DE3524118

A stationary tyndallometer provided for underground mining, which moreover can be used over long periods and via which control processes are regulated, provides for the scattered-light measuring chamber to have a tubular or semitubular shape and to have annular-gap nozzles or perforated metal sheets which are disposed correspondingly, are associated with the inlet and the outlet and are aligned parallel to the inner wall. In addition, the emitter tube and the receiver tube assigned to the scattered-light measuring chamber are connected via a light pipe which carries primar light and has a mechanical interrupter. Finally, there is associated with the scattered-light measuring chamber receiver a preamplifier which via cables is connected to a main amplifier and a digital section having a microprocessor.