Please explain a bit more....a pic may be in order. I have found that if the cube has the correct A/R coating, back reflections are at a minimum. I have a pair 473's that are doing 375-400mw out of the front apeture of the projector.That is after changing galvo mirrors,dichrioc's , and other measures of optics tweaking. It is not easy....but very rewarding after the battle is won. The polorization needs to be at least 100:1 for good results. If not....well there is a loss of power in using the cube.....check your laser with a half waveplate and meter. The laser beams and cube are at right angles and as straight as possible. Once the polorization orientation is found on the laser....a simple mark of the felt pen make easy location to orient beams into the cube. One H and one V.
You are the only one that can make your dreams come true....and the only one that can stop them...A.M. Dietrich