In a dye laser apparatus in which a particular copper vapor laser beam is directed into a dye cell forming part of the apparatus for producing or amplifying a dye laser beam, the improvement comprising an arrangement for providing said particular copper vapor laser beam and for directing it into said dye cell, said arrangement including:
- (a) means for producing a plurality of different copper vapor laser input beams;
- (b) an optical mixing bar including a main body for mixing light therein, a flat input face on one end of said main body, and a multi-faceted output face on the opposite end of said main body, whereby light entering said main body from said input face is mixed therein and exits said output face as a plurality of mixed output light beams corresponding in number to the number of facets making up the output face;
- (c) means for directing said copper vapor laser input beams onto the input face of said mixing bar, whereby to cause said input beams to mix within the main body of said mixing bar and exit the latter from its multi-faceted output face as a plurality of mixed copper vapor laser output beams which includes said particular copper vapor laser beam;
- and
- (d) means for directing said particular copper vapor laser beam into said dye cell of said dye laser apparatus from the output face of said mixing bar.