title: Narrow-bandpass multilayer mirrors for an extreme-ultraviolet Doppler telescope.
abstract: We have developed narrow-bandpass MoSi/Si multilayer mirrors for a Japanese sounding-rocket program. A high spectral resolution lambda/Deltalambda exceeding 40 was achieved by a two-mirror telescope with a multilayer coating. The single telescope had two bandpasses in the extreme-UV range for detecting a coronal high-velocity flow; the wavelength at peak reflectance (hereafter peak wavelength) in one of the bandpasses was 210.2 A, situated on the blue side of the target's Fe XIV 211.3-A coronal emission line, and the peak wavelength in the other was 213.3 A on the red side. A high uniformity in a peak wavelength of less than 1 A was achieved over a primary (secondary) mirror surface 158 (96) mm in diameter. The ratio of the reflectance for the Fe XIV line at 211 A to that for an intense He II line as a contaminant at 304 A in the telescope system became 2 x 10(5) owing to a wave trap consisting of a single Si layer on the MoSi/Si multilayer. The narrow-bandpass (approximately 5-A) telescope was launched on 31 January 1998 by sounding rocket S520CN-22, and images of the whole-Sun corona at Fe XIV 211 A were successfully obtained.
authors.affiliation: Solar Physics Division, National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan. hara@solar.mtk.nao.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Hara
authors.forename: S
authors.initials: S
authors.lastname: Nagata
authors.forename: R
authors.initials: R
authors.lastname: Kano
authors.forename: K
authors.initials: K
authors.lastname: Kumagai
authors.forename: T
authors.initials: T
authors.lastname: Sakao
authors.forename: T
authors.initials: T
authors.lastname: Shimizu
authors.forename: S
authors.initials: S
authors.lastname: Tsuneta
authors.forename: T
authors.initials: T
authors.lastname: Yoshida
authors.forename: W
authors.initials: W
authors.lastname: Ishiyama
authors.forename: T
authors.initials: T
authors.lastname: Oshino
authors.forename: K
authors.initials: K
authors.lastname: Murakami