Birefringence based multi-focus fs/ps-CARS spectroscopy for thermometry and hyperspectral microscopy.

Area of Science:

• Spectroscopy
• Nonlinear Optics
• Microscopy

Background:

• Coherent Anti-Stokes Raman Scattering (CARS) is a powerful technique for molecular spectroscopy.
• Current CARS methods often require sequential measurements, limiting acquisition speed.
• Simultaneous multi-point measurements are desirable for applications in gas phase analysis and imaging.

Purpose of the Study:

• To develop and demonstrate a multi-focus fs/ps-CARS scheme for simultaneous multi-point spectroscopy.
• To validate the technique for gas phase thermometry and microscopic imaging.
• To assess the impact of multi-focusing on acquisition speed.

Main Methods:

• Utilized a single birefringence crystal or birefringent stacks to create multiple focal points.
• Performed 1 kHz single-shot N2 spectroscopy for gas phase thermometry near a flame.
• Demonstrated simultaneous toluene spectra acquisition in a microscopy setup.
• Conducted two-point and four-point hyperspectral imaging of PMMA microbeads.

Main Results:

• Achieved simultaneous N2 spectroscopy at two points several millimeters apart for flame thermometry.
• Acquired simultaneous toluene spectra at two points 14 µm apart using microscopy.
• Demonstrated two-point and four-point hyperspectral imaging with increased acquisition speed.
• Confirmed the feasibility of multi-focus CARS for diverse applications.

Conclusions:

• The multi-focus fs/ps-CARS scheme enables simultaneous multi-point spectroscopy.
• The technique is effective for both gas phase measurements and microscopy.
• Multi-focusing significantly enhances acquisition speed for hyperspectral imaging.