Coating experiment with 1.6-m vacuum evaporation chamber

We have conducted a series of coating experiments using the newly installed 1.6 m evaporation chamber at the Advanced Technology Center (ATC) of the National Astronomical Observatory of Japan. The main task of this chamber is to re-aluminize the 1.6 m mirror of the Infrared Simulator at the ATC. The design concept of the 1.6 m chamber is basically the same with the 8.3 m coating facility for Subaru Telescope. Therefore, we could utilize this chamber to evaluate the fundamental performance of the larger chamber. The extensive coating experiments were done in the spring, autumn of 1996, and autumn of 1997. Reduction of the number of the filaments has lead to the increase in their size, which caused difficulty in the annealing process. Attempts are focused on securing the sufficient metal loads on the filaments. Then the filaments are fired to measure the spray pattern of a single filament exposure, or the uniformity pattern resulted from the full setup of filament arrays. Using small slide glasses, the important parameters of the resultant reflecting film that are the thickness, the uniformity of the thickness, and the spectroscopic reflectance are measured. The absolute value of the reflectivity is estimated to be around 91% immediately after opening the chamber. In order to cover a wide range of observing wavelengths for the Infrared Simulator, and eventually for the optical-IR Subaru Telescope, it is necessary to seek after a higher evaporation rate with these chambers.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.