01177nas a2200109   4500008004100000245006700041210006600108300001800174490000700192520080300199856006501002       2019                        eng d00aLabel-free CARS microscopy through a multimode fiber endoscope0 aLabelfree CARS microscopy through a multimode fiber endoscope  a30055–300660 v273 a<p>Multimode fibres have recently been employed as high-resolution ultra-thin endoscopes, capable of imaging biological structures deep inside tissue in vivo. Here, we extend this technique to label-free non-linear microscopy with chemical contrast using coherent anti-Stokes Raman scattering (CARS) through a multimode fibre endoscope, which opens up new avenues for instant and in-situ diagnosis of potentially malignant tissue. We use a commercial 125 &amp;\#x00B5;m diameter, 0.29 NA GRIN fibre, and wavefront shaping on an SLM is used to create foci that are scanned behind the fibre facet across the sample. The chemical selectivity is demonstrated by imaging 2 &amp;\#x00B5;m polystyrene and 2.5 &amp;\#x00B5;m PMMA beads with per pixel integration time as low as 1 ms for epi-detection.</p>  uhttp://www.opticsexpress.org/abstract.cfm?URI=oe-27-21-30055