiments shown are for illustrative purposes only and are not intended to impose specific limitations.

[0146] Figure 20 This is a waveform diagram of a three-dimensional imaging process provided in an embodiment of this application. Figure 20 for Figure 16 The waveform diagram during three-dimensional imaging in the illustrated embodiment is shown. Figure 17 The principle behind the 3D imaging schematic diagram of the illustrated embodiment is similar and will not be repeated here. Figure 16 In the illustrated embodiment, the drive signal generator produces two signals. One signal controls the laser modulation drive circuit, which in turn controls the pulsed laser to emit laser light. After beam shaping and expansion by the transmitting optical system, the laser pulse sequence is projected onto the target area. The laser pulse sequence reflected back from the target is filtered and shaped by the receiving optical system and then focused onto the photodetector. Figure 20The illustrated embodiment provides partial waveform diagrams corresponding to one possible implementation. The emission period of the laser pulse sequence is T, and each period contains M = 4 pulses. During the d-th laser pulse sequence emission period, the photodetector emits pulses T after the first pulse of the laser pulse sequence begins to be emitted. R Within the time interval, i.e., 0≤t≤T R The first detection was performed within the time period, and the photon counting sequence X of the first detection was obtained. d1 Its number of elements is K, and if the maximum detectable distance of laser three-dimensional imaging is R... max Then T R ≥2R max / c (where c is the speed of light in a vacuum), in the first detection, the modulation sequence Y1 also has K elements, and X d1 Multiplying the corresponding element in Y1 yields the modulation counting sequence Z from the first detection. d1 , will Z d1 Summing the elements in S yields S d1 This is used as a segmented cumulative counting sequence S within a certain laser pulse emission cycle. d The first element.

[0147] When T / M≤t≤T / M+T R A second detection is performed within the specified time period. Although no pulse emission occurs during the second detection, the photodetector can still detect the photon counting sequence X from the second detection. d2 Its number of elements is K. In the second detection, the number of elements in the modulation sequence Y2 is also K. X can be... d1 With X d2 Adding the corresponding elements together gives X d2’ , will X d2’ Multiplying the corresponding element in Y2 yields the modulation counting sequence Z in the second detection. d2 It can also make X d2 =X d1 , will X d2 Multiplying the corresponding element in Y2 yields the modulation counting sequence Z in the second detection. d2 , will Z d2 Summing the elements in the matrix yields S. d2 This is used as a segmented cumulative counting sequence S within a certain laser pulse emission cycle. d The second element.

[0148] Similarly, in the third, fifth, and seventh probes, the steps of the first probe are executed accordingly; in the fourth, sixth, and eighth probes, the steps of the second probe are executed accordingly. These steps will not be elaborated further here, and the results for S are obtained respectively. dThe remaining elements are obtained in the segmented cumulative counting sequence S during the d-th laser pulse sequence period. d like Figure 20 As shown in the bottom row. Finally, the corresponding units of the L segmented cumulative counting sequences S1, S2, ..., SL obtained from the L laser pulse sequence periods are added together to obtain the cumulative counting sequence S. By analyzing the spectral characteristics of the cumulative counting sequence S, the target information can be calculated, thereby realizing three-dimensional imaging.

[0149] In summary, in addition to the incoherent chirped signal amplitude-modulated continuous wave laser three-dimensional imaging technology (hereinafter referred to as Technology 1) mentioned above, existing technologies mainly include incoherent sinusoidal / pulse amplitude-modulated laser three-dimensional imaging technology (ITof, hereinafter referred to as Technology 2) and pulsed photon counting laser three-dimensional imaging technology (Dtof, hereinafter referred to as Technology 3). Compared with the above technologies, the present invention has the following advantages:

[0150] (1) Compared with technology 1, the present invention uses pulsed laser for detection, which avoids the problem of wasted laser emission energy during the A / D sampling interval in technology 1, thus greatly improving energy utilization and reducing the average laser emission power;

[0151] (2) Compared with technology 1, the present invention no longer uses broadband amplifiers, mixers and A / D devices in the receiving system, thus avoiding the problem of the above devices limiting the dynamic range of the received laser signal, thereby making the receiving system of the present invention have a larger dynamic receiving range;

[0152] (3) Compared with technology 1, the present invention uses a digitized chirped signal as a modulation sequence in the receiving system and uses a digital multiplier to realize sequence multiplication, thereby reducing the impact of the chirped signal frequency modulation linearity and frequency modulation flatness on the ranging performance.

[0153] (4) Compared with technology 2, the present invention has distance resolution because it uses chirped signals for correlation reception, and can effectively avoid the influence of multipath effect;

[0154] (5) Compared with technology 2, the present invention improves the anti-light interference capability by using correlation reception, Fourier analysis and spectrum detection. Therefore, the ranging performance is less affected by light interference and the laser energy required under the same detection conditions is less.

[0155] (6) Compared with technology 2, the present invention no longer uses A / D and has a larger dynamic reception range;

[0156] (7) Compared with technology 3, the present invention requires the transmission and processing of an accumulation count sequence, rather than a photon count sequence, thus greatly reducing the amount of data transmission;

[0157] (8) Compared with technology 3, the present invention extracts target distance information from the spectrum, reducing the impact of pulse shape distortion on ranging performance;

[0158] (9) Compared with technology 3, the present invention improves the anti-light interference capability by using correlation reception, Fourier analysis and spectrum detection, so the ranging performance is less affected by light interference.

[0159] This invention utilizes multiple direct receptions to form a distance-amplitude spectrum (frequency domain). Over-threshold detection in the frequency domain and the peak value of the spectrum determine the flight time. In specific implementations, the spectrum amplitude threshold can be adaptively set; the peak value can also be accurately determined. The overall scheme is a digital framework structure, which can ensure accuracy through a large number of FFT points. It maintains both quasi-accuracy and precision of detection despite a large computational load. The exposure time is introduced in the form of accumulated charge. Background light interference is suppressed at the algorithmic level through FFT and correlation reception (zero-mean FMCW correlation signal). In terms of energy utilization, the transmitted power is fully received, achieving the highest energy efficiency. The entire system and method solve some of the inherent problems of existing schemes and have broad application prospects and promotional value.

[0160] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0161] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need further definition and explanation in subsequent figures. The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A lidar detection system, characterized in that, It includes a drive signal generator, which acts on a laser source through a laser modulation drive circuit, and the laser source receives the drive signal to drive the emission of a pulsed probe laser sequence. An array-type return light receiver module receives the return light signal reflected by the object being detected within the field of view and generates a return signal; The counting sequence splicing module obtains a copy splicing signal based on the returned signal. The processing module generates a modulation signal based on the driving signal generated by the driving signal generator and calculates a distance-related signal with the copy splicing signal according to a preset rule. The processing module outputs the final distance information of the detected object according to the distance-related signal.

2. The lidar detection system according to claim 1, characterized in that, The laser source emits a detection laser sequence within less than one detection period and obtains a return signal. The counting sequence splicing module copies the return signal of the detection laser sequence emitted within the less than one detection period and splices the return signals to obtain the copied spliced ​​signal.

3. The lidar detection system according to claim 1, characterized in that, The laser source emits a detection laser sequence within one detection cycle and obtains a return signal. The counting sequence splicing module copies a portion of the return signal of the detection laser sequence emitted within the one detection cycle and performs a calculation with the return signal to obtain the copied spliced ​​signal.

4. The lidar detection system according to claim 1, characterized in that, Based on the most recent copied splicing signal, the counting sequence splicing module copies a portion of the most recent copied splicing signal and performs operations with it to obtain the copied splicing signal.

5. The lidar detection system according to claim 1, characterized in that, The lidar detection system also includes a counting sequence generation module, which generates an adaptive counting sequence based on the returned signal.

6. A detection method for distance detection using the lidar ranging system of claim 1, characterized in that, It includes a drive signal generator, which acts on a laser source through a laser modulation drive circuit, and the laser source receives the drive signal to drive the emission of a pulsed probe laser sequence. An array-type return light receiver module receives the return light signal reflected by the object being detected within the field of view and generates a return signal; The counting sequence splicing module obtains a copy splicing signal based on the returned signal. The processing module generates a modulation signal based on the driving signal generated by the driving signal generator and calculates a distance-related signal with the copy splicing signal according to a preset rule. The processing module outputs the final distance information of the detected object according to the distance-related signal.

7. The lidar detection method according to claim 6, characterized in that, The laser source emits a detection laser sequence within less than one detection period and obtains a return signal. The counting sequence splicing module copies the return signal of the detection laser sequence emitted within the less than one detection period and splices the return signals to obtain the copied spliced ​​signal.

8. The lidar detection method according to claim 6, characterized in that, The laser source emits a detection laser sequence within one detection cycle and obtains a return signal. The counting sequence splicing module copies a portion of the return signal of the detection laser sequence emitted within the one detection cycle and performs a calculation with the return signal to obtain the copied spliced ​​signal.

9. The lidar detection method according to claim 6, characterized in that, Based on the most recent copied splicing signal, the counting sequence splicing module copies a portion of the most recent copied splicing signal and performs operations with it to obtain the copied splicing signal.

10. The lidar detection method according to claim 6, characterized in that, It also includes a counting sequence generation module, which generates an adaptive counting sequence based on the return signal.

Images