Comparison of two experimental measurement methods for M2 factor

The measurement methods of M2 factor using hyperbolic fit and Hartmann-Shack sensor are studied experimentally. The results and experimental errors are compared and analyzed. It is shown that the measured M2 factor is approximately consistent using the two methods when the Hartmann-Shack wavefront sensor contains enough lenslet array, the reconstruction error is small and the orders of the Zernike polynomial is suitably chosen. Compared with the method using hyperbolic fit, the methods using Hartmann-Shack sensor has small scope of application. However, the method using Hartmann-Shack sensor is more simple when it contents the working condition.