Disk Surface Measurement Based On Phase Shifting Interferometry And Error Study

By changing the rod shape into a thin disk and increasing the surface/volume ratio, the thin-disk lasers can effectively solve the problem of thermal effect, and achieve a high average power, high peak power and high efficiency. However, further power scaling and better beam quality of thin-disk lasers are still severely limited by the thermal effect of Yb:YAG crystal, and therefore, measurements of the optical path difference of thin disk laser are quite necessary and important. This thesis investigates the commonly used methods for thermal effect measurement, and then select phase shifting interferometry to measure the OPD of disk crystal on non-operation condition.In this paper, the principle and calculation of the phase shift interference are introduced in details, then briefly describes the relationship between optical path difference and the optical aberration and the Zernike polynomials to establish a comprehensive analysis theory of OPD. After that, estimate the error sources that may occur during the experiment and mainly analyze the phase shifting error. Theoretically simulate the phase shifting error and its impact of OPD, and discuss the characteristics in different directions, different sizes and the random situations, at last, extract the contours of the aspherical curve and eliminate the ripple caused by phase shifting error. Set up experimental platform to measure the OPD of disk crystal, add a certain known error to the unknown phase shifting error to verify the inferences of theoretical analysis, and use the line fitting method to obtain the aspherical OPD without the phase shifting error, which has a certain significance for effect of stress during the crystal capsulation, thermal lensing measuring and improving the performance of the disk laser.