Euromedim 2006 :1st European Conference on Molecular Imaging Technology

Coherent Anti-Stokes Raman Scattering (CARS) Microscopy

12 May 2006, 12:00

15m

Palais du Pharo, Marseille

oral S9_S10 Molecular Imaging Molecular Imaging

Speaker

Mrs NADIA DJAKER (INSTITUT FRESNEL)

Description

Key words: Four-wave mixing, Coherent anti-Stokes Raman scattering (CARS) Microscopy, chemical imaging Coherent anti-Stokes Raman scattering microscopy (CARS) is a new approach for chemical imaging of molecular systems, with high sensitivity, high spatial resolution, and three dimensional sectioning capability, without using fluorophores that are prone to photobleaching. This technique permits to map selectively molecular species, by using vibrational properties of their chemical bounds. CARS is described by a four wave-mixing process, where the signal intensity depends nonlinearly on the incident intensities, and generated in a direction determined by the phase-matching condition. The CARS signal can be detected in both forward and backward directions [1]. The two signals provide complementary information about a sample: forward-detected CARS (F-CARS) microscopy is suitable for imaging objects of a size comparable to or larger than the excitation wavelength. Epi-detected CARS (E- CARS) microscopy provides a sensitive means of imaging objects having an axial length much smaller than the excitation wavelength because it avoids the large backgrounds from the solvent [2, 3, 4]. In this presentation, theoretical and experimental aspects of CARS microscopy in collinear excitation beam geometry are shown. Particular attention is given to the underlying physical principles behind the new features of CARS signal generation under tight focusing conditions. A brief overview of the instrumentation of CARS microscopy and its experimental characterization is provided by means of imaging of model systems and live unstained cells. References [1] A. Volkmer, J-X. Cheng, X.S. Xie, phys. Rev. Lett. 87, 23901 (2001). [2] J-X. Cheng, X.S. Xie, J. Phys. Chem B 108, 827 (2004). [3] J-X. Cheng, A. Volkmer, X.S. Xie, J. Opt. Soc Am. B 19, 1363 (2002). [4] N. Djaker, PF. Lenne, H. Rigneault, Proc. SPIE. 5463, 133 (2004).