The trick is going to be using far red light "only"
Ok, if that's where you're at, it's untested, and unproven but here's my idea to get far red only, on the cheap...

Infrared IR Laser Illuminator Circuit Build Instructions Schematic

scratch the batteries, use an old little ac/dc transformer power pack with a suitable voltage and sufficient current output. scratch the optics he picks, they dont spread the beam enough, try 10x gem scope or find an old photocopier and pick through its parts, old dvd burners that don't work so well anymore.. there are plenty of places to get free or close to free lens's and the laser he picks is too high in the IR range, a CD burner or the cd burning laser from a cd/dvd/multi unit burner has in ir laser with a 780nm frequency that gives off a very dim red color (to the human eye, don't look directly at it!) is very available and easily sourceable. My only speculation about the method here is, is the bandwidth from the 780nm wide enough to be in range to effect the Pfr.

playing with lasers can be really dangerous tho, if anyone out there is experimenting with this stuff like I am, please wear eye protection. If you power up a cdrom laser and think it isnt doing anything look at it through a digital camcorder or cellphone camera, don't pick it up and look into it.