  Many experimental setups, such as for the calibration of photosensors,
require light sources with sub-nanosecond timing precision. We present the
design and evaluation of a brightness controlled, picosecond light pulser based
on an avalanche transistor pulse driving circuit. It can be used with a large
variety of LEDs and VCSELs, enabling usage over a wide wavelength range, with
light curves as short as ~100 ps standard deviation.
