3D metrology system based on a bi-directional OLED microdisplay

Abstract

Expanding demands on manufacturing technology increase the requirements on necessary non-contact metrology. Several optical metrology systems are based on separated imaging (e.g. camera unit) and image generating units (e.g. projection unit). This fact limits the geometrical miniaturization of the system. We present a compact, highly integrated 3-D metrology system based on the fringe projection principle using a bi-directional OLED microdisplay. The microdisplay combines light emitting pixels based on OLED technology (projection unit) and light detecting pixels based on photo diode technology (camera unit) on one single device, realized by the OLED-on-CMOS-technology. This technology provides the opportunity for a further miniaturization of optical metrology systems. The 3-D metrology system is based on fringe projection onto the surface of the measurement object. The fringes will appear deformed when observed from a dierent angle (triangulation angle). From the deformation of the fringes the 3-D coordinates of all visible points can be calculated and thus the object shape can be determined. For the application of an 3-D Sensor and due an internal display eect, separate lenses for projection and imaging are necessary. The system principle and several optical system congurations are discussed. Due to the application of the bi-directional OLED microdisplay the fringe generating elements and the detectors will be combined into one single device. Based on this integrated device an ultra-compact and solid system concept for 3-D surface metrology is practicable