Replication of diffractive optics in silica glass

With the present trends toward miniaturization, the demand for complex optical elements with surface features is increasing. If these complex optical elements, such as diffractive optics, are fabricated in glass they should be superior to plastic, both in optical quality and environmental stability. Currently diffractive optics are manufactured by either photolithographic methods or single point diamond turning, and neither technique lends itself to high volume, low-cost manufacturing diffractive optics in glass. In recent years advances in the sol-gel process have made it possible to replicate fine-patterned surfaces in high purity silica glass by a molding technique. This paper reviews the results to date of the replication of the following different types of diffractive optics: (1) binary grating, (2) blazed grating, (3) hybrid diffractive/refractive optical element, and (4) plano kinoform.