IR illumination can be useful to take advantage of CCD cameras high sensitivity in the Infrared spectrum.
Most cameras have filters that eliminate the IR for color balance reasons. When this filter is removed IR sensitivity is increased with some corresponding loss of color balance.
Most light sources generate plenty of IR, but it may be filtered out to prevent burning of fibers. Filter(s) may need to be removed. Illumination fiber in the borescope will be heat damaged if too much IR is present, or cooling of light guide tip is not adequate.
Scopes built with fused quartz image fiber may lose image quality in the IR spectrum since the fiber is optimized for use in the visible light spectrum. Leached image bundles are recommended for IR use, or verification that fused quartz will perform well as applied is advised.
Fused quartz fiber being used in radioactive environments will degrade more slowly in the Infrared region.