Zone Plates

I have spent quite a bit of time working on creating my own zone plates.  The basic problem has been developing a technique that can produce good quality zone plates using simple, and available, technologies.  

I print a negative image of the zone plate to paper and use a use a 35mm camera, with high contrast film, to photograph the print.  The camera is positioned a precise distance from the print to accurately photo reduce the printed image onto the film.  The developed film, now the zone plate, is then placed into a slide mount for easy handling.

Image of Zone Plate

Printing

Epson Stylus Pro 7600 with Matte Black ink printing on Aurora White paper from RedRiver Paper.  The Epson Photo Black ink is much more reflective then the Matte Black ink.  The reflected light shows up on the film; and, produces a poor quality zone plate.  The print size I am using a 24" x 24".  

Photo Setup

The optical rail is built using extrusions from 80/20, Inc. Two photo floods are positioned on either side of the camera at 45 degree angles with respect to the optical rail and the print to be photographed.  The optical rail has a 24" x 24"foam core board on which the printed zone plate is mounted.  The print is simply clamped to the foam core board using OXO clips.  The optical rail is not entirely necessary; and, the photograph can be made using a tripod, but, the rail ensures the camera is perpendicular to the print; and, allows distance between the print and the camera to be easily changed.

Photography

I selected Rollei Ortho 25 because it is a very high contrast film with a transparent base.  The B+W Polarizer stops what little light is reflected off of the Matte Black ink from reaching the film.

Film - Rollei Ortho 25 

Camera - Olympus OM-1n using a 28mm ƒ 3.5 Zukio lens.  Focus is made easier using the Olympus Varimagni Finder.

B+W Polarizing Filter

Film Development

Rollei RHC High Contrast Developer

Plate Mounting

I use Gepe 35mm slide mounts to hold the developed film of the zone plate.  Gepe offers a variety of slide mounts which contain metal masks to block light.  The two mounts I use have circular masks with 7 or 14 mm clear in the center of the mask.  The zone plate fits quite well in the clear center of the slide mask. 

7mm (2.3mm Thick) Center Circle Single-Sided Anti-Newton Glass Slide Mount

14mm (2.3mm Thick) Center Circle Anti-Newton Glass Slide Mounts

Copyright 2015 by Mark Gavin