Temperature stability analysis of high absorptivity coating and stray light suppression performance in the space optical system

To ensure the stability of high absorptivity coating from −40 ∘ C to +75 ∘ C and reliable operation of space optical systems throughout the entire on-orbit lifetime, this paper investigates the variations in appearance, surface scattering of the coating, and influence on the point source transmittance (PST) of the baffle after the thermal cycling test. Results show minor variations in performance. The root mean square (RMS) roughness changes from 11.250 to 11.791 µm, the relative bidirectional reflectance distribution function (BRDF) variation is ≤18%, and the absorptivity slightly rises from 98.15% to 98.21%. The baffle PST remains stable, with a pre-to-post ratio of 1–1.1 for simulations and 0.8–1.4 for measurements. The coating exhibits excellent thermal stability within the target range and meets the preliminary requirements for space applications.