CPI Theory of Operation

This is a schematic view of the electro-optics in the CPI. The particle detection system (PDS) consists of two continuous-wave laser diodes with beams that are shaped into ribbons 2.4 mm wide and 0.5 mm thick. The intersection of the two PDS beams defines the sample volume of the instrument. When a particle passes through the intersection of the two laser beams, the imaging laser is pulsed and an image of the particle is cast on the CCD of the digital camera.

The data system and electronics in the sensor head perform three primary functions:

  • Particle images are extracted in real time from the million-pixel digital camera and sent to the data system host processor for display and storage.
  • The data system computer orchestrates sensor-head control, data collection, and data display and recording. The data system has an extensive graphical user interface (GUI).
  • A DSP controls functions in the sensor head, including: setting PDS laser power, conditioning and digitizing PDS detector signals, setting imaging laser power, acquiring and digitizing housekeeping signals, and controlling heaters.
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