The CE 318 automatic sun tracking photometer has been designed and realized to be a very accurate sun photometer with all the qualities of a field instrument : motorized, portable, autonomous (solar powered) and automatic.
Its main purpose is to measure sun and sky radiance in order to derive total column water vapor, ozone and aerosols properties using a  combination of spectral filters and azimuth/zenith viewing controlled by a microprocessor.

The sun photometer CE 318 is composed of an optical head, an electronic box and a robot. The optical head has two channel systems : the sun collimator, without lens, and the sky collimator with lenses. The sun tracking is equipped with a 4- quadrant detector. The electronic box contains two microprocessors for real time operation for data acquisition and motion control. In automatic mode, a ‘wet sensor′ detects precipitation and forces the instrument to park and to protect the optics. The robot is moved by step-by-step motors in two directions : in the zenith and azimuth planes. The computation of sun equations (like air mass) is performed by two CPU cards.

SPECIFICATIONS

Two types:
CE 318-1 : standard model with 5 filters 440, 670, 870, 936,1020 nm
CE 318-2 : polarized model with 8 filters 440, 670, 870, 870,870, 936, 1020

Components: Optical head with 2 collimators
FOV: Solar collimator: 1.2° / Sky collimator: 1.2°
Bandwidth: 10 nm at full width at half maximum
Detector: UV enhanced silicon detector for the sun. Silicon detector for the sky. Electronic box Robot for sun tracking
Operating temperature: -30 to +60°C
Sun tracking method: Tracking in zenith and azimuth planes Active tracking by a 4-quadrant detector Accuracy better than 0.1°
Power requirements: Internal batteries for the optical head External batteries for the robot Rechargeable by solar panels or 220VAC

References

[1] CIMEL CE 318 Specification - Web Page