Presentation + Paper
1 October 2024 Thermal, spectral, and operational upgrades to CHARMS and temperature dependent refractive index measurements of Si and Ge from 35 to 310 K
Author Affiliations +
Abstract
The Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA’s Goddard Space Flight Center (GSFC) has undergone some recent upgrades enabling refractive index measurements without the use of either liquid nitrogen (LN2) or liquid helium (LHe) cryogens, once again achieving sample temperatures around 30 K. CHARMS has also enjoyed the replacement of its very old, LN2-cooled, InSb mid-wave infrared (MWIR) camera with a new, state-of-the-art InSb camera cooled with a closed-cycle Stirling cooler enabling unattended operation. The new camera improves signal-to-noise in MWIR index measurements. We report on measurements of two each Si and Ge prisms from room temperature down to below 35 K which are the first to benefit from these two recent upgrades. We also report on upgrades to CHARMS still in work which will enable cryogenic index measurements in the Long Wavelength Infrared (LWIR) to wavelengths as long as 12.5µm for the first time.
Conference Presentation
(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.
Douglas B. Leviton, Manuel A. Quijada, and Mateo Batkis "Thermal, spectral, and operational upgrades to CHARMS and temperature dependent refractive index measurements of Si and Ge from 35 to 310 K", Proc. SPIE 13131, Current Developments in Lens Design and Optical Engineering XXV, 131310F (1 October 2024); https://doi.org/10.1117/12.3028402
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KEYWORDS
Silicon

Germanium

Refractive index

Temperature metrology

Prisms

Cryogenics

Mid-IR

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