Operator Manual: Spinning Disk Calibrator

The Droplet Measurement Technologies (DMT) spinning disk calibrator is used to simulate particles passing through the beam of several DMT instruments: The Cloud Imaging Probe (CIP), the Cloud Combination Probe (CCP), the Cloud, Aerosol, and Precipitation Spectrometer (CAPS), the Meteorological Particle Spectrometer (MPS), the Precipitation Imaging Probe (PIP), and older 1D and 2D OAPs. Within the following discussion, these are all referred to as the “instrument.” The spinning disk calibrator is referred to as the “spinning disk.”

The spinning disk consists of a glass disk with two-dimensional, opaque images on it that are rotated through the laser beam of the instrument. These images are most often circular, like particles,1 and they produce shadow images that are nearly identical to spherical droplets of the same size. Thus, the spinning disk is a useful and valid calibration device.

The spinning disk can be used for troubleshooting, since it provides a steady source of particles to the probe and exercises the complete optical and electrical systems of the instrument. In addition, the spinning disk can be used as an end-to-end confidence check prior to a data collection campaign.