I am running a behavior experiment with mice. The mice will be inside a dark soundproofed chamber performing a visual discrimination task. I am using a camera throughout sessions but need some visibility. The only light inside will be that of the monitor presenting the visual stimulus. But it is not enough. So I need to put some sort of red light at ~650 nm, since mice are less sensitive to longer wavelengths. It will not disturb their circadian rhythm, as I am conducting experiments during the light cycle. I just don't want any highly visible lights in the rig while they are performing the task other than what is presented on the monitor. Anyone have ideas of a small, inexpensive light? Ideally, I'd like to mount it with some parts from Thor Labs.

Thanks!