Fiber Bragg grating micro-displacement sensor and measuring method thereof
The invention discloses a fiber Bragg grating micro-displacement sensor and a measuring method thereof. The fiber Bragg grating micro-displacement sensor is composed of a cylindrical inner shell and an outer shell, four stainless steel flexible diaphragms are disposed in four symmetrical directions between the inner shell and the outer shell, places, in contact with the outer shell, of the flexible diaphragms are fixed by welding, the outer shell is fixed on the inner shell by the aid of pressure of the four flexible diaphragms, and fiber Bragg gratings are adhered on all of the four flexible diaphragms. The fiber Bragg gratings are placed horizontally, the inner shell is fixed, relative positions of the outer shell and the inner shell change in case that the outer shell is under the action of external micro-displacement changes, the diaphragms deform to drive the Bragg gratings thereon to deform, and wavelength of the fiber Bragg gratings shifts. Since the four diaphragms are different in deformation, size and direction of displacement changes can be judged by analysis of wavelength shift of the four Bragg gratings. 1. Micro-displacement of the fiber Bragg grating sensor, characterized in that comprises a housing (1), the inner shell (2), an inner shell (2) is arranged in the casing (1) internal, inner shell (2) and housing (1) is also arranged between the optical fiber Bragg grating (4). 2. Sensor according to Claim 1, characterized in that the housing (1) and inner shell (2) are cylindrical. 3. Sensor according to Claim 1, characterized in that optical fiber Bragg grating (4) is arranged in the elastic diaphragm (3) is. 4. Sensor according to Claim 3, characterized in that an elastic diaphragm (3) is made of stainless steel, and the inner shell (2) and the housing (1) between the placed on four symmetrical direction. 5. Sensor according to Claim 1, characterized in that optical fiber Bragg grating (4) surrounding the inner shell (2), and with the inner shell (2) parallel to the bottom. 6. Sensor as in Claim 3 or Claim 4, characterized in that an elastic diaphragm (3) and inner shell (2) phase contact, and welded to the casing (1) upper. 7. Optical fiber Bragg grating micro displacement sensor measuring method, which is characterized by comprising: The housing (1) by the angle θ with the horizontal direction, the displacement function of the size after h, through the detection optical fiber Bragg grating (4) the drift amount in the vertical direction the Bragg wavelength ΔλMN, the drift amount of the horizontal direction ΔλPQ, are respectively obtained through the calculation of the elastic diaphragm (3) variation MN vertical direction, horizontal direction change amount PQ, then calculated according to the formula and h the size of the θ: 8. Method according to Claim 7, characterized in that through the detected ΔλMN, ΔλPQ, computing MN, PQ is based on the following two method of formula: MN= 1/3 . 5 *ΔλMN PQ= 1/3 . 5 *ΔλPQ wherein ΔλMN, ΔλPQ units of mm, MN, nm of the PQ.