Phase-unwrapping-based dual-sideband swept-frequency laser ranging and velocity measurement device and method

Abstract

This invention discloses a double-sideband swept-frequency laser ranging and velocimetry device and method based on phase unwrapping. The device includes a single-frequency laser, a double-sideband modulator, an amplifier, a first coupler, a first demultiplexer, a second coupler, a second demultiplexer, a third coupler, a circulator, an optical antenna, a first photodetector, a second photodetector, a synchronous acquisition card, and a phase unwrapping and range / velocimetry demodulation module. This invention can obtain the distance values ​​corresponding to all sampling times within one sweep cycle, achieving an order-of-magnitude increase in system measurement rate; simultaneously, it can adapt to dynamic targets with arbitrary motion forms, without requiring a constant target velocity.

Description

Technical Field

[0001] This invention belongs to the field of laser measurement technology, and particularly relates to a double-sideband sweeping laser ranging and velocimetry device and method based on phase unwrapping. Background Technology

[0002] Laser ranging methods can be divided into non-interferometric methods (pulse method, intensity method, triangulation method, confocal method, etc.) and interferometric methods (multi-wavelength interferometry, white light interferometry, frequency sweeping interferometry, etc.). Compared with non-interferometric methods, interferometric methods based on the theory of optical field coherence have stronger resistance to environmental interference and higher accuracy. Among interferometric methods, frequency sweeping interferometry is not limited by the 2π phase ambiguity of traditional interferometric ranging, and can further improve ranging resolution and accuracy by increasing the frequency sweep bandwidth. Therefore, as an ideal method for large-range, high-precision absolute distance measurement, frequency sweeping interferometry has always dominated the field of laser ranging and is widely used in military, aerospace, equipment manufacturing and other fields.

[0003] However, sweeping interferometry, with its large ranging range and high accuracy, is only suitable for static distance measurement. Once the target moves, the sweeping interferometry will produce Doppler error, causing the measurement to fail. Currently, commonly used methods to eliminate Doppler error include triangular sweeping with a single sweeping laser, sawtooth sweeping with a dual sweeping laser, and sweeping laser plus a fixed-frequency laser. However, single sweeping lasers have poor dynamic adaptability; dual sweeping lasers and sweeping laser plus fixed-frequency laser systems are complex and have low reliability.

[0004] To address the aforementioned dynamic adaptability and system complexity issues, Nanjing University of Aeronautics and Astronautics proposed a ranging scheme based on microwave photonics technology (Laser Measurement Method and Device Based on Double-Side Band Modulation, Publication No.: CN107505626A). This method can eliminate Doppler error; however, it has several drawbacks: 1) it requires a two-stage interference structure (optical wave interference and microwave interference) to obtain the measurement signal; 2) it can only provide one distance value within one frequency sweep cycle; and 3) it requires the target to move at a uniform velocity; for non-uniform targets, the interference signal spectral peaks disperse, leading to measurement failure. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a double-sideband sweeping laser ranging and velocimetry device and method based on phase unwrapping, which can obtain the distance values ​​corresponding to all sampling times within a sweeping cycle, thereby achieving an order-of-magnitude improvement in the system's measurement rate; at the same time, it can adapt to dynamic targets with arbitrary motion forms and does not require the target speed to be constant.

[0006] The objective of this invention is achieved through the following technical solution: a double-sideband sweeping laser ranging and velocimetry device based on phase unwrapping, comprising: a single-frequency laser, a microwave source, a double-sideband modulator, an amplifier, a first coupler, a first demultiplexer, a second coupler, a second demultiplexer, a third coupler, a circulator, an optical antenna, a first photodetector, a second photodetector, a synchronous acquisition card, and a phase unwrapping and distance / velocity demodulation module; wherein, the single-frequency laser generates an optical carrier, which enters the double-sideband modulator along an optical fiber; the microwave source generates a linearly frequency-converted microwave signal for transmission. The double-sideband modulator generates top and bottom sideband swept beams that are perfectly mirror-symmetrical about the optical carrier frequency. These swept beams are amplified by an amplifier and then split into a first and a second top and bottom sideband swept beams by a first coupler. The first top and bottom sideband swept beams enter a first demultiplexer, where they are demultiplexed to form an upper and a lower sideband swept reference beam. The upper reference beam enters a second coupler, and the lower reference beam enters a third coupler. The second top and bottom sideband swept beams reach the optical carrier frequency after passing through the circulator. The light emitted from the optical antenna is reflected by the moving target and re-enters the antenna to form a measurement light carrying distance information. This measurement light then passes through the circulator and is routed to the second demultiplexer. The second demultiplexer separates the measurement light by wavelength to form an upper sideband swept measurement light and a lower sideband swept measurement light. The upper sideband swept measurement light enters the second coupler, and the lower sideband swept measurement light enters the third coupler. The upper sideband reference light and the upper sideband measurement light are coherently superimposed in the second coupler to generate an upper sideband ranging signal. The lower sideband reference light and the lower sideband measurement light... The measuring light is coherently superimposed in the third coupler to generate a lower sideband ranging signal; the upper sideband ranging signal is photoelectrically converted by the first photodetector to obtain an upper sideband ranging electrical signal, which enters the synchronous acquisition card; the lower sideband ranging signal is photoelectrically converted by the second photodetector to obtain a lower sideband ranging electrical signal, which also enters the synchronous acquisition card; the synchronous acquisition card samples the upper and lower sideband ranging electrical signals and transmits them to the phase unwrapping and distance-velocity demodulation module; the phase unwrapping and distance-velocity demodulation module obtains the real-time distance of the moving target based on the upper and lower sideband ranging electrical signals.

[0007] The aforementioned double-sideband sweep laser ranging and velocimetry device based on phase unwrapping further includes: a bias source; wherein the bias source causes the double-sideband modulator to operate in double-sideband carrier suppression mode, so that the linear frequency conversion microwave signal is modulated onto the optical carrier, generating a top and bottom sideband sweep light that is completely mirror-symmetrical with the optical carrier frequency as the center.

[0008] In the aforementioned double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping, the upper and lower sideband swept-frequency beams are obtained using the following formula:

[0009]

[0010] Among them, E out (t) represents the amplitude of the swept-frequency light in the upper and lower sidebands, E0 represents the amplitude of the output light from the single-frequency laser, and ω c f is the output light frequency of a single-frequency laser. a (0) is the starting frequency of the microwave source sweep, B is the sweep range of the microwave source, T is the sweep period of the microwave source, t is the time, and j is the imaginary unit.

[0011] In the aforementioned double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping, the upper sideband ranging signal is obtained by the following formula:

[0012]

[0013] Among them, s USB (t) represents the upper sideband ranging signal. Let t be the real-time phase of the upper sideband ranging signal at time t, k be the microwave source sweep rate, l(t) be the real-time distance of the moving target at time t, υ(t) be the velocity of the moving target, c be the speed of light, T be the microwave source sweep period, and t be the time.

[0014] In the aforementioned double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping, the lower sideband ranging signal is obtained by the following formula:

[0015]

[0016] Among them, s LSB (t) represents the lower sideband ranging signal. Let t be the real-time phase of the sideband ranging signal at time t, k be the microwave source sweep rate, l(t) be the real-time distance of the moving target at time t, υ(t) be the velocity of the moving target, c be the speed of light, T be the microwave source sweep period, and t be the time.

[0017] In the aforementioned double-sideband sweeping laser ranging and velocimetry device based on phase unwrapping, the phase unwrapping and distance / velocity demodulation module obtains the real-time distance of the moving target based on the upper and lower sideband ranging signals by: performing phase unwrapping and mathematical equivalent transformation on the upper and lower sideband ranging signals to obtain the relationship between the unwrapped phase increment of the upper and lower sideband ranging signals; obtaining the moving target velocity υ(t) based on the unwrapped phase increment of the upper and lower sideband ranging signals; and obtaining the real-time distance of the moving target based on the relationship between the unwrapped phase increment of the upper and lower sideband ranging signals and the moving target velocity υ(t).

[0018] In the aforementioned double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping, the relationship between the unwrapped phase increment of the upper sideband ranging electrical signal and the unwrapped phase increment of the lower sideband ranging electrical signal is obtained through the following formula:

[0019]

[0020] in, This represents the unwrapping phase increment of the lower sideband ranging electrical signal. ω represents the unwrapping phase increment of the upper sideband ranging electrical signal. c f is the output light frequency of a single-frequency laser. a (0) is the starting frequency of the microwave source sweep, l(t) is the real-time distance of the moving target at time t, l(0) is the real-time distance of the moving target at the starting time, T is the frequency sweep period of the microwave source, and t is the time.

[0021] In the aforementioned double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping, the velocity υ(t) of the moving target is obtained by the following formula:

[0022]

[0023] in, This represents the unwrapping phase increment of the lower sideband ranging electrical signal. The unwrapping phase increment of the ranging electrical signal above, ω c Let T be the output light frequency of the single-frequency laser, T be the frequency sweep period of the microwave source, and t be the time.

[0024] In the aforementioned double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping, the real-time distance to the moving target is obtained by the following formula:

[0025]

[0026] Where l(t) is the real-time distance of the moving target at time t. This represents the unwrapping phase increment of the lower sideband ranging electrical signal. The unwrapping phase increment of the ranging electrical signal above, f a (0) is the initial sweep frequency of the microwave source, ω c Let be the output light frequency of the single-frequency laser, T be the frequency sweep period of the microwave source, t be the time, k be the frequency sweep rate of the microwave source, and c be the speed of light.

[0027] A double-sideband swept-frequency laser ranging and velocities method based on phase unwrapping includes: a single-frequency laser generating an optical carrier, which enters a double-sideband modulator along an optical fiber; the double-sideband modulator generates upper and lower sideband swept-frequency beams that are perfectly mirror-symmetrical about the optical carrier frequency, which are then amplified by an amplifier and split into a first upper and lower sideband swept-frequency beam and a second upper and lower sideband swept-frequency beam by a first coupler; the first upper and lower sideband swept-frequency beam enters a first demultiplexer, which demultiplexes it to form an upper sideband swept-frequency reference beam and a lower sideband swept-frequency reference beam, which enters a second coupler and a third coupler; the second upper and lower sideband swept-frequency beam passes through a circulator and exits an optical antenna, is reflected by a moving target, and re-enters the optical antenna to form a measurement beam carrying distance information; the measurement beam carrying distance information passes through a circulator again and is routed to a second demultiplexer; the second demultiplexer... The multiplexer separates the measurement light carrying distance information into upper sideband swept measurement light and lower sideband swept measurement light according to wavelength. The upper sideband swept measurement light enters the second coupler, and the lower sideband swept measurement light enters the third coupler. The upper sideband reference light and the upper sideband measurement light are coherently superimposed in the second coupler to generate an upper sideband ranging signal. The lower sideband reference light and the lower sideband measurement light are coherently superimposed in the third coupler to generate a lower sideband ranging signal. The upper sideband ranging signal is photoelectrically converted by the first photodetector to obtain an upper sideband ranging electrical signal, which enters the synchronous acquisition card. The lower sideband ranging signal is photoelectrically converted by the second photodetector to obtain a lower sideband ranging electrical signal, which also enters the synchronous acquisition card. The synchronous acquisition card samples the upper and lower sideband ranging electrical signals and transmits them to the phase unwrapping and distance / velocity demodulation module. The phase unwrapping and distance / velocity demodulation module obtains the real-time distance of the moving target based on the upper and lower sideband ranging electrical signals.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) This invention can obtain the distance values ​​corresponding to all sampling times within a frequency sweep cycle, thereby increasing the system measurement rate by orders of magnitude; at the same time, it can adapt to dynamic targets with arbitrary motion forms, without requiring the target speed to be constant.

[0030] (2) The present invention utilizes optical field interference to perform measurements, eliminating the need for microwave interference devices in existing solutions. The system is simple and easy to implement.

[0031] (3) The present invention adopts an all-fiber structure, which has strong system scalability. By increasing the number of measurement channels, multi-target synchronous measurement can be achieved, thus possessing integrated testing capabilities and strong versatility. Attached Figure Description

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0033] Figure 1 This is a schematic diagram of a double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the sinusoidal distance measurement results provided in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the measurement results of the sinusoidal rate of change provided in an embodiment of the present invention;

[0036] Figure 4(a) is a schematic diagram of the curve of the arbitrary distance measurement value provided in the embodiment of the present invention;

[0037] Figure 4(b) is a schematic diagram of the measurement error curve of arbitrary distance variation provided by the embodiment of the present invention;

[0038] Figure 5(a) is a schematic diagram of the curve of any change rate measurement value provided in the embodiment of the present invention;

[0039] Figure 5(b) is a schematic diagram of the measurement error of arbitrary changing speed provided by the embodiment of the present invention. Detailed Implementation

[0040] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Figure 1 This is a schematic diagram of a double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping provided in an embodiment of the present invention. Figure 1 As shown, the device includes a single-frequency laser, a microwave source, a double-sideband modulator, an amplifier, a first coupler, a first demultiplexer, a second coupler, a second demultiplexer, a third coupler, a circulator, an optical antenna, a first photodetector, a second photodetector, a synchronous acquisition card, and a phase unwrapping and range / velocity demodulation module; wherein,

[0042] The single-frequency laser generates an optical carrier, which enters the double-sideband modulator along the optical fiber.

[0043] The microwave source generates a linearly frequency-converted microwave signal, which is transmitted to the double-sideband modulator. The double-sideband modulator generates upper and lower sideband swept beams that are perfectly mirror-symmetrical about the optical carrier frequency. These swept beams are amplified by an amplifier and then split into a first upper and lower sideband swept beam and a second upper and lower sideband swept beam by a first coupler. The first upper and lower sideband swept beam enters a first demultiplexer, where it is demultiplexed to form an upper and lower sideband swept reference beam. The upper reference beam enters a second coupler, and the lower reference beam enters a third coupler. The second upper and lower sideband swept beam passes through the circulator and exits the optical antenna. The exited beam is reflected by a moving target and re-enters the optical antenna to form a measurement beam carrying distance information. This measurement beam then passes through the circulator again and is routed to the second demultiplexer. The second demultiplexer then converts the distance-carrying beam into a measurement beam. The measurement light is split according to wavelength to form an upper sideband swept measurement light and a lower sideband swept measurement light. The upper sideband swept measurement light enters the second coupler, and the lower sideband swept measurement light enters the third coupler. The upper sideband reference light and the upper sideband measurement light are coherently superimposed in the second coupler to generate an upper sideband ranging signal. The lower sideband reference light and the lower sideband measurement light are coherently superimposed in the third coupler to generate a lower sideband ranging signal. The upper sideband ranging signal is photoelectrically converted by the first photodetector to obtain an upper sideband ranging electrical signal, which enters the synchronous acquisition card. The lower sideband ranging signal is photoelectrically converted by the second photodetector to obtain a lower sideband ranging electrical signal, which also enters the synchronous acquisition card. The synchronous acquisition card samples the upper and lower sideband ranging electrical signals and transmits them to the phase unwrapping and distance / velocity demodulation module. The phase unwrapping and distance / velocity demodulation module obtains the real-time distance of the moving target based on the upper and lower sideband ranging electrical signals.

[0044] like Figure 1 As shown, the device further includes a bias source; wherein the bias source causes the double-sideband modulator to operate in double-sideband carrier suppression mode, so that the linear frequency conversion microwave signal is modulated onto the optical carrier to generate a top and bottom sideband sweep light that is perfectly mirror-symmetrical with the optical carrier frequency as the center.

[0045] After a single-frequency laser is modulated by two double-sideband modulation, it generates upper and lower sideband swept beams that are perfectly mirror-symmetrical about the single-frequency laser frequency. This can be represented as:

[0046]

[0047] Among them, E out (t) represents the output optical amplitude of the double-sideband modulator, E0 represents the output optical amplitude of the single-frequency laser, and ω c f is the output light frequency of a single-frequency laser.a (0) is the starting frequency of the microwave source sweep, B is the sweep range of the microwave source, T is the sweep period of the microwave source, t is the time variable, and j is the imaginary unit.

[0048] After amplification and splitting, the aforementioned upper and lower sideband sweep frequency light can be used to obtain upper and lower sideband sweep frequency reference light at the output of the first demultiplexer. Subsequently, the aforementioned signal interferes and superimposes with the upper and lower sideband sweep frequency measurement light at the output of the second demultiplexer, ultimately forming the upper sideband ranging signal and the lower sideband ranging signal.

[0049]

[0050]

[0051] Among them, s LSB (t) represents the lower sideband ranging signal, s USB (t) represents the upper sideband ranging signal. Let be the real-time phase of the lower sideband ranging signal at time t. Let be the real-time phase of the upper sideband ranging signal at time t, k = B / T be the microwave source sweep rate, l(t) be the real-time distance of the target at time t, υ(t) = dl(t) / dt be the velocity of the target, and c be the speed of light in the medium. From the above equation, it can be seen that the upper and lower sideband sweep interference signals already carry the dynamic distance and velocity information of the target.

[0052] By performing phase unwrapping and mathematical transformation on the upper and lower sideband measurement signals, the upper and lower sideband swept frequency interference signals satisfy the following relationship:

[0053]

[0054] in, This represents the unwrapping phase increment of the lower sideband ranging electrical signal. ω represents the unwrapping phase increment of the upper sideband ranging electrical signal. c f is the output light frequency of a single-frequency laser. a (0) is the starting frequency of the microwave source sweep, l(t) is the real-time distance of the moving target at time t, l(0) is the real-time distance of the moving target at the starting time, T is the frequency sweep period of the microwave source, and t is the time.

[0055] Therefore, according to equation (1), the real-time velocity of the target to be measured can be obtained:

[0056]

[0057] In the above formula, the symbol df(t) / dt represents the time derivative of the function f(t). This represents the unwrapping phase increment of the lower sideband ranging electrical signal. The unwrapping phase increment of the ranging electrical signal above, ω c Let T be the output light frequency of the single-frequency laser, T be the frequency sweep period of the microwave source, and t be the time.

[0058] Furthermore, the real-time distance to the target can be obtained from equations (1) and (2):

[0059]

[0060] Where l(t) is the real-time distance of the moving target at time t. This represents the unwrapping phase increment of the lower sideband ranging electrical signal. The unwrapping phase increment of the ranging electrical signal above, f a (0) is the initial sweep frequency of the microwave source, ω c Let be the output light frequency of the single-frequency laser, T be the frequency sweep period of the microwave source, t be the time, k be the frequency sweep rate of the microwave source, and c be the speed of light.

[0061] This embodiment obtains the incremental phase of the upper and lower sideband sweep frequency signals through phase unwrapping. Then, the velocity value υ(t) at any time within a single sweep frequency cycle T can be measured using equation (2), and the distance value l(t) at any time within a single sweep frequency cycle T can be measured using equation (3). Furthermore, this measurement method is applicable to υ(t) of any form, eliminating the deficiency of existing technology that requires υ(t) to be a constant.

[0062] Specifically, compared with existing double-band swept interferometric ranging and velocity measurement techniques, this scheme has the following advantages:

[0063] (1) From the structure of the measuring device, this patent does not require microwave interference, but only optical interference to complete the optical frequency deskewing, and can also realize the physical channel separation of the upper and lower sideband sweep frequency signals.

[0064] (2) From the perspective of the implementation effect of the measurement method, compared with the existing scheme (which can only measure one distance value and one velocity value within one frequency sweep cycle T), this scheme can provide the velocity and distance values ​​corresponding to all sampling times within one frequency sweep cycle, thereby increasing the system measurement rate by an order of magnitude. (For example, the frequency sweep cycle T = 0.5ms and the sampling cycle T of the measurement system are...) s At a measurement rate of 100 ns, existing methods have a measurement rate of 2 kHz, while the method proposed in this patent has a measurement rate of 10 MHz, which can increase the measurement rate by 5000 times (3 orders of magnitude).

[0065] (3) In terms of the applicable objects of the measurement method, the existing solutions are only applicable to uniformly moving targets (the actual measurement objects often do not meet this requirement), while the method proposed in this patent is not limited by the form of target motion and is more universal, versatile and engineering valuable.

[0066] This embodiment also provides a double-sideband swept-frequency laser ranging and velocimetry method based on phase unwrapping, the method comprising:

[0067] A single-frequency laser generates an optical carrier, which enters a double-sideband modulator along an optical fiber.

[0068] A double-sideband modulator generates top and bottom sideband swept beams that are perfectly mirror-symmetrical and centered on the optical carrier frequency. These swept beams are then amplified by an amplifier and split into first and second top and bottom sideband swept beams by a first coupler. The first swept beam enters a first demultiplexer, where it is demultiplexed to form an upper and lower sideband swept reference beam. The upper reference beam enters a second coupler, and the lower reference beam enters a third coupler. The second swept beam passes through a circulator and exits the optical antenna. The exit beam is reflected by a moving target and re-enters the optical antenna to form a measurement beam carrying distance information. This measurement beam passes through the circulator again and is routed to the second demultiplexer. The second demultiplexer separates the measurement beam carrying distance information by wavelength to form the upper sideband swept beam. The measurement light and the lower sideband swept measurement light, the upper sideband swept measurement light enter the second coupler, and the lower sideband swept measurement light enters the third coupler. The upper sideband reference light and the upper sideband measurement light are coherently superimposed in the second coupler to generate the upper sideband ranging signal. The lower sideband reference light and the lower sideband measurement light are coherently superimposed in the third coupler to generate the lower sideband ranging signal. The upper sideband ranging signal is photoelectrically converted by the first photodetector to obtain the upper sideband ranging electrical signal, which enters the synchronous acquisition card. The lower sideband ranging signal is photoelectrically converted by the second photodetector to obtain the lower sideband ranging electrical signal, which enters the synchronous acquisition card. The synchronous acquisition card samples the upper sideband ranging electrical signal and the lower sideband ranging electrical signal and transmits them to the phase unwrapping and range-velocity demodulation module. The phase unwrapping and range-velocity demodulation module obtains the real-time distance of the moving target based on the upper sideband ranging electrical signal and the lower sideband ranging electrical signal.

[0069] Figure 2 This is a schematic diagram of the sinusoidal distance measurement results provided in an embodiment of the present invention; Figure 3Figure 4(a) is a schematic diagram of the sinusoidal velocity measurement results provided in the embodiments of the present invention; Figure 4(b) is a schematic diagram of the arbitrary distance measurement value provided in the embodiments of the present invention; Figure 5(a) is a schematic diagram of the arbitrary velocity measurement value provided in the embodiments of the present invention; Figure 5(b) is a schematic diagram of the arbitrary velocity measurement error provided in the embodiments of the present invention. The present invention can obtain the distance values ​​corresponding to all sampling times within a frequency sweep cycle, achieving an order-of-magnitude increase in the system measurement rate; it can also adapt to dynamic targets with arbitrary motion forms, without requiring the target velocity to be constant; the present invention utilizes optical field interference for measurement, eliminating the need for microwave interferometers in existing solutions, resulting in a simple and easy-to-implement system; the present invention adopts an all-fiber structure, providing strong system scalability, and by increasing the number of measurement channels, it can achieve simultaneous measurement of multiple targets, thus possessing integrated testing capabilities and strong versatility.

[0070] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping, characterized in that... include: The system includes a single-frequency laser, a microwave source, a double-sideband modulator, an amplifier, a first coupler, a first demultiplexer, a second coupler, a second demultiplexer, a third coupler, a circulator, an optical antenna, a first photodetector, a second photodetector, a synchronous acquisition card, and a phase unwrapping and range / velocity demodulation module; among which, The single-frequency laser generates an optical carrier, which enters the double-sideband modulator along the optical fiber. The microwave source generates a linearly frequency-converted microwave signal, which is transmitted to the double-sideband modulator. The double-sideband modulator generates upper and lower sideband swept beams that are perfectly mirror-symmetrical about the optical carrier frequency. These swept beams are amplified by an amplifier and then split into a first upper and lower sideband swept beam and a second upper and lower sideband swept beam by a first coupler. The first upper and lower sideband swept beam enters a first demultiplexer, where it is demultiplexed to form an upper and lower sideband swept reference beam. The upper reference beam enters a second coupler, and the lower reference beam enters a third coupler. The second upper and lower sideband swept beam passes through the circulator and exits the optical antenna. The exited beam is reflected by a moving target and re-enters the optical antenna to form a measurement beam carrying distance information. This measurement beam passes through the circulator again and is transmitted via optical fiber to the second demultiplexer. The second demultiplexer then converts the distance-carrying beam into a measurement beam. The measurement light is split according to wavelength to form an upper sideband swept measurement light and a lower sideband swept measurement light. The upper sideband swept measurement light enters the second coupler, and the lower sideband swept measurement light enters the third coupler. The upper sideband reference light and the upper sideband measurement light are coherently superimposed in the second coupler to generate an upper sideband ranging signal. The lower sideband reference light and the lower sideband measurement light are coherently superimposed in the third coupler to generate a lower sideband ranging signal. The upper sideband ranging signal is photoelectrically converted by the first photodetector to obtain an upper sideband ranging electrical signal, which enters the synchronous acquisition card. The lower sideband ranging signal is photoelectrically converted by the second photodetector to obtain a lower sideband ranging electrical signal, which also enters the synchronous acquisition card. The synchronous acquisition card samples the upper and lower sideband ranging electrical signals and transmits them to the phase unwrapping and distance / velocity demodulation module. The phase unwrapping and distance / velocity demodulation module obtains the real-time distance of the moving target based on the upper and lower sideband ranging electrical signals.

2. The double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping according to claim 1, characterized in that... It also includes: a bias source; wherein the bias source causes the double-sideband modulator to operate in double-sideband carrier suppression mode, so that the linear frequency conversion microwave signal is modulated onto the optical carrier to generate a top and bottom sideband sweep light that is completely mirror-symmetrical with the optical carrier frequency as the center.

3. The double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping according to claim 1, characterized in that: The upper and lower sideband swept light is obtained by the following formula: ； in, The amplitude of the sweep frequency optical wave in the upper and lower sidebands. For the output light amplitude of a single-frequency laser, The output light frequency of a single-frequency laser. This is the starting sweep frequency of the microwave source. This refers to the frequency sweep range of the microwave source. The frequency sweep period of the microwave source. For a moment, It is the imaginary unit.

4. The double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping according to claim 1, characterized in that: The upper sideband ranging signal is obtained by the following formula: ； in, The upper band ranging signal, Let t be the real-time phase of the upper sideband ranging signal, and k be the microwave source sweep rate. Let be the real-time distance of the moving target at time t. Let c be the velocity of the moving target, and c be the speed of light. The frequency sweep period of the microwave source. For a moment, The output light frequency of a single-frequency laser. This is the starting sweep frequency of the microwave source.

5. The double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping according to claim 1, characterized in that: The lower sideband ranging signal is obtained by the following formula: ； in, The signal is a bottom-band ranging signal. Let t be the real-time phase of the sideband ranging signal at time t, and k be the microwave source sweep rate. Let be the real-time distance of the moving target at time t. Let c be the velocity of the moving target, and c be the speed of light. The frequency sweep period of the microwave source. For a moment, The output light frequency of a single-frequency laser. This is the starting sweep frequency of the microwave source.

6. The double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping according to claim 1, characterized in that: The phase unwrapping and range / velocity demodulation module obtains the real-time distance of the moving target based on the upper sideband ranging electrical signal and the lower sideband ranging electrical signal, including: The relationship between the unwrapped phase increment of the upper sideband ranging signal and the unwrapped phase increment of the lower sideband ranging signal is obtained by performing phase unwrapping and mathematical equivalent transformation on the upper sideband ranging signal and the lower sideband ranging signal. The velocity of the moving target is obtained from the unwrapped phase increment of the upper sideband ranging electrical signal and the unwrapped phase increment of the lower sideband ranging electrical signal. The real-time distance of the moving target is obtained by relating the unwrapped phase increment of the upper sideband ranging signal and the unwrapped phase increment of the lower sideband ranging signal to the velocity of the moving target.

7. The double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping according to claim 6, characterized in that: The relationship between the unwrapped phase increment of the upper sideband ranging signal and the unwrapped phase increment of the lower sideband ranging signal is obtained by the following formula: ； in, This represents the unwrapping phase increment of the lower sideband ranging electrical signal. This represents the unwrapping phase increment of the upper-side ranging electrical signal. The output light frequency of a single-frequency laser. This is the starting sweep frequency of the microwave source. Let be the real-time distance of the moving target at time t. The real-time distance of the moving target at the initial moment. The frequency sweep period of the microwave source. Let c be the instant, and c be the speed of light.

8. The double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping according to claim 6, characterized in that: Speed ​​of moving target It can be obtained through the following formula: ； in, This represents the unwrapping phase increment of the lower sideband ranging electrical signal. The unwrapping phase increment of the ranging electrical signal above. The output light frequency of a single-frequency laser. The frequency sweep period of the microwave source. Let c be the instant, and c be the speed of light.

9. The double-sideband swept-frequency laser ranging and velocimetry device based on phase unwrapping according to claim 6, characterized in that: The real-time distance to a moving target is obtained using the following formula: ； in, Let be the real-time distance of the moving target at time t. This represents the unwrapping phase increment of the lower sideband ranging electrical signal. The unwrapping phase increment of the ranging electrical signal above. This is the starting sweep frequency of the microwave source. The output light frequency of a single-frequency laser. The frequency sweep period of the microwave source. Let k be the time interval, k be the frequency sweep rate of the microwave source, and c be the speed of light.

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