Time domain diffuse Raman spectrometer based on a TCSPC camera for the depth analysis of diffusive media

Area of Science:

• Biomedical Optics
• Spectroscopy
• Photonics

Background:

• Highly scattering media pose challenges for optical probing.
• Conventional Raman spectroscopy methods struggle with fluorescence contamination and depth resolution.

Purpose of the Study:

• To develop a time domain diffuse Raman spectrometer for depth-resolved analysis of scattering media.
• To demonstrate enhanced signal contrast and reduced fluorescence in tissue phantoms.

Main Methods:

• Utilized a novel time-correlated single-photon counting (TCSPC) camera for simultaneous spectral and temporal data acquisition.
• Employed time gating techniques to isolate Raman photons and suppress fluorescence.
• Developed a non-contact probe for measurements on tissue-mimicking bilayer phantoms.

Main Results:

• Achieved depth sensitivity by time gating Raman photons at specific delays.
• Successfully eliminated fluorescence contamination through early time gating (0-212 ps).
• Demonstrated a high contrast between layers in a bilayer phantom with an enhancement factor of 2170.

Conclusions:

• The developed time domain diffuse Raman spectrometer offers significant advantages for depth probing in scattering media.
• The system provides superior signal enhancement and fluorescence suppression compared to existing methods like SORS and FORS.