FAQ00438 of Photoelectric Sensors FAQ

A photoelectric sensor doesn't warrant use in outdoor.

Influence of direct sunlight

The sunlight deletes the light signal of the sensor and the sensor is the light shielding, or even if the light of a photoelectric sensor is intercepted, direct sunlight is considered as receiving signal and the sensor is light entering, when direct sunlight strikes to the lens of the receiver.
Additionally, the temperature of the sensor becomes more than the operating ambient temperature by direct sunlight, and the sensor might be destroyed.

Deterioration of resin used caused due to ultraviolet light, rapid temperature change and icing

Material used for case deteriorate due to ultraviolet light included in direct sunlight, rapid temperature change and icing.

Malfunction by rain and fog

As for through-beam and retro-reflective, the light of the sensor diffuse by rain and fog, and might be dark-ON operation by attenuating the amount of receiving.
As for diffuse-reflective, the light of the sensor reflects to rain and fog, and might be light-ON operation by receiving light.

Measures

Though it is not guaranteed when the sensor is unavoidably used, please avoid direct sunlight and wind and rain, and do not freeze by using a metallic type.
However, the malfunctions might be caused by rain and fog.