This is a very lightweight app that works as a light meter using your Android device's sensor. It's very simple to use, just launch it and it will show on screen current light measured in lux, standard unit for illuminance. It also keeps records for maximum and minimum lux measured.
Please beware that the data accuracy depends completely of device light sensor and because of that values shown should be taken only as indicative. For professional uses it is better to use a standarized and calibrated sensor.