Abstract: Interferometric testing of technical, optically rough surfaces is disturbed by high contrast speckle noise. Grazing incidence interferometry is an appropriate tool to increase the effective illuminating wavelength. This leads to dramatically reduced speckle noise. Increasing of the wavelength from the visible region to the infrared is another opportunity to diminish speckle. An IR-interferometric combining both methods is presented. The advantage of the IR-interferometer compared to the VIS-interferometer is the reduced anamorphotic distortion of the image, which increases the resolution in the z-direction of the cylinder and enables the measurement of rougher surfaces. The interferometric set-up consists of two diffractive axicons with the test piece in between. The axicons serve as references for the cylindrical test samples and as beam splitters and combiners. The plane wave of the 0- th diffraction order is the reference beam whereas the conical wave of the first order is deflected onto the object. After reflection from the cylindrical test sample the first order contains wavefront deformations due to deviations of the test sample from cylindricity. After recombination of the object and the reference beam by the second axicon a low frequency interference pattern is detected by a high resolution PtSi focal plane array. The surface deviations can be reconstructed with the methods of phase shift interferometry. !7
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