Abstract: A method for enhancing the temporal resolving power of an optical signal recording system such as a streak camera or photodetector by sinusoidally modulating the illumination or light signal at a high frequency, approximately at the ordinary limit of the photodetector's capability. The high frequency information of the input signal is thus optically heterodyned down to lower frequencies to form beats, which are more easily resolved and detected. During data analysis the heterodyning is reversed in the beats to recover the original high frequencies. When this is added to the ordinary signal component, which is contained in the same recorded data, the composite signal can have an effective frequency response which is several times wider than the detector used without heterodyning. Hence the temporal resolving power has been effectively increased while maintaining the same record length. Multiple modulation frequencies can be employed to further increase the net frequency response of the instrument.

Abstract: The test head manipulator comprises two bearings coupled to a frame. A lead screw is rotatably disposed between the two bearings. A non-translation mechanism is also provided to prevent the lead screw from translating along its longitudinal axis. A lead nut is threaded onto the lead screw, but is prevented from rotating about the longitudinal axis by a non-rotation mechanism. A carriage configured to couple with an electronic test head is coupled to the lead nut by means of a system of cables and pulleys. Therefore, when the lead screw is rotated, the lead nut translates along the longitudinal axis, moving the cables and translating the carriage and test head along a vertical path. The lead screw and nut are non-backdrivable to lock the carriage in position.

Abstract: A wafer clamping mechanism includes a clamp ring having a central opening corresponding to the geometry of a conventional semiconductor wafer. An overhang located about the opening engages the corresponding semiconductor wafer when in place on an electrode of a plasma reactor. The clamp ring is resiliently mounted on a housing which holds a second electrode. The clamp ring is automatically engaged against the wafer as the spacing between the two electrodes is adjusted to a desired gap width. A raised annular barrier on the lower electrode circumscribes the wafer and engages a mating surface on the clamp ring in order to enhance alignment of the clamp.