3D optical scanners are rapidly replacing Cartesian CMMs due to their advanced metrological benefits, such as dense 3D point cloud data capture, portability and measurement speed. To support 3D optical scanner manufacturers and end-users, the National Physical Laboratory (NPL, UK) has developed a 3D optical scanner dimensional characterisation facility, which comprises: test artefacts, test procedures and equipment to examine the performance of 3D optical scanners. One of the facility's tests characterises scanner ability to measure surface finishes common to precision engineering. The test utilises a multi-faceted test artefact, to allow measurement of the test materials against highly Lambertian reference coupons through a series of fixed angles. Sample surfaces representative of materials typical of precision components manufactured by the aerospace, automotive and power generation industries were measured. Results for a white light fringe projecting 3D optical scanner show sensitivity to certain aluminium finishes and specular surfaces. Measurements of sandpaper samples suggest a trend of increasing point cloud density with decreasing surface roughness. Colour measurements show sensitivity to blue and green surfaces, while maximum point cloud density is measured for other coloured surfaces.
展开▼
