Near-ultraviolet formation of refractive-index grating using phase mask

摘要

A method of making a phase mask for imposing on light transmitted therethrough an interference pattern. The method comprises various steps including the step of depositing a solidifiable material on a substrate with a first surface relief pattern. The solidifiable material is selected so that the phase mask is at least half as transmissive as it is absorptive of light characterized by a spectral line having a wavelength between 275 and 390 nm. The material is solidified and removed from the substrate so as to yield the phase mask with a second surface relief pattern complementary to the first surface relief pattern.