Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....
I looked at the site and it states this type of expander needs to be chained together to achieve higher divergences of up to 32x.I ran across their web site a couple of years ago and again recently, I'd love to have one of those but when I checked in prices, ouch.
Edit: Looking at the EO document on aspherical lenses, I am finding there is another accuracy measurement I need to be concerned with:
Power (Spherical) 2λ, 1/2λ, 1/10λ
2λ for "commercial" which I interpret as illuminators, 1/2λ for laser use and 1/10λ for precision laser use. The use of the word power is somewhat confusing to me, but I guess that means curvature accuracy.