Non-contact temperature sensing and optical scatter in cryogenically-cooled crystalline silicon
Abstract
Cryogenic crystalline silicon is a promising optical material for next generation gravitational-wave detectors due to its low mechanical loss (a driver of thermal noise), high thermal conductivity and zero coefficient of thermal expansion at 123 K. In this paper, we report on the design and results of an experiment to measure the temperature of a flat-flat uncoated crystalline silicon sample using a non-contact sensing method relying on interference (optical fringes) made from reflections between the front and back surfaces. We also propose a scheme for implementation of this technique for cryogenic test masses in future gravitational-wave detectors such as Einstein Telescope and LIGO Voyager. Additionally, we characterize the optical scattering of the sample in vacuum at cryogenic temperatures by using a high-sensitivity infrared camera. We measured relatively constant scatter with an average bidirectional reflectance distribution function (BRDF) of (4.43±0.2)× 10−3 sr−1 at a scattering angle of θs = 7.5∘ over the (cold-plate) temperature range of 123-294 K and saw no evidence for growth of cryogenic molecular layers (ice) on the sample in our current setup.
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BibTeX
@misc{kapasi2026noncontact,
title = {{Non-contact temperature sensing and optical scatter in cryogenically-cooled crystalline silicon}},
author = {Disha Pankaj Kapasi and Travis Counihan and Kevin Kimes and Alina Sendowsky and Alexandra Gruson and Daniel Martinez and Michael Rezac and Kevin Silverio and Sean Sorto and Joshua R. Smith},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41261},
eprint = {2610.41261},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41261},
}
RIS
TY - UNPB
TI - Non-contact temperature sensing and optical scatter in cryogenically-cooled crystalline silicon
AU - Disha Pankaj Kapasi
AU - Travis Counihan
AU - Kevin Kimes
AU - Alina Sendowsky
AU - Alexandra Gruson
AU - Daniel Martinez
AU - Michael Rezac
AU - Kevin Silverio
AU - Sean Sorto
AU - Joshua R. Smith
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2610.41261
UR - https://arxiv.org/abs/2610.41261
AB - Cryogenic crystalline silicon is a promising optical material for next generation gravitational-wave detectors due to its low mechanical loss (a driver of thermal noise), high thermal conductivity and zero coefficient of thermal expansion at 123 K. In this paper, we report on the design and results of an experiment to measure the temperature of a flat-flat uncoated crystalline silicon sample using a non-contact sensing method relying on interference (optical fringes) made from reflections between the front and back surfaces. We also propose a scheme for implementation of this technique for cryogenic test masses in future gravitational-wave detectors such as Einstein Telescope and LIGO Voyager. Additionally, we characterize the optical scattering of the sample in vacuum at cryogenic temperatures by using a high-sensitivity infrared camera. We measured relatively constant scatter with an average bidirectional reflectance distribution function (BRDF) of (4.43±0.2)× 10^−3 sr^−1 at a scattering angle of θ_s = 7.5^∘ over the (cold-plate) temperature range of 123-294 K and saw no evidence for growth of cryogenic molecular layers (ice) on the sample in our current setup.
ER -