Study Of Frequency Stabilization And The Application In Thermai Expansion Coefficients Measurement Of Materials Of Microchip Laser Feedback Interferometer

Microchip laser feedback interferometer is based on frequency-shifted optical feedback effects and the heterodyne phase measurement technique, which has an ultrahigh sensitivity and nanometer resolution, and can achieve fully noncooperative measurement of the materials with the surface reflectivity below 10-6. Therefore, it has broad application prospects in high precision measurement. Frequency stabilization and application in thermal expansion coefficients measurement of the interferometer are the research contents in this paper.The high-precision measurement of the interferometer depends on the accuracy and stability of the output wavelength of the light source, and the stability of the relaxation oscillation. Therefore, we develop a frequency stabilization Nd:YVO4 microchip laser with the full internal cavity diode-pumped by the separation temperature control of a semiconductor pump source and an Nd:YVO4 micro crystal. By validation, we have completed the targets such as:Easily adjustment to achieve a single longitudinal mode and linear polarization laser output; Frequency stability is better than 1.5×10-7 in a long time; Frequency repeatability is better than 5×10-7; The relaxation oscillation is stable in a long time. Finally, based on the analysis of the experiments, the parameters limiting the accuracy of frequency stabilization are identified, which can play a role in promoting the future research.The noncooperative and high sensitivity optical displacement measurement technology is very relevant to the study and the determination of high-precision thermal expansion coefficients of materials in a large temperature range. In this paper, we take full advantage of ultrahigh sensitivity of microchip laser feedback interferometer and carry out the application in the measurement of thermal expansion coefficients of materials. By validation, we have achieved the measurement of aluminum, steel 45 and carbon fiber composite samples by the system we proposed. Aluminum and steel 45 samples are determined in the temperature range of 298K-748K. Especially, confirming the precision within 5×10-7 K-1 and the accuracy within 0.4% from 298K to 598K by the system with a compensation path we designed. The research contents of thermal expansion coefficients measurement based on micro laser feedback interference provide the experimental and theoretical basis for the instrumentation of this system.