is produced using a 1 2 u03bc rule the twenty arabic numerals shown in fig4 a are used as shown in fig4 b in order to secure a large pattern area use is made of arabic numeral characters here the numeral 3 is used for the purposes of the explanation which are upright and projecting in the first quadrant rotated through 90 u00b0 and projecting in the second quadrant upright and indented in the third quadrant and rotated through 90 u00b0 and indented in the fourth quadrant fig5 a shows a separate pattern example here the coordinate numerals are replaced by binary bits and this is illustrated by the method in which the rule shown in fig5 b has been taken as one example this pattern has the advantage that pattern recognition is easily performed by a central processing unit and at present it is possible to construct a pattern with an aperture of 640 u03bc due to the high data densities the optical microscope cross cursor is accurately aligned about u00b1 0 5 u03bc on the central lines of the pattern using 2 3 and 4 in the flow chart and the coordinates of the stage at this time x o and y o are memorized by the central processing unit following this the x stage is moved by the amount x l the set distance from the optical axis of the optical microscope to the center of the stm needle by operation 5 and then the z stage is conveyed to the tunnelling region at low speed in operation 6 the stm makes a single frame surface scan of a frame of 10 u00d7 12 u03bc and the stm image is.