Figure 8
Phase unwrapping using multiple wavelengths. The sample consists of four grating lines carved into a glass substrate using focused ion beam milling. (a) Lens-free phase image obtained using a single wavelength; phase map is wrapped. (b) Unwrapped lens-free phase image obtained from a single wavelength reconstruction using a two-dimensional phase unwrapping technique based on minimum network flow36. (c) Unwrapped lens-free phase image obtained using reconstructions from multiple wavelengths. Eleven wavelengths are used within a scanning range of 501–531 nm and a scan step size of 3 nm. Refer to the Materials and Methods section for further details on multi-wavelength phase unwrapping. (d–f) Depth profiles of a–c, respectively. The blue dashed line in f is the depth profile of the sample gratings measured using an atomic force microscope (AFM).
