Patent ID: 7081613

Claim:
A retroreflective photoelectric sensor comprising: a light-emitting optical system having a light-emitting element and a first polarizer and serving to transmit light from said light-emitting element through said first polarizer; a light-receiving optical system having a second polarizer and a light-receiving element and serving to convert light received through said second polarizer into an electrical signal by said light-receiving element; a single lens for both emitting light from said light-emitting element and receiving light to said light-receiving element therethrough; a beam splitter serving to direct light received from said light-emitting optical system to said single lens and light received from said single lens to said light-receiving optical system; and a phase shifter inserted between said light-emitting optical system and said single lens, wherein said first polarizer and said second polarizer have mutually perpendicular polarizer axes.