Tech note: liquid Lenses

In a 3D-scanning microscope, it is fairly easy to scan in the xy-plane rapidly using a pair of galvano-mirrors. However, for z-axis scanning, we still rely on a slow stepper motor. An introduction of a liquid lens (discussed in slashdot) by Varioptics might allow a rapid changing of the focus position along the z-axis. The lens is made of water and oil sandwitched by two glass window in a conical structure. According to the article, "the interface between the oil and water will change shape depending on the voltage applied across the conical structure. At zero volts, the surface is flat, but at 40 volts, the surface of the oil is highly convex".