Rapid vibrational imaging with sum frequency generation microscopy

Abstract

We demonstrate rapid vibrational imaging based on sum frequency generation (SFG) microscopy with a collinear excitation geometry. Using the tunable picosecond pulses from a high-repetition-rate optical parametric oscillator, vibrationally selective imaging of collagen fibers is achieved with submicrometer lateral resolution. We furthermore show simultaneous SFG and second harmonic generation imaging to emphasize the compatibility of the microscope with other nonlinear optical modalities.

Polarization-Sensitive Sum-Frequency Generation Microscopy of Collagen Fibers

“…9,[15][16] Among the various forms of SFG microscopy, the point-scanning configuration with collinear excitation beams is attractive because the microscope layout is similar to a standard laser-scanning nonlinear optical microscope. 17 This configuration not only enables fast scanning capabilities with sub-micrometer lateral resolution, but also allows the simultaneous recording of images based on alternative forms of nonlinear optical contrast such as nonresonant second harmonic generation (SHG) 18 , which is especially useful when imaging microscopic structures with intrinsic non-centrosymmetry. The flexibility of this multimodal nonlinear microscopy approach is further exemplified by the implementation of phase-sensitive SFG detection, allowing direct recordings of ℑ { χ (2) } .…”

Accumulating advantages, reducing limitations: Multimodal nonlinear imaging in biomedical sciences – The synergy of multiple contrast mechanisms

“…Abbreviations: SHG-second harmonic generation, THG-third harmonic generation, 2PF-two photon excited fluorescence, 3PF-three photon excited fluorescence, SRG-stimulated Raman gain, SRL-stimulated Raman loss, CARS-coherent anti-Stokes Raman scattering, FWM-four wave mixing. stretching vibration [27]. On the other hand, processes relying on very general optical properties, e.g., refractive index changes in FWM and THG, are powerful for label-free visualization of the overall tissue structure, but provide only unspecific molecular information [19].…”

Multimodal and multiplex spectral imaging of rat cornea ex vivo using a white‐light laser source

“…The signal is generated from a tightly-focused confined volume, resulting in three-dimensional sectioning capability. So far, various kinds of nonlinear optical processes such as two-or three-photon excited fluorescence [3,4], second-or third-harmonic generation (SHG or THG) [5][6][7][8][9][10][11], sum frequency generation (SFG) [12], third-order sum frequency generation (TSFG) [13], coherent anti-Stokes Raman scattering (CARS) [14][15][16] and stimulated Raman scattering (SRS) [17][18][19] have been applied to microscopy. Since these nonlinear optical processes simultaneously take place, we are able to combine various multiphoton microscopic techniques [13,20].…”