Single-shot complete spatiotemporal Strehl ratio metrology of ultrashort laser pulses -- theory
Abstract
Ultra-high intensity femtosecond lasers at focus are now routinely used for relativistic motion of charged particles with peak intensities over 1018W/cm2. Such high-field experiments are very sensitive to the value of the peak intensity. Therefore, precise knowledge of the pulse intensity is a key prerequisite for the correct interpretation of experimental data. Accurate measurement of energy, spectral and spatial profiles being well established, peak intensity evaluation then only requires the determination of the spatiotemporal Strehl ratio. Here I propose a new method based on a simple analysis of a nonlinear effect. It diagnoses all the temporal, spatial and spatiotemporal coupling distortions. This method can even be implemented on target by using relativistic surface harmonic generation for example.