CN104677284A - Three-core fiber bragg grating probe micro-scale measuring device and method based on linear cavity optical fiber laser - Google Patents

Abstract

The invention discloses a three-core fiber bragg grating probe micro-scale measuring device and a three-core fiber bragg grating probe micro-scale measuring method based on a linear cavity optical fiber laser, and belongs to the technical field of precise instrument manufacturing and measurement. Three single-mode optical fibers are adopted to communicate a multi-way light switch with a three-core fiber bragg grating probe through a three-core optical fiber fan-out device and a three-core optical fiber respectively; the fiber bragg grating in the three-core fiber bragg grating probe and external reference grating are switched through the multi-way light switch so as to be used as wavelength selection devices of the linear cavity optical fiber laser respectively; the initial central wavelength of the external reference grating, the initial central wavelength of the fiber bragg grating in the three-core fiber bragg grating probe, and the initial central wavelength of the fiber bragg grating can meet linear working conditions of the three-core fiber bragg grating probe; the multi-way light switch is controlled through a computer to switch light paths; a spectral analyzer is adopted to respectively measure the wavelength of output laser of the linear cavity optical fiber laser; two-dimensional micro-scale measurement free of temperature coupling can be realized by using a differential data processing algorithm. The device and the method have the characteristics that functions of sensation and energy supply are integrated, the structure is compact and the sensitivity is high.

Description

Based on three core fibre grating probe micro-scale measurement device and methods of linear cavity fiber laser

Technical field

The invention belongs to exact instrument manufacture and field of measuring technique, particularly a kind of three core fibre grating probe micro-scale measurement device and methods based on linear cavity fiber laser.

Background technology

Along with the development of aerospace industry, auto industry, electronics industry and sophisticated industry etc., for the demand sharp increase of accurate micro-member.Owing to being subject to the restriction of space scale and micro-member capture-effect to be measured and measuring the impact of contact force, the precision measurement of micro-member yardstick becomes difficult to achieve, especially the degree of depth measuring small inner chamber component is difficult to improve, and these become " bottleneck " of restriction industry development already.Measuring to realize smaller szie, increasing and fathom, the most widely used way is exactly that the inner chamber using elongated probe to go deep into micro-member detects, and is measured the small inside dimension on different depth by the mode aiming at sender.Therefore, the precision measurement of current micro-member size combines the aiming signal sending type detection system with very thin probe based on coordinate measuring machine, due to the development comparative maturity of measurement of coordinates machine technology, can provide accurate three-dimensional space motion, therefore the detection mode of aiming triggering type probe becomes the key of micro-member size detection system.

At present, the Main Means of micro-member dimensional measurement comprises following several method:

1. Chinese Harbin Institute of Technology Tan Jiubin teaches and Cui Ji culture and education the people such as to be awarded and proposed a kind of probe structure based on two coupling fiber, two optical fiber are communicated with by end welding ball, welding ball is as gauge head, one comparatively long optical fibers introduce light, other one comparatively short-range missile go out light, overcome the limitation that low-light pearl scattering method fathoms, can realize that 0.01mm is not less than to diameter, aspect ratio be not more than 15: 1 micro deep-hole measure time fine sight.Although this method overcomes capture-effect to a certain extent, the luminous energy of the reverse transfer that coupling ball realizes is very limited, fathoms and is difficult to further lifting.

2. USA National Institute of Standard and Technology employs the probe of single fiber measuring staff in conjunction with low-light pearl, in the two-dimensional direction the imaging of optical fiber measuring staff is amplified about 35 times by optical design, differentiate with 2 area array CCDs and receive optical fiber measuring staff imaging on two-dimensional directional, then contour detecting is carried out to the image received, thus the minute movement in measuring process of monitoring optical fiber measuring staff, and then realize trigger-type measurement, the theoretical resolution of this detection system can reach 4nm, the probe diameter of detection system is Φ 75 μm, the aperture of Φ 129 μm is measured in experiment, its expanded uncertainty probable value reaches 70nm (k=2), ergometry is μ N magnitude.This method detection resolving power is high, and measuring accuracy is high, and the gauge head of use is easy to miniaturization, can measure the micropore of larger aspect ratio.But in method, the two dimension of detection optical fiber measuring staff is touched displacement and must be used two cover imaging systems, and cause system architecture more complicated, measurement data calculated amount is larger, and these factors cause the real-time of detection system poor, System's composition more complicated.

3. what Union Bank of Switzerland metering office have developed that a novel coordinate measuring machine is devoted to structural features nano-precision can the measurement of trace.This measuring machine have employed the novel touch probe of the flexure hinge structure based on stamp identification principle, and this design can reduce moving mass and guarantee omnidirectional soft, is a probe with three-D space structure detectivity.The ergometry of this sensing arrangement, lower than 0.5mN, supports removable probe simultaneously, and probe diameter is minimum to Φ 100 μm.Detection system combines the platform of the high position precision that is developed by Philips CFT, and the positional precision of platform is 20nm.The standard deviation of this measuring system measuring repeatability reaches 5nm, and the uncertainty of measurement result is 50nm.This kind of method complex structural designs, require that measuring staff has higher rigidity and hardness simultaneously, otherwise be difficult to realize effective tactile displacement sensing, this makes measuring staff structure be difficult to further miniaturization, the aspect ratio measured is restricted simultaneously, and the resolving power of detection system is difficult to further raising.

4. Chinese Harbin Institute of Technology Cui Ji culture and education is awarded and is proposed a kind of pore size measurement mechanism based on FBG Bending and method with people such as Yang Fuling, the probe that the method utilizes fiber grating to process and corresponding light source, pick-up unit are as aiming triggering system, coordinate two-frequency laser interferometer measuring motion, the pore size of different cross section can be obtained.The microscale sensor of the method is when tactile survey distortion, and the main stress of probe does not act on fiber grating, and the resolution of system is very low, is difficult to further raising.

In sum, in current microsize and coordinates detection method, probe due to optical fiber fabrication have probe size little, measure that contact force is little, the feature that aspect ratio is large, measuring accuracy is high measured and obtain extensive concern, utilize its distinctive optical characteristics and mechanical property to be accomplished in several ways minute sized precision measurement on certain depth.With the main Problems existing of measurement means be now:

1. the tactile displacement resolving power of detection system is difficult to further raising.The elementary magnification of existing detection system is lower, result in its overall magnification lower, is difficult to the further raising realizing its tactile displacement resolving power.Main micro-touch displacement exercising result can not be applied on fiber grating by the fiber grating probe based on the pore size measuring method of FBG Bending, and then the transducing signal being converted into spectral information is faint, and the resolving power of system is very low.

2. detection system poor real, is difficult to realize accurate on-line measurement.The detection method that USA National Institute of Standard and Technology adopts must use two-way area array CCD Received signal strength image, more complicated image algorithm must be used could to realize touching optical fiber measuring staff the high resolution monitoring of displacement, this causes measuring system to need data volume to be processed greatly to increase, reduce the real-time performance of detection system, be difficult to the synchronism realizing aiming at sender in small inner cavity size and two-dimensional coordinate measuring process Yu opening, only measure.

3. there is the radial coupling of touching displacement of two dimension.Probe based on the pore size measuring method of FBG Bending has each consistent to performance, coupling is there is when radial two dimension touches displacement sensing, and cannot be separated, cause two-dimensional measurement to there is very big error, the Measurement accuracy that radial two dimension touches displacement cannot be realized.

4. do not possess the decoupling ability of radial and axial detection.Above-mentioned detection method or do not possess axial detection ability or do not possess the decoupling ability of radial and axial detection, when carrying out micro-scale measurement, measuring process is complicated, it is low to measure efficiency.

Summary of the invention

The object of the invention is to overcome micro-member dimension measurement method resolving power in above-mentioned prior art low, the drawback that tested dimension is single, a kind of device and method being applicable to micro-member two dimension micro-scale measurement is provided, three core fibre grating probes both surveyed sensing element as touching, also as the wavelength selecting device of linear cavity fiber laser, after three core fibre grating probe tips are by tactile displacement effect, stress causes the parameter of fiber grating to change, the reflection kernel wavelength of the fiber grating as linear cavity fiber laser wavelength selecting device is changed, and change linear cavity fiber laser Output of laser centre wavelength further, due to three core fibre gratings and external reference grating respectively with single-core fiber grating and as gain media Er-doped fiber together with form the very short linear resonant cavity of length, the condition forming laser is met during extraneous input pumping light, thus outside Output of laser, the wavelength selecting device of linear cavity fiber laser be subject to touch survey affect time, the centre wavelength of Output of laser has very high sensitivity to tactile measuring tool.Multichannel photoswitch is adopted to carry out the passage of handover measurement fiber grating, obtain three core fibre gratings and external reference grating respectively respectively as the laser instrument Output of laser centre wavelength information under the wavelength selecting device of linear cavity fiber laser, afterwards differential data process is done to it, reduce the impact of temperature fluctuation on measurement result, substantially increase the adaptive faculty of this device to environment, thus realize a kind of brand-new temperature without the two-dimentional micro-scale measurement of coupling.

The object of the present invention is achieved like this: a kind of three core fibre grating probe micro-scale measurement devices based on linear cavity fiber laser, comprise pumping source, wavelength division multiplexer, single-core fiber grating, Er-doped fiber, Multichannel photoswitch, external reference grating, single-mode fiber, three core fibre fan-out devices, three core fibres, probe clamper, three core fibre grating probes, isolator, spectroanalysis instrument, computing machine; Described computing machine controls Multichannel photoswitch switching-over light path, pumping source is connected with by single-core fiber grating, Er-doped fiber and external reference grating or the linear resonant cavity that is made up of with three core fibre grating probes single-core fiber grating, Er-doped fiber by a port of wavelength division multiplexer, and another port of wavelength division multiplexer is connected to form path through isolator and spectroanalysis instrument, computing machine; Multichannel photoswitch is communicated with three core fibre grating probes with three core fibres by three core fibre fan-out devices by three single-mode fibers respectively, three core fibre grating probes are fixedly mounted with by probe clamper, and the fiber grating in three described core fibre grating probes and described external reference grating switch the wavelength selecting device respectively as linear cavity fiber laser by Multichannel photoswitch; The initial center wavelength X of described external reference grating ₁, the initial center wavelength X of fiber grating in three core fibre grating probes ₂with the initial center wavelength X of single-core fiber grating ₃the linear convergent rate responsive operation condition of three core fibre grating probe micro-scale measurement device and methods need be met: $0.8\sqrt{\frac{{{\mathrm{\Δ\λ}}_1}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}\≤|{\mathrm{\λ}}_1-{\mathrm{\λ}}_3|\≤1.2\sqrt{\frac{{{\mathrm{\Δ\λ}}_1}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}$ With $0.8\sqrt{\frac{{{\mathrm{\Δ\λ}}_2}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}\≤|{\mathrm{\λ}}_2-{\mathrm{\λ}}_3|\≤1.2\sqrt{\frac{{{\mathrm{\Δ\λ}}_2}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}.$

A kind of three core fibre grating probe micro-scale measurement methods based on linear cavity fiber laser, described method is: computing machine controls Multichannel photoswitch switching-over light path, pumping source provides pump light, entered by exciting erbium ion to produce excited radiation light in single-core fiber grating, Er-doped fiber and external reference grating or the linear resonant cavity that is made up of single-core fiber grating, Er-doped fiber and three core fibre grating probes by a port of wavelength division multiplexer, and multiple reflections is enhanced in resonator cavity; When the gain obtained in the oscillation period of radiant light in resonator cavity is greater than loss, produce the laser of narrow linewidth, the laser produced exports from another port of wavelength division multiplexer, and the wavelength of Output of laser detected by spectroanalysis instrument, transfers in computing machine; When there is tactile survey in three core fibre grating probes and component to be measured, the reflectance spectrum centre wavelength of the fiber grating in three core fibre grating probes will offset, thus change Output of laser wavelength, under the control of the computer by switching Multichannel photoswitch, spectroanalysis instrument is utilized to detect in three core fibre grating probes three fiber gratings and external reference grating respectively as Output of laser centre wavelength during wavelength selecting device; Data processing, when two fiber gratings outside three core fibre grating probe core are respectively as linear cavity fiber laser wavelength selecting device, linear cavity fiber laser Output of laser wavelength does differential data process, and decoupling zero one dimension radial direction touches displacement and temperature drift; When the fiber grating of three core fibre grating probe core and external reference grating are respectively as linear cavity fiber laser wavelength selecting device, linear cavity fiber laser Output of laser wavelength does differential data process, obtain and touch displacement without the radial axis touching displacement and temperature drift coupling, realize the two-dimentional micro-scale measurement without temperature coupling.

Advantage of the present invention is:

1. have that precision is high, contact force is little based on three core fibre grating probe micro-scale measurement device and methods of linear cavity fiber laser, do not damage tested component surface, the feature of probe long service life.

2. utilize linear cavity fiber laser to produce the laser of narrow linewidth as measurement light, sensing, energy supply are integrated, and system compact improves measurement sensistivity simultaneously.

3. optical detection signal is only in fiber grating internal transmission, contact in space is converted into the change of reflectance spectrum centre wavelength, be not subject to the impact of component capture-effect when measuring microscale component, measuring aspect ratio can reach 100: 1, meets the requirement of large aspect ratio microstructure micro-scale measurement.

4. can realize based on three core fibre grating probe micro-scale measurement methods of linear cavity fiber laser radial and axial without coupling measurement simultaneously, the step of micro-scale measurement is simplified, improve the efficiency of micro-scale measurement.

5. the differential compensation system of reference is each other devised in probe interior, in conjunction with the three core fibre grating probe micro-scale measurement installation methods based on linear cavity fiber laser, eliminate variation of ambient temperature to the impact of measuring, substantially increase the adaptive faculty of sensors towards ambient, space and environment that traditional measurement instrument cannot normally work can be deep into carry out precision measurement, as narrow and small hemi-closure space and inflammable and explosive environment etc., be also applicable to industry spot and measure.

Accompanying drawing explanation

Fig. 1 is the three core fibre grating probe micro-scale measurement apparatus structure schematic diagram based on linear cavity fiber laser;

Fig. 2 is the sectional view of A-A in Fig. 1;

Fig. 3 is the profile of three core fibre grating probes in Fig. 1;

In figure: 1. pumping source, 2. wavelength division multiplexer, 3. single-core fiber grating, 4. Er-doped fiber, 5. Multichannel photoswitch, 6. external reference optical fiber, 7. single-mode fiber, 8. three core fibre fan-out device, 9. three core fibres, 10. probe clampers, 11. 3 core fibre grating probes, 12. isolators, 13. spectroanalysis instruments, 14. computing machines.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the invention is described in further detail:

Technical scheme of the present invention is: a kind of three core fibre grating probe micro-scale measurement devices based on linear cavity fiber laser, comprise pumping source 1, wavelength division multiplexer 2, single-core fiber grating 3, Er-doped fiber 4, Multichannel photoswitch 5, external reference grating 6, single-mode fiber 7, three core fibre fan-out device 8, three core fibre 9, probe clamper 10, three core fibre grating probe 11, isolator 12, spectroanalysis instrument 13, computing machine 14; Described computing machine 14 controls Multichannel photoswitch 5 switching-over light path, pumping source 1 is connected with by single-core fiber grating 3, Er-doped fiber 4 and external reference grating 6 or the linear resonant cavity that is made up of with three core fibre grating probes 11 single-core fiber grating 3, Er-doped fiber 4 by a port of wavelength division multiplexer 2, and another port of wavelength division multiplexer 2 is connected to form path through isolator 12 and spectroanalysis instrument 13, computing machine 14; Multichannel photoswitch 5 is communicated with three core fibre grating probes 11 with three core fibres 9 by three core fibre fan-out devices 8 by three single-mode fibers 7 respectively, three core fibre grating probes 11 are fixedly mounted with by probe clamper 10, and the fiber grating in three described core fibre gratings 11 and described external reference grating 6 switch the wavelength selecting device respectively as linear cavity fiber laser by Multichannel photoswitch 5; The initial center wavelength X of described external reference grating 6 ₁, the initial center wavelength X of fiber grating in three core fibre grating probes 11 ₂with the initial center wavelength X of single-core fiber grating 3 ₃the linear convergent rate responsive operation condition of three core fibre grating probe 11 micro-scale measurement device and methods need be met: $0.8\sqrt{\frac{{{\mathrm{\Δ\λ}}_1}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}\≤|{\mathrm{\λ}}_1-{\mathrm{\λ}}_3|\≤1.2\sqrt{\frac{{{\mathrm{\Δ\λ}}_1}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}$ With $0.8\sqrt{\frac{{{\mathrm{\Δ\λ}}_2}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}\≤|{\mathrm{\λ}}_2-{\mathrm{\λ}}_3|\≤1.2\sqrt{\frac{{{\mathrm{\Δ\λ}}_2}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}.$

A kind of three core fibre grating probe micro-scale measurement methods based on linear cavity fiber laser, described method is: computing machine 14 controls Multichannel photoswitch 5 switching-over light path, pumping source 1 provides pump light, entered by exciting erbium ion to produce excited radiation light in single-core fiber grating 3, Er-doped fiber 4 and external reference grating 6 or the linear resonant cavity that is made up of single-core fiber grating 3, Er-doped fiber 4 and three core fibre grating probes 11 by a port of wavelength division multiplexer 2, and multiple reflections is enhanced in resonator cavity; When the gain obtained in the oscillation period of radiant light in resonator cavity is greater than loss, produce the laser of narrow linewidth, the laser produced exports from another port of wavelength division multiplexer 2, and the wavelength of Output of laser detected by spectroanalysis instrument 13, transfers in computing machine 14; When there is tactile survey in three core fibre grating probes 11 and component to be measured, the reflectance spectrum centre wavelength of the fiber grating in three core fibre grating probes 11 will offset, thus change Output of laser wavelength, by switching Multichannel photoswitch 5 under computing machine 14 controls, spectroanalysis instrument 13 is utilized to detect in three core fibre grating probes 11 three fiber gratings and external reference grating 6 respectively as Output of laser centre wavelength during wavelength selecting device; Data processing, when two fiber gratings outside three core fibre grating probe 11 centers are respectively as linear cavity fiber laser wavelength selecting device, linear cavity fiber laser Output of laser wavelength does differential data process, and decoupling zero one dimension radial direction touches displacement and temperature drift; When the fiber grating at three core fibre grating probe 11 centers and external reference grating 6 are respectively as linear cavity fiber laser wavelength selecting device, linear cavity fiber laser Output of laser wavelength does differential data process, obtain and touch displacement without the radial axis touching displacement and temperature drift coupling, realize the two-dimentional micro-scale measurement without temperature coupling.

Based on the innovative point of three core fibre grating probe micro-scale measurement device and methods of linear cavity fiber laser and technique effect be: three core fibre grating probes are directly as the wavelength selecting device of linear cavity fiber laser, touch displacement information and can directly act on linear cavity fiber laser, the wavelength of its Output of laser is changed, compared with traditional fiber-optic grating sensor pick-up unit, sensitivity of the present invention has and significantly improves, in the present invention, as the wavelength selecting device that three fiber gratings in three core fibre grating probes of sensor and external reference grating are again linear cavity fiber lasers simultaneously, sensor and sensor energy feedway are organically combined, and, Multichannel photoswitch under the control of the computer, switch the wavelength selecting device forming linear cavity fiber laser respectively, the two dimension completed under the prerequisite not increasing additional light device without temperature coupling touches displacement measurement, the fiber-optic grating sensor pick-up unit volume making the present invention more traditional reduces more than one times, cost reduces more than twice, in the present invention, the initial center wavelength X of external reference grating ₁, the initial center wavelength X of fiber grating in three core fibre grating probes ₂with the initial center wavelength X of single-core fiber grating ₃meet $0.8\sqrt{\frac{{{\mathrm{\Δ\λ}}_1}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}\≤|{\mathrm{\λ}}_1-{\mathrm{\λ}}_3|\≤1.2\sqrt{\frac{{{\mathrm{\Δ\λ}}_1}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}$ With $0.8\sqrt{\frac{{{\mathrm{\Δ\λ}}_2}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}}\≤|{\mathrm{\λ}}_2-{\mathrm{\λ}}_3|\≤1.2\sqrt{\frac{{{\mathrm{\Δ\λ}}_2}^2+{{\mathrm{\Δ\λ}}_3}^2}{8\ln 2}},$ Make the three core fibre grating probe micro-scale measurement device and methods based on linear cavity fiber laser have linear convergent rate response, significantly reduce the difficulty of signal transacting; Technique effect of the present invention is given prominence to.

Claims (2)

1., based on three core fibre grating probe micro-scale measurement devices of linear cavity fiber laser, comprise pumping source (1), wavelength division multiplexer (2), single-core fiber grating (3), Er-doped fiber (4), Multichannel photoswitch (5), external reference grating (6), single-mode fiber (7), three core fibre fan-out devices (8), three core fibres (9), probe clamper (10), three core fibre grating probes (11), isolator (12), spectroanalysis instrument (13), computing machine (14); Described computing machine (14) controls Multichannel photoswitch (5) switching-over light path, pumping source (1) is connected with by single-core fiber grating (3), Er-doped fiber (4) and external reference grating (6) or the linear resonant cavity that is made up of with three core fibre grating probes (11) single-core fiber grating (3), Er-doped fiber (4) by a port of wavelength division multiplexer (2), and another port of wavelength division multiplexer (2) is connected to form path through isolator (12) and spectroanalysis instrument (13), computing machine (14); It is characterized in that: Multichannel photoswitch (5) is communicated with three core fibre grating probes (11) with three core fibres (9) by three core fibre fan-out devices (8) by three single-mode fibers (7) respectively, three core fibre grating probes (11) are fixedly mounted with by probe clamper (10), and the fiber grating in three described core fibre grating probes (11) and described external reference grating (6) switch the wavelength selecting device respectively as linear cavity fiber laser by Multichannel photoswitch (5); The initial center wavelength X of described external reference grating (6) ₁, the initial center wavelength X of fiber grating in three core fibre grating probes (11) ₂with the initial center wavelength X of single-core fiber grating (3) ₃the linear convergent rate responsive operation condition of three core fibre grating probe (11) micro-scale measurement device and methods need be met: $0.8\sqrt{\frac{\mathrm{\Δ}{{\mathrm{\λ}}_1}^2+\mathrm{\Δ}{{\mathrm{\λ}}_3}^2}{8\ln 2}}\≤|{\mathrm{\λ}}_1-{\mathrm{\λ}}_3|\≤1.2\sqrt{\frac{\mathrm{\Δ}{{\mathrm{\λ}}_1}^2+\mathrm{\Δ}{{\mathrm{\λ}}_3}^2}{8\ln 2}}$ With $0.8\sqrt{\frac{\mathrm{\Δ}{{\mathrm{\λ}}_2}^2+\mathrm{\Δ}{{\mathrm{\λ}}_3}^2}{8\ln 2}}\≤|{\mathrm{\λ}}_2-{\mathrm{\λ}}_3|\≤1.2\sqrt{\frac{\mathrm{\Δ}{{\mathrm{\λ}}_2}^2+\mathrm{\Δ}{{\mathrm{\λ}}_3}^2}{8\ln 2}}.$

2. three core fibre grating probe micro-scale measurement methods based on linear cavity fiber laser, it is characterized in that: described method is: computing machine controls Multichannel photoswitch switching-over light path, pumping source provides pump light, entered by exciting erbium ion to produce excited radiation light in single-core fiber grating, Er-doped fiber and external reference grating or the linear resonant cavity that is made up of single-core fiber grating, Er-doped fiber and three core fibre grating probes by a port of wavelength division multiplexer, and multiple reflections is enhanced in resonator cavity; When the gain obtained in the oscillation period of radiant light in resonator cavity is greater than loss, produce the laser of narrow linewidth, the laser produced exports from another port of wavelength division multiplexer, and the wavelength of Output of laser detected by spectroanalysis instrument, transfers in computing machine; When there is tactile survey in three core fibre grating probes and component to be measured, the reflectance spectrum centre wavelength of the fiber grating in three core fibre grating probes will offset, thus change Output of laser wavelength, under the control of the computer by switching Multichannel photoswitch, spectroanalysis instrument is utilized to detect in three core fibre grating probes three fiber gratings and external reference grating respectively as Output of laser centre wavelength during wavelength selecting device; Data processing, when two fiber gratings outside three core fibre grating probe core are respectively as linear cavity fiber laser wavelength selecting device, linear cavity fiber laser Output of laser wavelength does differential data process, and decoupling zero one dimension radial direction touches displacement and temperature drift; When the fiber grating of three core fibre grating probe core and external reference grating are as linear cavity fiber laser wavelength selecting device, linear cavity fiber laser Output of laser wavelength does differential data process, obtain and touch displacement without the radial axis touching displacement and temperature drift coupling, realize the two-dimentional micro-scale measurement without temperature coupling.