Free-Form Micro-Lens Array Fabrication via Laser Micro-Lens Array Lithography

Micro-lens array (MLA) is widely used in various applications, such as imaging systems, light sources, optical sensors, and laser modulation.The traditional lithography method is a way to fabricate a micro-lens array while suffering from unavoidable drawbacks such as fixed-period patterns, high surface roughness, and small areas.Laser MLA lithography is a method that can direct write ~500, 000 micro-lenses in an area of 0.5 cm 2 within 70 s.The period and pitch size could be arbitrarily changed with multiple lens structures including square, rectangle, and ring.With thermal reflow, the surface roughness of photo-resist could achieve lower than 5 nm.By reactive ion-etching (RIE), the patterns on photo-resist are successfully transferred onto a quartz substrate with a high depth-to-width ratio.This method paves a flexible new way to make multiple kinds of micro-lens arrays, used for photolithography, optical imaging, and focusing.