2022 Fiscal Year Annual Research Report

大型低温重力波望遠鏡KAGRAのための圧搾真空源の開発、導入及び検証

Research Project

Project/Area Number	20F20803
Research Institution	National Astronomical Observatory of Japan
Principal Investigator	LEONARDI MATTEO 国立天文台, 重力波プロジェクト, 特別客員研究員 (90816448)
Co-Investigator(Kenkyū-buntansha)	EISENMANN MARC 国立天文台, 重力波プロジェクト, 外国人特別研究員
Project Period (FY)	2020-11-13 – 2023-03-31
Keywords	KAGRA / filter cavity / freq. dep. squeezing / sapphire / optical absorption / birefringence / liquid crystals
Outline of Annual Research Achievements	From April 2022, Dr. Eisenmann participated to the characterization and improvement of the Filter Cavity (FC) optical losses and design of the frequency dependent squeezing setup to be implemented in KAGRA in future runs. He performed several simulations on to optimize the FC's mirror properties in order to fit the KAGRA's requirement and also contributed in a major way in the design of the intermediate optics that will be crucial for the injection of frequency independent squeezing in the FC and from the FC to the interferometer. He also was a key member for the characterization of sapphire substrates and in the development of novel techniques to not only perform faster and more accurate characterization of the birefringence of sapphire but also to mitigate the effect of such birefringence in the automatic alignment system of KAGRA. On the development of novel characterization system, he in the first place optimized the already existing linear polarimeter, and then autonomously developed a novel technique based on liquid crystal technology. With such setup, currently under testing at NAOJ, samples as large as KAGRA mirrros will be characterized within one day, without loosing any precision compared to the current method. It is to be noted that current setup requires more than one week to perform the characterization, and this could become a problem in the future when the size of the test masses will be increased.
Research Progress Status	令和4年度が最終年度であるため、記入しない。
Strategy for Future Research Activity	令和4年度が最終年度であるため、記入しない。