M.P.and J.K.acknowledge funding from the Leibniz Science Campus Infecto Optics(Whole Blood Imaging project SAS-2015)and the DFG,projects SCHM2655/8-1 and SCHM2655/15-1.R.F.acknowledges financial support from the VW foundation.H.R.and S.A.M.acknowledge support from the Alexander-von-Humboldt Foundation and the Lee-Lucas Chair in Physics.M.P.,R.F.,and M.A.S.thank R.Heintzmann for important comments on the fibre design and J.Rüger,I.Leite and S.Turtaev for lending equipment and technical assistance with the focal scan measurement.The authors also thank R.Fatobene Ando for visual implementation of Fig.1a and J.Dellith for help with SEM imaging. （Whole Blood Imaging project SAS-2015）