Design of high volume fraction SiC/Al composite mirror in space remote sensor

The difference of linear expansion coefficient between a mirror and its support structure causes mirror thermal deformation which influences the surface accuracy of mirror and the image quality of optical system. In order to avoid above influence, the high volume fraction SiC/Al composite is chosen as the only material of a Φ600 mm mirror component. The Φ600 mm mirror structure parameters are specified by the reasonable mechanical design and finite element analysis. Using finite element analysis method, the static and dynamic characteristics of the mirror component are analyzed. Under the gravity load of 1 g, the surface figure accuracy of the high volume fraction SiC/Al composite mirror reaches RMS 12.6 nm, 12.7 nm, 12.6 nm, in X, Y, Z respective direction, nearly λ/50(λ=632.8 nm). The mechanical dynamic test results verify the structural performance and the capability of vibration resistance. The 1st order natural frequency of the mirror component is 556.6 Hz. After the test, the surface figure accuracy changs from RMS 0.021λ to 0.025λ, not showing obvious changes. The high volume fraction SiC/Al mirror can reach the same design indexes as SiC mirror and meet the space application requirements.