  We show that optical beams with orbital angular momentum (OAM) can be
generated even with incomplete computer generated holograms (CGH). These
holograms are made such that random portions of it do not contain any
information. We observe that although the beams produced with these holograms
are less intense, these beams maintain their shape and that their topological
charges are not affected. Furthermore, we show that superposition of two or
more beams can be created using separate incomplete CGHs interspersed together.
Our result is significant especially since most method to generate beams with
OAM for various applications rely on pixelated devices or optical elements with
imperfections.
