Stuttgart 2012 – scientific programme

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MO: Fachverband Molekülphysik

MO 1: Vibrational Spectroscopy

MO 1.4: Talk

Monday, March 12, 2012, 11:30–11:45, V38.03

Quantitative data analysis in hyperspectral CARS imaging — •Gregor Hehl¹, Alexander Kovalev², and Andreas Volkmer¹ — ¹3. Physikalisches Institut, Universität Stuttgart — ²Department of Zoology, Christian-Albrechts-Universität Kiel

Hyperspectral coherent anti-Stokes Raman scattering (CARS) imaging, the combination of spectrally and spatially resolved CARS detection, offers access to the full wealth of chemical and physical structure information encoded in vibrational signatures of chemical species on the sub-micron length-scale. Because of the coherent nature of the CARS process, a complex spectrum of the third-order nonlinear susceptibility is probed. However, the actual measurement of the CARS spectrum yields its power spectrum. In order to reconstruct the linear Raman response of the sample a spectral phase retrieval is necessary. Two different methods for the qualitative phase-retrieval have been proposed, that is the maximum entropy method (MEM) and the Kramers-Kronig transform. In this work, we demonstrate the full quantitative reconstruction of Raman responses of skin model lipids based on MEM. We show that identical information is obtained from CARS and spontaneous Raman spectra provided that the full coherent nature of the CARS experiment is taken into account. The proposed analysis scheme for hyperspectral CARS data allows fast chemical imaging of living cells and tissues in a label-free and fully quantitative manner.