Proceedings PaperCoded Hadamard Hartmann Sensor
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The Hartmann test to measure wavefronts is much more powerful than generally assumed. Its results need not to be worse than interferometric methods. Various authors have already demonstrated this fact and also our own work points in that direction. Here we would present an extension of the Hartmann test that increases its performance at low light levels. The traditional Hartmann test scans the aperture of the wave or lens to be measured with a single hole in an opaque screen. It is equally well possible to use a complete set of screens with any number of holes. By adequately adding the measurement results for each of the screens the contribution of each of the holes can be extracted. Thus the wave front can be reconstructed. The advantage of this method is a significant increase in signal to noise ratio provided the noise is signal independent.