With the improvement of the performance of electro-optical sensors and computer performance, lensless digital in-lineholography has been studied and applied widely. However, the resolution of the digital in-line holography system arelimited by pixel size and influenced by the twin image. To solve the problem, we proposed a resolution enhancementmethod, which collects two holograms with different sample-to-sensor distance. The reconstruction is based onGerchberg–Saxton iteration algorithm, using two normalized and interpolated holograms. We used two prior constraintsin the iteration process according to the iteration algorithm for phase retrieval: intensity of the two normalized hologramsand the non-negative absorption of the sample. In this method, the interpolation operation before phase retrieval candigitally reduce the sampling interval, and the interpolation point will be optimized with the iteration process. Wesimulated the resolution enhancement method, and the results of the simulation show that the resolution and imagequality of lensless digital in-line holography can be effectively improved.
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