Doctor of Philosophy, Princeton University (2018)
A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument.
Review of scientific instruments
2016; 87 (1): 014501-?
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.
View details for DOI 10.1063/1.4939435
View details for PubMedID 26827333