  Fraunhofer diffraction is a well-known phenomenon achieved with most
wavelength even without lens. A single-shot intensity measurement of
diffraction is generally considered inadequate to reconstruct the original
light field, because the lost phase part is indispensable for reverse
transformation. Phase retrieval is usually conducted in two means: priori
knowledge or multiple different measurements. However, priori knowledge works
for certain type of object while multiple measurements are difficult for short
wavelength. Here, by introducing non-orthogonal measurement via high density
sampling scheme, we demonstrate that one single-shot Fraunhofer diffraction
pattern of complex object is sufficient for phase retrieval. Both simulation
and experimental results have demonstrated the feasibility of our scheme.
Reconstruction of complex object reveals depth information or refraction index;
and single-shot measurement can be achieved under most scenario. Their
combination will broaden the application field of coherent diffraction imaging.
