European Facility For Airborne Research

Optical array probe. Cloud particle enters field of view passing through a laser beam. Particle shadow falls on a collecting optical array (normally a photodiode array). This is sampled at a rate such that the pixel resolution in time is the same as that in the across-array dimension. This forms a digitized shadow image of the particle.
From this size and shape are determined, and bulk parameters such as concentration and size spectra derived. Empirical relationships are used to calculate the mass of irregular particles (and hence the ice water content).

Environmental: Temperature (-20&degree;C to +40&degree;C)
Humidity (0 to 100 % non-condensing)
Altitude (0 to 60.000 ft ( 0-18,3 km))

Probe power 115VAC 50-400Hz 1 A
Heater power 28VDC 220W

Certified for all A/C

The Optical Array Probe Grey Scale Model OAP-2D-GB2 acquires information on particles passing through the
sample area in a form suitable for digital handling. The output bit stream
encodes not only the presence of a particles plus three levels of “grey”
information on the form of the particle image.
Particle information is acquired using a linear array of photodiodes to sense the shadowing of array elements by
particles passing through its field of view. Particles are illuminated by a He-Ne laser and imaged as shadowgraphs onto the photodiode array. If the image is dark enough on a particular element of the array, the output of a comparator will switch and provide output from an amplifier card.

Consult INTA