The inspection of technical surfaces is often performed by two-wavelength electronic speckle-pattern interferometry (ESPI) combined with a phase-shifting procedure. As in conventional specular interferometry, the characteristic fringe spacing in the generated interferogram is defined by the applied wavelengths and the sensitivity is therefore constant in one fringe pattern. Subsequently, this technique is limited to surface structures with similar phase gradients and low structural density. To measure more complex structures, a high-resolution generated reference wavefront (HRGW) is adapted to the measurement object for local sensitivity adaption. The feasibility of this principle is directly linked to the functionality of the used spatial light modulator (SLM). A key factor of a proper phase-control is the structural setup of the SLM. In this article, the general influence of the microstructure of SLMs in adaptive ESPI is evaluated.
Conference Committee Involvement (4)
Automated Visual Inspection and Machine Vision III