Originally Posted by
neskusen
Another interesting and probably important thing was that in Dkumpula's tests G2 was the only collimator lens made from AR coated single-element aspheric glass. Acrylic is a different material and the 3-element glass lens has more losses from more surfaces the beam has to pass through.
But aren't there other single element glass lenses like the G2, coated for the red spectrum?
The last lens included in my tests was the 400-700nm Single Element G2 lens sold by Aixiz. This lens performs nearly as well (and sometimes better) than DTR's G2 lens but is 1/3 the price. One downside is that this other G2 lens has slightly larger threads making it too tight to fit into the diode holders that Dave at Lasershowparts sells. It fits fine into DTR's diode holders though. I tend to use acrylic for lower power reds primarily because I can spare the loss with single mode builds (the reds are the brightest among current single mode red/blue/greens) and get a better otherwise uncorrected beam. I use G2s (DTRs or Aixiz depending on which diode holder I am using for that build) with the greens and blues.
With multimodes the considerations are slightly more complicated, but I think most people here would start with a DTR G2 lens.
Have fun with your build!
-David
"Help, help, I'm being repressed!"