The disclosed optical beam expander may include (1) a monolithic structure including (a) a first nonplanar mirror that receives a first collimated optical beam having a first width and reflects the first collimated optical beam to generate a noncollimated optical beam and (b) a second nonplanar mirror that receives a diverging optical beam and reflects the diverging optical beam to generate a second collimated optical beam having a second width greater than the first width, where the first nonplanar mirror and the second nonplanar mirror are fixed in orientation and position relative to each other and (2) a planar mirror that reflects the noncollimated optical beam from the first nonplanar mirror to provide the diverging optical beam to the second nonplanar mirror. Various other devices, systems, and methods are also disclosed.