Described are optical apparatuses and methods for forming optical apparatuses. The optical apparatus includes a plurality of individually fabricated segments and a holder. Each of the plurality of individually fabricated segments include an inner annular surface and an outer contact surface opposite to the inner annular surface. Each of the inner annular reflecting surfaces define a longitudinal segment axis. The holder contacts each of the outer contact surfaces of the plurality of individually fabricated segments. Each of the longitudinal segment axes of the plurality of individually fabricated segments are linearly aligned.