Auto and cross correlation measurements of femtosecond laser beams in SRS microscope

Ultrafast lasers are increasing their range of applications. In non-linear optical microscopy, the laser beam properties can influence the non-linear contrast efficiency and the image quality, so monitoring of the output waveform is often required. In order to obtain images, in Stimulated Raman Scattering (SRS) microscopy, two collinear laser beams, a high-power pump laser and a low power Stokes laser with different frequencies (omega(L)>omega(S)) are focused into a sample. In this paper the two laser sources, in our case a femtosecond Ti:Sapphire (Ti:Sa) oscillator and a femtosecond synchronized optical parametric oscillator (OPO) are characterized by non-linear interferometric measurements. Taking advantage of two-photon absorption (TPA), autocorrelation measurements of each laser beam and cross correlation measurements of Ti:Sa and OPO are carried out. Results are reported and discussed.