My housing came in the mail today. They said it came with the acrylic lense in it, but they included a coated glass one also. One of them appeared to only have one lense in the threaded holder. The other looked like it had multiple lenses in it. How do I know which is the coated glass lense?

The glass lens should be mounted in brass. The acrylic lens should be mounted in plastic. The glass lens mount should also be longer and the lenses will have a colored reflection (yellow if for blue light, blue if for red light).

If you still can't tell the difference, smash them with a hammer. The glass lens will shatter while the acrylic lens should deform.

By the way... that is an interesting thingy you got there. It looks like it can move a lot of heat.

Hey thank you! I'm hoping so. And I thought it looked "teckie" ya know. Both of the lense holders were black but one is much longer. On the longer one, it has what appears to be three lenses in it. One seems to be adjustable, and the one on the other end seems to have a little yellowish discoloration to it. The one on the other end...not so much. Which one do I place facing out? Oh and thank you for the help.

Place the side with the indentations in the casing outwards. The indentations are for spinning the lens to adjust it.

Only use glass lenses with 405nm/445nm lasers, as the acrylic lenses will melt. Lenses coated for 405nm/445nm have a yellowish tint when light is reflected off them. Lenses for red wavelengths will have a blue hue.

I would be much more likley to call the lens discoloration yellowish. It certainly isnt blue. I urdered it for a 445nm diode. It came with a 1W driver board. It came with everything except the diode.

Use the glass (yellowish AR coating) with your 445nm diode. The other one (acrylic) is just the one that comes with the module; so they just include it along with the module. That acrylic lens will melt under the 445nm wavelength and leave a residue on your diode's window; it's a pretty decent lens for 635nm and 660nm (red) lasers though.

Its pretty hard to confuse a metal cased lens from the very shiny black plastic case used with the stock lens.
the stock lens is much lighter ...plastic vs brass.
The 'discoloration' as you call it is the AR coating,.
Just remember the coating is NOT the same as the color of the diode you use it with- bluish--red diode... AMBER- blue or Bluray diode, if you see 'notches in both ends the larger ones go towards the front of your laser or away from the diode.
I keep my glass lenses for both red and b diodes together- thats how diff. they look to me.
Very good and clear photos showing all this very clearly are already here- you just need to refine your search skillz and terms and this thread can end.

The acrylic lens is also stocky--about half the height of the metal-cased lens.

Left is a blue laser with a blue coated lens, right is a 635 laser with a red coated lens . You can easily see the bluish coating on the red laser

Your picture reminds me of a mix between the US Air Force Academy's chapel and the Canada Place building

slightly off topic for the OP picture, the heat pipes are no longer working once they have been punctured. Also you should place more of the head of the aixiz module within the heatsink.