US 91972604 A description fig1 shows a schematic of a cube corner assembly 18 comprising a cylindrical base 10 to which are bonded three separate prism segments 39 12 14 and 16 cube corner assembly 18 is of the type described for example by e schmidtlin u201c wide angle open faced retroreflectors for optical metrology u201d photonics tech briefs 23 3 pp 15a u2013 16a 3 1999 cube corner assembly 18 is representative of the type of complex precision optical assembly the present invention is particularly adapted to measure and facilitate its assembly an embodiment of the present invention is shown fig2 a which is a diagrammatic elevational view showing a cube corner assembly 18 located on precision rotary table 26 adjusted so that the center of the cylindrical base 10 is on the axis of rotation of the rotary table 26 an optical system 20 for measuring absolute distance to orientation of and shape of the surfaces of the cube corner 18 is also shown optical system 20 includes an optical interferometer system which is under the control of a suitably programmed computer 13 preferably equipped with a graphical user interface gui for interacting with system performing data processing transferring instructions displaying results storing and formatting data and performing general housekeeping functions computer 13 is also adapted in a well known manner to provide precise control of rotary table 26 and receive feedback information indicating the precise orientation and position of rotary table 26 at any instant in time those skilled in the art will recognize that rotary table 26 may alternatively be controlled by controller electronics located separate from computer 13 reference is now made to fig2 b which shows diagrammatic plan views of a reference transmission flat.