| abstract |
A liquid monitoring system includes chamber structure with a monitoring region in which the liquid to be monitored is disposed, the monitoring region having two spaced wall portions and a supplemental wall portion. The system further includes a radiation source mounted adjacent one of the spaced wall portions or directing a beam of radiation along a horizontal path, and a sensor mounted adjacent the opposed wall portion for receiving radiation in a beam path. The incident radiation beam as it passes through the wall into the monitoring region is refracted at the region surface as a function of gas or liquid within the region. At a first refracting angle, the refracted beam impinges on the supplemental wall and is internally reflected, the reflected radiation passing along a reflected beam path and sensed by the detector to provide an indication of the fluid in the chamber. At a second refracting angle, the refracted beam is not reflected in a direction such that radiation from the source is sensed. |