Patent ID: 8366011

Claim:
A target for association with an object for which at least one of strain and fatigue damage is to be measured, the target incorporating a matrix code symbol, the matrix code symbol emitting a detectable physical quantity and including: a Data Matrix symbol having: a two-dimensional matrix having a perimeter and containing dark and light square data modules, wherein data is encoded based on the absolute position of the dark modules within the matrix; and a finder pattern of two solid bars and two bars of alternating dark and light square data modules on the perimeter of the matrix for indicating both orientation and printing density of the symbol, wherein all of the dark and light data modules of the matrix are the same dimension, wherein the two solid bars are on one pair of adjacent sides of the perimeter of the matrix and the two bars of alternating dark and light data modules are on the opposite pair of adjacent sides of the perimeter of the matrix, and wherein the finder pattern defines the perimeter of the Data Matrix symbol; a solid inner bar outside the perimeter of the Data Matrix symbol, only adjacent each of the finder pattern bars of alternating dark and light data modules; and at least one outer bar positioned adjacent each inner bar, with each inner bar being interposed between the perimeter of the Data Matrix symbol and the at least one outer bar, wherein the at least one outer bar is configured to increase the accuracy of the use of the Data Matrix symbol; wherein the inner and outer bars each have a width equal to the square data modules.