| 研究課題/領域番号 |
23K19053
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| 研究種目 |
研究活動スタート支援
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| 配分区分 | 基金 |
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| 審査区分 |
0203:素粒子、原子核、宇宙物理学およびその関連分野
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| 研究機関 | 国立天文台 |
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研究代表者 |
Eisenmann Marc 国立天文台, 重力波プロジェクト, 特任研究員 (80984541)
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| 研究期間 (年度) |
2023-08-31 – 2025-03-31
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| 研究課題ステータス |
交付 (2023年度)
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| 配分額 *注記 |
2,860千円 (直接経費: 2,200千円、間接経費: 660千円)
2024年度: 1,430千円 (直接経費: 1,100千円、間接経費: 330千円)
2023年度: 1,430千円 (直接経費: 1,100千円、間接経費: 330千円)
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| キーワード | birefringence / kagra / gravitational wave / liquid crystal / KAGRA / sapphire |
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| 研究開始時の研究の概要 |
Thermal noise is one of the limiting noise of gravitational waves detectors. To reduce it, it is planned to operate at cryogenic temperature with crystalline substrates and possibly use crystalline coatings. Such components can be birefringent which can drastically spoil the detectors performances. It is therefore required to accurately characterize the crystals birefringence before their installation to insure optimal performances. Here, we propose to use a pair of electro-optic components to achieve fast 2D birefringence measurement and compensation which will be crucial for these detectors.
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| 研究実績の概要 |
We developed characterization and simulations for electro-variable polarization retarder. Using a pair of identical liquid crystal, we were able to generate arbitrary polarization states covering most of the Poincare sphere at about 40Hz. This was then use to successfully compensate for the birefringence of a 23kg sapphire substrate in 1D. We also developed a birefringence measurement apparatus based on this technique that allows us to reconstruct the Jones matrix of optical elements in both transmission and reflection.
Finally, we also used a pair of LCD monitor as liquid crystal array to generate 2D polarization. After designing the mounting apparatus and performing the required calibration, we are now able to generate 2D polarization over large beam.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
1: 当初の計画以上に進展している
理由
We developed an automated calibration and characterization of a liquid crystal cell. We were able to generate polarization states as predicted from our simulations. This was then used to successfully compensate for the birefringence of a 23kg sapphire by a factor 100 000. This result has been accepted for publication.
We also developed a new way to measure birefringence of sample in transmission and reflection based on this technique. It is an initially unplanned benefit of our experimental apparatus. We were also able to succesfully control in 2D birefringence, albeit with low efficiency. This was however useful to test this technique and developed the required software and hardware.
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| 今後の研究の推進方策 |
The plan for next fiscal year is to develop 2D the birefringence readout. The strategy is to use similar components as used in the polarization actuation part. We also plan to improve the efficiency of the 2D polarization actuation.
We will also finalize the newly developed birefringence measurement technique. It will also allow us to study new components as well as possibly studying the Jones matrix of components that are not yet described by this formalism.
We expect these results to lead to publications.
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