Digital in-line holography reconstruction using plane and spherical wave fronts

C. RAMIREZ; C. IEMMI; J. CAMPOS

Santiago de Compostela

Congreso; ICO 23; 2014

International Commission for Optics

In digital holography, the interference and diffraction phenomenon of a wave front are recorded with aCCD detector and is stored in a computer. Next, the wave front can be numerically reconstructed usingan approximation of the diffraction equation. Although the resolution of the CDDs is improving, they arestill very far from the conventional holographic materials. Thus, the angle between the reference waveand the object wave must be small. In consequence, in the reconstruction step the non-diffracted order,the conjugate wave and the object wave are superimposed. In digital holography, most of the systems arebased in a Mach-Zehnder interferometer, where reference and object wave fronts travel by different paths.This makes the interferometer more sensible to vibrations, air flows, etc. Yamaguchi et al proposed asystem based on the phase-shifting interferometry (PSI) technique which is used to suppress the undesiredterms with an in-line configuration [1]. The Digital In-Line holography technique (DIL) is based on acommon path configuration, thus it is more robust and compact.DIL holography has been widely used for the detection of particle fields [2][3] in differentapplications. We study different illumination configurations in order to record digital holograms of smallparticles located in several planes in order to calculate its position and velocity.