Abstract: A robot arm, comprising a pair of arm elements interconnected by a pivotal joint, includes a hand for supporting an article. Two additional linking elements of known lengths, interconnected by a free-floating pivotal joint, are pivotally coupled, at the free end of one linking element to the hand of the robot arm, and at the free end of the other linking element to a known position. Sensing devices at the free-floating pivotal joint and at the known position monitor, respectively, the angle between the linking elements and the attitude of such other linking element at the known position, in order to determine the location of the hand and, thus, of an article supported therein. Since the linking elements are not load-bearing, the determination is independent of any load on the hand such as may deform the arm elements.

Abstract: A cold-cathode ion source includes a specially shaped hollow anode and specially shaped anode-cathode insulators to preclude the buildup of short-circuiting bridges of sputtered cathode material. When used with solid feed material, the source can also include an oven-anode having cavities for vaporizing the solid feed material and passages connecting the cavities to the bore of the anode. The geometry of the oven-anode provides an increasing temperature gradient from the cavities to the bore that minimizes condensation of vaporized feed material that could block the ports.