We demonstrate a digital holographic system for the fast inspection of the interior of micro parts, which is capable of working in an industrial environment. We investigate micro objects using Two-Wavelength-Contouring with a synthetic wavelength of approximately 90 μm. Special consideration is given to the mechanical robustness of the system. A compact Michelson-setup in front of the imaging optics increases the robustness for the measurement as the light paths of the object and reference have almost a common path. We also implement the Two-Frame Phase Shifting method for the recording of a complex wavefield. The use of two cameras for different polarized states for the object- and reference wave allows the recording of a complex wavefield in a single exposure per wavelength. The setup allows determining the shape of the interior surface of the object and faults such as scratches with a measurement uncertainty of approximately 5 μm.
Aleksandar Simic, Hendrik Freiheit, Mostafa Agour, Claas Falldorf, and Ralf B. Bergmann, "In-line quality control of micro parts using digital holography," Proc. SPIE 10233, Holography: Advances and Modern Trends V, 1023311 (Presented at SPIE Optics + Optoelectronics: April 26, 2017; Published: 15 May 2017); https://doi.org/10.1117/12.2265780.
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