Patent ID: 7045766
Filing Date: 2006-05-16
Classification: G01V

Abstract:
1. A retroreflective photoelectric sensor comprising: a light-emitting optical system having a light-emitting element that emits an expanding beam of light with a fixed gate angle, a first polarizer and a light-emitting lens arranged sequentially; a light-receiving optical system having a light-receiving lens, a second polarizer and a light-receiving element arranged sequentially; a first phase shifter inserted between said first polarizer and said light-emitting lens; and a second phase shifter inserted between said second polarizer and said light-receiving lens, said first phase shifter and said second phase shifter each serving to shift the phase by ⅜–⅝ with respect to the wavelength; wherein said first polarizer and said second polarizer have mutually perpendicular polarizer axes.