Abstract: A capacitance measuring device and method including a ratio transformer, a reference capacitor(s), and multiplying digital to analog converters connected to form a bridge, the converter being adjustable to at least partially balance the bridge. The bridge can further include a 90.degree. phase shifter and reference capacitors to balance the real part of the unknown impedance. An internal calibration scheme calibrates various components of the bridge.

Abstract: An apparatus is disclosed for analyzing trace elements in a gas sample. A unique feedback system is provided for accurately regulating and sensing the pressure supplied to the ion chamber of the device. The feedback system is capable of compensating for a wide range of input gas pressures. The apparatus also includes an improved closed ion source which is resistant to corrosion and aids in the reduction of noise. In addition, a method is disclosed to calibrate the detector for accurately scaling the measurements of trace elements.

Abstract: Process and apparatus for measuring the difference in the concentration of paramagnetic components between an unknown gas and a standard gas by periodically alternate entry of both gases into the gap chamber (2) of a magnetic circuit (1) and by detecting the periodical variations of the magnetic flux caused by the gases in the magnetic circuit.In this process,(a) the two gases are brought into the gap chamber (2) from opposite directions through gas lines (5, 6),(b) the boundary zone between the two gases perpendicular to the magnetic lines of force is moved back and forth in the gap chamber periodically by an alternating flow generator (7), and(c) constantly a portion of the gas mixture is made to escape through an exhaust line (9) from the region of the gap chamber (2) by the inflowing of at least one of the two gases.

Abstract: An aligner for aligning a mask and a wafer during photolithography of a semiconductor chip uses detection of the differential capacitance between two sets of conductive fingers on the mask and ridges on the wafer. An A.C. signal is coupled between the ridges and the fingers and the phase or amplitude of the signals is detected. An aligner utilizing multiple groups of ridges and fingers allows rotational alignment or two axis lateral alignment. An aligner having reference ledges to which the mask and the wafer are capacitively coupled allows alignment when the distance between the mask and the wafer is too great to permit meaningful capacitive coupling between the mask and the wafer to occur.