Optoelectronic sensor and method for measuring contamination of a front screen

An optoelectronic sensor for the detection of at least one object in a monitored zone,

• comprising a housing having a front screen;
• a measuring unit having at least one measurement light transmitter for transmitting measurement light through the front screen and at least one measurement light receiver for generating a received measurement signal from measurement light remitted by the object;
• a movable deflection unit for the periodic deflection of the measurement light;
• a contamination test unit moved along with the deflection unit and having at least one contamination test light transmitter for transmitting contamination test light onto the front screen and at least one contamination test light receiver for generating a received contamination test signal from contamination test light remitted at the front screen;
• and a control and evaluation unit that is configured to detect the object by evaluating the received measurement signal and to evaluate the contamination of the front screen by evaluating the received contamination test signal,
• wherein the contamination test unit has at least two contamination test light transmitters and/or at least two contamination test light receivers to form a plurality of contamination test channels;
• and wherein the control and evaluation unit is configured to evaluate the contamination of the front screen using the received contamination test signals of the plurality of contamination test channels.