We demonstrate a novel approach termed targetphaselocking that could improve the entire beam wavefront quality of a 500 TW Nd 3+ :phosphate glass laser facility. The thermal and static wavefront from frontend to target is corrected by using one deformable mirror that receives feedback from both the focalspot sensor and wavefront sensor, and only the main laser of the laser system is employed in the correction process, with auxiliary calibration light no longer necessary. As a result, a static focal spot with full width at half maximum of 8.87 × 5.74 µm is achieved, the thermal wavefront induced by flashlamppumped Nd 3+ :phosphate glass is compensated with PV from 3.54-0.43 µm, and a dynamic focal spot with intensity exceeding 10 20 W cm −2 is precisely predicted at the target with such an approach.

The feasibility of the closed-loop adaptive optic system based on laser far-field information was experimentally demonstrated, which can significantly increase the working efficiency of the multi-beamline high power solid laser facility. A stochastic parallel gradient descent algorithm with mean-radius cost function was applied in the adaptive optics that was installed in one chosen beamline in the SG-III laser facility. The far-field diameter from a reference laser was corrected from about 275 to 100 µm, very close to the ideal limit of 75 µm. Multiple-wavefront correction can be performed with this far-field detection based adaptive optics system, and the experimental result validates the practicability of the proposed system in the multi-beamline high power solid laser facilities.