Using coherent anti-Stokes Raman scattering (CARS) to image brain tissues

We present our findings on using coherent anti-Stokes Raman scattering (CARS) microscopy to image brain tissue slices. Compared with other modalities such as confocal and two-photon laser scanning microscopy, CARS microscopy offers chemical selectivity with high sensitivity without the need for any labeling agents. CARS microscopy uses two laser frequencies, whose energy difference is tuned to target a specific molecular vibration. This creates a vibrational coherence that, when probed, can give rise to a substantial chemically-selective signal. CARS overcomes the drawback of weak inelastic scattering of conventional Raman spectroscopy. As a modality that uses the intrinsic chemical selectivity to image specimen, CARS avoids the photobleaching problem and perturbations to cell functions induced by fluorescent proteins. It can acquire three-dimensional images with high resolution, in addition to the high sensitivity and chemical selectivity. In this work, we demonstrate the performance of using CARS to acquire images of mouse brain tissues and compare it with standard histology images.