CustomOptical Elements with Dimensions as Small as0.20 mm. Bern Optics (Westfield, MA) offers custom optical elements with dimensions as small as 0.20 mm. They can be custom engineered, ground, and polished to micron tolerances in a variety of configurations, including lenses, prisms, axicons, filters, windows, domes, and mirrors, as well as special components with combinations of plano, spherical, and cylindrical surfaces. Typically created from optical and filter glasses, these tiny elements can be produced to submillimeter dimensions, with or without specialized coatings.