The revolution of smartphones and tablets has driven the demand for very compact camera optics. The only possible solution for such integrated optics is the usage of micro-optics. Especially microlens arrays and complex Fresnel lenses are integrated into the camera optics. The manufacturing requirements for such optics are very precise shape control and excellent surface roughness. Gray scale lithography is used to generate molds, which are replicated by LIGA to create a metal shim (typically Nickel). These shims can be used as a master tool to create replications by molding, imprinting or hot embossing.
Besides lenses gray scale lithography can be utilized to fabricate many other micro-optics components. Examples are micro prisms, waveguides, blazed gratings or micro-mirrors. Computer Generated Holograms (CGH) and special security labels are other applications where gray scale lithography shows its performance.
Fabrication of diffraction gratings is a very challenging application due to the strict requirements of surface quality, groove position, and groove profile. Especially if VLS (Variable Lines and Space) gratings are required standard methods like interference lithography are not applicable. The Direct Write Lithography allows fast and precise manufacturing of VLS and standard gratings. The DWL 2000 with a minimum feature size of 500 nm is the best solution for this application.