Measurement of non-compensated angular dispersion and the subsequent temporal lengthening of femtosecond pulses in a CPA laser

Closed analytical formulae are given for the residual angular dispersion resulted from the non-parallel surfaces of both a grating pair and a prism pair pulse compressor. Accurate measurements of the angular dispersion of pulses leaving the misaligned pulse compressors agree well with the first principle simulation curves. The corresponding lengthening of the transform limited 18 fs pulses was also determined. Finally, it is experimentally proved that by simultaneous monitoring of angular dispersion and pulse duration, the stretcher-compressor system of a chirped pulse amplification laser can be aligned very precisely.