Abstract: A group of diode lasers emitting beams at a first wavelength is positioned above and below a stack of laser diodes emitting beams at a second wavelength. The first wavelength beams are directed to a dichroic portion of a compound prism and are reflected outwardly. The second wavelength beams are directed to the opposite surface of the dichroic portion but pass through without reflection and so are directed into substantially the same outward plane as the first wavelength beams. The compound prism combines beams of two different wavelengths to achieve a greater power density in the given plane than can be obtained with beams of either wavelength alone.