Phase-transforming optical element formed by partial etching or by partial etching with reflow

摘要

An optical element includes a transmissive layer comprising a multitude of discrete volumes of first and second optical media arranged along the transmissive layer. The discrete volumes are arranged to approximate a desired phase function (typically modulo 2π) and are smaller than an operational wavelength in order to provide a range of phase delays needed to adequately approximate the desired phase function. Effecting at least partial reflow of one or both of the optical media can smooth the morphology of the transmissive layer so as to reduce unwanted diffraction or scattering.