Fig. 4
Phase image series collected with three fringe spacings: (1) s \(=\) 2.4 nm, (2) s \(=\) 2.1 nm, and (3) s \(=\) 1.7 nm. a, d, and g Reference-measurement images with long exposure time ta of 15 s for (1), (2), and (3), respectively. b, e, and h Original phase images, labelled “Noised,” with ta of 3 s for (1), (2), and (3), respectively. c, f, and i Phase images, labelled “Denoised,” after the application of the noise reduction to (b), (e), and (h), respectively. j, k, and l Plots of the phase shift measured along the R–S line in (a)–(c), (d)–(f), and (g)–(i), respectively. Black, blue, and red plots in (j)–(l) indicate the results from reference-measurement image [from (a), (d), and (g)], noised image [from (b), (e), and (h)], and denoised image [from (c), (f), and (i)], respectively