Lighting Research & Technology

A new concept which should facilitate the calculation of illumination from long linear light sources is proposed and a general theory of the infinite linear source is given.

The errors incurred when applying infinite source relations to finite layouts are assessed for three types of sources.

How the results of this analysis can be applied to practical design tasks is shown in a few examples of fluorescent lamp layouts.

This paper extends the work of Waldram and others on the revealing power of street lighting installations. It is shown that values of revealing power, approximating closely to the true values, can be calculated from the mean pedestrian illumination E_m and the road surface luminance B. Curves are given showing this approximate revealing power as a function of the two quantities B and B/E_m. The curves may be used to find the revealing power to any desired accuracy for any type of installation by a simple calculation of averages. The broad effects of changes in the lighting installation may also be understood with the aid of these curves.