The measuring projector combines the advantages of the measuring microscope with those of the profile projector.  On its ground screen, the image can be compared with a drawing just as quickly as with a profile projector.  Since it is equipped with scales along its coordinate axes, individual points can be probed with the reticle in the same manner as with the measuring microscope.  In the 1970s, Dr. Sigfriend Werth developed the “Tastauge” optical edge sensor – the first opto electronic sensor for measuring projectors designed to enable automatic probing of object points.  The Tastauge performed the same function normally performed by the human eye, but only for highly contrasted objects.  Introduced in 1980 and combined with a CNC control, this new sensor technology made it possible to automate optical coordinate measuring machines for the first time.  Interstingly, the measuring uncertainty of the machines built at that time was in the range of only a few micrometers.