Impact and correction of CCD nonlinear response on measurement of the laser beam quality

In the process of measuring laser beam quality by using the CCD, the influence of nonlinear optoelectronic response of the CCD on the beam propagation ratios M2 was analyzed in the paper through comparing the wavelength of different lasers. As the beam width values from four different wavelength lasers measured by non-linear calibrated CCD were relatively large, the measuring accuracy of laser beam quality will be affected to a certain extent. Therefore, a new calibration method of optoelectronic response based on the CCD will be put forward. By setting up a laser beam quality measurement system based on CCD measurement and building the near-field and far-field transmission model of Gaussian laser beam as well as multiple sampling from laser beams' caustic profile in different positions of a certain transmission direction, the photoelectric response linear range can be obtained with statistical methods. The result of simulation and experiment shows that by using the optoelectronic response character's calibration result of the CCD to make nonlinear gray level restoration on images, the laser beam quality factor M2 can be measured more accurately and the relative error can be decreased by 2.36% compared with the measuring result by the international standard laser beam profiler. The method mentioned in the paper can effectively increase the measuring accuracy of the laser beam quality factor M2 and it has great application values on evaluating the laser beam quality.