Hand-held photo-electric probe - for non-contact rotary speed measurement has cylindrical swivelling head

摘要

The cylindrical swivel head is incorporated at one end of the unit which can rotate through 180 degrees and is indexed to point in a variety of fixed directions. The rotation is coplanar with a cylindrical section and occurs about the same axis as the cylinder. In this way a sliding contact, feeding the light source and carrying the received signal, can move around the inner wall of the cylinder. A lens at the top produces a parallel beam from the light source, and through the centre is a small diameter photo detector. This feeds an amplifier in the body of the unit, which also houses the supply batteries.