On-line detecting and controlling conception for time-delay measurement in ultrafast laser pulse pump-probe

A novel optical system for detecting and controlling the time-delay value of probe light in the femtosecond pulse pump-probe measurements is presented based on the simultaneous phase-shifting interferometry scheme. The intensity distributions of interference pattern are calculated based on the Jones theory to optimize the optical system, by which the analytical expressions for phase-shifting length between the neighboring interferograms and the relevant phase-delay value are derived. To meet the requirement of practical application, possible latent errors in the process of detecting time-delay are analyzed. In particular, a minimum time-resolution with attosecond level at 800 nm wavelength was achieved. The results show that this system satisfies the requirement of femtosecond pulse pump-probe high-precision measurement.