The Finite Element Analysis(FEA) method is used in thermal analysis on axial temperature difference effects on the imaging quality of space remote sensor optical system

and deformations of Primary Mirror(PM) surface and Second Mirror(SM) surface. The FEA model was set up by PATRAN software

and temperature distribution calculation was completed by NASTRAN/NT software. The thermal elasticity deformations of main surfaces were expressed in Zernike polynomial and the analysis results were computed by ZEMAX optical design software to carry out the interface between the thermal analysis and the optical analysis. The results show that the axial temperature difference not only brings the defocus

but also effects on the image quality of the optical system. So temperature control is needed in focusing.Finally

this paper suggests that the axial temperature difference requirement of the PM is 0.8 ℃

the SM is 1.0 ℃

and between PM and SM is 3.0 ℃.