Design and performance of a low-intensity LED driver for detector study purposes

A custom LED driver producing light pulses with very low intensity and O(10 ns) duration was designed and constructed. A microcontroller was employed to handle the amplitudes and the repetition rates of the output pulses. In addition, it also provided both a PC control of the system through a RS232 interface and an external trigger I/O. A WLS fibre directly coupled to a LED provides unique characteristics of the output light pulse. The combination of a quasi delta light pulse source and physical absorption-emission medium results in an output light profile maximally close to the plastic sctintillators. The light generator is intended to be used to test the response and the rate capability of different photodetectors. Its design, operational characteristics, and stability are described and discussed.