Improvement on the surface roughness of micro lens array in the excimer laser machining process

A new process that improves the surface roughness of micro lens array after the excimer laser machining is studied. The results show that the smoother surface has been fabricated by this innovatory method. The excimer laser with mask projection machining has been successfully applied for the fabrication of 2.5D micro parts. Furthermore, the workpiece dragging machining is capable of manufacturing microstructure array with curved surface by using various shape of mask. But during the machining process, the laser is cutting shoot by shoot and the material is gradually removed layer by layer. The laser marks on the curved surface of micro lens array is obvious and inevitable. This defect limits the product of dragging in real optical application. To overcome this drawback, an improved process is studied. When the desired shape of lens array was machined by the excimer laser machining, the attaching photo resist with the thickness of several micro meter is coated on the rough surface by spin coating or spraying. Then the lens array is baked to get the mirror surface. This original method combines the advantage of the higher fill factor and the smoother surface for the fabrication of micro lens army.