TEMPERATURE DEPENDENCE OF ARRAY SPECTRORADIOMETERS AND IMPLICATIONS FOR PHOTOBIOLOGISTS

摘要

Miniature CCD array spectroradiometers are increasingly used by photobiologists in a range of applications where rapidly changing spectral information is required to be captured at specified times, such as in medical applications (Coleman, 2008), solar monitoring (Seckmeyer, 2010) or measurements of sunbed emissions (Ylianttila, 2005). Although CCD array spectroradiometers offer many advantages, amongst their limitations, some of their characteristics are influenced by ambient temperature (Blumthaler, 2013). The performance of some of these devices had been previously investigated in laboratory conditions; however, there remained a need for systematic study of temperature dependence to determine the conditions under which they can be expected to function accurately outside of a temperature-controlled environment. The initial results from analysing the performance of six spectroradiometers are presented, including two thermo-electrically cooled models with in-built fans. The following characteristics were investigated: 1. Thermal stability and relaxation to changing ambient temperatures 2. Dark signal as a function of both ambient temperature and integration time 3. Changes in sensitivity with ambient temperature 4. Relative wavelength shifts due to ambient temperature changes Each spectroradiometer had different thermal relaxation properties and took a different length of time to stabilise after a change in ambient temperature. Signal-to-noise ratios became unmanageable for combinations of high ambient temperatures and long integration times for non-TE-cooled instruments, as the dark signal standard deviations grew to a substantial proportion of well depth. Whilst TE-cooling was effective in improving noise management, it did not substantially mitigate changes of sensitivity with ambient temperature.