Combination of a nano-coordinate measuring machine with a low coherent digital holographic microscopy sensor for large scale measurements

A variety of microscopy techniques allow measuring different local physical properties of a surface under test. One of the key properties of interest in production and development of micro- and nano components is a nanometer resolution even in a measurement range of a few centimeters. By integrating a low coherent digital holographic microscope (DHM) into a coordinate measuring machine with sub nanometer resolution and nanometer uncertainty, a DHM with an outstanding measuring range is realized which enables simultaneous investigation of form and roughness of specimens with sizes up to 25 mm×25 mm×5mm along the x, y and z-axes. Different modes of scanning strategies have been analyzed and error compensated for micro and nano structured optical components with a surface diameter up to 25mm. For calculation of the correlation and thus effective coherence length, which is used for analysis of the topography of the specimen, a comprehensive theoretical approach is demonstra ted and experimentally verified.