OPTICAL-SYSTEM OF THE INFRARED TELESCOPE IN-SPACE

A 15-cm Ritchey-Chretien telescope with diamond-turned metallic mirror s has been developed for use in the cryogenically cooled infrared spac e mission, Infrared Telescope in Space (IRTS). The IRTS is designed to register infrared emission from 1 mum to 1 mm with a relatively wide beam (8' to 30' depending on the wavelength). It will be operated at s uperfluid helium temperatures (approximately 1.8 K). We tested the per formance of the telescope system both at room temperature (approximate ly 300 K) and at near-liquid-nitrogen temperature (approximately 100 K ) to investigate the effects of the support stress and the temperature on the telescope. The results indicated that the Hartmann constant st ays within the design goal (approximately 1') even in the worst case. The origin of aberrations is examined and possible improvements for fu ture application are discussed.