Cold Chopper System for Mid-infrared Instruments

摘要

We have developed a cold chopper system for mid-infrared observations. This system is installed into the newlydeveloping mid-infrared instrument, MAX38, for the University of Tokyo Atacama 1.0-m telescope. It is cooled to about9K. The cold chopper mirror is controlled by a piezoelectric actuator with a flexure hinge lever, and enables square-wavechopping at a frequency up to 7.8 Hz. At the moment, the maximum throw of the chopper is 30 arcseconds on the sky.This cooled chopping mirror system can also be applied to the tip-tilt mirror for SPICA infrared space telescope. Wecarried out the first light with Kanata 1.5-m telescope at Higashi-Hiroshima Observatory (Hiroshima, Japan) in June2007 and March 2008. In this observation, we demonstrated that the cold chopper could cancel out the atmosphericturbulence noise of a frequency of 5 Hz at 8.9 micron.