High-precision calibration method for fiber Bragg grating strain sensing based on an optical lever

The high-precision strain calibration of a fiber Bragg grating (FBG) is critical to the engineering application of fiber grating sensors. In this paper, a strain calibration method based on the optical lever is proposed for the FBG sensor. The optical lever is used to measure a tiny displacement through optical amplification. Comparing with traditional strain calibration using a beam structure and strain gauge as the medium, the proposed method avoids problems of low sensitivity and stress transfer. The strain of an FBG was calibrated using an optical lever through theoretical analysis and experimentation. The principle of strain sensing and calibration is presented for the FBG to further study strain calibration of the FBG. The FBG strain is calibrated at a room temperature of 26 degrees C and the sensitivity of the FBG strain calibration is 1.13pm/mu epsilon. The effect of the temperature on strain calibration of the FBG using the optical lever is explored and the temperature of the FBG is controlled using a temperature control module to control the temperature of the thermoelectric cooler. The temperature of the thermoelectric cooler is not controlled in a stable manner, and the relationship among the central wavelength, temperature, and strain in the experiment is thus affected by the room temperature, which is not ideal. In future work, temperature compensation can be adopted to make the calibration of the FBG more accurate. Strain calibration using the optical lever method is clearly more accurate than previous strain calibration methods.