Research On Mirror Coating Of Large Diameter Astronomical Optics Telescope

When the large aperture optics telescope is working, the primary mirror contact with the atmospheredirectly, pointing to the sky. After observation for long time, Some contamination such as dust particles inthe atmosphere will continuously fell to accumulate on the primary mirror, deteriorate the reflectance of thetelescope’s primary mirror, strengthen the stray light from primary mirror surface to the system detector.Cleaning the primary mirror regularly can Appropriate mitigation the speed of reduction of the of the primarymirror’s optical properties. In order to maintain the best observation effect on the astronomical telescope,every2-3years, recoating the primary mirror in large aperture astronomical optical telescope.In this dissertation,a research of coating the primary mirror in large aperture astronomical opticaltelescope is presented, use the first coating machine ZZ3200, which can deposition aluminum reflective filmfor large telescope primary mirror from the top to down. Discuss some problems respectively,such as thereflective film layer’s material, uniformity, molecular dynamics simulations of coating process, the structureof the vacuum chamber, the transporting and lifting of the primary mirror, old film stripping, cleaning forcoating, etc. Finally, for coating the Lijiang2.4-meter telescope primary mirror, which has the largest singleblock primary mirror in China in present, make the process arrangement about the primary mirror coatingprocess of Lijiang2.4-meter telescope, and the security management and other documents, finally completethe coating of primary mirror in Lijiang2.4-meter telescope.Firstly, discuss the choice of material for coating metal reflecting film to primary mirror in astronomicaloptical telescope, depend on the layout of evaporation source in the ZZ3200coating machine, discuss thenonuniformity of thickness of the Al coating, and the influence from the nonuniformity of thickness of the Alcoating to the imaging quality of telescope. Study the protected film of the primary mirror of astronomicaloptical telescope, analyse the influence from protected layer to the reflectance of the primary mirror, fromprotected layer to the old film stripping. Use the structure of ZZ3200coating machine, make moleculardynamics simulations of coating process. Make the process arrangement about the primary mirror coatingprocess of Lijiang2.4-meter telescope, and the security management and other documents. Based on theabove analysis, we complete the work of coating the primary mirror in Lijiang2.4-meter telescope use theZZ3200coating machine in October2012, And customize in yunnan observatory2.4m telescope primarymirror coating specification and related process card. This research work will provide the reference for largeastronomical telescope primary mirror coating in China In the future.By measurement of the accompany plated glass, the average reflectance in the range of350to1100nm is87.16%. After complete the Al coating to primary mirror in Lijiang2.4-meter telescope, observation resultsshow that the limiting magnitude increase more than one magnitude both imaging observation and spectrummeasurement.