The most common tolerances for specifying the optical quality of aspheric mirrors such as off axis parabolas are surface accuracy and reflected wavefront error. Surface error is the deviation of the surface from its perfect form. Wavefront error is the deviation of the resulting reflected or transmitted wavefront from its perfect shape. At first glance, the decision to specify optics based on its wavefront quality…
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Off-Axis Blog
Metallic Coatings for Off-Axis Parabolas
Metals provide the most efficient means to enhancing the reflectivity of an optical mirror. Metallic coatings, are readily manufacturable, provide broadband performance and are less sensitive to incident angle, group velocity dispersion (GVD) and polarization than dielectric coatings. Due to high absorption, metallics, in general, often have lower laser damage threshold than dielectrics. Because metallic coatings are relatively soft, protective dielectric overcoat(s) are applied to…
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