Actually, I'm in complete agreement with you about the picture caption, sorry I wasn't more clear.

I know that in dye lasers it's often common to have a filter tube around the lamp, usually just for water flow, to absorb the NIR before it causes thermal shock in the liquid. I'll look into this more.

Thanks for your explanation of spectralon, as that makes a great deal of sense. Yes, it would've been helpful if the article had not been deleted. It is often helpful to include a small parenthetical explanation of specialized words anyway. I can see where using a polished and AR coated rod would be beneficial in such a cavity, coupling more light than difussing it through the surface of the rod. I know from sad experience that keeping the light diffused either way is almost a necessity, to keep the rod from cracking. -{ I believe I also read that on the Kentek website, and in one of the most accurate sources I've found on lasers, Principles of Lasers by Oratio Svelto, although the book is a little difficult to follow as 80% of it is written in math.

Anyhow, thanks again for all of your assistance -D