An optical 3D shape and deformation measurement system for the analysis of dental biomaterials

Non-destructive analyses of biomaterials in prosthetic dentistry require sensitive measurement techniques for the determination of deformations. An optical 3D shape and deformation measurement system is presented, which combines Electronic Speckle Pattern Interferometry (ESPI) with Digital Speckle Photography (DSP) and photogrammetric 3D shape acquisition by digital image correlation of a projected laser speckle pattern. While ESPI is employed to measure deformations in the direction of the optical axis, DSP is used to determine deformations orthogonal to this axis. The photogrammetric 3D shape acquisition is applied to determine deformations that exceed the measurement range of ESPI and DSP. The system is validated by comparisons of acquired measurement data with results from finite element analysis. Various parameters of the measurement system, such as the average size of the projected speckles and the apertures of the cameras, are optimized with focus on simultaneous measurements with all three techniques.