Daniel Riley with Prof. John Ruhl

 Construction of a Cryogenic Rotational Mechanism for the SPIDER Half Wave Plate

The purpose of the project will be to design and construct a mechanism for rotating a large sapphire half wave plate in a cryogenic environment using a stepper motor to provide discrete rotations. The intent is that the design will be implemented in the SPIDER project for surveying the CMB. The project will begin by building a model of the system for lab testing. I will have to investigate if it is capable of achieving all our design parameters in a cryogenic environment. The system will need to be able to provide enough torque to rotate the load as well as provide enough speed to rotate the half wave plate in a timely manner. I will then have to investigate properties of the mechanism such as its robustness, and heat production. Finally, depending on the progress made in the testing of the mechanism, I will be examining optical properties of the sapphire half wave plate itself using a Fourier Transform Spectrometer.