Double-wavelength recording used in a pulsed digital micro-holographic system to record ultra-fast processing of the order of femto-second is reported for the first time, where a BBO crystal is used to generate harmonic wave of the incident laser wave, and both of the basic and the frequency doubled waves are time-delayed and introduced to a Michelson＇s interferometer to record two sub-holograms with different spatial frequencies on a single frame of a CCD. In the experiment, an ultrafast dynamic process of air ionization induced by a single femto-second laser pulse is recorded with holography by this system, and both of intensity and phase difference images digitally reconstructed are obtained through Fourier transformation and digital faltering, which show clearly the dynamic process of formation and propagation of the plasma, with a time resolution of the order of femto-second.
In this paper,a digital holography system with short-coherence light source is used to record a series of holograms of a micro-object.The three dimensional reconstruction is completed by the least-square-polynomial-fitting with a series of two dimensional intensity images which are obtained through holographic reconstruction.This three dimensional reconstruction method can be used to carry out three-dimensional reconstruction of a micro-object with strong laser speckle noise,which can not be obtained from the conventional method.
