Method and apparatus for measuring the duration of optical radiation pulses

摘要

An extension of the noncollinear second harmonic generation technique for pulse autocorrelation measurements is described. A diffraction-grating is used to produce a tailored, expanded beam, with a differential time delay along its expanded axis. When this beam is combined with an inverted replica of itself at the frequency-doubling crystal, the monitored spatial profile of the generated second harmonic beam gives directly the duration of the incident laser pulse. A time resolution of better than 1 picosecond (ps) is obtained at 500 nanometers (nm), and a total measurement range of DIFFERENCE 80 ps. The optical system here described enables the extension of the measurement range in a simple manner.