| abstract |
An apparatus for detecting the concentration of particles in a liquid includes a light-emitting portion for emitting examination light which is totally reflected-by a boundary surface contiguous to the liquid to be examined, a photosensor for receiving the totally-reflected light, a reference sensor for directly receiving the examination light, and a judgment portion for finding the reflectance from outputs of the two sensors to compute the particle concentration. In case that the liquid to be examined is lubricating oil of an engine, the concentration of carbon particles is calculated, thereby judging the deterioration of the lubricating oil. |