Transmissive Diffractive Membrane Optic for Large Aperture Lightweight Optical Telescope

摘要

Transmissive diffractive membrane optic can be used in space optical telescope to reduce the size and mass of imaging system. Based on the international research results about transmissive diffractive membrane, a 4-level diffractive substrate with 100mm apertures was designed and transmissive diffractive membrane was fabricated by spin coating. High-precision support structure for diffractive membrane with surface precision 0.12λ, RMS (λ=632.8nm) was introduced, and that can meet the diffractive imaging requirements. Diffraction efficiency of the diffractive membrane supported by support structure was tested, and the test results showed that diffraction efficiency was ＞50%. The step figure test results illustrated the etched deep precision was less the 10nm. The imaging wavefront test result demonstrated a wavefront error of about 38 run RMS. The transmissive diffractive membrane optic can be very useful for large aperture imaging system to realize low mass and low cost.