Systems and methods for measuring a pulse length (.tau..sub.0) of an ultra-short light pulse (P.sub.0) based on processing a number of substantially similar light pulses. The system includes an autocorrelation optical system adapted to receive the light pulses P.sub.0 and create from each light pulse two beams having an associated optical path length difference .DELTA.OPL. Providing a different .DELTA.OPL for each light pulse creates an autocorrelation interference pattern representative of an autocorrelation of the light pulse P.sub.0. An LED detector detects the autocorrelation interference pattern and generates therefrom an autocorrelation signal. A signal-processing unit forms from the autocorrelation signal a digital count signal representative of a number of counted peaks in the autocorrelation signal above the full-width half maximum. Control electronics unit causes the varying .DELTA.OPL and provides a difference signal (S.sub..DELTA.) representative of the .DELTA.OPL to the s
