Experimental characterization of focusing by high-numerical-aperture zone plates.
High-numerical-aperture zone plates have important applications in high-resolution optical maskless lithography as well as scanning confocal microscopy. We describe two methods to experimentally characterize the focusing properties, i.e., the point-spread function, of such diffractive lenses. The first method uses spot exposures in photoresist and the second uses a conventional knife-edge scan. The experimental results agree well with rigorous theoretical calculations.
Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge 02139, USA. rmenon@nano.mit.edu
Rajesh
R
Menon
Dario
D
Gil
Henry I
HI
Smith