a Simultaneous two-colour CARS imaging with real-time nonresonant background subtraction from a mouse tissue sample at a surface depth of 45 μm. a i CARS image acquired at 2940 cm−1 (CH3 stretching vibration). a ii Off-resonance background CARS image at 2770 cm−1. a iii Background-free image of (i) at 2940 cm-1 after subtraction of the nonresonant background (ii). b Multi-lamellar lipid vesicle (MLV) imaged with conventional (i) and symmetry-resolved CARS (SR-CARS) at 1133 cm-1 (ii) and (iii). ii The incident circularly polarised pump, Stokes, probe and anti-Stokes light have co-rotating handedness (mF = 0). iii the incident circularly polarised pump, probe and anti-Stokes light have co-rotating handedness and the Stokes light has counter rotating handedness (mF = 2). c High-speed polarisation-resolved CARS image sequence on a MLV moving over the sample surface taken at different times of the observation sequence shown as a composite image of S2 and φ2 as coloured sticks and with the acousto-optic modulation (AOM) as a grey background. a reproduced with permission from the OSA . b Adapted from  and licenced under CC BY 4.0. c reproduced with permission from the OSA .