Fabrication of curved diffractive optical elements by means of laser direct writing, electroplating, and injection compression molding

摘要： In this work, a new process chain for the fabrication of curved micro-structured optical elements by injection compression molding is investigated. The fabrication is demonstrated for the example of a curved di?ractive optical element (DOE). In a ?rst process step a master substrate is fabricated using laser direct writing on a curved glass substrate. Blazed di?ractive micro-structures with lateral feature sizes down to 5 μm and height of 1.6 μm are created. A subsequent electroplating process is applied to create a nickel stamper to be used as a tool insert for the molding process. During electroplating, a 3 mm nickel layer is formed, transferring the di?ractive structures from the master substrate into a solid mold insert. The nickel stamper shows an accurate reproduction of the micro-structures. The mold insert is integrated into an injection compression molding tool to replicate the optical elements. Results show that the blazed di?ractive structures are replicated with a high quality. Tests of the components within a chromatic-confocal measurement setup con?rm that they can potentially replace expensive conventional elements.