There isn't really an established ratio, but the violet output should be around the red output. But this doesn't really matter because it would be better to fine tune the current to get your desired color, especially since some violet laser diodes have different wavelengths/brightness than others.
how about pulse driving the lasers and if you get the right frequencys the color blends should look good right? im going to try it with rgy and once i figure out how to get a good yellow i think i could apply a 405nm and get the same results right? it seems like you need around a 30-40mW green if you have about a 150mw red and then around a 170mW violet. i think thats about right. thats what im going for just thought i could give you what ive figured out so far.
i figured i would add the violet after only because im buying it later on. and think about an a r/g led flash it between colors fast enough and it looks yellow at lower speeds which are still high to the human eye and then point that into a spiro and it would separate them unless you moved to much higher speeds. im going to look into this and report my findings to see if that can help.