The bins contain data about each pulse, and this data correlates to particle sizes. The PHA examines the magnitude of the pulse and places its value into an appropriate sizing channel, called bins. Pulse height analyzer (PHA): The pulses from the photodetector are sent to a pulse height analyzer (PHA).An amplifier converts the pulses to a proportional control voltage. Photodetector: The photodetector is an electric device that is sensitive to light, and when particles scatter light, the photodetector observes the flash of light and converts it to an electric signal, or pulse.The sample medium (air, liquid or gas) is drawn into the viewing volume, the laser passes through the medium, the particles scatter (reflect) light, and a photodetector tallies the scattered light sources (the particles). Controlled flow: The viewing volume is a small chamber illuminated by the laser.Lasers and optics: A laser operates on a single wavelength, so the light source is consistent with constant power output to illuminate the particle sampling region.Laser optical particle counters employ five major systems: Light scattering by particles use instrumentation comprising a high-intensity light source (a laser), a controlled media flow (air, gas or liquid) and highly sensitive light-gathering detectors (a photo detector). Particle counters function primarily using the principles of light scattering, although other technologies may also be employed.
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