Micromachining of a roller mould and roll-to-roll imprinting to form large area optical films with radial Fresnel lens arrays

Abstract

This paper reports on roll-to-roll (R2R) imprinting of radial Fresnel lens arrays using a directly diamond turned roller mould. A four-axis synchronized tool-workpiece interactive motion is realized by using an ultra-precision machining system, and a rotating-tool diamond turning process has been developed for precision machining of a roller mould for forming optical films with radial Fresnel lens arrays via imprinting. A R2R UV imprinting system with slot die coating has been developed, and optical films with radial Fresnel lens arrays (diameter ϕ = 30 mm, feature height h = 50 µm, and focal length f = 60 mm) are fabricated through R2R UV imprinting. The performance of the imprinted radial Fresnel lenses is evaluated by testing its light concentration capability, and a light concentration ratio of ×16 has been achieved.