Calibration method for high-power and wide-band laser beam divergence angle

In the evaluation and analysis of high-power laser system, the beam quality of laser is the decisive factor of the system beam quality and also an important index of acceptance and appraisal of laser, among which the beam divergence angle is an important parameter to identify the laser beam quality. The range of laser wavelength tested in this system is relatively wide, generally between 0.532 μm~10.6 μm, and no suitable detector can cover the whole band. Therefore, a new method was adopted to solve the measurement problem of wide-band beam divergence angle. The method of combining charge coupled device (CCD) imaging and scanning slit was used to measure the wide-band beam divergence angle. The CCD method was used to measure the laser beam divergence angle in visible and near-infrared band (0.532 μm~1.2 μm), and the scanning slit method was used to measure the laser beam divergence angle in mid-infrared band (1.2 μm~10.6 μm). The combination of the two methods can accurately measure the laser beam divergence angle in different wavebands.