Danny, i can't report own experiences, because i only have made denisyuks with the violet LD so far. What i found was, that even with 0.5% AmDi, when the coating is a bit thicker it already gets difficult to have good results, as the plate appears very dark in 405nm light. I would assume that for single beam reflection and coating thicknesses around 5-6um 1% would be a resonable upper limit.
If you want to use a setup in which beams hit the plates from both sides i would think that above 2% AmDi the transparency of the coating would not be sufficient to get a high DE. Even when the beams come from different sides of the plate they need to meet within the coating. If the plates don't have sufficient transparency, you would get a central plane at half of the coating thickness with the best beam ratio which would quickly get worse in both directions. I think 4% would be too much unless you were using very thin coatings.
Besides that with a higher AmDi content one would expect a larger amount of blueshift. This fear was my main reason for using only 0.5% AmDi.
With 16mW spread to fully illuminate a 8x10 plate you are already getting a sensitivity of 1.16mJ/cm2 if there are no losses at all. 8 times less would mean 144uJ/cm2, which would be great of course
Colin, thanks, i'll go through Phils postings then.
