title: Optical system of the Infrared Telescope in Space.
abstract: A 15-cm Ritchey-Chretien telescope with diamond-turned metallic mirrors has been developed for use in the cryogenically cooled infrared space mission, Infrared Telescope in Space (IRTS). The IRTS is designed to register infrared emission from 1 µm to 1 mm with a relatively wide beam (8' to 30' depending on the wavelength). It will be operated at superfluid helium temperatures (~ 1.8 K). We tested the performance of the telescope system both at room temperature (~ 300 K) and at near-liquid-nitrogen temperature (~ 100 K) to investigate the effects of the support stress and the temperature on the telescope. The results indicated that the Hartmann constant stays within the design goal (~ 1') even in the worst case. The origin of aberrations is examined and possible improvements for future application are discussed.
authors.forename: T
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authors.lastname: Onaka
authors.forename: T
authors.initials: T
authors.lastname: Yagi
authors.forename: H
authors.initials: H
authors.lastname: Shibai
authors.forename: H
authors.initials: H
authors.lastname: Murakami
authors.forename: T
authors.initials: T
authors.lastname: Tanabé
authors.forename: T
authors.initials: T
authors.lastname: Kohno