Abstract: We present a method for fast inspection of metallic micro parts. It is based on the combination of two-wavelength contouring and digital holographic microscopy (DHM). For fast evaluation, an autofocus algorithm to refocus the object digitally without the need for any external intervention is proposed. The method enhances the microscope objective’s depth of focus compared with imaging techniques by standard microscopy. Compared to standard DHM, an object side telecentric objective is utilized to overcome irreversible depth distortions caused by standard microscope objectives. The method is demonstrated by reconstructing the three- dimensional shape of a metallic deep drawn micro cup. Experimental results confirm the improved depth of focus of DHM.

Keywords: Digital holographic microscopy, Holographic contouring, Shape and deformation measurement, Depth of focus, Micro deep drawing parts.

_________________________________________________________________________________________