Fabrication of hybrid kinoform fanout elements in dichromated gelatin

A technique of fabricating periodic, Fourier-transform kinoforms in DCG is described. It involves recording an off-axis volume phase hologram using a plane reference wave and an object wavefront generated from a binary-amplitude computer generated hologram (CGH). The CGH is designed such that, by spatially filtering out all but its first diffraction order, an almost uniform amplitude, continuous phase wavefront can be generated at the holographic plane. An off-axis DCG volume phase hologram can therefore be recorded which, when replayed with a plane wave, generates the kinoform wavefront. As this fabrication technique has much in common with the concept of the hybrid hologram, first proposed by Bartelt and Case (1982), the DCG fanout elements are referred to as hybrid kinoforms