Determination of wavefront distortion of an aerodynamic window in a high-power laser

The optical characteristics of new type jet injecting aerodynamic window have studied experimentally with HARTMANN diagnostic apparatus. When the pressure of sealed vacuum chamber is changed from 2500 Pa to 771.4 Pa, the Strehl ratio is determined from 0.94 to 0.90. From these optical characteristics it can be analyzed, that the injection flow pressure and the structure of aerodynamic window influences the passed beam quality on. It was shown that the passed beam well be divergence, as the injection flow pressure becomes large. It is related to the radius gradient of air density distribution, caused by gas flow from circular nozzle. And heterogeneous distribution of air bleed hole makes the wavefront tilt so that the passed laser beam well shift.