Universität Stuttgart
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Item Open Access Photothermal interferometry for nondestructive subsurface defect detection(1986) Sodnik, Zoran; Tiziani, Hans J.A symmetrical interferometer as thermal expansion detector was developed for photothermal nondestructive material analysis. Phase and amplitude exchange phenomena have been observed, when introducing an electronic reference phase shifter mixed to the interferometer signal. Experimental and theoretical results obtained with this system are presented.Item Open Access Dual wavelength heterodyne interferometry for rough surface measurements(1990) Fischer, Edgar; Sodnik, Zoran; Ittner, Thomas; Tiziani, Hans J.For interferometric topography measurements of optically rough surfaces dual wavelength heterodyne Interferometry (DWHI) is a powerful tool. A DWHI system based on a two-wavelength HeNe laser and a matched grating technique is described. This set-up improves system stability and simple heterodyne frequency generation.Item Open Access Remote nondestructive material analysis by photothermal interferometry(1987) Sodnik, Zoran; Tiziani, Hans J.Interferometry is used for the detection of thermal waves to study material properties. A symmetrical interferometer as thermal expansion detector was developed for photothermal nondestructive material analysis. After mixing a phase shifted reference signal electrically to the interferometer signal, phase and amplitude exchange phenomena have been observed.Item Open Access Nondestructive evaluation of solids by photothermal interferometry on nonreflective surfaces(1988) Sodnik, Zoran; Tiziani, Hans J.Thermal expansion interferometry is a simple and very sensitive tool for nondestructive material analysis. In its basic form highly reflective surfaces are needed however. We developed a modified experimental set-up that can be used on any surface and found a theoretical description in good agreement with the results.