Noninvasive object imaging with single-shot low-resolution speckle pattern through strongly-scattering turbid layers

Noninvasive object imaging through strongly-scattering turbid layers has attracted the attention of many experts due to the potential application in the biomedical imaging and bioscience. The traditional speckle correlation method with Gerchberg-Saxton (GS) algorithm is used to restore object in a single-shot speckle pattern. However, this method suffers from the problems of convergence to local minimums, many iterations and cannot determine the object direction, due to the randomly assign initial value to GS algorithm. Bispectrum analysis method enables the directional Fourier phase retrieved using single-shot speckle pattern, but there are the problems of requiring high-resolution speckle pattern, low SNR and selecting the size of filter window. Therefore, we report an effective noninvasive imaging method through strongly-scattering turbid layers on the basis of bispectrum analysis and GS algorithm to restore the object in a low-resolution speckle pattern. Meanwhile, the new expression of Gaussian filter function is introduced contribute to determine the window size of filter in the processes of bispectrum analysis. In this proposed approach, the window size of filter is determined by the adjust factor according to the new form of Gaussian filter function, and the initial Fourier phase with directional information is generated by bispectrum analysis in a low-resolution speckle pattern. Then the initial Fourier phase is used as the randomly assign initial value to retrieve Fourier phase of object. Hence, the proposed method required no high-resolution, multiple iterations, nor randomly assign initial values to restore directional object. This work carries out simulations and experiments to demonstrates noninvasive object imaging in the low-resolution speckle pattern through strongly-scattering turbid layers.