AI Article Synopsis
- The text discusses the cryogenic half-wave plate rotation mechanisms developed for Spider, a telescope that studied the cosmic microwave background.
- These mechanisms function at extremely low temperatures and feature a compact design with a large clear aperture for optimal performance.
- A worm gear driven by a cryogenic stepper motor ensures precise adjustment and stability of the telescope's orientation, supported by an optical encoder for accurate angle monitoring.
Article Abstract
We describe the cryogenic half-wave plate rotation mechanisms built for and used in Spider, a polarization-sensitive balloon-borne telescope array that observed the cosmic microwave background at 95 GHz and 150 GHz during a stratospheric balloon flight from Antarctica in January 2015. The mechanisms operate at liquid helium temperature in flight. A three-point contact design keeps the mechanical bearings relatively small but allows for a large (305 mm) diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows for precise positioning and prevents undesired rotation when the motors are depowered. A custom-built optical encoder system monitors the bearing angle to an absolute accuracy of ±0.1(∘). The system performed well in Spider during its successful 16 day flight.
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| http://dx.doi.org/10.1063/1.4939435 | DOI Listing |
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