The Boresight Alignment Tool is an optical benchtop or self-standing tool used to precisely co-align instruments with multiple free-space optical inputs or outputs. It consists of a large parabolic mirror and an optical fiber mounted at the mirror’s focal point. A single-mode or multi-mode fiber is used to generate either a Gaussian beam or a beam with spatial intensity fluctuations  (simulating optical turbulence). In addition, a large precisely collimated optical beam can be easily created for general lab use including interferometric.