AN INSTRUMENT FOR MANUFACTURING ZONE-PLATES BY USING A LATHE

A laser writing system is developed in order to manufacture precise an d inexpensive zone-plates. The zone-plates are a key component of an i nterferometer that measures shape error of spherical or aspherical mir rors on an ultraprecision lathe. The laser writer is mounted on the sl iding table of the lathe. A glass plate coated with photoresist is att ached to a chuck of the lathe and rotated. The zone-plate grating is w ritten on the glass plate by a focused laser beam. Zone-plate writing is sped up by reducing the necessary number of computer instructions, causing no loss in the accuracy of the zone-plate. The accuracy of the zone-plate obtained by this inexpensive method is 0.1 mum and the sam e as that achieved by an electron beam writer.