Homogeneous Light

Homogeneous Light means light of one definite colour only, due to vibrations of one frequency. It is impossible to get pure homogeneous light, but it may be approached very closely with the sodium flame, the constituents of which are two colours in the yellow portion of the spectrum, very nearly of the same frequency. Mixed light may be rendered more nearly homogeneous by filtering away certain of its various ingredients by passing the light through some medium that will only transmit certain colours.