Influence of dark current to in-line digital holography

Abstract

Digital holographic particle image velocimetry (DHPIV) is a promising technique for the measurement of the instantaneous flow velocity within a volume of the flow. But some physical recording parameters (such as the wavelength, the particle size, the recording distance, etc.) and the characteristic parameters of the CCD camera (i.e. full factor, CCD size, pixel size, dark current level,etc.) will considerably affect the reconstructed result of the particle field. This paper gives the influence mode of the CCD camera’s dark current to digital holography, and detailedly discusses its influence to in-line digital holography, especially to the particle field holography. The numerical simulation indicates that there is no influence with homogeneous dark current distribution because it only acts as a proportional attenuator to reduce the incidence intensity on the CCD chip. But the influence will increase with increasing the amplitude and inhomogeneousness of the dark current level, especially for high particle concentration. At the same time, the paper gives the corresponding error evaluation of the reconstructed particle field under different dark current level.