The invention relates to a detector unit which is made for connection to
an optical bus which is formed by detector units of the same type
arranged adjacently. The detector unit has a light transmitter, a light
receiver and at least one optical connection path by which two optical
interfaces are optically connected. At least one optical anomaly is
arranged along the optical connection path which is made for the coupling
of light of the light transmitter into the optical connection path and
for the coupling of light out of the optical connection path to the light
receiver.