Time‐lens based hyperspectral stimulated Raman scattering imaging and quantitative spectral analysis

We demonstrate a hyperspectral stimulated Raman scattering (SRS) microscope through spectral‐transformed excitation. The 1064 nm Stokes pulse was from a synchronized time‐lens source, generated through time‐domain phase modulation of a continuous wave (CW) laser. The tunable pump pulse was from linear spectral filtering of a femtosecond laser output with an intra‐pulse spectral scanning pulse shaper. By electronically modulating the time‐lens source at 2.29 MHz, hyperspectral stimulated Raman loss (SRL) images were obtained on a laser‐scanning microscope. Using this microscope, DMSO in aqueous solution with a concentration down to 28 mM could be detected at 2 μs time constant. Hyperspectral SRL images of prostate cancer cells were obtained. Multivariate curve resolution analysis was further applied to decompose the SRL images into concentration maps of CH 2 and CH 3 bonds. This method offers exciting potential in label‐free imaging of live cells using fingerprint Raman bands. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)