LIGHT SECTIONING WITH IMPROVED DEPTH RESOLUTION

Light sectioning of an object surface uses the line deformation imaged by a CCD camera to compute the object profile. Because of the low opt ical magnification between the object and the CCD image plane, the mea sured CCD line deformation is small and leads to low resolution in pro file measurements. To obtain larger CCD line deformation without decre asing the field of view, we propose to use an additional cylindrical l ens to magnify only the horizontal deformation (which contains the pro file information) without modifying the vertical field of view. The li mitations of this anamorphic system, such as maximum object depth and magnification, are theoretically determined. The improvements given by the cylindrical lens are calculated, and experimental profiles (pyram id, cylinder) show a gain in depth resolution of approximately 2 to 3 over an earlier light sectioning system. The depth resolution, which w as 0.36 mm with the previous system, is now improved to 0.15 mm for an average object distance of 350 mm.