Environmental Engineering Reference
In-Depth Information
in Figure 4. The development of photometers, which are radiometers with a spectral
response function that closely mimics the CIE luminous efficacy function V(O), requires
sophisticated filters for accurate spectral matching. Uncertainty ratings for photometers
are measured by how well the spectral response fits the desired function; however, for
UV photobiology, a single, simple figure of merit number is not sufficient, since errors
in the long-wavelength response generally will result in a greater error than if the same
error exists in the short-wavelength region. It is generally better to calibrate a UV
radiometer against several types of reference sources (e.g., tungsten-halogen lamp,
xenon-arc lamp, solar simulator, etc.) and use this calibration factor with similar types
of source.
Figure 4. The CIE Photopic and Scotopic visual response functions.
Action spectra: general aspects
An action spectrum is defined as the relative spectral effectiveness of
monochromatic radiation in eliciting a defined response relative to a wavelength of
maximal effectiveness. Provided that multiple action spectra do not overlap (i.e., one
chromophore is present), weighting a broad spectrum source by an action spectrum can
Search WWH ::




Custom Search