Just to clarify a bit -
Near-IR is the portion of the EM spectrum just beyond visible red. This is the space where security camera illuminators and IR remote controls operate. Smartphone cameras have IR-cut filters in front of the lens to improve picture quality for visible-light photos.
Far-IR is the stuff that we perceive as heat. It still behaves as light, sort of - it can be bounced off of metal reflectors - but it cannot be picked up by visible light cameras, even those with no IR filter. Thermal imagers use an entirely different type of sensor called a microbolometer as well as a radically different type of lens material. A microbolometer is essentially blind to visible light as well as near-IR but is sensitive to the much longer wavelengths that regular sensors can't see. Flir and Seek Thermal both have relatively inexpensive thermal imagers available, some as smartphone attachments and others as standalone units with their own LCD screens. Thermal cameras used to cost thousands of dollars, but a consumer-grade camera can be purchased for a few hundred bucks these days.
Near-IR LEDs and lasers work well with the relatively cheap first generation night vision tubes.