Micro-testing by ultra-sensitive imaging

An unconventional imaging technique based on synthetic apertures was presented on the 107. Jahrestagung of the DGaO (Poceedings, A25). For lensless holographic microscopy commonly the coherent illumination of a sample by a pinhole is used. We replaced the pinhole by a pinhole-array. - The photon flux is increased by the number of pinholes (up to 16 pinholes are used). - The interference pattern generated by a multi pinhole source is very intensive. - It becomes possible to use larger pinholes with increased throughput (typical are diameters of 2 µm). Simultaneously the numerical detection aperture can be increased by coherent multi-spot source. The array-illumination enables an increase of the detection sensitivity with a CCD by a factor of more than 100 … 1000. The technique is applied on imaging of calibration standards in sub-µm and µm ranges. Bright field and phase contrast images can be derived from the measured intensity pattern simultaneously.