205 results about "Heterodyne" patented technology

The invention relates to the technical field of laser ranging, in particular to a double-optical-comb hybrid ranging device which comprises a signal detection optical path system and a signal demodulation optical path system. Wherein the signal detection optical path system comprises a first optical frequency comb, a first optical isolator, a first optical collimator, a first beam splitter prism, a reference mirror, a Faraday rotator, a convergence mirror and a target reflector; the signal demodulation optical path system comprises a second optical frequency comb, a second optical isolator, a second optical collimator, a half-wave plate, a second beam splitter prism, a third beam splitter prism, a first polarization controller, a first photoelectric detector, a reflector, a polarization beam splitter prism, a second polarization controller and a second photoelectric detector. A third polarization controller; and a third photoelectric detector. According to the invention, three ranging technologies of asynchronous optical sampling ranging, multi-heterodyne interference ranging and synthetic wavelength ranging are fused, and the problem that a large ranging range and high ranging precision cannot be simultaneously considered in the ranging process is solved.

The invention belongs to the technical field of computer vision and optical measurement, and discloses a three-dimensional reconstruction method and device based on multi-frequency fringe synchronous optimization and a medium, and the method comprises the following steps: based on a monocular structured light system, projecting a plurality of groups of sine fringe images with different frequencies to the surface of an object to be measured through a projector, and carrying out the stepping of a plurality of phases, acquiring a corresponding image sequence by using a camera; using a structured light phase shift method to obtain a relative phase value of a pixel point; obtaining an initial absolute phase value and modulation intensity based on a structured light phase shift method and a multi-frequency heterodyne method; and carrying out joint optimization on the absolute phase and modulation intensity parameters of the multi-frequency fringes through a Gaussian-Newton iteration method. According to the method, the anti-noise capability and the reconstruction precision are improved, a parameter adjustment and threshold recovery mechanism is introduced in the optimization process, the convergence stability and abnormal value elimination are ensured, and the method is suitable for high-precision structured light application scenes such as industrial vision measurement and complex surface detection.

The invention provides a non-power-cut test method for mutual inductance parameters of a power transmission line under excitation of different-frequency signals and a related device, and solves the problems of difficulty in accompanying stop and high safety risk of adjacent lines. The method comprises the following steps: selecting one circuit in the same corridor for power failure, connecting the head end with an induced electricity suppression device, and performing three-phase short-circuit grounding at the tail end; injecting a different-frequency sinusoidal current of 45-55Hz into the power failure line; the synchronous measurement device collects head and tail voltage and current of a running line based on a satellite synchronous clock; extracting pilot frequency signals through two-stage notch filtering and Fourier transform; and different-frequency zero-sequence self-impedance and mutual impedance are calculated and converted into power-frequency impedance. According to the invention, accurate test without power failure can be realized, and safety and power supply reliability are guaranteed.

The invention discloses a cultural relic restoration decision-making method and system based on computer three-dimensional modeling, and relates to the technical field of cultural relic restoration, and the method comprises the following steps: building a unified time baseline, generating a phase reference field, introducing a double-frequency comb interference structure to reconstruct a humidity refraction field, locking a zero-phase anchor point, and forming an initial constraint condition of a scanning path; under an initial constraint condition, an airflow phase gradient is obtained by adopting a Schlenn pilot frequency chromatography method, a nonlinear diffraction nucleus is calculated, and a refraction residual spectrum is output for modeling correction. According to the method, humidity disturbance is recognized through interference measurement and chromatography, real-time compensation is achieved in combination with phase sheath and humidity control, the crack and material characteristics are fused through neural field modeling, the solidification process is played back in combination with a mineralization mechanism, and the three-dimensional modeling precision and the restoration decision scientificity are improved.

A zero-optical-path-difference double-frequency heterodyne grating ruler comprises a light source, a signal detecting and processing system, a polarization splitting prism, a first quarter-wave plate, a rectangular prism, a second quarter-wave plate, a third quarter-wave plate, a total reflection mirror, a long-strip prism, a reference grating and a 45-degree-placed polaroid. The two measuring light paths of the system always keep zero optical path difference, so that the measuring precision can be ensured, and the environmental stability of the system is also remarkably improved. And a high-precision and high-robustness measurement scheme is provided for precision equipment such as a photoetching machine and a precision motion platform.

The invention discloses a planetary atmospheric trace gas spectrum telemetering and in-situ fusion detection system and method, and belongs to the technical field of deep space exploration. The detection system has a telemetering mode and an in-situ detection mode, and comprises a telescope module, a laser light source module, a heterodyne spectrum telemetering module, an in-situ absorption spectrum module, a gas sampling and enriching module and a signal acquisition, processing and control module. In the on-orbit stage, a heterodyne spectrum telemetering module is adopted, and a laser light source and sunlight signals are subjected to frequency mixing for atmospheric component telemetering; and after the detector enters an atmospheric descending section, the in-situ absorption spectrum module performs in-situ absorption spectrum measurement by utilizing the detection light of the same laser light source. By performing space-time fusion and joint inversion on the data acquired in the two modes, coherent detection from large-range general survey to fixed-point detailed survey is realized, the problems of load separation of telemetering and in-situ detection and difficulty in data fusion are solved, and the detection efficiency, the data consistency and the integration level of the system are greatly improved.

The invention relates to a Rydberg atomic communication receiving system and method based on AT split peak value analysis, and belongs to the technical field of quantum communication. The system comprises a detection laser, a coupling laser, an AOM / EOM, a function generator, a high-frequency signal generator, a cesium atom gas chamber, a photoelectric detector, a lock-in amplifier, a data acquisition module and a microwave signal output module. The AOM / EOM modulates the frequency of the detection laser; the microwave signal output module generates an AM modulation microwave signal and transmits the AM modulation microwave signal to the cesium atom gas chamber, so that the target Rydberg state atoms generate an AT splitting effect to calibrate system parameters; the photoelectric detector and the lock-in amplifier obtain a first harmonic component based on the transmission light. During communication, the system is arranged in a microwave electric field received by communication, and the data acquisition and processing module outputs AM modulation microwave signals received by the recovered cesium atom gas chamber based on calibrated system parameters and phase locking. The method solves the problem of signal distortion existing in EIT-AT direct communication transmission and the problem of tedious operation of a heterodyne method.

The invention relates to a fringe projection high-reflection surface phase unwrapping method based on frequency reuse. The fringe projection high-reflection surface phase unwrapping method comprises the steps of collecting a multi-frequency fringe image and dividing the multi-frequency fringe image into an overexposure area and a non-overexposure area, solving a wrapped phase in the non-overexposure area by adopting a generalized phase shift method, obtaining an initial unwrapping phase based on a multi-frequency heterodyne algorithm, and performing block filtering and interpolation processing to obtain a fringe projection high-reflection surface phase unwrapping phase. A continuous unwrapped phase containing a high-reflection area is obtained, a complementary Gray code consistent with a wrapped phase period is constructed in combination with a multi-threshold constraint and is used for correcting the stripe level of an overexposure area, brightness attenuation design is further carried out on low and medium frequency stripes, frequency reuse is achieved, and the high-reflection area is obtained. Obtaining an unwrapped phase of an overexposure point in a non-high-frequency stripe and mapping the unwrapped phase to a high frequency; the method comprises the following steps of: extracting and fusing a wrapped phase by adopting one-dimensional Fourier and Hilbert transform for areas with overexposure of each frequency, and selecting and inhibiting spectrum leakage through a complete period, so that effective correction of the wrapped phase and stripe level of an overexposure point is realized, and a reliable unwrapped phase is obtained.

The invention discloses a device for generating Mach-Zehnder interference, a photo-thermal spectrum gas sensing device based on the device and a detection method, and belongs to the technical field of laser spectrum gas sensing. The interference device sequentially comprises an optical frequency comb and a first light beam splitter on a light transmission path; a movable arm reflector group is arranged on the light path of one light beam B in the two light beams split by the first light beam splitter, the path of the light beam B is changed through the movable arm reflector group, the light beam B intersects with the light path of the other light beam C, and a beam combiner is arranged at the intersection; the movable arm reflector group is connected with a driving mechanism, the driving mechanism is used for driving the movable arm reflector group to do linear motion, and the track of the linear motion is parallel to the straight line where the light beam B is located. The interference device does not need to use a local oscillator optical comb and a signal optical comb to carry out multi-heterodyne interference, can directly use the moving speed of a movable arm reflector group in a Mach-Zehnder interference structure to calculate a down-conversion factor, and maps each longitudinal mode of the signal optical comb in an optical frequency to a radio frequency component one by one.

The invention discloses a multidimensional communication sensing system integrating an optical transmission network and BOTDR / DAS distributed sensing, and relates to the technical field of optical fiber communication and optical fiber sensing. The system comprises an OTN transmission subsystem, an optical fiber link and a BOTDR / DAS fusion sensing subsystem. Wherein the OTN transmission subsystem is used for realizing high-capacity data transmission through an optical fiber link; and the BOTDR / DAS fusion sensing subsystem is used for realizing strain, temperature and vibration distributed measurement of an optical fiber link through a Brillouin scattering and Rayleigh backscattering mechanism. According to the system, a double-self-heterodyne demodulation architecture and a reverse wavelength division multiplexing mechanism are adopted, cooperative demodulation and high-isolation transmission of BOTDR and DAS signals are achieved under the common-fiber condition, and high-speed communication and distributed temperature, strain and vibration synchronous monitoring within the 100 km range can be achieved. According to the method, a technical foundation can be laid for realizing physical layer intelligentization of the in-service power OTN.

The invention relates to a reduced-size FMCW lidar imager system. The imager system comprises an optical source 10 for a coherent, continuous and frequency-modulated primary signal Sp in order to illuminate the scene 2; an optical collection element 41 configured to collect a backscattered signal Sret,c; a photodetector 50 intended to receive a heterodyne signal Sh associated with the collected signal Sret,c; and a processing unit 60 configured to determine the distance zsc from the scene based on a beat frequency of the heterodyne signal sh. It is configured to fully direct the primary signal Sp to the scene 2. It additionally comprises a reflector 42 configured to reflect a portion Spr,nc, called uncollected signal Sret,nc, of the backscattered signal Sret, not collected by the optical collection element 41, in the direction of the scene 2.

The invention discloses an aircraft composite material structure health monitoring system and method, and relates to the field of aircraft material health monitoring, and the system comprises a DAS integrated optical module which is used for generating and transmitting an optical pulse pair subjected to heterodyne phase modulation to a single-mode optical fiber sensing network, and converting backward Rayleigh scattering light into an electric signal; the single-mode optical fiber sensing network is arranged on the surface of the aircraft composite material structure and is used for converting an acoustic emission signal containing the physical change of the aircraft composite material structure into an optical phase change signal by utilizing a coherent Rayleigh scattering effect; the digital signal processing module is used for carrying out signal processing on the electric signal by utilizing a heterodyne phase modulation method based on instantaneous frequency tracking so as to identify and position the damage of the aircraft composite material structure; and the alarm output module is used for outputting a damage position, a damage degree grade and an alarm signal of the airplane composite material structure in real time when the structural damage is detected, so that full-distribution and wide-range online accurate monitoring is realized.

The application relates to the technical field of laser speed measurement, and discloses a laser Doppler speed measurement system and a speed measurement method. The system comprises a dual-frequency laser device, a first detection beam splitter, a second detection beam splitter, a first detection device, a second detection device and a signal processing device. The dual-frequency laser device is optically connected with the first detection beam splitter and the second detection beam splitter. The first detection beam splitter and the second detection beam splitter are respectively optically connected with the first detection device and the second detection device. The first detection device and the second detection device are optically connected with the signal processing device. The application constructs a set of optical path "cross pairing" dual-channel differential heterodyne interference systems, so that the interference optical path of each detection device simultaneously contains frequency components from two lasers. The inherent output frequencies of the two detection devices are equal in size and opposite in sign, have common mode rejection characteristics, effectively reduce the dependence of the system on the long-term stability of the core frequency shift device, and improve the measurement accuracy and reliability.

A line monitoring system can include a laser source to emit a probe signal over a first bandwidth; a polarization preserving tap to receive the probe signal and split the probe signal into a first portion and a second portion; a polarization rotator to receive the first portion and send the first portion to a transmission system; a loop tap to receive the second portion and receive a loop signal from the transmission system, wherein the loop signal is derived from the first portion; a photodetector coupled to receive an interference signal from the loop tap, wherein the interference signal is generated by mixing the loop signal with the second portion, wherein the photodetector is arranged to output a power signal based on the interference signal; and a power measurement system to measure the power signal over a second bandwidth comparable to the first bandwidth at a given measurement frequency.

The application discloses a permanent magnet synchronous motor position estimation method based on secondary harmonic tracking. When the permanent magnet synchronous motor is in zero speed and low speed state, a high-frequency sinusoidal pulse voltage signal is injected into the estimated d-axis of the motor. The secondary harmonic current response signal is extracted, and the amplitude thereof is obtained through heterodyne and low-pass filtering processing. The system is converged to the minimum point of the current secondary harmonic amplitude through the minimum value gradient tracking method, so that the effective detection of the zero speed and low speed position of the permanent magnet synchronous motor is realized. The application can realize the unique position convergence point in the whole error range, so as to improve the estimation performance and robustness of the system in the zero speed and low speed interval.

The invention discloses a compact double-frequency heterodyne triaxial grating ruler, and belongs to the technical field of precision optical measurement. The grating ruler adopts an integrated compact structure formed by stacking a double-frequency cross-polarization laser light source, a prism and detector module, a beam combining prism module and a two-dimensional reflecting grating from top to bottom. The method is characterized in that measurement light is made to deviate from the center of a beam combining prism in a beam combining prism module for normal incidence, the geometrical configuration of the beam combining prism is combined, and multi-stage diffraction light beams generated after the measurement light is irradiated to a two-dimensional reflection grating are spatially separated in the prism; and two beam combining gratings with orthogonal scribed line directions are utilized to carry out common-path beam combination on + / -1 level diffraction beams representing X and Y axial displacements to form X, Y and Z three-axis measurement beams which are independent from each other on a spatial light path. And finally, photoelectric conversion and signal processing are carried out through a prism and a detector module, and the three-degree-of-freedom displacement is calculated synchronously. The device effectively inhibits inter-axis crosstalk, has the advantages of being compact in structure, easy and convenient to install and adjust and high in environment interference resistance, and is suitable for the ultra-precision measurement field of photoetching machines, precision motion platforms and the like.

A method and system for measuring physical parameters using sensors of the birefringent Fiber Bragg Grating type is provided. In some embodiments, a method and a system for querying a sensor of the birefringent Fiber Bragg Grating (FBG) type (e.g., in birefringent fiber), employing heterodyne optical detection and integrated photonic technology is provided.

The application discloses a kind of bandwidth saving coherent transmission method and PON system, it is related to optical access network technical field, including: in downlink transmission direction, OLT sending end generates M digital subcarriers, after digital-analog conversion, it is carried out double polarization modulation, as downlink signal is sent to ONU receiving end;Each subarea ONU receiving end carries out heterodyne coherent detection to the partial spectrum of downlink signal, and downlink signal occupies the single sideband spectrum of ONU end light source;In the direction of uplink transmission, the data of corresponding digital subcarrier is generated by ONU sending end, and single sideband modulation is carried out based on ONU end light source, as uplink signal is sent to the OLT receiving end of corresponding subarea, and uplink signal occupies another single sideband spectrum of ONU end light source;OLT receiving end carries out analog-digital conversion and digital signal processing after heterodyne coherent detection.The application selects subcarrier by configuring light source of different wavelength at ONU end to reduce device bandwidth, so that PON system reduces cost while maintaining transmission capacity, sensitivity and flexibility.

This invention provides an acoustic wave sensing system based on master-slave laser phase-locked loop (PLL). A frequency-locking unit locks the frequency difference between the master and slave lasers to a highly stable reference frequency source, thus separating the acoustic wave signal from the background noise. The slave laser is then exposed to the acoustic field under test, and its output light frequency and phase are modulated accordingly by acoustic wave disturbances. The master and slave lasers generate a heterodyne beat frequency optical signal via a beam combining unit. A phase comparison unit compares this beat frequency electrical signal with a reference radio frequency signal to generate an error signal proportional to the instantaneous phase difference. A servo control unit conditions and amplifies the error signal, driving a tuning unit to adjust the output frequency and phase of the slave laser in real time, forming a negative feedback closed loop. The adaptive compensation characteristics of the closed-loop control give the system a strong ability to suppress slowly varying interferences such as environmental temperature changes and mechanical vibrations.

The invention discloses a MicroLED-based structured light 3D camera and a phase optimization method, and belongs to the technical field of computer vision and optical measurement. The camera is composed of a three-dimensional imaging unit and a control unit, and the three-dimensional imaging unit integrates a micro projector based on a MicroLED and a monocular industrial camera, so that a flexible extension structure can be adopted to extend into narrow areas such as pipelines and precision parts; the control unit is responsible for image projection, image acquisition control and three-dimensional reconstruction; according to the phase optimization method, an initial phase is obtained by combining a multi-frequency heterodyne method with a four-step phase shift method, then a gray model is constructed to solve parameters such as a background item and a modulation item pixel by pixel, iterative correction is performed on pixels exceeding a dynamic range, and meanwhile, a gray and phase dual convergence criterion is set to complete phase optimization. Miniaturization, low power consumption and high real-time performance are achieved by means of the MicroLED, phase calculation precision and robustness are improved through iterative optimization, and a scheme is provided for precision part detection, medical endoscopic imaging and the like.

This application relates to the field of optical polarization measurement technology, specifically to a wide-spectrum, high-bandwidth static spectral modulation Stokes polarization measurement device, comprising a polarization modulation module, a spectral sampling module, and a high extinction ratio polarizer. The polarization modulation module includes a phase retarder and a linear polarizer; the spectral sampling module has sub-nanometer spectral resolution; the high extinction ratio polarizer includes a halogen tungsten lamp and a Glan Taylor prism for generating high-purity linearly polarized light; the obtained demodulation factor and the modulation spectrum acquired by the spectral sampling module are used to invert the Stokes parameters using zero-heterodyne coherent demodulation technology. This application employs a phase retarder with high birefringence, which, for the same thickness, produces an optical path difference tens of times greater than that of quartz, increasing the Stokes polarization measurement bandwidth by a factor of the response and improving the measurement accuracy of polarization spectral parameters. Simultaneously, the zero-heterodyne coherent demodulation method is used to eliminate the dispersion interference of the phase retarder through calibration.

The invention relates to the technical field of vehicle-mounted mobile meteorological detection, in particular to a vehicle-mounted mobile meteorological detection system and method. The method comprises the following steps: activating a laser radar system of a vehicle-mounted end to collect back scattering signals of a target air mass corresponding to each collection point on a voyage route, performing inversion based on the back scattering signals to obtain an extinction coefficient of the target air mass, and determining the boundary of the target air mass based on the variation of the extinction coefficient of the target air mass on the voyage route; determining a wind field vertical profile of the target air mass based on the heterodyne spectrum; and obtaining a posterior failure probability of the moving trend of the target air mass based on Bayesian inversion analysis, and predicting the moving trend of the target air mass based on the posterior failure probability. According to the method, the air mass boundary can be accurately determined, the height of the vertical profile of the wind field is calculated, the air mass moving trend is analyzed and predicted through Bayesian inversion, and the accuracy of air mass moving trend prediction is improved.

The invention discloses a woven fabric density detection method and a woven fabric density detection device. The method comprises the following steps: forming a parallel transmission section by a to-be-detected fabric and an accompanying fabric and keeping a gap between the to-be-detected fabric and the accompanying fabric; projecting detection light to the parallel transmission section, and collecting a time-varying signal of light intensity penetrating through or reflected from the double-layer fabric; acquiring the movement speed of the to-be-detected fabric, and establishing a time corresponding relation with the light intensity signal; performing spectral analysis on the light intensity signal to extract a beat frequency signal; and calculating the weaving density of the to-be-detected fabric according to the frequency value and the movement speed of the beat frequency signal and the mapping relation between the frequency value and the movement speed. According to the scheme, the stable time domain beat frequency signal can be generated by utilizing the spatial heterodyne effect of the double-layer fabric, the spatial density information is converted into the time frequency information for measurement, the influence of motion blur and phase drift is effectively eliminated, the transmission or reflection detection mode is selected through adaptive judgment, the adaptability to different types of fabrics is improved, and the detection accuracy is improved. High-precision and high-stability weaving density on-line detection is realized.

The present application relates to the technical field of electromagnetic detection, in particular to a Rydberg electric field meter electromagnetic induction method and system for submarine underground cable detection, wherein the direct measurement of radio frequency electric field is introduced into the detection process, the atomic energy level displacement is used to sensitively perceive the weak electric field, and the weak electric field is converted into an optical signal for transmission and demodulation, thereby effectively overcoming the problems of serious signal attenuation and noise interference of the traditional electromagnetic induction equipment under deep water or complex geological conditions, and the submarine cable buried deeper or with weaker current signal can be detected, meanwhile, the electric field response amplitude and phase information obtained through heterodyne demodulation, combined with the spatial position information, constructs the electric field response data containing multi-dimensional physical characteristics, changes the single criterion mode of only relying on the signal strength peak value for positioning, and the multi-dimensional data is introduced into the neural network model for electric field image reconstruction, so that the more detailed electric field spatial distribution around the cable can be restored.

Systems and methods of microscopy include and / or apply a laser light source configured to produce an excitation light; a modulator configured to modulate the excitation light to produce a modulated light; a pulse compressor configured to compress a pulse of the modulated light to produce a pre-compensated light; a beam scanner configured to raster scan the pre-compensated light on a sample; a detector configured to receive a light signal from the sample and produce a detection signal; and a lock-in amplifier configured to receive the detection signal and perform an electronic heterodyne amplification of the detection signal.

This invention discloses a deep-ultraviolet nanosecond-gated Raman and LIBS detection system and method for suspended soil particulate matter nutrients, belonging to the field of optical and smart agriculture sensor technology. The system includes: a laser ejection sampling unit for in-situ soil ablation to generate aerosols; an optical tweezers unit for capturing and suspending individual soil particles; a deep-ultraviolet laser excitation unit for emitting nanosecond dual-pulse lasers to excite the same particle to generate Raman and LIBS signals; a spatial heterodyne spectral interferometry imaging unit for slitless, high-throughput coaxial signal collection and the formation of interference fringes; and a timing control unit for time-division multiplexing detection of Raman and LIBS signals through nanosecond gating. This invention eliminates matrix effects and achieves highly sensitive in-situ, non-destructive, and synergistic detection of atomic and molecular information in single soil particles. Furthermore, Raman and LIBS are used to distinguish the organic content and total composition of nitrogen, phosphorus, and potassium, enabling precise quantification of soil nutrients.

The present disclosure relates at least to optical frequency hopping for channel presence detection in an optical network. An optical channel monitor (OCM) for optical channel attenuation detection in a fiber optic communication system and a method of using the OCM are disclosed, comprising: (a) heterodyne sampling of an optical signal from an optical fiber with light from a light source, the frequency of the light from the light source varying at a constant slope over time; (b) suspending the sampling in step (a); (c) after step (b), heterodyne sampling of the optical signal with light from the light source by frequency hopping; (d) concurrently with step (c), sampling, by the controller, the response of the optical signal to each frequency jump in step (c); and (e) in response to determining, by the controller, that at least one sample in step (d) exceeds a predetermined tolerance or range of the sample, the controller generates an error signal.

An optomechanical inertial sensor includes a monolithic mechanical resonator having a frame and a test mass coupled to the frame by two leaf spring flexures such that the test mass is displaced along a sensing direction relative to the frame when the frame accelerates along the sensing direction, the test mass including a mirror, and a heterodyne laser interferometer for measuring motion of the test mass in the sensing direction. Multiple optomechanical inertial sensors may be combined to sense in three or more directions.

The application discloses a laser phase noise measurement method based on delay self-heterodyne and digital demodulation, and relates to the technical field of laser measurement, and comprises the following contents: after being adjusted by a variable optical attenuator, to-be-measured laser is divided into a frequency shift arm and a delay arm, the frequency shift arm is frequency-shifted by an acousto-optic modulator, the delay arm is delayed by a delay optical fiber, and original electric beat frequency signals are obtained by a balanced photoelectric detector after the two arms are coupled; homologous and synchronous quadrature demodulation is carried out on the original electric beat frequency signals, envelope credibility judgment and abnormal sample repair are combined, and a continuous differential phase sequence is obtained; actual optical time delay is determined according to the beat frequency spectrum characteristics and the continuous differential phase sequence, and a differential phase power spectral density is formed; then, transmission relationship conversion is carried out according to the actual optical time delay, bounded spectrum compensation is implemented on a zero point neighborhood and a low credibility frequency point, and an intrinsic phase noise power spectral density is obtained. The application can improve the stability, continuity and result credibility of phase noise measurement under the condition of short delay.

The invention discloses a water flow velocity measurement system based on laser heterodyne interference of an unmanned aerial vehicle platform, and the system comprises the unmanned aerial vehicle platform located above the water surface, and the unmanned aerial vehicle platform carries a laser heterodyne velocity measurement device. The laser heterodyne speed measuring device comprises a laser emitting unit, a light path module and a signal processing unit, the laser emitting unit emits laser penetrating through the light path module to the water surface to form a receiving and transmitting combined light path; the laser passes through the light path module to form reference light and measuring light, heterodyne signals are generated accordingly, and the signal processing unit obtains flow velocity information according to the heterodyne signals. The maneuverability of the unmanned aerial vehicle platform is combined with the high precision of the laser heterodyne interference technology, so that the non-contact measurement effect which is high in precision, low in cost and suitable for a complex water body is achieved.