It should be recognized that the XY stage 11 may be of any conventional form as long as it may be driven in some manner by the motors l2 and I3 respectively, and mechanically designed to provide sufficient servo response (i.e. taking into ac count such factors as stiffness, backlash, lead, inertia, resonance. etc.) i In the first embodiment of the tool 10, as shown in FIG. 4, very minute positioni