Measurement and computer-aided optimization of spectral power distributions

Abstract

This paper describes a rapid and reliable method of measuring the spectral power distribution of a lamp. The computer program which calculates the colour rendering index and the correlated colour temperature from this s.p,d, is used to study the influence on colour rendering and correlated colour temperature of adding a line to the spectrum of a metal halide (HPI) lamp. Another application of the computer program shows that with spectra consisting of only three spectral lines it is possible to achieve a general colour rendering index Ra~80. It appears that the three lines have to be chosen in three different wavelength regions, namely a blue line in the region 455-485 nm, a green line in the region 525-560 nm and a red line in the region 595-620 nm. With decreasing colour temperature the optimal wavelengths shift slightly to longer wavelengths whilst the general colour rendering index slightly increases.