Diagnosis of the spot and drift of a cw-COIL laser beam

ABSTRACT A dynamic spot diagnostic system has been developed to quantitatively measure the instability of a continuous-wave chemical oxygen iodine laser (CW-COIL). The system can measure the real time changes in drift, vibrationof low frequency, intensity profile and spot diameter for the CW-COIL laser beam. The cause that induces theinstability of laser beam was tentatively analyzed in this paper. The experimental results provided a basis forimproving the COIL laser and for studying the laser-material interactions.Keywords: chemical oxide iodine laser, CCD, beam drift 1 INTRODUCTION At present, the CW-COIL lasers are the practically useful chemical lasers of short wave length. The laser beams can improve the coupling energy with the target. By comparison with the HF and DF lasers, it attracts more and more attention as the second generation of chemical lasers. During the development of akilowatt level CW-COIL laser, its beam was found to be instable including drift ,low frequency vibration,varying spot profile and intensity. Some of the unstable factors can be attributed to the laser device, andare of bad influence on the laser-material interactions. Meanwhile, the turbulence and absorption in air can