by Mark Gavin
I’ve been developing an application to generate Fresnel Zone Plates; and, ran into an interesting problem. A Zone Plate is similar to a lens in its ability to focus light. It differs from a lens by using diffraction instead of refraction.
The problem I encountered is that Acrobat creates many significant drawing artifacts when it renders this PDF drawing to the screen. In the above screen capture; only the rings centered on the center of the graphic are real. All other rings, centered off of the center, are drawing artifacts.
A zone plate consists of a single set of concentric rings progressively getting thinner and closer together as they move out from the center. The application directly draws the rings of the zone plate to a PDF file as vector artwork. All of the other PDF viewing applications also introduce artifacts; but, they render these artifacts differently then Acrobat 8.
Following are links to a couple of PDF Zone Plate files to test in your favorite PDF viewer:
The appearance of the artifacts displayed will change as you alter the document magnification on the screen.
The intent of the application is to print the drawing to a wide format printer; then, photo-reduce the drawing onto a film negative in order to produce a zone plate.
