Using a digital holographic microscope setup, it is possible to measure dynamic volume changes in living cells. The cells were investigated time-dependently in transmission mode for different kinds of stimuli affecting their morphology. The measured phase shift was correlated to the cellular optical thickness, and then of the cell volume as well as the refractive index were calculated and interpreted. For the characterization of the digital holographic microscope setup, we have developed a transparent three-dimensional (3-D) reference chart that can be used as a lateral resolution chart and step-height resolution chart included in one substrate. For the monitoring of living cells, a biocompatible and autoclavable flow chamber was designed, which allows us to add, exchange, or dilute the fluid within the flow chamber. An integrated changeable coverslip enables inverse microscopic applications. Trypsinization, cell swelling and shrinking induced by osmolarity changes, and apoptosis served as model processes to elucidate the potential of the digital holographic microscopy (DHM).
We present a phase-shifting holographic set-up for the microscopic imaging of adherent cells. The superposition of an object wave field and a reference wave is recorded on a digital sensor with three reference wave phases. The reference phases are then recovered by statistical analysis of the recorded intensities. Subsequently, the object wave phase is calculated by the generalized phase shifting algorithm. After phase unwrapping and background subtraction, the phase shift introduced by the adherent cell culture is reconstructed. As the interferograms are recorded in the image plane of the microsope objective, the full lateral resolution is achieved in contrast to off-axis holography where the reconstruction requires numerical propagation for the separation of 0<sup>th</sup> and 1<sup>st</sup> order. Our approach uses three arbitrary unknown reference phases and poses thus minimum requirements on the mechanical and thermal stability of the set-up. We give preliminary results of images from a Vero cell line and pollen grains.
A novel 3d reconstruction method for medical application has been applied for the examination and documentation of a 2000-year-old bog body. An ultra-fast pulsed holographic camera has been modified to allow imaging of the bog body from different views. Full-scale daylight copies of the master holograms give a detailed impressive three-dimensional view of the mummy and can be exhibited instead of the object. In combination with a rapid prototyping model (built by the Rapid Prototyping group of the <i>Stiftung caesar</i>, Bonn, Germany) derived from computer tomography (CT) data our results are an ideal basis for a future facial reconstruction.
A method to measure precisely the 2D portrait of patients undergoing maxillofacial surgery based on holography is presented. We record holograms of patients with a pulsed Nd:YLF laser system on high resolution photographic glass plates. These images contain the 3D spatial information which, due to the extremely short recording time, is not affected at all by involuntary movements. The reconstructed real image of the hologram is sliced into a series of 2D projections by means of a screen. A first approach to reconstruct the patient's 3D surface information from the captured data set is presented.