In vivo coherent anti-Stokes Raman scattering imaging of sciatic nerve tissue

We report in vivo nonlinear optical imaging of mouse sciatic nerve tissue by epidetected coherent anti‐Stokes Raman scattering and second harmonic generation microscopy. Following a minimally invasive surgery to open the skin, coherent anti‐Stokes Raman scattering imaging of myelinated axons and second harmonic generation imaging of the surrounding collagen fibres were demonstrated with high signal‐to‐background ratio, three‐dimensional spatial resolution, and no need for labelling. The underlying contrast mechanisms of in vivo coherent anti‐Stokes Raman scattering were explored by three‐dimensional imaging of fat cells that surround the nerve. The epidetected coherent anti‐Stokes Raman scattering signals from the nerve tissues were found to arise from interfaces as well as back reflection of forward coherent anti‐Stokes Raman scattering.