Real time diagnosis of transient pulse laser with high repetition by radial shearing interferometer.

Transient, high repetition pulse laser can be applied to test numerous physical parameters, where in situ, real time measurement and isolation of vibration is highly demanded. Because of its short half-width, high power, high repetition, and even large distortion, the laser presents unique challenges to conventional diagnosing methods. A system based on a novel cyclic radial shearing interferometer is proposed to diagnose the transient, high repetition pulse laser with common path, no reference plane, and high precision. With the spatial-carrier methods, the system needs only one interferogram to reconstruct amplitude and wavefront of the laser. The theories of amplitude and wavefront reconstruction have been validated by computer simulation, and errors less than 1/1000lambda are obtained for both. Comparing with the results of the ZYGO interferometer, an error less than 1/20lambda for both peak-valley and root-mean-square values is gained with good repeatability for the wavefront. The calibration process and real time diagnosis of a high repetition pulse laser are presented then. Finally, the error consideration and system optimization are discussed in detail.