Ok chaps I was waiting for someone to pick me up on this. Yes I guess the Blue is most precious but I did a load of tests at the weekend - and repeated them over to measure the pass and bounce percentages of each dichro with each wavelength. From this I have concluded several things which I will write up at some point - one being that the layout that looses the smallest amount of photons overall is the one I have gone for. Trust me there has been a great deal of consideration gone into the layout. Though the blue beam looks bright its actually only about 2% of the blue beam overall - this is off a green reflecting dichro - if I had done it the other way with green through and a blue bounce dichro then I would have lost 15% green and about the same 2% of the blue - though ther is a way to improve the blue dichro perfomance which I will reveal when I write my results up but was not practical in my layout and the limited space I have.
Also yes the white beam does bounce off a 45 degree mirror and yes there will be a loss but can you suggest a way of getting the beam into the scanners any other way! without me having the lasers off in thin air to the side. Plus there is a big advantage as this is an adjustable mirror so it allows you to fine tune the position of the beam hitting the scanners to make sure its on target.
been finishing the dichro adjustable mounts tonight to get rid of some of the blu tak
Rob