Device and method for measuring six degrees of freedom

A method of measuring orientation of a target, the method comprising:

• providing a tracking unit and the target, the tracking unit structured to emit a first laser beam and a second laser beam, the second laser beam shaped into a two-dimensional pattern, the target including a target structure, a retroreflector, and a position sensor assembly, the retroreflector and the position sensor assembly rigidly affixed to the target structure, wherein, for the case in which the retroreflector is positioned so as to retroreflect the first laser beam to the tracking unit, the position sensor assembly is disposed on a plane that lies between the tracking unit and a vertex of the retroreflector;
• illuminating the target with the first laser beam and the second laser beam;
• tracking a movement of the retroreflector with the first laser beam;
• recording a position of the two-dimensional pattern on the position sensor assembly to create a measured signature value of the two-dimensional pattern on the position sensor assembly;
• iteratively comparing the measured signature value with a theoretical signature value;
• and
• calculating three orientation angles of the target from the measured signature value when a difference between the measured signature value and the theoretical signature value satisfies convergence criteria.