Abstract: A dark-field particle monitor and a method for reducing errors due to stray light in the particle monitor provides a particle monitor having (i) an optical element focussed on the laser beam for detecting particles and (ii) a filter for preferentially selecting light incident on said filter in a preferential direction. In one embodiments the filter is implemented by a narrow band filter having maximum transmission for light having a wavelength of the laser beam.

Abstract: A method and an apparatus for synchronizing particle counts to process events provide a trigger signal related to the process events in lieu of a time-based trigger signal. In one embodiment, the controller to a particle counter further subdivides a process event into sub-intervals to allow profiling of particle counts during the process event. In one embodiment, the controller of the particle counter receives multiple trigger signals corresponding to multiple trigger signal sources, each trigger signal source being identified by a source tag. Particle counts and time-stamps are maintained for each source of the trigger signals.

Abstract: A raster scan apparatus provides a scanning assembly capable of moving in a sinusoidal motion along a first direction and stepping in fine steps in a second direction perpendicular to the first direction. In one embodiment, a piezoelectric bimorph sets in scanning motion a scanning assembly formed by a wafer holder and leaf springs. The amplitude of the scanning motion is controlled by a voltage applied across the piezoelectric bimorph. A Hall effect sensor provides an output signal indicating the instantaneous location of the scanning assembly in motion. The output signal of the Hall effect sensor is compared against a predetermined threshold to provide a trigger signal for synchronization. The output signal of the Hall effect sensor is also fed back to the source of sinusoidal voltage to adaptively adjust the sinusoidal voltage so as to achieve a predetermined amplitude for the scanning motion.

Abstract: Disclosed is a conductivity detector for use in chromatography systems. The improved conductivity detector provides digital processing of a conductivity signal to provide improved stability. The detector compares a trial offset signal with a detected conductivity signal and when the compared values are within a predetermined value the detector processes the compared value and the final offset value thereby providing improved accuracy with higher resolution.

Abstract: An electronic solid state system is provided for starting and operating one or more fluorescent lamps, and which supplies power to the lamps at a relatively high frequency, and at a relatively high power factor. The system includes a circuit which forces the line current to be proportional to the applied input voltage so as to maintain high power factor concomitantly with the removal of flicker by high frequency operation. High power efficiency is achieved through the use of a switching resonant inverter output circuit which is ideally suited to fluorescent lamp applications because of its low harmonic energy content, and because it can accommodate a wide range of resistive loads at high efficiency. The system may also incorporate a dimming circuit for the fluorescent lamps.