Form Metrology of Aspheres & Freeforms
ZYGO has extensive experience developing instruments and accessories to perform high quality surface measurements of simple shapes such as flats and spheres. More complex surface shapes like aspheres and freeforms present a modern metrology challenge whether calculating the precise deviation from prescription or determining lens base radius. Surfaces with inflection, rotational asymmetry, and even unique point cloud definitions can be measured with Zygo products to identify exactly how the lens shape differs from the design. While a typical application will use a PV or RMS result to determine the form of a lens, the non-contact, full area surface measurement can also identify more localized errors or asymmetries caused by the manufacturing process.
There are several parameters to consider when selecting a metrology tool for aspheric or freeform optics. Test surface size, aspheric departure, number of surfaces, and measurement time are a handful of considerations that help guide tool selection or measurement technique. ZYGO works with customers to help inform these critical measurement decisions, removing the complexity from complex surfaces.