Extended focused imaging in a holographic microscopy imaging system

In most optical imaging systems, a three-dimensional object lying within the depth-of-field (DOF) will produce a clear and sharp image, while the parts outside will become blurry. Therefore, especially in microscopy, increasing the DOF is highly desirable, which can be achieved computationally through extended focused imaging (EFI). To construct the EFI image, we first use a depth-from-focus algorithm to create a depth map for each pixel by calculating its entropy. Based on the depth map, we show how to achieve EFI in a holographic microscopy imaging system called optical scanning holography. Computational results on objects with multiple axial sections are presented to validate the proposed approach.