The present disclosure generally relates to methods of forming optical devices comprising nanostructures disposed on transparent substrates. A first process of forming the nanostructures comprises depositing a first layer of a first material on a glass substrate, forming one or more trenches in the first layer, and depositing a second layer of a second material in the one or more holes to trenches a first alternating layer of alternating first portions of the first material and second portions of the second material. The first process is repeated one or more times to form additional alternating layers over the first alternating layer. Each first portion of each alternating layer is disposed in contact with and offset a distance from an adjacent first portion in adjacent alternating layers. A second process comprises removing either the first or the second portions from each alternating layer to form the plurality of nanostructures.