Study on high power laser beam quality measurement technology

High-power lasers are widely used in the field of industry, science and military. But there is no standard method for characterization and diagnosis of high-power laser beam quality for a long time, which brings great difficulties to the performance test of high-power laser systems. So it is necessary to measure the beam quality for high-power lasers and evaluate the performance of the laser systems scientifically. There are many traditional methods for beam quality determination, such as product of beam divergence angle and beam width, encircled energy ratio, Strehi ratio, diffraction limit factor and beam propagation factor M², and so on. The paper made a deep analysis for these methods and chose M² factor as a key parameter to determine the beam quality, according to which, A kind of beam quality measurement device was developed. Experiments showed that this device can describe the laser beam intensity distribution in two-dimension and three-dimension space correctly, which can also give the value of beam width, beam divergence and beam pointing stability in real-time.