Yeah, you can definitely limit it to the tunica, just don’t shine it anywhere else. I’m no physicist but it think the waves (light, photons.) will penetrate through your shaft (obviously light won’t be beaming out the other side, but there could still be some photons/energy coming out) Which could also be good since it gets the whole picture, not just the surface like the topical creams. But then again you would have to be mindful of where it’s coming out on the other side if you don’t want to get anywhere else. I don’t know if shining it on your balls would be good or bad for them? Wouldn’t want to fry your boys, but you can direct it pretty easily.
We need to someone to take the plunge and try this.
Generally it’s a good idea to avoid shining anything on your scrotal area. Heat decreases sperm count in the short-term, but prolonged exposure to a close heat source can cause permanent damage according to some articles that were posted here before. When using an IR lamp try to make sure you cover your scrotal area with a white cloth or tissue paper, as firegoat recommends.