Abstract

Recently a quick an easy method for optical alignment of the Mach-Zehnder interferometer (MZI) by an equilateral hyperbolic zonal plate (EHZP) has been proposed (1). When an EHZP is placed in front of the MZI, the light emerging from the interferometer produces only one focal cross on a field of view uniformly illuminated if the interferometer is adjusted and the principal focal distance of the EHZP is higher than the length of the MZI arms. However, when the interferometer is not adjusted, two focal crosses, defocalization of crosses and wedge fringes, may appear on the observation plane. These quantitative information, indicate, axial positioning error (transversal shift), length difference between arms (longitudinal shift), and arms axes mutually inclined (angular shift), respectively. A more refined adjustment may be achieve, if the observation is maked in a plane different to EHZP focal plane. In this case the hyperbolic family curves that can observe in the former plane (or elliptical, if we observe in the rear focal plane), overlap making moiré patterns, whose frecuencies and slope are in direct relationship with the relative adjust of the interferometer arms.

© 1987 Optical Society of America