Thermal Testing for Cryogenic CMB Instrument Optical Design

TL;DR

This paper discusses thermal testing of cryogenic optical components in a CMB instrument, focusing on how thermal filters and cold optics reduce thermal load and improve instrument stability for sensitive measurements.

Contribution

It presents in situ thermal testing results of cryogenic optical components in a CMB instrument, refining models for future instrument design.

Findings

Thermal filters effectively reduce thermal load on cryogenic stages.

In situ measurements validate and refine thermal models for cryogenic optical systems.

Results inform design choices for future CMB instruments.

Abstract

Observations of the Cosmic Microwave Background rely on cryogenic instrumentation with cold detectors, readout, and optics providing the low noise performance and instrumental stability required to make more sensitive measurements. It is therefore critical to optimize all aspects of the cryogenic design to achieve the necessary performance, with low temperature components and acceptable system cooling requirements. In particular, we will focus on our use of thermal filters and cold optics, which reduce the thermal load passed along to the cryogenic stages. To test their performance, we have made a series of in situ measurements while integrating the third receiver for the BICEP Array telescope. In addition to characterizing the behavior of this receiver, these measurements continue to refine the models that are being used to inform design choices being made for future instruments.