Performance of a cryogenic test facility for 4 K interferometer delay line investigations

The next generation of space-borne instruments for far infrared astronomical spectroscopy will utilize large diameter, cryogenically cooled telescopes in order to achieve unprecedented sensitivities. Low background, ground-based cryogenic facilities are required for the cryogenic testing of materials, components and subsystems. The University of Lethbridge Test Facility Cryostat (TFC) is a large volume, closed cycle, 4 K cryogenic facility, developed for this purpose. This paper discusses the design and performance of the facility and associated metrology instrumentation, both internal and external to the TFC. Additionally, an apparatus for measuring the thermal and mechanical properties of carbon-fiber-reinforced polymers is presented

Development of a cryogenic far-infrared grating spectrometer for a post-dispersed fourier transform spectrometer

Recent advances in far-infrared detector technology have led to increases in raw sensitivity of more than an order of magnitude over previous state-of-the-art detectors. With such sensitivity, photon noise becomes the dominant noise component, even when using cryogenically cooled optics, unless a method of restricting the spectral bandpass is employed. One method is to use a low-resolution diffraction grating spectrometer to post-disperse the signal from a high-resolution instrument, such as a Fourier transform spectrometer (FTS). This concept has been adopted for the SAFARI instrument on the SPICA mission. This paper discusses the development of a prototype cryogenic grating spectrometer that has been used to evaluate the concept of a post-dispersed polarizing FTS over the range from 285-500 μm

Composite Material Evaluation at Cryogenic Temperatures for Applications in Space-Based Far-Infrared Astronomical Instrumentation

Over half of the light incident on the Earth from the Universe falls within the Far-Infrared (FIR) region of the spectrum. Due to the deleterious effects of the Earth's atmosphere and instrument self-emission, astronomical measurements in the FIR require space-borne instrumentation operating at cryogenic temperatures. These instruments place stringent constraints on the mechanical and thermal properties of the support structures at low temperatures. With high stiffness, tensile strength, strength-to-mass ratio, and extremely low thermal conductivity, carbon fibre reinforced polymers (CFRPs) are an important material for aerospace and FIR astronomical applications, however, little is known about their properties at cryogenic temperatures. We have developed a test facility for exploring CFRP properties down to 4 K. We present results from our ongoing study in which we compare and contrast the performance of CFRP samples using different materials, and multiple layup configurations. Current results include an evaluation of a cryostat dedicated for materials testing and a custom cryogenic metrology system, and preliminary cryogenic thermal expansion measurements. The goal of this research is to explore the feasibility of making CFRP-based, lightweight, cryogenic astronomical instruments