Abstract: A voltage-isolating passageway for providing high voltage isolation between a component maintained at high DC voltage and a component maintained at a substantially lower voltage is described. The voltage-isolating passageway incorporates a transverse magnetic field across its passageway, which reduces the potential energy of charged particles (e.g., electrons) passing through the passageway. The voltage-isolating passageway includes a passageway and at least two magnets. The passageway has two openings and the two magnets are positioned along opposite and exterior surfaces of the passageway wherein the first and second magnets impose a magnetic field in a transverse direction with respect to a lengthwise axis of the passageway. In one embodiment, each of the passageways have small diameters and transfer gases at small flow rates.

Abstract: A periodic structure is illuminated by polychromatic electromagnetic radiation. Radiation from the structure is collected and divided into two rays having different polarization states. The two rays are detected from which one or more parameters of the periodic structure may be derived. In another embodiment, when the periodic structure is illuminated by a polychromatic electromagnetic radiation, the collected radiation from the structure is passed through a polarization element having a polarization plane. The element and the polychromatic beam are controlled so that the polarization plane of the element are at two or more different orientations with respect to the plane of incidence of the polychromatic beam. Radiation that has passed through the element is detected when the plane of polarization is at the two or more positions so that one or more parameters of the periodic structure may be derived from the detected signals.