Relative intensity noise measurement of femtosecond laser beams in SRS microscope

"Noise" of lasers is a short term for random fluctuations of various output parameters, which can play a fundamental role in many applications. In non-linear optical microscopy, the laser beam properties can influence the non-linear contrast efficiency and the image quality. Therefore, laser noise effects should be reduced to acceptable levels. In Stimulated Raman Scattering (SRS) microscopy, two synchronized trains of femtosecond pulses with independent tunability over a wide spectral range are required. The high performance of the SRS imaging requires a reduction of the relative intensity noise (RIN) and timing jitter between these two synchronized pulses trains. In this paper, relative intensity noise (RIN) of the two femtosecond laser sources, in our case a Ti:Sapphire (Ti:Sa) oscillator and a femtosecond synchronized optical parametric oscillator (OPO) are measured.