Abstract: A non-linear strain gage includes a target for association with an object for which at least one of strain and fatigue damage is to be measured, a sensor, and a computer. The target incorporates a nested binary code symbol for perimeter-based deformation and strain analysis and emits a detectable physical quantity. The binary code symbol includes a boundary binary code symbol having a perimeter constructed of line segments and at least a core code symbol that provides encoded data. The core code symbol is nested within and concentric with the boundary binary code symbol. A method of measuring strain on an object directly using the non-linear strain gage is also provided.