Excess gain indicates how much light a sensor receives under certain conditions. This value is compared to the amount of light the sensor needs to switch. Excess gain 1 indicates that the sensor receives a minimum quantity of light, just enough to work. Excess gain 50 indicates that the sensor receives fifty times more light then needed for proper operation. In a clean environment, excess gain 1.5 is sufficient to ensure proper operation of the sensor in case of offset or gradual consumption of the LED. If dust, fume or mist is expected to contaminate the lens, excess gain should be higher than 1.5. All values for the sensing ranges stated in this catalog refer to excess gain 1.