Seminar Title:	An interferometer for measuring angular motion
Speaker:	Dr. Fabián Erasmo Peña Arellano
Affiliation:	(University of Birmingham, United Kingdom)
When:	Tuesday Morning, Mar. 1st, 9:00 a.m
Where:	Room 327, Office Block, 2 West Beijing Road (PMO, CAS)
	Welcome to Attend
	( PMO Academic Committee & Academic Circulating committee)

　

　 Abstract　　

  This talk will review the development of a homodyne polarization interferometer for measuring the angular displacement of a torsion balance. The most important quality of this interferometer is its immunity to mirror tilt misalignments. Using paraxial theory it will be shown how to build a cat's eye retroreflector in order to provide a larger amount of tilt immunity in comparison with the traditional approach that uses cube-corners. The cat's eye is, however, subject to aberrations, and therefore, it must be optimized using real ray tracing. The optimization procedure is carried out using Zemax, a commercial software package for optical design. The optical path difference that the interferometer measures as the mirror tilts is also calculated with Zemax. The results are described in terms of the Seidel aberrations and the error introduced in a measurement is calculated. A prototype of the interferometer was built with optical components available from stock. It provides an angular range of approximately ±0.75°.