Colour temp. constancy checking appts. for light source e.g. commercial or laboratory fluorescent lamp

摘要

The constancy checking appts. involves incoming light (2) which is homogenised by a scattering glass pane (3) before falling on two filters (4,5) transparent to different spectral regions. The intensity of the light transmitted by each filter is measured by a photodiode (6,7) and displayed. The amplification factors of the photodiodes are balanced by means of an adjustment screw (8) in one of the optical paths. The use of at least two sensors with corresp. filters enables x and y colour co-ordinates to be ascertained and a warning to be given when the light source is sufficiently aged to require replacement.