A LED based white light source (WLS) is designed and constructed to determine the color characteristics of the samples
having specular and diffuse reflectance properties at the standard measurement conditions of 0/45 and d/8. The light
source is composed of high power cool white and ultraviolet light emitting diodes (LEDs) which are operable in
adjustable current levels. In order to combine the light beams emerging from two LED sources, a 1x2 fiber optic
combiner is used. Optical characterizations of the light source designed and influences of several colorful LEDs called
Royal-Blue, Blue, Cyan, Green, Amber, Red-Orange and Red on spectrophotometric properties of the light source are
In order to establish light emitting diode (LED) based spectrophotometric standard light source we used high-power Luxeon Star white LEDs having nominal electrical powers of 5W and 1W. Especially designed aluminum cooling block was used to protect LEDs from heating and to reduce heating effects on optical and electrical parameters. The chromaticity coordinate (CC) and correlated color temperature (CCT) properties of each LED were characterized by the measuring of spectral power distribution between 360 nm and 830 nm wavelength range. Then using spectral power distribution values and CIE color-matching functions at 2° observer, tristimulus values and CCs were calculated in both CIE-1931 and CIE-1960 spaces. CCTs then were calculated using computer interpolation method.