Dual-frequency microcavity optical frequency comb radar single-detector parallel detection processing method and device

Abstract

The application discloses a dual-frequency microcavity optical frequency comb radar single-detector parallel detection processing method, and belongs to the field of optical precision measurement. The parallel detection processing system comprises two signal microcavity optical frequency combs and a local oscillator microcavity optical frequency comb with a small frequency difference, a signal generator, a circulator, a diffractive optical element, a beam combiner, a balanced detector and a multi-channel data parallel data acquisition and processing module. The signal generator is used for modulating the microcavity optical comb to generate the signal microcavity optical frequency comb and the local oscillator microcavity optical frequency comb with the frequency difference. The coaxial transceiving and comb tooth space separation are realized through the circulator and the diffractive optical element. The single-pixel balanced detector and the acquisition and processing module are used to realize the multi-channel signal parallel acquisition and processing of different comb teeth, and the distance, angle and speed information of a target object are calculated. The application combines the frequency asynchronous sampling of the dual microcavity optical combs and the coherent parallel detection of the single-pixel balanced detector, can simplify the hardware of the frequency modulation continuous wave radar, and saves the number and cost of the detectors.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of optical precision measurement, and relates to a double-frequency-modulation micro-cavity optical frequency comb radar single-detector parallel detection processing method and device. BACKGROUND

[0002] Three-dimensional laser radars have important significance in the fields of machine vision, target recognition, early warning, obstacle avoidance, positioning and tracking. Existing three-dimensional laser radars generally need to be combined by multiple light sources, inertial scanning components, multiple detectors and the like, which poses great challenges to volume, cost and stability.

[0003] The optical frequency comb has the characteristics of wide spectrum and multiple longitudinal modes, the repetition frequency of the micro-cavity optical comb reaches dozens or even hundreds of GHz, the linear frequency modulation of each comb tooth can be realized by cooperating with a signal generator, the spatial separation of different comb teeth can be realized by cooperating with a diffractive optical element, and finally the parallel detection collection and processing of multiple signals can be realized by using a single balanced detector according to the double optical comb asynchronous sampling principle, so that the laser radar system is simplified, the volume is reduced, and the cost is saved. SUMMARY

[0004] In order to realize a laser radar with a single signal light source, no inertial scanning and single-pixel detection processing, the purpose of the application is to provide a double-frequency-modulation micro-cavity optical frequency comb radar single-detector parallel detection processing method and device. The signal generator is used to modulate the micro-cavity optical comb to generate a signal micro-cavity optical comb and a local oscillation micro-cavity optical comb with a repetition frequency difference. The coaxial transceiver and comb tooth spatial separation are realized through a circulator and a diffractive optical element. The single-pixel balanced detector and the acquisition and processing module are used to realize the parallel acquisition and processing of different comb tooth signals, and the distance, angle and speed information of the target object are calculated.

[0005] The purpose of the application is realized by the following technical solutions:

[0006] The double-frequency-modulation micro-cavity optical frequency comb radar single-detector parallel detection processing method disclosed by the application comprises the following steps,

[0007] Step one, the signal micro-cavity optical frequency comb is triangularly linearly swept according to the sweep signal given by the signal generator, and a plurality of signal optical comb teeth are output. The signal optical comb tooth is a pulse signal in the time domain, has comb teeth with equal intervals in the frequency domain, and has the characteristics of the sweep signal of the signal generator.

[0008] Step two, the signal optical comb tooth passes through the optical fiber circulator, then passes through the diffractive optical element, is separated in space, is irradiated onto the measured target at the same time, returns to the diffractive optical element in the original path, is converted into a combined beam A again, and is output through the optical fiber circulator again.

[0009] Step three, the local microcavity optical frequency comb according to the signal generator gives a sweep signal to perform a triangular wave linear sweep, and outputs a plurality of local light comb teeth; the plurality of local light comb teeth are also a pulse signal in the time domain, and have comb teeth with equal intervals, and the signal generator sweep signal characteristics in the frequency domain. However, the repetition frequency of the local microcavity optical frequency comb has a small repetition frequency difference with the repetition frequency of the signal microcavity optical frequency comb.

[0010] Step four, the combined light A of step two and the local light comb teeth of step three enter the beam combiner, the signal light comb teeth and the local light comb teeth are combined, and the beat frequency between different comb teeth is detected by the balanced detector and converted into an electrical signal to obtain an electrical signal C; the distance, angle and speed information of each comb tooth corresponding to the target object are calculated according to the electrical signal C;

[0011] The distance calculation formula is

[0012]

[0013] The angle calculation formula is

[0014]

[0015] The speed calculation formula is

[0016]

[0017] Wherein, n is the serial number of the optical comb tooth, L n is the distance of the target point corresponding to the nth signal light comb tooth, c is the speed of light 3x10 8 m / s, t is the flight time of light, B is the sweep width 50MHz, f u (n) is the upper frequency of the nth signal light comb tooth and the nth local light comb tooth after beat frequency, f d (n) is the lower frequency of the nth signal light comb tooth and the nth local light comb tooth after beat frequency, θ n is the diffraction angle corresponding to the nth comb tooth, i.e. the angle information of the target, λ n is the laser wavelength of the nth signal light comb tooth, d is the slit interval of the diffractive optical element 1μm, m is the spectral order, v n is the speed of the target point corresponding to the nth signal light comb tooth, △f r The repetition frequency difference between the signal microcavity optical frequency comb and the local microcavity optical frequency comb. According to the sweep width, the upper frequency and the lower frequency of the beat comb tooth, the slit interval of the diffractive optical element, the laser wavelength,

[0018] The small repetition frequency difference refers to the repetition frequency difference between 1kHz and 500MHz.

[0019] The application discloses a dual-frequency microcavity optical frequency comb radar single-detector parallel detection processing device, which is used for realizing the dual-frequency microcavity optical frequency comb radar single-detector parallel detection processing method. The dual-frequency microcavity optical frequency comb radar single-detector parallel detection processing device comprises two signal microcavity optical frequency combs and a local oscillation microcavity optical frequency comb with a small frequency difference, a signal generator, a circulator, a diffractive optical element, a beam combiner, a balanced detector and a multi-channel data parallel data acquisition processing module.

[0020] The signal generator outputs a linear frequency modulation triangular wave, modulates the frequency offset of the signal microcavity optical frequency comb and the local oscillation microcavity optical frequency comb, so that each comb tooth is linearly frequency modulated; the signal microcavity optical comb is used as signal light, passes through the circulator and the diffractive optical element, is separated in space and irradiates a target object; after being diffused and reflected, the signal light returns along the original path, passes through the diffractive optical element again, is combined into a bundle of return comb tooth light, i.e., return signal light, in space, passes through the circulator, and then the return signal light and the local oscillation microcavity optical frequency comb pass through the beam combiner to be combined into one, and finally pass through a balanced detector to detect a coherent beat frequency signal. Since the signal microcavity optical frequency comb and the local oscillation microcavity optical frequency comb have a small frequency difference, the beat frequency signals between different comb teeth are separated in frequency, and one balanced detector can realize the measurement of the distance and speed information of the target in different spaces by different comb teeth. Through the multi-channel signal data acquisition processing module and the corresponding comb tooth spatial angle information of the diffractive optical element, the multi-dimensional information of the distance, angle and speed of the target object corresponding to the multi-channel comb tooth can be calculated.

[0021] The two microcavity optical combs are microcavity optical combs with a frequency difference and linear frequency modulation.

[0022] The single-pixel detector is one of a balanced detector and a single-photon detector.

[0023] Beneficial effects:

[0024] 1. The dual-frequency microcavity optical frequency comb radar single-detector parallel detection processing method and device disclosed by the application utilize a signal generator to modulate a microcavity optical comb, generate a signal microcavity optical comb and a local oscillation microcavity optical comb with a frequency difference, realize coaxial transmission and reception and comb tooth spatial separation through a circulator and a diffractive optical element, realize multi-channel signal parallel acquisition and processing of different comb teeth by using a single-pixel balanced detector and an acquisition processing module, calculate the distance, angle and speed information of a target object, can realize coherent parallel detection and acquisition processing of multi-channel ranging signals corresponding to different comb teeth of a microcavity optical comb frequency modulation continuous wave radar, and realize single-pixel detection and processing of multi-channel radar ranging signals.

[0025] 2、Traditional laser radar needs inertial scanning device, and multiple light sources and multiple detectors are used for three-dimensional point cloud imaging, the system structure is complex and the cost is high, the disclosed double-frequency microcavity optical comb radar single-detector parallel detection processing method and device combines frequency asynchronous sampling of double microcavity optical combs and coherent parallel detection technology of single-pixel balanced detector, only one signal optical comb, one local oscillator optical comb and one balanced detector are needed to realize multi-channel parallel detection processing of single-pixel detector without inertial device, which simplifies the hardware of the frequency-modulated continuous wave radar and saves the number of detectors and cost. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of a double-frequency microcavity optical comb radar single-detector parallel detection processing device.

[0027] Figure 2 It is a principle diagram of a double-frequency microcavity optical comb radar single-detector parallel detection processing device.

[0028] Among them, 1 is a signal generator, 2 is a signal microcavity optical comb, 3 is a fiber circulator, 4 is a diffractive optical element, 5 is a local oscillator microcavity optical comb, 6 is a beam combiner, 7 is a balanced detector, and 8 is a multi-channel signal parallel acquisition and processing module. DETAILED DESCRIPTION

[0029] In order to better illustrate the purpose and advantages of the present application, the content of the application will be further described below in combination with the drawings and examples.

[0030] Example 1

[0031] As shown in the figure, the double-frequency microcavity optical comb radar single-detector parallel detection processing method disclosed in the present embodiment has the following specific implementation steps: Figure 2 Step one, the signal microcavity optical comb 2 performs triangular wave linear frequency sweeping according to the sweep signal given by the signal generator 1, and outputs multiple signal comb teeth; the signal comb teeth are a pulse signal in time domain, have comb teeth with equal intervals in frequency domain, and have the characteristics of the sweep signal of the signal generator 1, the repetition frequency of the signal microcavity optical comb 2 is 100GHz, the spectral width covers 1530nm-1630nm, the sweep period is 10us, and the sweep range is 50MHz.

[0032] Step two, the signal comb teeth pass through the fiber circulator 3, then pass through the diffractive optical element 4, are separated in space, and are irradiated onto the measured target at the same time, pass through the target and return to the diffractive optical element 4 in the original path, are converted into a combined beam A again in space, and are outputted through the fiber circulator 3;

[0033]

[0034] ​Step three, the local microcavity optical frequency comb 5 performs linear sweep of triangular wave according to the sweep signal given by the signal generator 1, and outputs a plurality of local optical comb teeth; the plurality of local optical comb teeth are also a pulse signal in time domain, and have comb teeth with equal intervals in frequency domain, and have the characteristics of the sweep signal of the signal generator 1. However, the repetition frequency of the local microcavity optical frequency comb 5 has a small repetition frequency difference with the repetition frequency of the signal microcavity optical frequency comb 2, the repetition frequency of the local microcavity optical frequency comb 5 is 100.3 GHz, the repetition frequency difference is 300 MHz, the spectral width covers 1530 nm-1630 nm, the sweep period is 10 μs, and the sweep range is 50 MHz.

[0035] Step four, the combined light A of step two and the local optical comb tooth of step three enter the beam combiner 6, the signal optical comb tooth and the local optical comb tooth are combined, the beat frequency is performed between different comb teeth, the beat frequency is detected by the balanced detector 7 and converted into an electrical signal, and the electrical signal C is obtained; the distance, angle and speed information of each comb tooth corresponding to the target object are calculated according to the electrical signal C;

[0036] The distance calculation formula is

[0037]

[0038] The angle calculation formula is

[0039]

[0040] The speed calculation formula is

[0041]

[0042] Wherein, n is the serial number of the optical comb tooth, L n is the distance of the target point corresponding to the nth signal optical comb tooth, c is the speed of light, t is the flight time of light, B is the sweep width 50 MHz, f u (n) is the upper frequency after the nth signal optical comb tooth and the nth local optical comb tooth are beat, f d (n) is the lower frequency after the nth signal optical comb tooth and the nth local optical comb tooth are beat, θ n is the diffraction angle corresponding to the nth comb tooth, that is, the angle information of the target, λ n is the laser wavelength of the nth signal optical comb tooth, d is the slit interval of the diffractive optical element 4, m is the spectral order, v n is the speed of the target point corresponding to the nth signal optical comb tooth, △f r The repetition frequency difference between the signal microcavity optical frequency comb 2 and the local microcavity optical frequency comb 5 is 300 MHz.

[0043] The small repetition frequency difference refers to the repetition frequency difference between 1 kHz and 500 MHz.

[0044] As Figure 1The double-frequency-modulation microcavity optical frequency comb radar single-detector parallel detection processing device is used for realizing the double-frequency-modulation microcavity optical frequency comb radar single-detector parallel detection processing method. The double-frequency-modulation microcavity optical frequency comb radar single-detector parallel detection processing device comprises two signal microcavity optical frequency combs 2 and local oscillator microcavity optical frequency combs 5 with a small repetition frequency difference, a signal generator 1, a circulator 3, a diffractive optical element 4, a beam combiner 6, a balanced detector 7 and a multi-channel data parallel data acquisition processing module 8.

[0045] The signal generator 1 outputs a linear frequency modulation triangular wave, which modulates the frequency offset of the signal microcavity optical frequency comb 2 and the local oscillator microcavity optical frequency comb 5, so that each comb tooth is linearly triangularly frequency-modulated, and a plurality of different frequency band frequency-modulated continuous wave lasers are simultaneously emitted. The signal microcavity optical comb 2 serves as signal light, passes through the circulator 3 and the diffractive optical element 4, is spatially separated into different comb teeth, is irradiated to a target object, is diffusely reflected and returns along the original path, then passes through the diffractive optical element 4, is spatially combined into a return comb tooth light, i.e., a return signal light, passes through the circulator 3, and then the return signal light and the local oscillator microcavity optical frequency comb 5 pass through the beam combiner 6 to combine two into one, and then pass through a balanced detector 7 to detect a coherent beat frequency signal. Since the signal optical frequency comb and the local oscillator optical frequency comb have a small repetition frequency difference, the beat frequency signals between different comb teeth are separated in frequency. A balanced detector 7 can realize the measurement of the distance and speed information of the target in different spaces by multiple comb teeth. Through the multi-channel signal data acquisition processing module 8 and the corresponding comb tooth spatial angle information of the diffractive optical element 4, multi-dimensional information of the distance, angle and speed of the target object corresponding to the multiple comb teeth is solved.

[0046] The two microcavity optical combs are microcavity optical combs with a repetition frequency difference and linear frequency modulation, and the linear frequency modulation includes triangular wave modulation and sawtooth wave modulation.

[0047] The single-pixel detector is one of a balanced detector 7 and a single-photon detector.

[0048] The above specific description further details the purpose, technical solution and beneficial effects of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A parallel detection and processing method for a single detector in a dual-frequency-modulated microcavity optical frequency comb radar, characterized in that: Includes the following steps, Step 1: The signal microcavity optical frequency comb performs a triangular wave linear frequency sweep based on the sweep signal given by the signal generator, and outputs multiple signal optical comb teeth; the signal optical comb teeth are a beam of pulse signal in the time domain, and have the characteristics of equal spacing of comb teeth and sweep signal from the signal generator in the frequency domain; Step 2: After the signal light comb passes through the fiber optic circulator, it is then separated in space by a diffractive optical element and simultaneously illuminated onto the target. The signal light comb then returns to the diffractive optical element through the same path and is converted into a combined beam A, which is then output through the fiber optic circulator. Step 3: The local oscillator microcavity optical frequency comb performs a triangular wave linear frequency sweep based on the sweep signal given by the signal generator, outputting multiple local oscillator optical comb teeth; these multiple local oscillator optical comb teeth are a beam of pulse signal in the time domain, and have the characteristics of equally spaced comb teeth and a sweep signal from the signal generator in the frequency domain; however, the repetition frequency of the local oscillator microcavity optical frequency comb has a slight difference from the repetition frequency of the signal microcavity optical frequency comb; Step 4: The combined beam A from Step 2 and the local oscillator comb from Step 3 enter the beam combiner. After the signal beam comb and the local oscillator comb are combined, they beat at different frequencies, which are detected by the balanced detector and converted into electrical signals, resulting in electrical signal C. Based on electrical signal C, the distance, angle, and velocity information of the target object corresponding to each comb tooth are calculated. The distance calculation formula is: The angle calculation formula is as follows The velocity calculation formula is as follows Where n is the sequence number of the comb teeth, L n Let c be the distance to the target point corresponding to the nth signal optical comb tooth, t be the time of flight of light, B be the sweep width, and f be the distance to the target point corresponding to the nth signal optical comb tooth. u (n) represents the upper frequency after the nth signal optical comb tooth and the nth fundamental resonant comb tooth beat together, f d (n) represents the lower frequency after the nth signal optical comb tooth and the nth fundamental resonant optical comb tooth beat together, θ n λ represents the diffraction angle corresponding to the nth comb tooth, i.e., the angular information of the target. n Let d be the laser wavelength of the nth signal optical comb tooth, d be the slit spacing of the diffractive optical element, m be the spectral order, and v be the wavelength of the laser. n Let Δf be the velocity of the point on the target corresponding to the nth signal optical comb tooth. r The frequency repetition rate difference between the signal microcavity optical frequency comb and the local oscillator microcavity optical frequency comb.

2. The parallel detection and processing method for a single detector in a dual-frequency-modulated microcavity optical frequency comb radar as described in claim 1, characterized in that: The term "minor frequency difference" refers to a frequency difference between 1 kHz and 500 MHz.

3. A dual-frequency-modulated microcavity optical frequency comb radar single-detector parallel detection and processing device, used to implement the dual-frequency-modulated microcavity optical frequency comb radar single-detector parallel detection and processing method as described in claim 1 or 2, characterized in that: It includes two signal microcavity optical frequency combs with small repetition rate difference and a local oscillator microcavity optical frequency comb, a signal generator, a circulator, diffractive optical elements, a beam combiner, a balanced detector, and a multi-channel parallel data acquisition and processing module; The signal generator outputs a linearly frequency-modulated triangular wave, which modulates the frequency deviation of the signal microcavity optical frequency comb and the local oscillator microcavity optical frequency comb, making each comb tooth linearly frequency-modulated. The signal microcavity optical comb serves as the signal light. After passing through a circulator and diffractive optical elements, the different comb teeth are spatially separated. After being diffusely reflected back to the target object, the light returns along the original path and passes through the diffractive optical elements again, where it is spatially combined into a single beam of returning comb tooth light, i.e., the returning signal light. After passing through the circulator, the returning signal light and the local oscillator microcavity optical frequency comb are combined into one beam by a beam combiner. Then, a balanced detector detects the coherent beat frequency signal. Because the signal optical frequency comb and the local oscillator optical frequency comb have a small repetition rate difference, the beat frequency signals between different comb teeth are separated in frequency. A single balanced detector can realize the measurement of the target's distance and velocity information by multiple comb teeth in different spaces. After passing through a multi-channel signal data acquisition and processing module, in conjunction with the spatial angle information of the comb teeth corresponding to the diffractive optical elements, multi-dimensional information calculation of the target object's distance, angle, and velocity corresponding to multiple comb teeth is realized.

4. The dual-frequency-modulated microcavity optical frequency comb radar single-detector parallel detection and processing device as described in claim 3, characterized in that: The two microcavity optical combs are microcavity optical combs with a repetition rate difference and linear frequency modulation.

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