The instrument uses a closed-loop recirculating stream of particles in liquid suspension. Images of back-lit particles are strobed and captured by a high-resolution CMOS monochrome camera. Image size is 5 megapixels, with a darkness digitization resolution of 256 gray levels. Telecentric lenses are used for good depth of field. Lens powers available are 1X (for particles larger than 100 microns, nominally) and 5X (particles less than 100 microns). Instrument control features include Fill, Drain, Rinse and Debubble.
Images are analyzed in real time as they come from the camera. Software analyzes images using a variable gray level threshold, focus discrmination, pixel area limits, rejection based on shape settings, and other parameters that can be optimized for the particular kind of particles present.