Transmittance densitometer

摘要

In a transmittance densitometer comprising a sample stage with a central measuring light path passing therethrough which is illuminated interiorly, there are provided a semi-transparent illumination plate provided for the sample stage, the semi-transparent illumination plate surrounding the measuring light path and capable of diffusing transmission light, and a local illumination chamber disposed beneath the illumination plate, the chamber optically isolated from illumination light directing to the measuring light path and the sample stage, whereby an illumination lamp disposed interiorly of the local illumination chamber is turned on under the control of the level of an ambient light shielding cylinder which partially defines the measuring light path.