When an optically rough surface is illuminated by the coherent light, we can only capture speckle pattern due to random constructive and destructive interference between light waves scattered from elementary areas of the rough surface. Here we compare two different correlography-based speckle imaging models, the results demonstrate that there is no obvious difference in imaging capabilities between two models. The spatial light propagation processes are both assumed to be far-filed Fraunhofer diffraction in two models. In order to verify the far-field distance, we capture speckle patterns in different imaging distance (range from 5cm to 100cm). We found that the far-field diffraction is always applicable in our experiments if the speckle size satisfies the Nyquist criterion, and we analyzed the relationship between speckle contrast and imaging distance, the curve of the relationship between reconstructed image size and imaging distance is fitted, the physical interpretation of the function parameters is given.
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