Optimization research for digital hologram recording system of big objects

A optical system using concave lens, which is used to image a big object preliminarily, is presented. This is an applicable method in digital holography detection. Digital holography reconstruction is studied according to inverse calculation of Collins' formula and setup optimization for digital hologram recording system is presented. Theoretical study implies that using concave lens can make the recording system more compact. Further more, in order to make the system be suitable for multi-wavelength illumination, the focal length of lens is modified according to wavelength of irradiation, and the setup optimization is performed so as to record hologram successfully with multi-wavelength illumination. To valid this method, several holograms are recorded under dual-wavelength illumination with the setup and object fields are reconstructed through focus modification.