Abstract: Apparatus for precisely measuring the location of points on working media, such as a PCB, includes: a base panel having a surface area at least equal to that of the largest working medium to be measured, a reference mark, and a grid of fiducial marks each located at precisely-known locations with respect to the reference mark; a coarse positioning device movable over the base panel; a fine positioning device carried by and movable over the coarse positioning device; and a holder for holding a working medium substantially in contact with the base panel. The apparatus further includes first measuring means for measuring the location of a preselected point on the coarse positioning device with respect to a preselected fiducial mark of the base panel; and second measuring means carried by the fine positioning device for measuring the location of a point to be measured on the working medium with respect to the preselected point on the coarse positioning device.