Compact optical to follow the path of a tool along a line of travel on a workpiece

THIS UNIT TO MONITOR OPTICAL RACE TOOL 20 ALONG A LINE MOVEMENT ON A WORKPIECE 26 INCLUDES LIGHT SOURCE 32 TO PROVIDE LIGHT RAYS BEAM PARALLEL 33 SOURCE 32 LIGHT BEING mOUNTED ON TOOL 20 SO aDJACENT TO THE TOOL REAR 20; A REFLECTOR 34 POSITIONED PARALLEL THINKING AT LEAST PART OF PARALLEL RAYS OF LIGHT BEAM 33 LEADS ON LINE MOVEMENT OF THE TOOL 20 SO THAT THE LIGHT OF PARTING IS ESSENTIALLY 31 PROJECTED CUT IN TWO BY LINE MOVEMENT ; CAMERA AND 42 WITH OPTIONAL FILTER 60 SELF-CORRELATION ESTABLISHING AN IMAGE PARTING 31 PROJECTED LIGHT ON WORKPIECE 26 EVEN IF THE TOOL IS 20 FOR EXAMPLE WELDING MACHINE CONTINUOUS SEALS PRODUCT THAT SPARKS THE VISUAL FIELD THROUGH THE CAMERA 42.