The technology described in this invention patterns curved surfaces without using fixed masks by accurately projecting light onto the photoresist-coated surface. In a departure from existing laser-based approaches, this systems has a light projection system made up of an array of MEMS mirrors, each of which can be tilted to control whether individual pixels get illuminated. The projection module is attached to a six degree-of-freedom robotic arm that positions it in relation to the object being patterned, which is itself mounted on a rotary axis.
Before a patterning operation, a 3D scan is carried out to characterize the geometry of the target surface. This scan data is used to construct a digital model of the surface made up of a large number of triangular facets. For each triangle, the system orients the projection module normal to its centroid and adjusts the mirror array to selectively direct light from an LED source onto the triangle. This procedure is repeated until the entire surface has been patterned. A camera mounted in-line with the projection module images previously patterned areas to provide data for feedback control of projection system position to maintain accuracy over large areas.
Preliminary tests by the Inventors have demonstrated that resolutions up to 5 µm are achievable using this system. Further performance improvements are expected from the use of thinner photoresist layers.