Based on the analysis of a 1.2m-diameter active primary mirror system under gravity load, several performance
parameters of actuator are reported in this paper. The actuator is demanded to satisfy the active optics correction, support
the axial load of primary mirror, and compensate the deformation of axial supports. The quasi-Zernike polynomials are
employed to fit the maximal allowed surface error of telescope to compute the force accuracy of actuator. Moreover, the
axial load and deformation of primary mirror system is analyzed by using the finite element (FE) method. Through the
above procedures, the performance parameters, such as force range, force accuracy, axial stroke and displacement
resolution, are obtained.