Here, first and second light beams

Here, first and second light beams have “similar polarization states” if a polarizing beam splitter set to pass a maximum amount of the light energy of the first light beam will also pass at least 50% or at least 70% or at least 85% of a maximum amount of the light energy of the second light beam that the polarizing beam splitter can pass- thereby making it impractical or inefficient to use a polarizing beam splitter as a light combiner to combine the light of the first and second light beams (without first adjusting polarization states of the first and/or second light beams to be more nearly orthogonal using additional optical elements)