Factors affecting focusing performance of continuous phase plate concentration

To improve the far field focal spot in inertial confinement fusion, the paper analyzes the main factors affecting the focusing performance of continuous phase plates. The encircled energy fraction and the far-field root-mean-square spot size are analyzed. The results show that, the aperture error, alignment error and amplitude distortion error have little effect on the focusing ability of continuous phase plates. The wavefront distortion lowers the energy concentrated especially when the correlation length is equivalent to the minimum spatial period (about 10 mm) of continuous phase plates. Thus improving the correlation length of the wavefront distortion in the inertial confinement fusion system is an effective way to improve the energy concentration degree of the focal spot.