Fig. 1. Schematic diagram of a coherent diffraction microscope with two lasers at 543 (green) and 432 nm (blue) in the same orientation.

Fig. 2. Optical image of double-layered silica spheres on a 30 nm thick Si3N4 membrane. The silica spheres were arranged in the form of (a) “C” and (b) “T” (b) on two sides of the membrane. The yellow arrows indicate spheres on the other side of the membrane. Scale bar, 10 μm.

Fig. 3. Experimental 2D diffraction patterns of the double-layered sample measured with the (a) green and (b) blue lasers. (c,d) The low spatial frequency regions of diffraction patterns (a,b) show that the missing intensity data are confined within the central speckles.

Fig. 4. Front view of the oversampled diffraction patterns on the Ewald spheres with the (a) blue and (b) green lasers. (c) The spherical diffraction patterns for two input wavelengths on a 3D Cartesian grid. (d) A schematic of the cross section of the diffraction patterns projected on the Ewald spheres for the green and blue lasers.

Fig. 5. (a,b) 3D image (amplitude and phase) of the double-layered sample reconstructed from the diffraction patterns shown in Fig. 3. The central reconstructed slices of the spheres in (c) the front “C” and (d) back “T” layers. The blue dashed circles indicate the regions with a relatively low intensity due to the overlapped area of the two spheres perpendicular to beam direction.