A beam combiner includes a first beam-input face, a beam-output face, and
first and second reflectors. The first beam-input face receives first and
second beams of electromagnetic energy respectively having a first and
second wavelengths. The first reflector reflects the first received beam
toward the beam-output face, and the second reflector passes the first
beam from the first reflector and reflects the received second beam
toward the beam-output face. In one alternative, the first beam-input
face also receives a third beam of electromagnetic energy having a third
wavelength, the beam combiner includes a third reflector that reflects
the received third beam toward the beam-output face, and the first and
second reflectors pass the third beam from the third reflector. In
another alternative, the beam combiner includes a second beam-input face
that receives a third beam directed toward the beam-output face, and the
first and second reflectors pass the third beam.