Piecewise interferometric generation of precision gratings.

A simple interferometer and associated technique, allowing for sequential exposure of small segments in the writing of a large grating, is described. The increased intensity thus afforded greatly aids in overcoming nonlinear and reciprocity effects in the recording medium. Furthermore, the technique eliminates the need for a large collimator and errors introduced by imperfect collimation. Demonstration gratings written with this technique have shown maximum registration errors of +/-35 nm.