Development of the reflector panel for the new 10-m millimeter/submillimeter telescope

We are developing high quality reflector panels for the new 10-m telescope for millimeter/sub-millimeter waves, which is to be a prototype antenna for LMSA/ALMA. The telescope consists of 205 reflector panels, and is expected to achieve the surface accuracy of 17 micrometer for the entire telescope. Each reflector panels are machined from a single block of aluminum in size of 80 cm X 80 cm and weighs 15 kg/m2. The panel surface needs to be processed not to focus the sun-light on to the sub-reflector and the support structure to protect them from heating up. We have examined several methods for surface processing, including scratching the surface by a steel-wool or a sandpaper, and to blast sand like small particles against the panel surface. As a result, we found the sand-blast process to be the acceptable solution. The scattering width for the sun-lights were measured to be 86 degree(s) (FWHM), which feeds less than 1% of the incident sun- light to the sub-reflector, and causes temperature increase of only 45 degree(s)C. The sub-millimeter reflectivity of the sand- blasted panel was measured with the Fourier transform spectrometer which showed that the sand-blast process does not affect the reflectivity for the sub-millimeter waves up to 1.5 THz. The reflector panel mounted on the telescope is yet to be processed for scattering the sun-light in the near future.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.