“…On the contrary, the Zernike phase contrast microscopy (ZPCM) [12] does not require staining, yet suffers from the halo effect [13], object size inaccuracy, and a narrow field of view. Recently, dramatic progress has taken place in staining-free imaging in the burgeoning field of quantitative phase-contrast microscopy [3,4,[14][15][16][17], such as by differential interference microscopy [18][19][20], digital holographic microscopy [5,[21][22][23][24], and holographic interference microscopy [25,26].…”