The Master4Light mobile control unit from Majantys is for driving and measuring the optical properties of LEDs. Measuring 48 × 36 × 20 cm, it integrates an adjustable current source generator for driving the LEDs and two thermocouple inputs to probe their temperature in real time. Current may be continuous or pulsed, with various amplitudes and frequencies. A spectrophotometer connected to an 80-mm-diameter integrated sphere measures the optical parameters. The LED is set on top of the sphere port, which is connected to a power output. The control unit connects to an external 9-VDC adapter and a remote PC via a USB port. The software provides access to the measured spectrum and to parameters such as color coordinates, dominant wavelength, correlated temperature and color rendering index.