Optical Surfaces Ltd (Kenley, Surrey, UK) can typically produce off-axis parabolic mirrors up to 600 mm in diameter with surface accuracy's to lambda/20 p-v depending upon off-axis angles. With proprietary polishing techniques, Optical Surfaces can, depending on the surface accuracy required, achieve the natural limit to the off-axis angle of around 25-30 degrees and surface micro-roughness on aspherics of ~1 nm rms. A range of coatings is available for standard and custom components from metallic – with protective overcoat – to multilayer dielectrics and ultra-hard coatings. Parabolic mirrors are the most common type of aspheric used in optical instruments. They are free from spherical aberrations, and thus focus a parallel beam to a point or a point source to infinity.
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