The addition of fiber optic sensors considerably extends application solutions for photoelectric sensors, allowing their installation in confined areas, as well as in areas in which intrinsic safety would normally disallow the use of electronics. Glass fiber optic sensors are made of the finest high quality 70 micron glass fibers which are bundled in PVC, PUR or metal sheaths, as well as in chrome-nickel tubes. The front surfaces of the fibers, which are set and glued into the sensing head, are precisely ground and polished to provide outstanding optics. Plastic fiber optics are less expensive than glass and can be cut to the desired length by the user. Even difficult multiple sensing problems can be solved by using fiber optic sensors.