Abstract

The zone plate is a diffraction optical element which images by interference, rather than by reflection or refraction. The applications of the zone plate include X-ray microscopy, focusing and coupling elements in opto-electronics, X-ray astronomy and etc. The focusing profile of the zone plate has been studied quite well. However, the wavefront aberration of the zone plate was less tested or evaluated by the interferometer¹. We use a sinusoidal grating in the Ronchi interferometer to split the wavefront under test into three. The wavefront aberration for both amplitude and phase zone plate may be calculated by taking a few measurements from the three-beam interferograms. The accuracy of the test will be discussed. Since the grating is also a diffraction optical element, it may live together with the zone plate in the region of various radiations.

© 1988 Optical Society of America