Particle analysis with digital holography

The recording of holograms and the numerical reconstruction of the wave fields became possible with the development of high-resolution CCD-cameras and fast computers. This technique called Digital Holography is used for example in particle measurements and deformation analysis. Using an inline holography setup for particle measurements the particle distribution is calculated numerically from the recorded hologram. By varying the recording distance particles can be found in different depths of the analyzed volume. Using holographic film, the reconstruction process provides only the intensity of the recorded objects. With Digital Holography also the phase of the reconstructed object wave can be calculated. The question is whether the phase of the reconstructed optical field contains additional information compared to the intensity which can be used for example to find the depth coordinate with a much higher resolution. However the experiments show that the dimension of the recording system, the wavelength of the light used and the distance between object and recording system are still limiting factors for lateral and depth resolution. The presented paper gives an overview over phase reconstruction in particle analysis.