Abstract: A device for detecting and reporting fire phenomena, particularly sparks in a gas stream that might be charged with solid particles and flows through a conveyance line uses a displacement body that extends longitudinally in the flow direction of the conveyance line. The displacement body is disposed on a shaft, and a deflector is disposed at one end of the displacement body, in front of a light-permeable ring, in the interior of which a reflector is disposed. By way of an adjustable mirror at the other end in the interior of the displacement body, a signal is reflected into the interior of the shaft. The device also includes an optical reception unit and an evaluation unit at the end of the shaft.