text: referring now to fig1 and 2 , a mirror 1 is pivoted about axis 0 -- 0 on trunnion bearings 15 . connected to the mirror 1 and forming a normal to the mirror is rod 2 . links 3 , 4 , and 5 , along with fixed length from point 6 to point 7 form a rhombic parallelogram 6 , 7 , 16 , 11 , with point 7 lying on axis 0 -- 0 . axis 7 - 16 lies in the plane of links 3 and 8 . the rod 2 passes through a slider bearing 11 . bearing 11 is located at the vertex of the parallelogram opposite the vertex 7 . rod 2 is a diagonal in the parallelogram . rod 2 bisects the angle formed by side 6 - 7 and side 7 - 16 of the parallelogram ; the parallelogram angle formed by sides 6 - 11 and 11 - 16 is also bisected by rod 2 . a central ray 13 of a beam forms angle θ with mirror normal 12 and is reflected by mirror 1 . the reflected ray 14 forms angle θ with normal 12 . normal 12 is the angle bisector of the angle 2 θ between 13 and 14 . if ray 13 is coincident with axis 6 - 7 , angle θ will be equal to angle φ between axis 6 - 7 and rod 2 . likewise angle θ between reflected ray 14 and normal 12 will be equal to angle φ between axis 7 - 6 and rod 2 . ray 14 is then coincident with axis 7 - 16 . the relationship of each corresponding angle remains true for all possible angles of reflection . axis 6 - 7 is the analog of normal 12 , all on the reverse side of mirror 1 . in the constructional form illustrated in fig1 a beam may be directed to the desired target by positioning the device such that axis 6 - 7 is coincident with the beam axis , and the axis 7 - 16 is coincident with the axis to the target . the directing of the beam is strictly a mechanical function independent of the presence of such beam and may be accomplished by boresighting , mechanical connection , or similar means , along the particular axis . the device may be utilized to direct a beam from a variable source to a fixed target by positioning the device such that axis 6 - 7 is coincident with the axis to the target , and positioning axis 7 - 16 to be coincident with the axis of the beam . the device may be utilized to direct a beam from a variable source to a variable target by maintaining particular axis alignment . although only the preferred embodiment of devices for carrying out the invention have been described above , it is not to be construed that my invention is limited to such embodiments . other modifications may be made by those skilled in the art without departing from the spirit and scope of the invention defined below .