Talbot effect of a grating under ultrashort pulsed-laser illumination

The Talbot effect of a grating under ultrashort short-pulsed light illumination is analyzed from its Fresnel diffraction equation. We find that the Talbot self-imaging effect gradually diminishes when the full width Δτ at half maximum of the incident ultrashort laser pulse decreases. If Δτ is within a few tens of femtoseconds, the self-imaging effect disappears. We note that the maximal value of the sharp peak of the intensity distribution at the first Talbot distance increases steadily along with the increase of Δτ. Therefore, by using this phenomenon, the width of an ultrashort laser pulse can be measured roughly.