Spacing stability of tunable Fabry-Perot filter in ICF facility

In the 9th laser system of SGⅡ inertial confinement fusion(ICF) facility, tunable Fabry-Perot(F-P) filter is adopted to compensate the FM-AM(frequency modulation-amplitude modulation) effect, according to the technical requirements of compensation device, a precise displacement monitor system using the capacitive displacement sensor with nanometer scale precision to stabilize the spacing of the tunable F-P filter is proposed firstly，then the basic structure and operating principle of the monitor system are analyzed. The design scheme of the driving circuit for capacitive displacement sensor and the data processing as well as the system controlling software are discussed, and the precision of capacitive displacement sensor is calibrated. The experimental results show that the spacing stab