We present a theoretical and experimental investigation of an interferometric technique for converting a linearly polarized Gaussian beam into a radially polarized doughnut beam. The experimental setup accomplishes the coherent summation of two orthogonally polarized TEM01 and TEM10 beams that are obtained from the transformation of a TEM00 beam by use of a simple binary diffractive optical element. We have shown that the degree of radial polarization is maximum at a given distance from the interferometer output port that depends on the diameter of the incident beam at the interferometer input port.
We report a novel process technology of hemispherical shaped microlenses, using isotropic wet etching of silicon in an acid solution to produce the microlenses molds. Governed by process parameters such as temperature and etchant concentration, the isotropic wet etching is controlled to minimize various defects that appear during the molding creation. From the molds, microlenses are fabricated in polymer by conventional replication techniques such as hot embossing and UV-molding. The characterization of molds and measurements of replicated microlenses demonstrate high smoothness of the surfaces, excellent repeatability of mold fabrication and good optical properties. Using the proposed method, a wide range of lens geometries and lens arrays can be achieved.
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