Information processing in digital holographic imaging and measurement

According to Fresnel diffraction theory, the principles of imaging and shape measurement are analyzed concisely. The model of phase aberration in numerical reconstruction is built. The zero-order diffraction and unwanted first-order image can be removed by using frequency filtering. Based on lensless Fourier transform digital holographic setup, the experiment is conducted by using a US Air Force test target as microscopic object. The accurate phase image is obtained by combining the automatic procedure for phase aberration compensation with manual adjustment of reconstructing parameters. The lateral resolution of the intensity image of 3.10mum without any pre-magnification is demonstrated experimentally, and higher resolution of phase image has been achieved. The results show that in the case of strong noise, the inexact reconstruction parameters can be gained only by the automatic procedure. In order to obtain the accurate phase information, the finer manual adjustment is necessary subsequently. It is the committed step that recording high quality digital hologram in digital holography.