Computer Generated Matched Filters by e-Beam Lithography

E-beam lithography as a means of realizing computer generated holograms has been discussed by Freyer et al. (1) and by Athale et al. (2). The main advantages of e-beam techniques are the capabilities of focusing electron beams of very narrow dimensions (typically 0.1 to 10 microns) and positioning these beams very accurately on the writing surface. Ultra flat glass plates, plated with chromium then coated with a thin layer of electron sensitive photo-resist, form the writing surfaces. Exposure of the material to the computer located e-beam is followed by development of the photo-resist, and then by etching of the exposed chromium to produce a binary pattern on the glass substrate. Suitable patterns written in this way on the chromium provide a convenient means of achieving holographic elements.