Infrared diodes illuminator scope
Illuminating capablity depends on


radiation output power
how well you can focus the radiation to the area which is under interest and how much you will get there watts/square meter
the reflectance of the objects under interest (as contrast between them and background)
the sensitivity of the receiver(=camera)


Video cameras are generally able to make BW video in nearly visible (sub 1um) IR light. Many cameras actually have their own IR led light which is ON if you select the night shoot mode. You can experiment with one. Get a led. If you can make elementary radiation beam calculations, you can easily expand one led low power low directivity test results to multiple led higher power high directivity (lens or reflector) results when the camera is the same.

Remember: If your IR light is at the same place as the camera, the distance degrades the available IR reflection very fast - doubling the distance drops the received radiation to 1/16th part. You'll do much better, if you keep the light near the area under interest and only you and the camera stay further. Beware: direct radiation from IR source to camera and bright spots spoil the detection possiblities.