Comparison of the reconstruction algorithms in digital micro-holography

To improve the quality of the reconstructed image, the common used three reconstruction algorithms in digital holographic microscopy, Fresnel transform algorithm, angular spectrum algorithm, and convolution algorithm, all based on fast-Fourier-transform (FFT) are investigated and compared. By using off-axis lensless Fourier setup the digital hologram of a USAF test target is recorded and reconstructed numerically with the three algorithms at different reconstruction distances. The results show that by Fresnel transform algorithm the lensless Fourier transform digital hologram can be reconstructed at any distances. For convolution and angular spectrum algorithms, there is an optimal reconstruction distance. For convolution algorithm, when the reconstruction distance is different from the optimal distance, the image resolution is decreased, particularly for small distance. When the reconstructing distance is slightly smaller and very larger than the optimal one the high quality image can also be obtained by using angular spectrum algorithm. Angular spectrum algorithm is better than convolution algorithm. The Fresnel transform algorithm is the optimal numerical reconstruction algorithm in digital holographic microscopy.