Off-Axis Blog

AOS Quality Grades for Aspheres

Posted: August 28, 2016

AOS offers multiple quality grade options depending on the application desired. These quality grades can differ significantly in price to allow customers to select the most affordable option for their application and budget. Conventional ways of specifying optical quality in aspheric optics often do not address mid-spatial error tolerances, which are key to predicting imaging quality. Defining the specification for gradient limits the amplitudes of…

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Specifying Wavefront vs. Surface Error in Aspheres

Posted: July 11, 2016

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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Metallic Coatings for Off-Axis Parabolas

Posted: July 2, 2016

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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