Abstract: A sweeping machine which includes a debris collection hopper and filter assembly which is readily attached to the lift bars of a conventional forklift so as to be manipulated both horizontally and vertically by the forklift and which is mounted thereto so as to float relative to the forklift in order to follow the contour of the surface being swept.

Abstract: A focused beam of light from a light source is directed into a closed smoke chamber, having inlets for admitting smoke particles, toward a reflector which reflects and refocuses the beam back into the light source, the direct beam and the reflected beam passing through a test zone within the chamber. In the event that smoke particles enter the test zone, the direct and reflected beams strike and bounce off of those particles to produce scattered radiation that will be picked up and detected by a light responsive sensor to generate an alarm signal. By closely controlling, rather than baffling the light, optimum operation is obtained, efficiency is enhanced and false alarms are minimized.