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Updated: Feb 1, 2026

Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb
Published on: December 2, 2017
Note: An automatic liquid nitrogen refilling system for small (detector) Dewar vessels
E Deniz1, K B Eberl1, J Bredenbeck1
1Institute of Biophysics, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany.
Abstract:
Many infrared spectroscopy setups are in principle stable enough to run overnight or longer, but the detector's Dewar vessel must be refilled manually with liquid nitrogen (LN2) every couple of hours. Commercial automatic LN2 refilling systems work reliably only for large Dewars. Here, we present a refilling system which can non-invasively be applied to already installed small Dewars. The system reliably refills LN2 once it has dropped below an adjustable level, with quick refilling (<3 min) for a 0.6 l Dewar. Our design protects the setup and the detector from overflowing or running without LN2.
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