INFLUENCE OF THE FINITE APERTURE AND OBSERVATION OF HIGHER LONGITUDINAL-ORDER FRINGES IN FIZEAU INTERFEROMETRY

The interference pattern of a Fizeau interferometer, ideally a (nearly ) self-imaging field, is examined under true measurement conditions. T he quality of the higher longitudinal-order fringes is investigated by finite-aperture diffractive calculations. A specific symmetry propert y of the volume interference pattern, namely the invariance of the int ensity structure under a rotation of the interferential wedge about it s apex, is studied by nondiffractive simulations that take into accoun t the instrument geometry and finite incident wave. The formation of t he higher longitudinal-order fringes is verified experimentally. The p ossibility of transferring these fringes close to the device by a suit able non-normal incidence is demonstrated. The existence of various fr actional Talbot planes is also confirmed.