Előadó: Váczi Tamás (SZFI)
Az előadás témája: Development of a spectrally focussed femtosecond SRS system for microscopy and spectroscopy
Az előadás időpontja: 2021. február 9., kedd, 10.00
Helyszín: videokonferencia, https://letsmeet.wigner.hu/szeminarium
The basic principles and practical aspects of constructing a system for spectrally focussed, femtosecond laser-based simulated Raman scattering (SRS) applications are presented. The system is based on a turnkey dual-output laser unit for rough tuning, glass inserts for pulse chirp, optomechanics for controlling spatial and temporal overlap, and a galvanometric scanning two-photon microscope with transmitted balanced simulated Raman gain detection. Spectral focussing allows fast, high-precision, highly selective SRS imaging and spectroscopy through delay tuning but requires the careful matching of the chirp parameters of the two pulses. The optimisation of the system including the total group delay distortion, balanced detection, the acousto-optic modulator transfer function, polarization rotation correction etc. are explained, all aiming at increasing the signal-to-noise ratio. Demonstrating examples are shown including polymer SRS spectra, label-free tissue imaging, concentration series of alkyne-tagged molecules, and a case of resonant SRS enhancement.