Abstract: A system for measuring the wavefront characteristics of a powerful laser close to an emitting or transmitting surface of the laser. The system includes a beam sampler that has a sampling aperture for sampling radiation from a sampled area along the emitting or transmitting surface. The beam sampler includes a reflector for directing un-sampled radiation onto an absorber, which absorbs un-sampled radiation. Radiation sampled by the beam sampler is sensed using a sensor.

Abstract: A system for measuring the wavefront characteristics of a powerful laser close to an emitting or transmitting surface of the laser. The system includes a beam sampler that has a sampling aperture for sampling radiation from a sampled area along the emitting or transmitting surface. The beam sampler includes a reflector for directing un-sampled radiation onto an absorber, which absorbs un-sampled radiation. Radiation sampled by the beam sampler is sensed using a sensor.

Abstract: A method and apparatus for maintaining the cells of a fuel cell stack are disclosed. The apparatus includes a fuel cell maintenance device including means for imposing a low impedance across at least one cell of a fuel cell stack, e.g., a switch, and a pulse generator. The pulse generator is capable of pulsing a cathode of the at least one cell of through the low impedance imposing means, e.g., when the switch is closed. The method transparently maintains the cells of a fuel cell stack, and includes sequentially pulsing the cathodes of a plurality of cells in a fuel cell stack, and maintaining a consistent number of the cells providing power to a load of the fuel cell stack while sequentially pulsing the cathodes of the cell.

Abstract: The invention includes, in one embodiment, a system for monitoring a plurality of cell voltages of an electrochemical device for a plurality of cells connected in series, the system including: a plurality of connecting pins for removable connection across the plurality of cells; a plurality of differential amplifiers, each differential amplifier having a plurality of laser wafer trimmed resistors providing matching, so that common mode signals are rejected, while differential input signals are amplified, each differential amplifier having two inputs and one output, where the inputs are each connected to the plurality of connecting pins; a switching network having a plurality of inputs and one output, the inputs of the switching network connected to the outputs of the differential amplifiers; not more than one analog to digital converter per 16 cells having an input connected to the output of the switching network and adapted to provide digital values indicative of the voltages measured by the plurality of dif