A simple ultra-violet sensor and integrating recorder for long-term field operation

The ultra-violet sensor and integrating recorder described are designed primarily for monitoring narrow-band solar ultra-violet radiation received by specimens exposed in weathering trials. The performance of the selenium-cell based sensor is discussed in terms of optical stability, linearity of response, spectral sensitivity, cosine response and temperature dependence. A solar-powered digital integrating recorder is described which is capable of several months of unattended operation. A method is presented for the absolute calibration of sensors without reference to standard sources.