Noncontacting Measurement of Distortion by Digital Holographic Interferometry

Digital holographic interferometry is a coherent‐optical method for noncontacting measurement of full field deformations in the micrometer‐range. While deformations in the range of the wavelength of the used laser‐light are determined by comparison of the phases of the wave fields reconstructed from the recorded holograms, for larger deformations the form of the object surface has to be measured by a holographic interferometric contouring method, followed by numerical comparison of two such measured contours. Here we present such methods for determining the distortions of hot moving components leading to a concept for an in‐process distortion measurement enabling early interaction with e. g. the quenching process to control the resulting distortion.