A compact digital holographic system based on a multifunctional holographic optical element with improved resolution and field of view

Abstract

The spatial resolution and field of view (FOV) of the digital holographic system are limited by the finite pixel size of the image sensor. In order to record high-resolution digital holograms of larger objects at a shorter object-to-sensor distance, which is desirable for applications such as display, non-destructive testing, etc., the holographic system must have a larger FOV. We propose a compact off-axis digital holographic setup in which a multifunctional holographic optical element (MHOE) is employed in the path of the object and reference beams to improve the system's resolution simultaneously enhancing the FOV by utilizing the same specifications of the digital sensor. In this configuration, a diffractive optics property of the MHOE enhances the spatial resolution of the optical system. At the same time, the lens function recorded in the same MHOE enables a large imaging area. The experimental results obtained with the proposed configuration are compared to conventional digital holography, where the proposed configuration shows a 423% increase in the FOV. The quality of the reconstructed image with the proposed configuration is measured by calculating the structural similarity index measure (SSIM) value. Experimental results and simulations have verified the feasibility of the proposed system. Furthermore, the proposed system is incredibly compact due to the use of the MHOE.