2026年度 第2回　物理コロキウム

Dear all,
We will have a seminar by Dr. Ryota Takaku. The abstract of his talk is provided below. We look forward to your participation.

題目 Title	レーザー加工で新しい宇宙観測への窓を作る Opening a new window for observational cosmology using a laser fabrication
講師 Lecturer	高久諒太 先生（石野研　助教） Dr. Ryota Takaku (Ishino Lab. Asst.Prof.)
日時 Date and Time	5月14日（木）13:00 May 14 (Thu) 13:00 -
場所 Place	第24講義室 Lecture room 24
Abstract	Sapphire, alumina, and silicon are attractive materials for millimeter- and submillimeter-wave optical elements, such as a window, filter, and lense. In addition, a continuously rotating half-wave plate (HWP) is used in CMB polarization observations to mitigate the effect of 1/f noise and probe cosmic inflation. Although these materials have advantages such as high thermal conductivity and low dielectric loss, their refractive indices are higher than 3, which require a broadband anti-reflection coating (ARC). Sub-wavelength structures (SWS), also known as moth-eye structures, function as a broadband ARC. Ultra-short pulsed laser ablation is a useful method for fabricating SWS on such hard materials. We have developed a laser-machining method to fabricate SWS for millimeter- and submillimeter-wave applications, with the aim of integrating them into cosmological and astrophysical telescopes. 　I will introduce results demonstrating that our technology has been used in actual telescopes, discuss the statistical contribution of an actual HWP with SWS to cosmological parameter estimation, and describe potential extensions of our technology.
世話人	世話人　 吉村浩司（内線 8499）