Progress on large aperture transport mirrors

For the requirements of Inertial Confinement Fusion(ICF) facility for large aperture transport mirrors with higher performance, key technologies and special processing involved in mirror machining are explored. Some kinds of machining technologies, including the manufacturing of K9 glass blanks, optics cold processing, coating for transport mirrors and laser conditioning are investigated. The precision annealing process of 400 mm aperture K9 glass blank is proposed to implement the high precision optical finishing. Moreover, Low-defect coating is achieved. A preprocessing device for the larger aperture optical element is established and a laser conditioning platform for large aperture transport mirror is also realized. Finally, the paper reviews main achievements of development of large aperture transport mirrors. A 400 mm aperture transport mirror with an incidence angle of 45° shows its surface roughness to be higher than 99.8%, surface figure(PV value) lower than λ/3, and the laser-induced damage threshold higher than 30 J/cm2(5 ns) at 1 053 nm. The large aperture transport mirrors have been successfully used in the higher power laser equipment of SG ICF facility, which supports the stable operation of the facility. ? 2016, Science Press. All right reserved.