Computational micro-imaging

We present results of computational imaging in case of a digital inline holographic lens-free microscope. The set-up consists of a laser diode, a micro-fluidic channel for sample guiding and an imaging sensor (CCD). We present new videos of living human white blood cells. The interference pattern of object wave with a references wave is detected directly and the image reconstruction (phase contrast image) is done by a computer (NA up to 0.85). The interference pattern of all objects in a 3D-volume is detected by one exposure. Objects located in different heights can be imaged by numerical focusing to the different z-planes done by a computer. Typically a lens-based set-up has a small and fixed working distance. For the presented micro-imaging the distance between sample and detector can vary between 1 mm and 20 mm. This function of a long distance zoom lens is reached by the computer. A lens is normally corrected for one special sample covering (cover glass). In digital holographic micro-imaging the thickness of glass sample carriers and coverings is corrected numerically and can vary between 1 to 6 mm. Furthermore a numerical auto calibration is incorporated.