In-line digital holographic microscopy based on intensity measurements at two planes

We propose a new approach of in-line digital holographic microscopy (DHM) with the capability of enhancing the hologram acquisition rate together with improved reconstruction capability. The method is based on the recording of two interferograms of the same object at slightly different planes. The technique utilizes the full spatial bandwidth of the camera and do not require phase-shifting of the reference beam. Furthermore, we exploit the method of subtraction of average intensity of the entire hologram to suppress the zero-order diffracted wave. The twin image is eliminated by Fourier domain processing of the two recorded holograms. Experimental results of both amplitude and phase objects demonstrate the feasibility of this method. Since the two interferograms can be recorded simultaneously by using two CCD or CMOS sensors, this new in-line DHM technique has the potential applications in biomedical research for the visualization of rapid dynamic processes at cellular level.