Improved digital holographic reconstruction algorithm for depth error reduction and elimination of out-of-focus particles.

The digital holography has immense potential related to many applications of science and engineering. It has many advantages compared to conventional holography i.e. characterization of online dynamic phenomena and imaging in small scale microscopic systems. However, its primary limitation is the size of sensors and number of sensors compared to the conventional holographic plate. The critical issue of digital holography is the numerical reconstruction procedure. The present study proposes a new reconstruction algorithm known as 'Within Depth Intensity Averaging (WDIA)'. The effectiveness of the WDIA algorithm is demonstrated using both experiment and simulation for single particle, 2D and 3D distribution of particles. The 3D distribution of particles is experimentally simulated by using gelatin film on the glass slide. The particle images from digital holography compare well with that of microscopic images demonstrating the success of the proposed algorithm compared to the existing reconstruction procedure. The depth error significantly reduces (maximum 100%) and particles of any size can be characterized by the WDIA reconstruction algorithm contrary to the existing reconstruction algorithm available in literature. The effect of particle number density, particle size and sample volume depth on reconstruction effectiveness using the WDIA algorithm has been investigated and compared with the literature demonstrating its superiority in performance.