GIONO Gabriel, D2, SOKENDAI, Mitaka（supervisor：Suematsu Yoshinori, Katsukawa Yukio, Hara Hirohisa）
Current progress on the CLASP telescope alignment.
The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a sounding rocket instrument currently under development at NAOJ. CLASP aims to measure for the first time the polarization of the Lyman-Alpha line (121.6nm) emitted from the solar upper-chromosphere and transition region, and derived the magnetic field strength and orientation through the Hanle effect.
CLASP instrument is composed of a classical Cassegrain telescope focusing the light inside an inverse-mount Wadsworth spectrograph. A polarization analyzer is located on both of the two channels, and a rotating half-waveplate is used for the polarization modulation.
As part of CLASP development, both telescope’s primary and secondary mirrors have to be properly align in order to ensure a good image and spectrum quality.
In this colloquium, the current progress on the telescope’s alignment will be presented. As an introduction, the experiment “double-pass” configuration will be explained as well as the basic principle of telescope’s alignment. Then, the measured wavefront error (WFE) and how it was retrieved from the interferences fringes will be shown. Finally, the adjustment estimation on the secondary mirror tilt will be derived by comparing the WFE aberration coefficient to ray-tracing simulations.