Dual/differential coherent anti-Stokes Raman scattering module for multiphoton microscopes with a femtosecond Ti:sapphire oscillator.

In the last decade, coherent anti-Stokes Raman scattering (CARS) microscopy has emerged as a powerful multiphoton imaging technique offering label-free chemical sensitivity and high three-dimensional resolution. However, its widespread application in the life sciences has been hampered by the use of costly pulsed lasers, the existence of a nonresonant background requiring involved technical solutions for its efficient suppression, and the limited acquisition speed of multiplex techniques addressing several vibrational resonances, if improved chemical specificity is needed. We have recently reported a differential CARS technique (D-CARS), which simultaneously measures two vibrational frequencies, enhancing the chemical selectivity and sensitivity without introducing costly hardware, while maintaining fast acquisition. In this study, we demonstrate a compact, fully automated, cost-effective module, which integrates on hardware and software level with a commercial multiphoton microscope based on a single 100 fs Ti:Sapphire oscillator and enables D-CARS microscopy in a user-friendly format for applications in the life sciences.