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Injection molded high precision freeform optics for high volume applications

: Dick, Lars; Risse, Stefan; Tünnermann, Andreas


Advanced Optical Technologies 1 (2012), No.1, pp.39-50
ISSN: 2192-8584
ISSN: 2192-8576
Journal Article
Fraunhofer IOF ()
freeform surface; injection molding; plastic optic; slow tool servo technology; ultra precision manufacturing

Injection molding offers a cost-efficient method for manufacturing high precision plastic optics for high-volume applications. Optical surfaces such as flats, spheres and also aspheres are meanwhile state-of-the-art in the field of plastic optics. The demand for surfaces without symmetric properties, commonly referred to as freeform surfaces, continues to rise. Currently, new mathematical approaches are under consideration which allow for new complex optical designs. Such novel optical designs strongly encourage development of new manufacturing methods. Specifically, new surface descriptions without an axis of symmetry, new ultra precision machining methods and non-symmetrical shrinkage compensation strategies have to be developed to produce freeform optical surfaces with high precision for high-volume applications. This paper will illustrate a deterministic and efficient way for the manufacturing of ultra precision injection molding tool inserts with submicron precision and show the manufacturing of replicated freeform surfaces with micrometer range shape accuracy at diameters up to 40 mm with a surface roughness of approximately 2 nm.