Total internal reflection enabled wide-field coherent anti-Stokes Raman scattering microscopy

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Spectroscopy

Background:

• Coherent anti-Stokes Raman scattering (CARS) microscopy enables vibrationally resolved imaging.
• Achieving strong excitation fields over large areas is a key challenge for wide-field CARS.
• Existing methods face limitations in excitation efficiency and spectral range.

Purpose of the Study:

• To develop a novel wide-field CARS microscope with enhanced excitation efficiency.
• To enable rapid and simultaneous acquisition of vibrationally resolved images over a large field of view.
• To validate the system's performance on biological samples.

Main Methods:

• Implementation of a total internal reflection excitation scheme.
• Utilization of a femtosecond Ti:Sapphire oscillator for pump and broadband near-infrared Stokes pulses.
• Exploitation of spectral broadening and chirp of the Stokes pulse for tunable vibrational mode selection.

Main Results:

• Demonstration of a new wide-field CARS microscope design.
• Successful excitation of third-order optical responses over a large focal region.
• Acquisition of high-quality CARS images from model and complex biological samples.
• Broad spectral access to Raman modes (1000-3500 cm⁻¹).

Conclusions:

• The developed wide-field CARS microscope effectively overcomes excitation challenges.
• The system provides a versatile platform for rapid, large-area, vibrationally resolved imaging.
• This technique holds promise for advanced biological sample analysis.