In some implementations, an optical assembly includes an optical power monitor to receive a portion of an optical beam and to perform a measurement on the portion of the optical beam; an optical tap to tap the optical beam and provide the portion of the optical beam; and an optical element to allow the portion of the optical beam from the optical tap to propagate toward the optical power monitor, wherein the optical element includes an absorptive material to absorb light other than the portion of the optical beam that is propagated toward the optical power monitor.