Systems and methods are described for delivering droplets. One embodiment provides a system comprising nozzles adapted to deliver droplets to target points on the substrate, a first camera, and means for determining an angular rotation of the substrate in a coordinate system. In some embodiments the means for determining the angular rotation includes a second camera. The substrate has a top surface and alignment marks. The nozzles have droplet delivery openings oriented towards the substrate for delivery of the droplets. The first camera is oriented substantially towards the nozzle openings, and the second camera is oriented substantially towards the substrate top surface.