1820results about "Converting sensor output optically" patented technology

The invention provides a wavelength deviation compensation method and system for rapid wavelength analysis of a far-end fiber bragg grating, and relates to the technical field of fiber bragg grating sensing, and the method comprises the steps: collecting grating reflection spectrum signals of different transmission distances, carrying out frequency domain transformation to separate phase components, and building a mapping relation between the transmission distance and dispersion cumulant; calculating an initial wavelength offset estimation value; identifying a refractive index section, and establishing a segmentation compensation coefficient; constructing a wavelength-strain-temperature three-dimensional space, and optimizing a compensation coefficient according to the trajectory curvature; and updating the compensation coefficient according to the residual gradient. The wavelength analysis precision of the far-end fiber bragg grating can be improved, and the influence of dispersion on measurement is reduced.

The invention discloses a multi-turn memory optomagnetic encoder hybrid system, belongs to the technical field of position and angle measurement encoders, and aims at solving the problems that an existing optomagnetic hybrid encoder is complex in signal processing, long in axial length, insufficient in precision stability and prone to losing the number of turns and the position. The system comprises an optical encoder, a gallium arsenide magnetic signal acquisition sensor, a multi-antipode unequal magnetic ring, a processor, a hardware circuit, an ultra-low power consumption circuit, a signal acquisition module, a signal processing module and the like, integrates self-developed magnetic angle analysis, turn number memory correction and other algorithms, and adopts dual-redundancy design and intelligent signal mode switching. The method simplifies the signal processing flow, shortens the axial length, improves the measurement precision and stability, enhances the environmental adaptability and fault-tolerant capability, prolongs the endurance, and is suitable for the position angle measurement in a high-precision and severe environment.

The invention relates to the technical field of sensors, and provides a grating position sensor. A scanning assembly and a light source module are relatively fixed, and an incident diaphragm and an increment detector are arranged in the scanning assembly; the increment detector is spatially divided into at least two first detector regions for detecting a first phase increment signal component and at least two second detector regions for detecting a second phase increment signal component, and the at least two first detector regions are spatially separated from each other; performing redundant detection on the first phase increment signal component; the at least two second detector areas are separated from each other in space so as to perform redundancy detection on the second phase increment signal component; the position metering element is suitable for being fixed on a measured object or a measuring datum plane and can generate relative displacement with the scanning assembly. The invention provides a grating position sensor with strong anti-pollution capability. The grating position sensor can keep a high-reliability working state for a long time in a complex or severe industrial environment.

The invention provides a tunable laser source output wavelength adjusting device and method, and the method comprises the steps: starting a tunable laser source, carrying out the preheating, and resetting a motor motion unit; acquiring an initial light-emitting wavelength based on a pre-stored relation curve between the light-emitting wavelength of the laser source and the position of the motor; controlling the output wavelength of the laser source through the coarse tuning parameter of the motor motion unit, traversing the tunable output range of the tunable laser source, and collecting the wavelength position of the reflection peak value of the fiber bragg grating and the corresponding optical power value; according to the reflection peak wavelength position, through voltage regulation and control of stacked piezoelectric ceramics, step scanning is carried out according to a target wavelength, and a laser source output wavelength is dynamically adjusted to obtain a fine scanning wavelength; and judging whether the deviation between the fine scanning wavelength and the target wavelength meets the preset precision or not, if so, locking the output wavelength, otherwise, repeatedly regulating and controlling until the conditions are met. According to the invention, traditional current-wavelength dependence is broken through, and wavelength demodulation is realized through electromechanical collaborative calibration and two-stage scanning.

The invention discloses a kilometer deep well roadway toughness regulation and control supporting system and a dynamic design method, and belongs to the field of deep well roadway supporting. The supporting system comprises a multi-layer collaborative structure and an intelligent regulation and control module, the multi-layer collaborative structure sequentially comprises a shape memory alloy energy absorption layer used for resisting impact loads and a gradient pore foam metal buffer layer used for energy grading dissipation from inside to outside, and the multi-layer collaborative structure is connected with roadway surrounding rock in an anchoring mode through an anchor rod anchoring structure; the intelligent regulation and control module comprises a distributed optical fiber sensor array used for monitoring surrounding environment signals of surrounding rock in real time, an electrostriction driver used for regulating and controlling the rigidity of the multi-layer cooperative structure and a multi-channel data fusion terminal used for achieving underground and surface data transmission synchronization. By the adoption of the kilometer deep well roadway toughness regulation and control supporting system and the dynamic design method, the problems that a traditional supporting mode is too high in material rigidity, lacks dynamic regulation and control capacity and is insufficient in impact toughness can be solved.

An optical frequency domain reflectometer with environmental disturbance resistance and large strain measurement capability belongs to the field of distributed optical fiber sensing and comprises an opposite sweep frequency light frequency modulation continuous wave signal generation module, a light splitting device, a modulation device, a circulator, a polarization controller, an optical coupling device, a photoelectric conversion module and a data acquisition and processing module. An optical signal generated by an opposite sweep frequency light frequency modulation continuous wave signal generation module is divided into probe light and local oscillation light through a light splitting device, the probe light is modulated through a modulation device and sent to an optical fiber through a circulator, and a Rayleigh back scattering light signal generated by the optical fiber and the local oscillation light interfere in an optical coupling device to obtain interference light; the photoelectric conversion module mixes beat frequency signals of interference light, and the data acquisition and processing module analyzes and processes the beat frequency signals. According to the invention, the position information of the Rayleigh backscattering point is marked by using the modulated probe light, the Rayleigh scattering signal at the corresponding position is restored, crosstalk between channels is inhibited, and high-precision measurement in a large dynamic range and resistant to environmental disturbance is realized.

The invention discloses an all-fiber vortex interference system and a phase variation measurement method, belongs to the field of optical precision instrument design and test, and aims to realize ultrahigh-precision phase variation measurement by using an all-fiber structure. The vortex interference system comprises a light source module, an optical fiber beam splitting module, an optical fiber sensing module, an optical fiber mode conversion module, an optical fiber mode interference module and an imaging module in sequence along an optical path. The phase variation measurement method is a phase variation demodulation method based on angular Fourier transform, which is provided for the all-fiber vortex interference system. The interferometer provided by the invention does not need a complicated light path alignment step of a traditional interferometer, and the sensitivity of the all-fiber vortex interferometer is further improved.

A system, apparatus and method directed to detecting malposition of a medical device within a vessel of a patient, such as an Azygos vein. The medical device can include a multi-core optical fiber including a plurality of core fibers, where each of the plurality of core fibers includes a plurality of sensors is configured to reflect a light signal based on received incident light, and change a characteristic of the reflected light signal for use in determining a physical state of the multi-core optical fiber. The system can include a console having non-transitory computer-readable medium storing logic that, when executed, causes operations of providing a broadband incident light signal to the multi-core optical fiber, receiving reflected light signals, processing the reflected light signals, and determining whether the medical device has entered the Azygos vein of the patient based on the reflected light signals.

The invention discloses a rain and sewage pipeline defect detection method and system based on distributed optical fibers. The method comprises the following steps: 1, laying sensing optical fibers in a pipeline; 2, calibrating an excitation position; 3, collecting and demodulating optical fiber vibration data; 4, performing defect identification and defect positioning on data processed by an intelligent algorithm; vibration signals are sent out through the excitation device, signal collection is carried out in combination with the distributed optical fiber sensing module, efficient recognition and accurate positioning of pipeline defects are achieved in cooperation with an intelligent detection algorithm, and hidden diseases which cannot be perceived by naked eyes can be recognized. By means of an intelligent defect recognition algorithm, signals collected by the optical fiber sensing module are deeply analyzed, the positions and the disease degrees of the defects in the pipeline can be automatically judged, dependence on manual image interpretation is avoided, and automation and intelligentization of pipeline defect detection are achieved. The system has the advantages of being high in adaptability, wide in coverage range, efficient, accurate, high in intelligent processing capacity, low in cost, high in efficiency and the like.

The invention relates to the technical field of optical fiber performance analysis, in particular to a multi-core fiber grating multi-parameter decoupling method based on improved CNN-LSTM. According to the method, a multi-core fiber grating temperature, vibration and three-dimensional deformation detection system is built, center wavelength data under the action of different physical loads are collected, and the center wavelength data are matched with corresponding real physical quantities to build a supervised learning data set. After abnormal value elimination, filtering noise reduction and normalization processing are carried out on collected signals, stratified sampling and data enhancement are adopted to construct a training set and a test set. An improved CNN-LSTM model is established, multi-parameter nonlinear mapping and feature focusing are realized in combination with convolutional feature extraction, time sequence modeling and an attention mechanism, training is performed by taking RMSE as a loss function and an Adam optimizer, and an early stop mechanism is set to prevent overfitting. After training is completed, wavelength data to be measured are input into the model, and temperature, vibration and three-dimensional deformation results after decoupling can be output.

The invention discloses a novel photoelectric coding measuring method for a multistage coarse high-precision translation rotating platform. The invention relates to the fields of engineering measurement technology, precision machining and the like, and solves the problem that the measurement precision of an existing photoelectric translation rotary encoder needs to be improved. The camera is fixed on the rotating or translating device, and an encoding device of the encoder is fixed on the immovable rack; an encoding device of the encoder consists of an encoding array and a fine measurement light spot which are uniformly distributed; in the rotation or translation process of the motion device, collecting an encoding array image of an encoder and a precise measurement light spot image through a camera; identifying a coarse precision absolute position measurement value of the rotation angle according to the coding array image; according to the number of displacement pixels in a precise measurement light spot image, a coarse-precision absolute position measurement value is subdivided to the measurement precision which is one of the total number of column pixels of a camera, a high-precision measurement value of a rotation angle or a translation amount is calculated according to a gravity center algorithm, and the photoelectric coding measurement precision can be remarkably improved.

The invention relates to a micro-ring resonator based on a multi-circle square structure, the micro-ring resonator comprises a coupling waveguide and a multi-circle square micro-ring resonant cavity, the coupling waveguide comprises an S-bend waveguide, an input waveguide and an output waveguide which are all single-mode waveguides, and the multi-circle square micro-ring resonant cavity comprises a crossed waveguide chain and a multi-mode waveguide section connected with the crossed waveguide chain. The multi-mode waveguide section comprises a multi-mode straight waveguide and a 90-degree multi-mode Euler bending waveguide. By introducing the multi-mode waveguide, the energy distribution of the guided mode on the side wall is reduced, and the transmission loss of the micro-ring resonant cavity is reduced. Through the arrangement of the multi-circle square micro-ring resonant cavity, the length of the micro-ring is increased within a limited size, and the Q value of the multi-circle square micro-ring resonant cavity is improved. By means of the 90-degree multimode Euler bending waveguide, compact 90-degree turning is achieved, generation of a high-order mode is restrained, and meanwhile the micro-ring surrounding area is increased. Therefore, a solution can be provided for the high-performance sensing unit for the integrated micro-ring sensor.

The invention discloses a multi-mode visual tactile sensor and a sensing method thereof. The sensor is composed of a sensing cover and an imaging box body, the sensing cover is fixed on the imaging box body, the sensing cover is provided with a flexible sensing layer, an embedded mark point array combining inert ink and thermochromic ink is arranged in the sensing layer, during tactile sensing, a light source is provided through the imaging box body, and multi-mode sensing data is obtained. Therefore, displacement tracking and temperature sensing are realized at the same time. According to the invention, multi-mode sensing of five modes of a two-dimensional texture pattern, a three-dimensional texture image, a three-dimensional displacement field, a three-dimensional force field and a two-dimensional temperature field can be realized under a single optical frame, real-time co-registration measurement can be realized, and a high-integration-level solution is provided for a robot touch system. The problems that an existing visual tactile sensor cannot sense multi-mode information synchronously, force field reconstruction calculation is complex, and temperature sensing capacity is lacked are solved, and the visual tactile sensor is suitable for application scenes such as robot tactile sensing, man-machine interaction, intelligent artificial limbs and industrial detection.

An optical path testing device and an optical path testing method divide output light from a laser light source into a probe optical path and a local optical path and convert modulated light obtained by modulating input light of the probe optical path into probe light including pulsed light, generate a beat signal by causing signal light and input light of the local optical path to interfere with each other, acquire a signal indicating backscattered light in the optical fiber on the basis of the beat signal, and analyzes a loss distribution, generate the modulated light by performing, on the output light, modulation based on a frequency changing from a start frequency to an end frequency, generate an analysis signal by averaging the backscattered light in each different frequency band included in the beat signal between the different frequency bands and acquire the loss distribution.

The invention discloses an FPI and MZI optical fiber sensor based on a PDMS microcavity and application thereof, relates to the technical field of optical fiber sensors, and aims to solve the problem of lack of an optical fiber sensor with a double-effect cooperative regulation mechanism in the prior art. According to the technical key points, the FPI and MZI optical fiber sensor based on the PDMS microcavity is composed of a first single-mode optical fiber, a multimode optical fiber, the PDMS cavity and a second single-mode optical fiber which are connected in sequence, the first single-mode optical fiber and the multimode optical fiber are welded, the microcavity exists between the multimode optical fiber and the second single-mode optical fiber, PDMS is injected into the microcavity to form the PDMS cavity, and the PDMS cavity is connected with the PDMS microcavity. One end, far away from the PDMS cavity, of the second single-mode optical fiber is a cutting end surface; the critical surface of the multimode optical fiber and the PDMS cavity is a reflector 1, the critical surface of the second single-mode optical fiber and the PDMS cavity is a reflector 2, and the reflector 1 and the reflector 2 form a Fabry-Perot interferometer. The sensor combines the working principles of FPI and MZI, and can realize accurate measurement of temperature.

The invention belongs to the technical field of distributed optical fiber sensing (DAS) system signals, and discloses a time axis phase unwrapping method and system based on an FPGA (Field Programmable Gate Array), and the method comprises the steps of phase data acquisition, stable group formation, phase progressive unwrapping, assembly line and cache cooperative processing and quality measurement closed-loop correction. According to the system, real-time phase extraction of interference signals is achieved through the FPGA demodulation unit, phase change is dynamically unwrapped through the reliable period screening unit and the phase progressive unwrapping unit, a self-adaptive unwrapping mechanism is formed in combination with anomaly judgment and threshold updating logic, and through collaborative design of an annular cache and a three-level assembly line comparator, the interference signal is obtained. According to the method, parallel transmission and time sequence synchronization of data are achieved, the precision and stability of phase unwrapping can be effectively improved in a complex noise environment, hardware delay and resource occupation are remarkably reduced, and the method is suitable for real-time signal unwrapping processing of a high-precision distributed optical fiber sensing system.

The invention relates to the technical field of optical fiber sensing, in particular to a tunable laser parameter optimization method for fiber bragg grating demodulation, which comprises the following steps of: setting scanning ranges of currents of a left Bragg reflector and a right Bragg reflector, generating a current combination sequence according to arc radius parameters, inputting the current combination into a tunable laser, collecting an output wavelength, and identifying a wavelength tuning channel and a central point thereof; and arranging the center points of the channels in sequence, and generating smooth and continuous channel center lines on the left current dimension and the right current dimension by adopting cubic spline interpolation so as to obtain a continuous and executable tuning path. According to the method, a smooth and continuous channel center line is constructed through a segmented arc scanning path and cubic spline interpolation, and an initial lookup table is formed by combining phase current fine scanning and ordered splicing, so that high-quality wavelength coverage under low sampling amount is realized, and the problems of data redundancy and channel boundary mode hopping in a traditional method are solved.

A fibre-optic sensor for measuring a physical quantity, such as a pressure, force, acceleration or tilt, includes an optical fibre having a measurement section for measuring a strain in the fibre, and first and second structural members. The optical fibre is connected to a first fibre connection section of the first structural member and to a second fibre connection section of the second structural member. The first and second connection sections are arranged on opposite sides of the measurement section, such that at least the measurement section is suspended between the first and second fibre connection sections. At least one of the structural members is movable relative to the other in dependence of the physical quantity that is measured. The structural members are made from materials having different coefficients of thermal expansion such that a temperature induced strain in said optical fibre due to a temperature change is reduced.

The invention provides a compensation method for asymmetric errors of a double-path weak measurement system and the double-path weak measurement system, which can be applied to the technical field of quantum measurement. The compensation method comprises the following steps: under the condition that wide-spectrum light passes through a double-path weak measurement system and the size of a signal which is weakly coupled with a weak coupling module is within a preset range, applying a square wave signal with a preset amplitude to a push-pull phase modulator, and performing binary detection by using an acquisition module to obtain four first detection signals; under the condition that the preset amplitude is not 0, determining a first error introduced by asymmetric loss of the double-path weak measurement system according to the corresponding four first detection signals; according to the four first detection signals corresponding to the square wave signal with the preset amplitude of 0 and the first error, determining a second error introduced by filter asymmetry of the double-path weak measurement system; according to the first error and the second error, asymmetric error compensation is carried out on the response formula, and it is ensured that the double-path weak measurement system has high sensitivity and stability.

The invention discloses a seesaw type optical fiber end face weak force sensor which comprises a seven-core optical fiber, a seesaw type additive structure and an interference light beam. The seven-core optical fiber is composed of a central main fiber core and six symmetrically-distributed auxiliary fiber cores. The seesaw-type additive structure is composed of a short vertical beam, a vertical beam on a central main fiber core of the seven-core optical fiber and a cross beam connected to the vertical beam, and the whole structure is prepared through the two-photon polymerization technology of a femtosecond laser processing platform; the interference light beam is composed of two light beams in an interference cavity, wherein the lower surfaces of the left side and the right side of the seesaw-type additive structure are aligned with the end faces of two auxiliary fiber cores on the left side and the right side of the seven-core optical fiber. According to the invention, a two-photon polymerization technology is used to build an additive structure on the end face of the seven-core optical fiber, so that the sensing structure is small in overall size and is suitable for application in a limited space; the Fabry-Perot interferometers on the two sides of the sensing structure are connected in parallel to form an optical dynamic vernier structure, the sensitivity is improved through differential amplification of weak mechanical disturbance, and the anti-interference capability is enhanced through common-mode denoising.

The invention belongs to the technical field of distributed optical fiber sensing, and relates to a coding difference phase noise and distortion cooperative suppression optical frequency domain reflection method, which comprises the following steps: acquiring upper and lower frequency sweeping and beat frequency signals; separating the upper and lower sweep-frequency beat-frequency signals to obtain an upper sweep-frequency beat-frequency signal and a lower sweep-frequency beat-frequency signal; acquiring an upper sweep frequency beat frequency electric signal and a lower sweep frequency beat frequency electric signal; and the upper frequency-sweeping beat-frequency electric signal is delayed by one spatial resolution and then is mixed with the lower frequency-sweeping beat-frequency electric signal, or the lower frequency-sweeping beat-frequency electric signal is delayed by one spatial resolution and then is mixed with the upper frequency-sweeping beat-frequency electric signal, a frequency-mixing signal after phase frequency noise and frequency domain distortion suppression is obtained, and the Fourier frequency domain spectrum of the frequency-mixing signal is analyzed. The invention also provides a coding difference phase noise and distortion cooperative suppression optical frequency domain reflection system. The system comprises a positive and negative double-sideband sweep frequency light acquisition device, an optical splitter, a spectrum spreading device, an interference device, a beat frequency signal acquisition device and an electric delay unit. According to the invention, phase noise and frequency domain distortion noise can be effectively suppressed.

The invention relates to the technical field of distributed optical fiber sensing, in particular to a method for separating multi-source signals in a distributed optical fiber sound wave sensing system, which comprises the following steps: determining the number of sensing channels based on aliasing signals transmitted by one optical fiber and collected by the distributed optical fiber sound wave sensing system; estimating the number of source signals in the aliasing signals to obtain the number of the source signals; comparing the number of the sensing channels with the number of source signals, and selecting a signal separation strategy according to a comparison result; and carrying out separation processing on the aliasing signal to obtain a separation signal. According to the invention, the reliability and engineering application value of processing the multi-source aliasing signal in a complex environment are significantly improved.

The application discloses a kind of EFPI optical fiber sensor multi-sensor multiplexing temperature-pressure demodulation system and method, including ASE broadband laser, optical circulator, EFPI optical fiber sensor, 2-way wavelength division multiplexer, N-way wavelength division multiplexer, N-way wavelength division demultiplexer, photoelectric detector, FBG, 1*2 optical fiber coupler, optical spectrometer, data processing system;The input port input of the optical circulator is connected with ASE broadband laser, the output port cir2 is connected with two cascaded FBGs, the output port cir3 is connected with EFPI optical fiber sensor, the input port of 2-way wavelength division multiplexer is connected with the output port cir4 of optical circulator, and the output port is connected with N-way wavelength division multiplexer;N-way wavelength division multiplexer is accessed via the input port of 1*2 optical fiber coupler, and outputs two-way signals, one-way is connected with N-way wavelength division demultiplexer via N-way photoelectric detector and data processing system, and the other way is connected with optical spectrometer;N channels are connected by cascaded FBG, and the cascade of N EFPI optical fiber sensors is realized.

The application belongs to the technical field of distributed optical fiber sensing, and particularly relates to a long-distance distributed optical fiber broadband acoustic vibration sensing system. The application utilizes the same laser to transmit and generate back Rayleigh scattering light and interference light in the same sensing optical fiber, and further constructs a distributed optical fiber acoustic vibration sensing system combined with Φ-OTDR and MZI, which comprehensively utilizes the performance advantages of both, utilizes a very simplified optical system scheme, realizes the function fusion of the two sensing structures on one sensing optical fiber, reduces the resource waste caused by the transmission of sensing signals by different sensing optical cables respectively, maximizes the optical fiber resource utilization rate, and reduces the system cost; utilizes a frequency division multiplexing demodulation scheme in the digital domain, expands the frequency response range on the basis of ensuring the high positioning accuracy of the system, realizes the simultaneous detection of the two systems by a single core, simultaneously realizes the high positioning accuracy and the continuous non-blind area detection in the broadband frequency range, and improves the reliability.

The invention discloses a large-aperture telescope shafting angle detection method based on an arc grating encoder. The method comprises the following steps of: tensioning and mounting a linear grating ruler along the circumference of a shaft system turntable to form an arc grating body; n reading heads are uniformly arranged along the circumference of the rotation direction of the shaft system, the rotation position information of the shaft system is read, the effective range of the arc grating is calculated and converted into angle information, and the resolution of the arc grating is calculated; installing a full-circle grating, obtaining the detected shafting rotation position information, comparing the detected shafting rotation position information with the arc grating angle detection information, and verifying the correctness of the position information obtained by the arc grating. The arc grating is used for replacing an angle measurement grating, the measuring range and the resolution of the arc grating can be accurately obtained, the correctness of information obtained by the arc grating is verified through the concentric-shaft full-circle grating, the closed-loop effect does not exist, the machining difficulty is low, meanwhile, the length of the grating ruler can be selected according to the rotation range of a shaft system, and the measurement precision is high. And the installation and adjustment difficulty is reduced.

The invention provides a visual tactile sensor, a geometric calibration method and computer equipment, and the visual tactile sensor comprises a base which is internally provided with an imaging unit; the light source module is arranged on the base and comprises 3N single-point light sources which are arranged around the imaging unit and can be independently controlled, and N is larger than or equal to 1; and the elastic housing is arranged on the base in a covering manner, and the imaging unit and the light source module are wrapped in the elastic housing. By constructing the novel curved surface visual tactile sensor and the matched geometric calibration method thereof, the problems that a traditional plane sensor is weak in multi-direction contact sensing capacity, difficult in curved surface calibration and the like are effectively solved, data generated by a physical model are used for training a lightweight neural network, and the accuracy of the curved surface visual tactile sensor is improved. Real-time surface normal prediction under single-frame three-color image input is realized, and the precision and reasoning speed of three-dimensional reconstruction are considered while hardware dependence and calibration cost are remarkably reduced.

The invention discloses a transformer winding temperature and strain double-parameter monitoring method, system and device and a medium, and relates to the technical field of transformer monitoring, and the method comprises the steps: arranging a temperature sensing unit and a strain sensing unit on an optical fiber; a first reflection spectrum signal and a second reflection spectrum signal of the transformer winding are obtained and demodulated, and a first temperature signal of the transformer winding and a mixed signal containing a second strain signal and a second temperature signal are obtained; and taking the first temperature signal as compensation, and decoupling the mixed signal to obtain a second strain signal of the transformer winding. The fiber bragg grating technology is adopted, a plurality of sensors are inscribed on one optical fiber, synchronous measurement of temperature and strain is achieved, and strain data are compensated through winding temperature changes. According to the invention, the defects that only a single physical quantity can be monitored and the strain measurement accuracy is influenced by the temperature in the prior art are overcome, and accurate, convenient and efficient monitoring of the temperature strain of the transformer winding is realized in combination with online monitoring software.

The invention discloses an optical fiber sensor and a preparation method thereof, and belongs to the technical field of optical fiber sensing, and the optical fiber sensor comprises an optical fiber body adopting a splicing structure of a single-mode optical fiber, a tapering coreless optical fiber and a single-mode optical fiber; the cascaded F-P structure comprises a sensing cavity and a reference cavity which are arranged on the tapering coreless optical fiber; the metal enhancement layer comprises a silver film and a gold nanorod array which are sequentially arranged on the surface of the tapering coreless optical fiber, the thickness of the silver film is 30-50 nm, the length-diameter ratio of gold nanorods is 3: 1-5: 1, and the diameter of the gold nanorods is 40-60 nm; the sensitive material coating comprises a polydimethylsiloxane (PDMS) film coated on the surface of the sensing cavity and a polyvinyl alcohol (PVA) film coated on the surface of the gold nanorod array, the thickness of the PDMS film is 3-7 microns, and the concentration of the PVA film is 2-4 wt%; according to the optical fiber sensor and the preparation method thereof provided by the invention, a synergistically enhanced sensing system is formed, and high sensitivity, amplification and multi-parameter detection capability are considered at the same time.

The invention belongs to the technical field of distributed optical fiber sensing, and relates to a phase-frequency noise suppression optical frequency domain reflection measurement method and system without an auxiliary interferometer. The measurement method comprises the following steps: acquiring positive and negative double-sideband sweep-frequency light with the same sweep-frequency range and opposite sweep-frequency directions; dividing the positive and negative double-sideband sweep frequency light into double-sideband detection light and double-sideband local oscillation light according to a preset proportion; configuring a pseudo-random noise code, and modulating the pseudo-random noise code to the double-sideband probe light to obtain spread spectrum double-sideband probe light; the spread spectrum double-sideband detection light enters the sensing optical fiber and is reflected back to the backward Rayleigh scattering light, and the backward Rayleigh scattering light and the spread spectrum double-sideband local oscillation light interfere with each other to output up-down sweep frequency beat frequency signals; separating the upper and lower sweep-frequency beat-frequency signals to obtain an upper sweep-frequency beat-frequency signal and a lower sweep-frequency beat-frequency signal; and after the upper sweep frequency beat frequency signal and the lower sweep frequency beat frequency signal are respectively decoded, a beat frequency signal is separated through band-pass filtering, the beat frequency signal is subjected to frequency mixing processing to obtain a frequency mixing signal after phase frequency noise suppression, and the frequency spectrum of the frequency mixing signal is analyzed.

The invention relates to the technical field of wind power blades, in particular to a distributed optical fiber monitoring system for monitoring cracks of a wind power blade. Comprising a distributed optical fiber sensor, a demodulator, a wireless network bridge, a junction box and a jumper wire, when the surface of a wind power blade main body is subjected to abnormal stress, the distributed optical fiber sensor is synchronously subjected to the abnormal stress, so that strain information of the blade surface is monitored, and the strain information is transmitted to the demodulator through an optical fiber signal; finally, the demodulator transmits data to a remote monitoring platform and gives an alarm in time, a remote operator can stop operation of the fan in time, dangerous accidents are avoided, the distributed optical fiber sensors do not belong to electrical equipment, optical signal transmission is adopted, the danger of lightning triggering is eradicated, and the safety of the fan is improved. Alarm and early warning can be carried out in advance when 1 mm tiny cracks appear on the blade body, the aim of early finding and early treatment is achieved, losses are reduced to the minimum, and small faults are prevented from becoming major safety accidents.