Lux meter is so called light intensity meter used in many areas like hospitals, industrial facilities, and even living houses to determine comfort level. Photographers use light meters to adjust exposure time and so on. If you Google around you will find standard light intensity values that should be kept in working area. This is really interesting topic and causes lots of debates what intensity is enough and what is not. If you would like to experiment with adjusting light intensity in your area, you definitely need a measurement tool which would allow you to keep track of changes. Embedded-lab has built a digital light meter using BH1750 digital light sensor module and Arduino.
Using Arduino it outputs intensity value on eight 7-segment LED display stick driven by MAX7219. It is capable of displaying intensity value in Lux and Foot-candle. Light intensity module connects to Arduino using I2C interface. Its measuring range is from 0 to 65535 Lux. Once turned ON meter takes measurement every second.