Abstract: A collimation lens system for converging the light from an LED into a light beam, includes a central lens aligned along the optical axis of the LED for converging inner light from the LED, the central lens including an aspheric collimation plano convex lens having a planar entrance surface and an aspheric exit surface; and a peripheral lens surrounding the central lens for converging outer light from the LED, the peripheral lens including a total internal reflection collimation lens having an entrance surface and an exit surface and including a high order aspheric total internal reflection surface for reflecting the outer light by total internal reflection. The central lens and the peripheral lens share a common focal point at which the LED may be positioned.

Abstract: A novel method to fabricate nanoscale pits on Au(111) surfaces in contact with aqueous solution is claimed. The method uses in situ electrochemical scanning tunnelling microscopy with independent electrochemical substrate and tip potential control and very small bias voltages. This is significantly different from other documented methods, which mostly apply high and short voltage pulses. The most important advantages of the present method are that the dimensions and positions of the pits can be controlled with high precision in aqueous environment so that nanopatterns of the pits can be designed, and that the operations are simple and require no instrumental accessories. Parameters, which control the pit formation and size, have been systematically characterized and show that the primary controlling parameter is the bias voltage. A mechanism based on local surface reconstruction induced by electronic contact between tip and substrate is in keeping with the overall patterns for pit formation.