Direct Comparison of Hyperspectral Stimulated Raman Scattering and Coherent Anti-Stokes Raman Scattering Microscopy for Chemical Imaging

Frequency-Domain Low-Wavenumber Hyperspectral Stimulated Raman Scattering Microscopy

“…Details of the conventional frequency-domain hSRS microscope based on spectral focusing can be found in previous publications. − Modifications of the system to achieve low-wavenumber SRS detection are discussed in the Results and Discussion. To facilitate two-dimensional imaging in the low-wavenumber region, a translational stage (H101 and ProScan III, Prior Scientific) is used to enable one-dimensional sample scanning together with one-dimensional galvo mirror scanning.…”

“…Solid and liquid samples for hSRS imaging were prepared by sandwiching a small amount of sample between two thin glass coverslips with double-sided tape serving as the spacer. 41 A small drop of pure dimethyl sulfoxide (DMSO) or chloroform was sandwiched between the glass coverslips for spectral resolution measurements. A mixed sample of DMSO and chloroform, prepared via serial dilution to the desired ratio, was used to measure the concentration dependence of the SRS signal.…”

Coherent Raman scattering microscopy of lipid droplets in cells and tissues

“…Due to the interference of the nonresonant background, raw CARS spectra might show slightly broader peaks with redshifted peak centers. 101 Due to the higher order laser intensity dependence of the pump beam, the CARS image gives better spatial resolution compared with SRS under the same imaging condition. 101 Due to the position-dependent phase effect, small LDs above the focus usually have positive intensity, and those below the focus might have a shadowing effect showing as dark spots in CARS images.…”

“…101 Due to the higher order laser intensity dependence of the pump beam, the CARS image gives better spatial resolution compared with SRS under the same imaging condition. 101 Due to the position-dependent phase effect, small LDs above the focus usually have positive intensity, and those below the focus might have a shadowing effect showing as dark spots in CARS images. 42 In the epi direction, the interference of nonresonant background is alleviated for CARS with a sacrifice in signal intensity.…”

Coherent Raman Microscopy: From Instrumentation To Applications

“…Clark et al present a side-by-side comparison of hyperspectral SRS and CARS in terms of sensitivity, spatial resolution, and spectral resolution9 . Both techniques are implemented with spectral focusing of femtosecond lasers, a commonly employed approach that uses the spectrally chirped broadband femtosecond lasers to achieve narrowband Raman resolution.…”