Fig. 3.

Diffraction patterns of the exit waves from the two defined objects, cell A and cell B, and their azimuthally averaged, unit-integral-normalized power spectral densities. In both cases the exit wave amplitudes were Fourier transformed and then squared to yield the diffraction intensity. Both defined objects have the signal decline with spatial frequency in a power law relationship with a slope of about 3.3 over most frequencies. For cell A, this trend then levels off at a spatial frequency of about 10 µm⁻¹ where the pixel-by-pixel uncorrelated protein thickness dominate the diffraction pattern; this yields a flat power spectrum corresponding to a delta (δ) function in real space. For cell B, the overall round shape of the object gives rise to Airy rings in the diffraction pattern which show up at spatial frequencies above 10 µm⁻¹.