Light detection and ranging system with doppler shift suppression

Abstract

A LIDAR system to reduce or suppress frequency shifts caused by movement of an object in a scene relative to the LIDAR, comprising: a light source; an input aperture (101); a splitter (2) configured to separate reflected light into a reference channel (4) and a first imaging channel (3); a first imaging light IQ receiver (5) configured to obtain a first interference signal; a reference light IQ receiver (6) configured to obtain a reference interference signal; an imaging oscillator (111) configured to be time coherent with the reflected light; at least one mixer (12) connected to the first imaging light IQ (5) and the reference light IQ (6) and configured to obtain a first intermodulation product having a higher frequency and a related intermodulation product having a Doppler frequency shift scaling thereof.

Description

Technical Field

[0001] The object of this invention is a light detection and ranging (LIDAR) system that enables the reduction or complete suppression of frequency shift (an effect known as Doppler shift) caused by the movement of objects in a scene relative to the LIDAR. Background Technology

[0002] LIDAR devices create a distance map to a target by illuminating it with a laser and using sensors to measure the reflected light. Differences in laser characteristics (including total round-trip time, phase, or wavelength) can be used to create a digital three-dimensional (3D) representation of the target.

[0003] LiDAR is commonly used to create high-resolution maps and is applied in geodesy, geographic information science, archaeology, geography, geology, geomorphology, seismology, forestry, atmospheric physics, laser guidance, airborne laser sweep mapping (ALSM), and laser altimetry. This technology is also used in the control and navigation of some autonomous vehicles.

[0004] Some LiDAR systems utilize so-called coherent detection. In this detection scheme, the light reflected from the sample is mixed with a local oscillator that is coherent with the reflected light. This method has several advantages, such as allowing for optical gains in single-photon sensitivity, and the ability to measure distance using changes in the phase and wavelength of light.

[0005] A common problem encountered when using this type of LIDAR is the frequency shift caused by the movement of objects in the scene relative to the device (this effect is called Doppler shift). Such a frequency shift can be significant relative to the bandwidth of the signal used to measure the correlation characteristics of the object, and can complicate the extraction of such correlation data. This problem becomes particularly important if the relative speed of the object is high, such as in the case of vehicles, airplanes, or satellites.

[0006] This frequency shift is variable, often unknown, and can significantly extend the bandwidth of the detected signal. In the case of ground vehicles, relative speeds can reach 300 km / h and higher. This relative speed corresponds to a Doppler frequency shift of 54.0 MHz with an illuminance of λ = 1.55 μm. This variable frequency shift complicates the electronic readout and signal processing chain of systems that rely on coherent detection of the object signal.

[0007] Even if the signal chain remains manageable for a small number of channels, it still increases the cost, size, and complexity of the final LIDAR system. Furthermore, it presents a major obstacle to the practical implementation of multi-channel coherent LIDAR systems with a large number of inputs.

[0008] Several methods have been developed to address this issue, one of which is to use non-uniform sampling or other compressed sensing schemes to reduce the total data rate of the signal.

[0009] In general, all developed methods share the same drawbacks: complex electronic readout circuitry and generic signal processing chains, which make them expensive, large in size, and often difficult to implement and scale for multi-channel structures with a large number of channels. Summary of the Invention

[0010] The LIDAR system object of this invention describes a modification of a coherent LIDAR system utilizing one or more input apertures, and its implementation is simple. The purpose of this invention is to reduce or completely eliminate the frequency shift (this effect is called Doppler shift) caused by the movement of objects in the scene relative to the LIDAR.

[0011] In this invention, reducing or eliminating frequency shift is accomplished by measuring the Doppler frequency shift signal in a reference channel and then using the mathematical properties of signal mixing in the time domain to shift the frequency of one or more imaging channels to eliminate or reduce the Doppler frequency shift.

[0012] Specifically, the LIDAR system of the present invention with suppressed Doppler frequency shift includes at least one light source configured to emit a first light aimed at an external object. The first light is diffusely or specularly reflected on the object and then received (and thus is reflected light) in at least one input aperture.

[0013] The reflected light can then be separated in a splitter located after at least one input aperture, the splitter being configured to separate the reflected light into a reference channel and at least one first imaging channel.

[0014] Then, a portion of the separated reflected light is guided through at least a first imaging channel to a first imaging light in-phase and quadrature (IQ) receiver associated with the first imaging channel. The first imaging light IQ receiver is configured to obtain a first interference signal comprising a first in-phase component and a first quadrature component.

[0015] Additionally, another portion of the reflected light is guided through the reference channel to a reference light IQ receiver associated with the reference channel. The reference light IQ receiver is configured to obtain a reference interference signal comprising a reference in-phase component and a reference quadrature component.

[0016] At least the local optical oscillator is associated with the first imaging light IQ receiver and the reference light IQ receiver, and is configured to be temporally coherent with the reflected light.

[0017] Finally, in one embodiment, the system includes at least one mixer. The mixer is connected to a first imaging light IQ receiver and a reference light IQ receiver and is configured to obtain a first intermodulation product with a higher frequency and a related second intermodulation product with its Doppler shift scaling or complete cancellation.

[0018] The system described above is one possible embodiment of the present invention. However, the system may include a reference aperture and multiple input apertures, or a reference channel and multiple imaging channels associated with one or more input apertures. The system may also include a single local optical oscillator associated with all optical IQ receivers, or a reference local optical oscillator associated with a reference optical IQ receiver and an imaging local optical oscillator associated with an imaging optical IQ receiver, or a reference local optical oscillator associated with a reference optical IQ receiver, and multiple imaging local optical oscillators (each imaging local optical oscillator associated with one or more imaging optical IQ receivers).

[0019] The system may also include an optical amplitude and / or phase modulator applied to the imaging local optical oscillator, such that the generation of intermodulation products occurs directly at the photodetector without the need for electronic mixing. Attached Figure Description

[0020] To supplement the description and to aid in a better understanding of the features of the invention, preferred examples of actual embodiments of the invention are provided, along with a set of drawings that form part of the specification, wherein the following is illustrated using illustrative and non-limiting features.

[0021] Figure 1 An example LIDAR system for imaging an object is shown in an embodiment of the present invention.

[0022] Figure 1A The present invention illustrates an input aperture, an optical IQ receiver, and a scheme for a reference local optical oscillator and an imaging local optical oscillator in an embodiment of the invention.

[0023] Figure 1B An alternative implementation of the present invention is shown, wherein 2x4 multi-mode interference (MMI) is used for the optical IQ receiver.

[0024] Figure 2 This invention illustrates a scheme for a LIDAR system with a reference channel and an imaging channel in an embodiment of the present invention.

[0025] Figure 3 An embodiment of the present invention illustrates a scheme for a LIDAR system having an imaging channel array and a reference channel, wherein orientation information is encoded in the relative phase between them.

[0026] Figure 4 A scheme for a LIDAR system according to an embodiment of the present invention is shown, which has multiple input apertures and an amplitude modulator for directly mixing reference signals on a photodetector.

[0027] Figure 5 Two schemes for the Gilbert cell are shown, one of which includes a photodetector to enable direct multiplication of the differential photocurrent.

[0028] Figure 6 An integrated scheme for a Gilbert cell using switched capacitors is shown. Detailed Implementation

[0029] With the help of Figures 1 to 6 The preferred embodiments of the present invention are described below.

[0030] This invention relates to a LIDAR system, for example Figure 1 The LIDAR system (100) shown is included. The LIDAR system (100) includes at least one light source (102) configured to emit light (110) aimed at an external object (108). The light is reflected from the object (108), and the reflected light (112) is received by a light receiving unit (104). More specifically, in a first embodiment of the invention, light is received at a reference input aperture (103) and an imaging input aperture (101), as discussed in more detail with reference to the following figures. The light source (102) may represent a single light source or multiple light sources with different wavelengths. In some embodiments, the light source (102) includes one or more laser sources.

[0031] The LIDAR system (100) also includes a processor (106) configured to receive electrical signals from the light receiving unit (104) and perform one or more processes using the received electrical signals. For example, the processor (106) can use the received electrical signals to reconstruct a 3D image including an object (108). As described above, when attempting to capture reflected light (112), the movement of the object (108) (indicated by the upward arrow) causes a frequency shift due to the movement of the object (108) relative to the LIDAR system (100), an effect known as Doppler shift.

[0032] like Figure 1A As shown, the reference input aperture (103) enables the LIDAR system (100) to generate a reference interference signal between the reflected light from the object (108) and the reference oscillator (113). This reference interference signal is then used to modulate the interference signal formed between the reflected light (112) from the object, collected by the imaging input aperture (101), and the imaging oscillator (111).

[0033] In any given implementation, such as in Figure 1A As shown in the embodiments, one or more of the reference input aperture (103) and the imaging input aperture (101) may overlap, and the reference oscillator (113) and the imaging oscillator (111) may also overlap.

[0034] According to some embodiments, the reference oscillator (113) and the imaging oscillator (111) exhibit some degree of temporal coherence with the reflected light (112), making it possible to process the resulting interference signal at electrical frequencies.

[0035] In one example, such as Figure 1A As shown, the system includes a single input aperture (101, 103). In this case, the system includes a light source (102) that emits light aimed at the target (108). The light is reflected from the target and enters the system through the input aperture (101, 103). The reflected light (112) is split into a first imaging channel (3) and a reference channel (4) by a separation element (2). The separation element (2) can be a 1×2 separator.

[0036] According to some embodiments, at least two channels (e.g., a reference channel (4) and a first imaging channel (3)) are affected by object movement via Doppler shift in substantially the same way, while the non-Doppler information-carrying modulation remains different between them. This allows the signals on the two channels to be combined in a manner that eliminates or greatly reduces the Doppler shift while restoring the information-carrying modulation.

[0037] like Figure 1A As shown, the first imaging channel (3) is fed to the first imaging optical IQ receiver (5), and the reference channel (4) is fed to the reference optical IQ receiver (6). The first imaging optical IQ receiver (5) is associated with an imaging oscillator (111), and the reference optical IQ receiver (6) is associated with a reference oscillator (113). According to some embodiments, within the optical IQ receivers (5, 6), the two oscillators (111, 113) are fed through a 90° mixer that generates the phase shift between the in-phase component (7, 9) and the quadrature component (8, 10) of each channel.

[0038] In other embodiments, the IQ receivers (5, 6) are implemented using 2x4 MMI couplers, which are designed to provide phase shift between each of the four outputs (7, 8, 9, 10) and two inputs (3, 4). Figure 1BAn embodiment is shown in which the first imaging light IQ receiver (5) is a 2x4 MMI coupler fed by the first imaging channel (3) and the imaging oscillator (111), and the reference light IQ receiver (6) is a 2x4 MMI coupler fed by the reference channel (4) and the reference oscillator (113).

[0039] In one embodiment, the imaging oscillator (111) performs wavelength scanning according to a standard frequency-modulated continuous wave (FMCW) scheme, while the reference oscillator (113) maintains its wavelength constant. According to some embodiments, the reflected light (112) has a component coherent with both components in the oscillators (111, 113). Therefore, either the illumination is a combination of the two components, or the two components share a common source with the illumination, ensuring mutual coherence.

[0040] According to some embodiments, a first imaging light IQ receiver (5) is associated with a first imaging channel (3) and configured to obtain a first interference signal including a first in-phase component (7) and a first quadrature component (8). A reference light IQ receiver (6) is associated with a reference channel (4) and configured to obtain a reference interference signal including a reference in-phase component (9) and a reference quadrature component (10).

[0041] Both interference signals will be affected by Doppler in essentially the same way (with slight differences in some embodiments due to the different wavelengths). However, only the first interference signal associated with the imaging oscillator (111) carries information about the distance between the object (108) and the LIDAR system (100) in its interference frequency.

[0042] like Figure 2 As shown, the first interferometric signal and the reference signal are mixed in at least one mixer 121-124 (sometimes collectively referred to as 12) to generate two intermodulation products. For example, the mixing produces a first intermodulation product with a higher frequency that can be discarded, and an output intermodulation product (16) with a lower frequency. The Doppler shift of the output intermodulation product is significantly scaled, and it provides the possibility of bringing ranging and amplitude information to the baseband, thereby minimizing the sampling frequency and electronic readout complexity.

[0043] To illustrate, as discussed herein, a first interference signal and a reference interference signal are derived for this implementation. It is assumed that the imaging input aperture (101) and the reference aperture (103) are substantially in the same position, except for a possible relative phase shift if the imaging input aperture (101) is part of the array. Using two wavelengths (with associated wavenumbers and angular frequencies, respectively...) and When two light sources with equal amplitude A illuminate the scene equally, the light signal at a distance x from the light source is:

[0044] Here, it is assumed that the first wavelength of the first light source in the LIDAR system experiences a constant. Linear frequency modulation. If the object reflecting the light emitted by the first light source is a single diffuse reflector, then at a distance... The object at that location has an intensity reflectivity in the direction of the input aperture (101). And the relative velocity in the direction between the input hole (101) and the object. The reflected field of the light collected at the input aperture (101) is:

[0045] Where, if an array of apertures exists, then i is the index of the input aperture. The Doppler frequency shift is represented in the formula. and As can be seen in the item, the frequency of the reflected light is corrected.

[0046] To calculate the interference signal in the optical IQ receivers (5, 6), for simplicity, it is assumed that the two wavelength components of the reference oscillator and the imaging oscillator (111, 113) have uniform amplitude:

[0047]

[0048] After passing through the imaging light IQ receiver (5) and the reference light IQ receiver (6), the first interference signal and the reference interference signal are respectively:

[0049]

[0050] Among these, the beating product, where the difference in optical angular frequency persists, would be a very high frequency for electrical standards once detected. For example, assuming the two wavelengths of light from a source differ by 0.1 nm at a wavelength of 1.55 μm, the frequency of the intermodulation product would be 12.5 GHz.

[0051] Conversely, when the local oscillator and the frequency of the reflected light are equal, the beat frequency product is demodulated to a lower frequency, which is derived from the frequency difference between the transmitted and received phase modulation frequencies plus or minus the Doppler shift.

[0052] According to some embodiments, for the typical speed of ground vehicles, the Doppler frequency shift will be equal to or less than 100 MHz, thus allowing for the suppression of higher mixing terms (including mixing terms related to optical angular frequency differences) using a low-pass filter. Therefore, as... Figure 2 As shown, the first set of low-pass filters (13) can be associated with optical IQ receivers (5, 6) to filter the first in-phase component (7), the first quadrature component (8), the reference in-phase component (9), and the reference quadrature component (10).

[0053] The low-frequency components of the interference signal are provided as follows: 3.

[0054] 4.

[0055] Depth and velocity information are encoded in the frequencies (and phases) of the two photocurrents. By focusing only on the frequency information, it was observed that... and The frequencies are:

[0056]

[0057] These two frequency shift components scale differently with changes in line speed. Modulation constant The distance-derived frequency is directly affected. However, the Doppler shift remains independent and determined by the nature of the scene. Since the Doppler shift can reach frequencies of tens of megahertz, it typically requires fast acquisition electronics, which can increase the cost of the system. These video frequencies can also be a problem when scene detection is magnified using multiple parallel imaging channels (3).

[0058] However, the difference between these two frequencies is:

[0059] According to some embodiments, if the two wavelengths of light emitted by two light sources are chosen to be close to each other (e.g., 0.1 nm apart at a wavelength of 1.55 μm), the difference in Doppler frequency shift is significantly reduced (for a wavelength of 50 m / s). (Reduce by 2kHz).

[0060] However, it is worth noting that the two wavelengths can be equal. In this case, the Doppler frequency shift can be completely suppressed while preserving the frequency shift caused by FMCW. This method simplifies the optical system and the associated electro-optical circuitry.

[0061] If the two wavelengths are equal, the Doppler shift can be completely suppressed, shifting the signal frequency back to baseband. In systems requiring numerous input apertures (101), this lower Doppler frequency enables significant reductions in line rate, data throughput, and hardware complexity. If the Doppler frequency remains constant, then the Doppler shift should be eliminated from the FMCW modulation for measurement. One example of achieving this is to vary K in the FMCW frequency sweep over time (e.g., alternating its signs) and compare the resulting electrical shift between the two modulation slopes.

[0062] One example method for subtracting the frequencies obtained from the optical IQ receivers (5, 6) is to multiply one current by the complex conjugate of the other current. Standard mixing techniques can be applied. This can be done in the digital or analog domain and potentially based on an interference signal as shown below:

[0063] In one embodiment, such as Figure 2 As shown, this can be achieved using one or more mixers 121-124 connected to the outputs of the first imaging light IQ (5) and the reference light IQ (6) or the output of the first low-pass filter bank (13). Each of the four multiplication terms described above contains a frequency difference. The first intermodulation product (low frequency) and the sum including the Doppler frequency The second intermodulation product.

[0064] When the four multiplicative terms are combined, the terms related to the Doppler frequency are eliminated, leaving only the low-frequency intermodulation products (whose frequency is calculated per...). The depth information contained in the product is retained as the output intermodulation product (16).

[0065] According to some embodiments, a second set of low-pass filters (23) is used to filter out the high-frequency components of each multiplication term, thereby retaining only the low-frequency intermodulation products. These low-frequency intermodulation products are located at their frequencies (in terms of per... The output intermodulation product (16) contains depth information. According to some embodiments, the output intermodulation product (16) is amplified using one or more nonlinear amplifiers (25).

[0066] exist Figure 2 In the illustrated embodiment, one or more mixers 121-124 include a first mixer 121 and a second mixer 122. The first mixer 121 is designed to mix a first quadrature component (8) and a reference in-phase component (9) to give a multiplication term. The second mixer 122 is designed to mix the first in-phase component (7) and the reference in-phase component (9), giving the multiplication term. .

[0067] In alternative demodulation techniques, one can process the individual components of the interference signal, namely the first in-phase component (7), the first quadrature component (8), and the derivative of the reference interference signal, as provided by the time derivative module (15), which generates the time derivative of the reference in-phase component (90) and the time derivative of the reference quadrature component (91), and is applicable to FM demodulation techniques that simultaneously perform baseband conversion and demodulation.

[0068] This is particularly useful in embodiments where both the imaging oscillator and the reference oscillator are identical, because in this case, the frequency difference in the multiplication term as described above... Furthermore, the use of time derivatives enables the extraction of depth information from frequency-coded signals into the amplitude of the time-derived signal.

[0069] For example, in the case where the imaging oscillator and the reference oscillator are the same, the operation that can be performed in one or more mixers (121)-(124) is:

[0070]

[0071] Similar to the direct mixing method, in this case, the above four multiplication terms can be generated and combined to retain only the DC component, or alternatively, a second set of low-pass filters (23) can be used to filter out the higher frequency components of each multiplication term and retain only the DC component whose amplitude contains depth and Doppler information.

[0072] To separate Doppler and depth information, K in the FMCW frequency scan can be varied over time (e.g., its symbols can be alternated), and the resulting DC components between the two modulation slopes can be compared.

[0073] The disadvantage of direct FM demodulation is the reflectivity of the object ( The frequency shift and amplitude are mixed in this DC value. According to some embodiments, this can be addressed by demodulating the amplitude separately.

[0074] Alternatively, when the imaging oscillator and the reference oscillator are the same, it can also be obtained from (e.g., by...) Figure 2 The first mixer (121) and the second mixer (122) in the process provide a multiplication term between the signal component and the reference component before the time derivative to obtain the object reflectivity.

[0075] In order to use the direct FM demodulation method Figure 2A time-differentiation module (15) and one or more mixers (121)-(124) are shown, including a third mixer (123) designed to mix the first in-phase component (7) and the time-differentiated reference orthogonal component (91), and a fourth mixer (124) designed to mix the first orthogonal component (8) and the time-differentiated reference orthogonal component (91). Therefore, Figure 2 The embodiments provided in the text provide a demodulation scheme that includes both frequency and amplitude demodulation.

[0076] Figure 3 An implementation is shown in which multiple imaging channels (3) are combined with a common reference channel (4) obtained from reflected light (112) from the same scene, but mixed with a separate light source (a light source of a different wavelength, but coherent with at least a portion of the power collected from the scene).

[0077] Figure 3 The advantage of the scheme shown is that the relative phase difference in the electrical domain (included in the IQ data) between the different imaging channels (3) is maintained after demodulation. This allows the demodulated signals from the imaging channels (3) to be coherently combined in order to recover different orientations.

[0078] For different mixers (in) Figure 3 (collectively referred to as 12), different construction schemes can be used. For example, the mixer can be implemented in the analog domain based on circuits that rely on translinear schemes. One of these circuits could be a Gilbert cell. Figure 5 An example is described in the document. The advantage of this circuit is that it can operate in all four quadrants of the interference signal. According to some embodiments, assuming that the input to the unit is differential and voltage-based, the photocurrent from the aforementioned optical IQ receivers (5, 6) can be amplified to voltage by the transimpedance amplifier (14) and, if appropriate, derived in the analog domain.

[0079] To simplify the Gilbert cell, the photocurrent of a balanced differential pair can be used as the source of the input signal and current bias. This reduces the need for intermediate transimpedance amplifiers and makes the cell easier to replicate for large-scale integration. According to some embodiments, an imaging oscillator (111) mixed with different imaging channels (3) can be generated from a single imaging input aperture (101) and distributed as a voltage signal across the detection array (e.g., the imaging channel) without significant scalability issues.

[0080] To simplify the reading of the cell, such as Figure 6As shown, an integrated scheme with switched capacitors and multiplexed video outputs can be applied. The readout of this switched capacitor can be constructed in the same way as a conventional imaging sensor. For example, the switched capacitors can be organized in columns, and a multiplexing scheme can be used to route analog values ​​to the appropriate ADC circuitry.

[0081] Finally, to provide the required mixing functionality, the amplitude of the optical local oscillator to each imaging channel can also be modulated. If this is done, electronic mixing is not required after light detection, which offers an advantage in terms of system complexity. According to some embodiments, an optical modulator (17) is used to modulate the amplitude of the optical local oscillator, such as... Figure 4 As shown. In one embodiment, the optical modulator (17) is an optical amplitude modulator, whether based on electro-optical absorption, a Mach-Zehnder interferometer, or something else.

[0082] If amplitude modulation leaves a certain degree of phase modulation, a phase modulator can be added in series to ensure constant phase operation and avoid unwanted frequency shifts in the reference channel. Amplitude modulation can also be achieved in different ways, such as through optical amplifiers or laser current modulation.

[0083] In some embodiments, the first in-phase component (7), the first quadrature component (8), the reference in-phase component (9), and the reference quadrature component (10) are multiplied by different versions of the signal and shifted 90° relative to each other to directly obtain the desired mathematical result. To physically achieve this, separately modulated reference signals can be assigned to each output mixer (12). Given that the modulation applied to both channels is also orthogonal in the electrical domain, in some embodiments, they can be added together to the modulated signal, such as... Figure 4 As shown.

[0084] According to some embodiments, the product between the first in-phase component (7) and the first quadrature component (8) or the product between the reference in-phase component (9) and the reference quadrature component (10) produces a high-frequency intermodulation product that can be filtered out.

[0085] According to some embodiments, in order to separate amplitude and distance information, the modulation signal applied to the optical modulator (17) can be switched between different modes (with or without a time derivative), enabling the alternating recovery of depth information and / or signal amplitude. This time-domain multiplexing can be applied to implementations using integrators synchronized with the switching of the demodulated signal, or it can be replaced by other multiplexing schemes (frequency-domain multiplexing, code multiplexing, etc.). The demodulated signal can be switched on the imaging channel and the reference channel using a switch (27).

[0086] According to some embodiments, Figure 4 The combination of the two implementation options described above is shown—for the case of a single wavelength, Doppler frequency demodulation via amplitude modulation of the optical reference signal and time multiplexing of amplitude / frequency demodulation.

Claims

1. A LiDAR system for optical detection and ranging with suppressed Doppler frequency shift, wherein, The system includes: - At least one light source (102) is configured to emit a first light. - At least one imaging input aperture (101) and an imaging channel (3) associated with said at least one imaging input aperture (101) are configured to receive input reflected light reflected by a moving object (108) illuminated by said light source (102). - At least one reference aperture (103) and a reference channel (4) associated with said at least one reference aperture (103) are configured to receive reference reflected light reflected by the moving object illuminated by said light source (102). - At least one imaging oscillator (111). - At least one imaging light receiver (5) associated with the at least one imaging input aperture (101) and the at least one imaging oscillator (111) is configured to obtain an interference signal between the input reflected light and the at least one imaging oscillator (111). - A reference oscillator (113), wherein the at least one imaging oscillator (111) is individually modulated relative to the reference oscillator (113). - A reference light receiver (6) associated with the at least one reference aperture (103) and the reference oscillator (113) is configured to obtain a reference interference signal between the reference reflected light and the reference oscillator (113), and - At least one mixer (12) is connected to the at least one imaging optical receiver (5) and the reference optical receiver (6) and is configured to generate an intermodulation product (16) between the interference signal and the reference interference signal, such that the Doppler frequency shift caused by the moving object (108) is eliminated or reduced.

2. The LIDAR system according to claim 1, wherein, The at least one imaging light receiver (5) is an optical in-phase orthogonal IQ receiver configured to obtain an interference signal between the input reflected light and the at least one imaging oscillator (111), the interference signal including a first in-phase component (7) and a first quadrature component (8), and the reference light receiver (6) is an optical IQ receiver configured to obtain a reference interference signal, the reference interference signal including a reference in-phase component (9) and a reference quadrature component (10).

3. The LIDAR system according to claim 2 further includes a time derivative module (15) associated with the reference optical receiver (6), the time derivative module (15) being used to perform time derivatives on the reference in-phase component (9) and the reference quadrature component (10).

4. The LIDAR system according to claim 2, wherein, The at least one mixer (12) includes: - A first mixer (121) for mixing the first quadrature component (8) and the reference in-phase component (9), and - A second mixer (122) is used to mix the first in-phase component (7) and the reference in-phase component (9).

5. The LIDAR system according to claim 2, wherein, The at least one mixer (12) includes: - A first mixer (121) for mixing the first orthogonal component (8) and the reference orthogonal component (10), and - A second mixer (122) is used to mix the first in-phase component (7) and the reference orthogonal component (10).

6. The LIDAR system according to claim 2, wherein, The at least one mixer (12) includes: - A third mixer (123) is used to mix the first in-phase component (7) and the time-differentiated reference orthogonal component (91), and - A fourth mixer (124) is used to mix the first orthogonal component (8) and the time-differentiated reference orthogonal component (91).

7. The LIDAR system according to claim 2, wherein, The at least one mixer (12) includes: - A third mixer (123) is used to mix the first in-phase component (7) and the time-differentiated reference in-phase component (90), and - A fourth mixer (124) is used to mix the first orthogonal component (8) and the time-differentiated reference in-phase component (90).

8. The LIDAR system according to any one of claims 4 to 7 further includes a low-pass filter (23) associated with each mixer (12).

9. The LIDAR system according to claim 1, wherein, The reference oscillator (113) and the at least one imaging oscillator (111) share a common source.

10. The LIDAR system according to claim 1, wherein, The at least one reference aperture (103) is the same as the at least one imaging input aperture (101), and the reference channel (4) and the imaging channel (3) are derived therefrom via the separator (2).

11. The LIDAR system according to claim 1, wherein, The wavelength of the reference oscillator (113) remains constant, and the wavelength of the at least one imaging oscillator (111) is scanned according to the standard frequency modulated continuous wave (FMCW) scheme.

12. The LIDAR system of claim 1 further includes one or more low-pass filters (13) associated with the at least one imaging optical receiver (5) and the reference optical receiver (6), the one or more low-pass filters (13) being configured to filter the interferometric signal and the reference interferometric signal.

13. The LIDAR system according to claim 2 further includes a transimpedance amplifier (14) located after the reference optical receiver (6) and the at least one imaging optical receiver (5) and configured to amplify the reference in-phase component (9), the reference quadrature component (10), the first in-phase component (7) and the first quadrature component (8).

14. The LIDAR system according to claim 1 or any one of 4 to 7, wherein, The mixer (12) is a Gilbert unit.

15. A light detection and ranging LIDAR system, comprising: - At least one light source (102) is configured to emit a first light. - At least one imaging input aperture (101) and an imaging channel (3) associated with said at least one imaging input aperture (101) are configured to receive input reflected light reflected by a moving object (108) illuminated by said light source (102). - At least one reference aperture (103) and a reference channel (4) associated with said at least one reference aperture (103) are configured to receive reference reflected light reflected by the moving object illuminated by the light source. - At least one imaging oscillator (111). - At least one imaging light receiver (5) associated with the at least one imaging input aperture (101) and the at least one imaging oscillator (111) is configured to obtain an interference signal between the input reflected light and the at least one imaging oscillator (111). - Reference oscillator (113). - A reference light receiver (6) associated with the at least one reference aperture (103) and the reference oscillator (113) is configured to obtain a reference interference signal between the reference reflected light and the reference oscillator (113), and - An optical modulator (17), connected to the at least one imaging oscillator (111), is configured to apply amplitude or phase modulation to the at least one imaging oscillator (111) using a signal derived from the reference channel (4), such that the intermodulation product (16) between the interference signal and the reference interference signal appears at the output of the at least one imaging optical receiver (5), thereby eliminating or reducing the Doppler shift caused by the moving object.

16. The LIDAR system according to claim 15, wherein, The at least one imaging light receiver (5) is an optical in-phase orthogonal IQ receiver configured to obtain an interference signal between the input reflected light and the at least one imaging oscillator (111), the interference signal including a first in-phase component (7) and a first quadrature component (8), and the reference light receiver (6) is an optical IQ receiver configured to obtain a reference interference signal, the reference interference signal including a reference in-phase component (9) and a reference quadrature component (10).

17. The LIDAR system according to claim 15, wherein, The reference oscillator (113) and the at least one imaging oscillator (111) share a common source.

18. The LIDAR system according to claim 15, wherein, The at least one reference aperture (103) is the same as the at least one imaging input aperture (101), and the reference channel (4) and the imaging channel (3) are derived therefrom via the separator (2).

19. The LIDAR system according to claim 15, wherein, The wavelength of the reference oscillator (113) remains constant, and the wavelength of the at least one imaging oscillator (111) is scanned according to the standard frequency modulated continuous wave (FMCW) scheme.

20. The LIDAR system of claim 15 further includes one or more low-pass filters (13) associated with the at least one imaging optical receiver (5) and the reference optical receiver (6), the one or more low-pass filters (13) being configured to filter the interferometric signal and the reference interferometric signal.

21. The LIDAR system according to claim 16, wherein, The system further includes a transimpedance amplifier (14) located after the reference optical receiver (6) and the at least one imaging optical receiver (5) and configured to amplify the reference in-phase component (9), the reference quadrature component (10), the first in-phase component (7), and the first quadrature component (8).

22. A method for suppressing Doppler frequency shift in an optical detection and ranging LIDAR system, the method using the system of any one of the preceding claims, and comprising the following steps: - Fire the first beam (110) aimed at the moving object (108). - Receive reflected light (112) from the moving object (108). - Obtain the first interference signal between the reflected light (112) and the imaging oscillator (111). - Obtain the reference interference signal between the reflected light (112) and the reference oscillator (113), and - Obtain the intermodulation product (16) between the interference signal and the reference interference signal, such that the Doppler frequency shift caused by the moving object (108) is eliminated or reduced.

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