Thermal lensing in cryogenic sapphire substrates
نویسندگان
چکیده
We report the reduction of the thermal lensing in cryogenic sapphire mirrors, which is planed to be used in the Large scale Cryogenic Gravitational wave Telescope (LCGT) project. We measured three key parameters of sapphire substrate for thermal lensing at cryogenic temperature. They are optical absorption coefficient, thermal conductivity and temperature coefficient of refractive index at cryogenic temperature. On basis of these measurements, we estimated the shot noise sensitivity of the interferometer with thermal lensing by using a wave-front tracing simulation. We found that thermal lensing in cryogenic sapphire mirrors is negligible. ∗ Present address: High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan E-mail: [email protected] Thermal lensing in cryogenic sapphire substrates 2
منابع مشابه
Cryogenic measurement of the optical absorption coefficient in sapphire crystals at 1.064 μm for the Large-scale Cryogenic Gravitational wave Telescope
We have applied laser calorimetry to the measurement of optical absorption in monocrystalline sapphire at cryogenic temperatures. Sapphire is a promising candidate for the mirror substrates of the Large-scale Cryogenic Gravitational wave Telescope. The optical absorption coefficients of different sapphire samples at a wavelength of 1.064 μm at 5K were found to average 90 ppm/cm.
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