Adafruit digital infra red visible light sensors with i2c 5v ready adafruit 439 the adafruit tsl2561 arduino compatible digital light luminosity lux sensors can be re configured to detect illuminance from 01 to 40 000 lux on the fly containing two sensors a full spectrum sensor which includes the human visible and infra red wavelengths and an infra red sensor the boards allow you to calculate the illuminance in lux this is handy for controlling lcd brightness according to ambient