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Updated: Feb 3, 2026

Author Spotlight: Unveiling the Potential of VSFG Microscopy in Studying Mesoscopically Heterogeneous Self-Assembled Structures
Published on: December 1, 2023
High-resolution infrared imaging of biological samples with third-order sum-frequency generation microscopy
Adam M Hanninen1, Richard C Prince2, Raul Ramos3
1Department of Astronomy and Physics, University of California, Irvine, CA 92697, USA.
Abstract:
We studied the use of vibrationally resonant, third-order sum-frequency generation (TSFG) for imaging of biological samples. We found that laser-scanning TSFG provides vibrationally sensitive imaging capabilities of lipid droplets and structures in sectioned tissue samples. Although the contrast is based on the infrared-activity of molecular modes, TSFG images exhibit a high lateral resolution of 0.5 µm or better. We observed that the imaging properties of TSFG resemble the imaging properties of coherent anti-Stokes Raman scattering (CARS) microscopy, offering a nonlinear infrared alternative to coherent Raman methods. TSFG microscopy holds promise as a high-resolution imaging technique in the fingerprint region where coherent Raman techniques often provide insufficient sensitivity.
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