Visualization 2: Refractive index variance of cells and tissues measured by quantitative phase imaging Mingguang Shan Mikhail E. Kandel Gabriel Popescu 10.1364/OE.25.001573.v002 https://opticapublishing.figshare.com/articles/media/Visualization_2_Refractive_index_variance_of_cells_and_tissues_measured_by_quantitative_phase_imaging/4951199 The phase second order derivative along x of the data in Video 1. The color bar indicates phase in units of (rad/µm)^2, as explained in the Fig. 2c caption. Originally published in Optics Express on 23 January 2017 (oe-25-2-1573) 2017-01-23 00:00:00 23 January 2017 Optics Express Video 1. color bar 2 c caption phase imaging