Development of crystalline mirrors for high precision measurements of space and time

2015 Fiscal Year Final Research Report

• Project/Area Number: 26610073
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Flaminio Raffaele 国立天文台, 重力波プロジェクト推進室, 特任教授 (10723108)
• Co-Investigator(Renkei-kenkyūsha): Ueda Akitoshi 国立天文台, 光赤外研究部, 助教 (30332159) ; Tatsumi Daisuke 国立天文台, 重力波プロジェクト推進室, 助教 (70333276)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: Coatings / Crystals / Absorption / Scattering

Outline of Final Research Achievements

High precision measurements of distances, time or frequency, use high finesse optical cavities. Their sensitivity are limited by the mirror thermal noise. The purpose of this research has been to develop new mirrors based on crystalline coatings in order to decrease the thermal noise. First we investigated possible materials and deposition techniques through discussions with laboratories and industries working in the field of crystal coatings growth. We then have produced and characterized several samples made of GaAs/AlAs multilayers coatings deposited on GaAs wafers. Finally we have produced and characterized a two inches mirror made of a GaAs/GaAlAs coating deposited on a sapphire substrate. Despite a few defects, the final mirror has a very low roughness (<1 A) and a very small optical scattering (<6ppm).

Free Research Field

Gravitational wave astronomy