High-speed low-frequency chirped coherent anti-Stokes Raman scattering microscopy using an ultra-steep long-pass...

Area of Science:

• Biomedical Optics
• Spectroscopy
• Microscopy

Background:

• Coherent anti-Stokes Raman scattering (CARS) microscopy is valuable for live cell imaging and label-free pathology.
• Low-frequency CARS imaging (<300 cm^-1) is underexplored due to limitations in existing techniques.
• Current methods for low-frequency CARS microscopy have long pixel dwell times and system complexity.

Purpose of the Study:

• To develop a simplified and faster CARS microscopy technique for the low-frequency spectral range.
• To enable label-free imaging in the few terahertz spectral range without complex instrumentation.
• To reduce pixel dwell time for high-speed imaging applications.

Main Methods:

• Implemented a sharp-edge approach using an ultra-steep long-pass filter (ULPF) for chirped-CARS (C-CARS) spectroscopy.
• Demonstrated C-CARS in the low-frequency regime without requiring lock-in detection or double-notch spectral shaping.
• Showcased the technique's ability to perform spectroscopy without post-processing analysis.

Main Results:

• Achieved C-CARS in the low-frequency spectral range using a ULPF-generated sharp-edge filter.
• Enabled C-CARS spectroscopy without the need for post-processing data analysis.
• Successfully imaged collagen in a biological sample with a significantly reduced pixel dwell time of 200 microseconds.

Conclusions:

• The sharp-edge C-CARS method provides a simplified and efficient approach for low-frequency CARS imaging.
• This technique facilitates rapid, label-free imaging in spectral regions previously difficult to access.
• Potential applications include high-speed imaging of live cells and dynamic processes in microfluidic channels.