  We have demonstrated several inexpensive methods which can be used to measure
the deflection angles of prisms with microradian precision. The methods are
self-referenced, using various reversals to achieve absolute measurements
without the need of a reference prism or any expensive precision components
other than the prisms under test. These techniques are based on laser
interferometry and have been used in our lab to characterize parallel-plate
beamsplitters, penta prisms, right angle prisms, and corner cube reflectors
using only components typically available in an optics lab.
