Lensless in-line holographic microscope resolution enhancement method from two intensity measurements based on data interpolation

Abstract

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