| 摘要 |
A retroreflective photoelectric sensor may be of a biaxial type or of a coaxial type. A sensor of the biaxial type includes a light-emitting optical system having a light-emitting element, a first polarizer and a light-emitting lens arranged sequentially in this order, a light-receiving optical system having a light-receiving lens, a second polarizer and a light-receiving element arranged sequentially in this order, and a phase shifter inserted between the first polarizer and the light-emitting lens of the light-emitting optical system. The polarizer axes of the first and second polarizers are mutually perpendicular. A phase shifter such as a ½ wave plate may further be placed between the first polarizer and the light-emitting lens of the light-emitting optical system.
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