Hey all - I'm just now getting into night vision, and I have two units I want to equip with IR aiming lasers, one is a DD DDM4 PDW with Eotech EXPS-3, and the other is a full-length DDM4 with an LPVO. I have an NGAL clone for the PDW, and I'm looking at a 3EIR DIR (also known at the TNVC DIR. DIR-ONE, DESIGNATE IR and DIR-1) Dual-beam Vis / IR LAM, because it sits so very low and doesn't obstruct the LPVO. The problem is, I cannot afford the version with the IR ILLUM.

I'm new to all this, but it seems to me there are a lot of aiming lasers that do NOT have integrated illuminators, just lasers. Are there helmet-mounted IR lasers or WML IR leads that can be helmet-mounted that would be just as effective as an integrated IR illum? What are the disadvantages to helmet-mounted Vs rifle-mounted in this application? Are there helmet-mounted versions or heads with adjustable dispersion / beam width?

Would love to hear some opinions. Thanks very much all!

Firearm mounted IR illuminator is obviously faster to use when shooting and is generally pointed towards the target.

Helmet mounted IR illuminator would be used for different tasks, like searching and looking around and not needing to use the firearm.

Also, feel free to browse the NV subforum.

https://www.ar15.com/forums/Armory/NV-Tech-Talk/18/

You really want some sort of focused beam for illumination. When using something like a Surefire Vampire, etc. what you get is a huge blast of illumination. This can cause the tube to dim and make things around the targeted area harder to see. With something like a MAWL/PEQ/NGAL/RAID/ETC what you get is a tidy illumination factor of one spot/area of interest, and it doesn't dim the image overall. Think of it like your cell phone camera. When you tap the screen aiming at the light colored object, everything else gets dim. When you use area-lighting adjustment over the average of the whole screen, you can see everything. Laser and focused (D2) illumination achieves the latter, while a M600V or similar, the former.

Trying to fiddle with something that's stuck to your head, one handed, while holding a carbine to adjust dispersion... suboptimal. :)
You want your illuminator and aimer on the gun's rail where you can widen or tighten the beam, or just activate it while in a firing grip.

One's helmet might have a low power, wider, soft light like a Streamlight Sidewinder, Princetons, etc. for navigating and up-close admin work.
As mentioned above, long range IR illum is focused so that you don't wash out everything.
I'd get a combo unit where you have IR illum and IR laser in one unit, somewhat "slaved" vs. separate torch / IR torch / laser / IR laser, etc.
Either save up for the ones you mentioned, or -- since you mentioned copy NGALs, there's lots of inexpensive options that might be worth a try to see if you like them (see threads like this one for people's experiences experimenting with low price IR illum and IR lasers.  

Thanks for this guys, and this makes a lot of sense.

One last question - imagine if one were to set up a particular rifle specifically for night use .... say one of my M1A rifles. Is there a long range, tightly focused IR light head I could replace my Modlight PLHv2 with, and then use a LAM that doesnt have it's own illum?

What about switchable IR/white light heads? Does such a thing exist? I know Z-bolt makes a DUAL light body, but you also have to buy two of thier light heads, they wont sell just the dual body ... one of several reasons I despise that company.

Yes, there are a lot of IR only heads.  Tightest focused option would probably be a BE Meyers Kiji.  Lots of other stuff out there, though, take a look at Arisaka/Malkoff and Modlite as well.

As for dual output, Surefire is the only game in town as far as I’m aware.  Vampire heads generally aren’t all that “focused” though and are fairly low output (comparatively) to dedicated IR head options.

If there's a night shoot near you, go see what guys are running and you'll get a feel for what you want.