Patent ID: 9329027
Filing Date: 2016-05-03
CPC Classification: G01B,G01S

Claim Text:
1. A measuring unit for determining a relative position and relative orientation between the measuring unit and an arrangement of at least three optical elements, the at least three optical elements being spaced apart from each other by known distances, the measuring unit comprising: a length measuring device comprising a length measuring head that emits measuring beams at at least three locations which are spaced apart from each other by known distances; at least one beam directing device comprising an adjustable optical element that directs the measuring beams onto the optical elements of the arrangement; and a control device to control the at least one beam directing device, the control device being operative to select the optical elements onto which the measuring beams are directed such that a solid angle defined by vectors between the locations at which the measuring beams are emitted and the optical elements onto which the measuring beams are directed is greater than a threshold; the at least one beam directing device being controllable to direct at least one of the measuring beams onto several optical elements of the arrangement in a time-sequential manner to perform plural length measuring operations in a time-sequential manner such that in the plural length measuring operations each measuring beam of the at least one measuring beam respectively impinges on only one of the optical elements; and wherein the length measuring head and the at least one beam directing device measure at least six lengths in total.