reflective however not every part of the surface is necessarily reflective the parts that are reflective reflect almost all of the light e g greater than 90 of the incident light and preferably greater than 95 of the light the reflective light from the surfaces 130 is received by an imager 140 via a pupil 145 in one embodiment the pupil is a simple opening in another embodiment the pupil is a transmissive object that allows light to pass through it although the transmissive object may bend the light the reflective surface 130 includes regions 132 e g sections that are flat in at least one direction with steps 136 between the regions 132 these regions reflect the light form the sources 110 to the pupil 145 as shown the regions 132 are flat in a direction from right to left in other words a cross section of the surface 130 in a plane that is perpendicular to the pupil has regions that are flat as user herein the term u201c flat u201d means that as one moves in a particular direction along the surface in the region a direction of the movement does not change e g curve up or down on a macroscopic scale i e larger.