Abstract: A set of processing and testing methods for optical elements with small angles are proposed for the assembly process of a large-scale infrared camera. 6 mirrors are added in processing and inspection, and the heights of the four feature points, the reverse sides and the initial angles of the machined element with 4 silicon carbide lenses are monitored. 6 mirrors are inspected using an interferometer. The angle between the processed surface and the initial surface of element and the height difference between the high point and the low point of element are calculated from the obtained interference fringes for guiding the amount of finish and machining angle of further processing. The value of the angle between the mirror surface of back surface and the back surface of element is calculated by the difference between their interference fringes. By processing, on the 80 mm-wide adjustable pad, an angle between the top and bottom surfaces finally is 0.21″, and the height difference between the upper edge and lower edge of adjustable pad is 0.100λ (λ=632.8 nm), that is, 63.28 nm, which is within the error range. The adjustable pad is mounted in an optical system, which meets the design requirements through mechanical and thermo-optical tests. The results show that it is feasible to use optical machining method to obtain the plane with the required small angle for small-sized mechanical parts. An interferometer is used to perform interference detection on the surface of auxiliary mirror, and the amount of finish on the surface of element is calculated. The surface height difference of the processed parts calculated from the interferogram of auxiliary mirror can meet the needs of the optical system installation and adjustment. Key

Key words: large-scalespaceinfraredcamera, partwithsmallangle, opticalmachinningmethod, opticaltestingmethod