COOLED BAFFLE SYSTEM FOR SPACEBORNE INFRARED TELESCOPES

摘要

We report the design and testing of a compact system of baffles for cooled infrared telescopes. The baffle system consists of a reflecting forebaffle and a black aftbaffle and provides a high level of rejection of emission from off-axis sources. The firebaffle reflects radiation incident at angles greater than 40 degrees off axis out of the telescope, thereby reducing the aperture heat load. The black aftbaffle absorbs radiation scattered or diffracted by the forebaffle, as well as radiation from sources within 40 degrees off axis. We describe ground-based measurements at lambda = 0.9 mu m of the baffle system at ambient temperature and rocketborne measurements at far-infrared wavelengths of the baffle system at similar to 3 K. The effective emissivity of the cooled forebaffle was measured to be 7 x 10(-3). The system has been successfully used in rocketborne measurements of the diffuse infrared background and will be used in the Infrared Telescope in Space. [References: 23]