Measurement of angle and axis of rotation in a carousel interferometer: a detailed analysis.

A detailed analysis of a carousel interferometer is presented for the measurement of an unknown angle and axis of rotation. The technique exploits a set of compensator glass plates and a right-angle prism that is placed in each of the two arms of the interferometer. The two sets are placed at the same rotational stage, while the end mirrors of the interferometer are static. When rotation takes place, individual and relative optical path differences are generated in the two beams of the interferometer. The generated phase differences contribute toward finding the angle and axis of rotation. The analysis is presented for any initial position of the interferometer, i.e., the radial vector from the axis of rotation to the apex of one of the prisms used. The results show the slight variations in the error and nonlinearity when different parameters are manipulated. Moreover, the trade-off between the maximum size of the prisms and the radial distances are also presented.