The range between 780 and 1000 nm can still be inspected with normal monochrome CMOS cameras, whose sensitivity decreases progressively at this wavelength, but is in principle sufficient.

For longer wavelength IR ranges, Peltier-cooled sensors and special semiconductor materials (InGaAs) must be used. Cameras for mid-IR analysis are called thermal imaging cameras. Here, too, the optics are no longer made of ordinary glass, but of materials such as germanium.

Sony's SenSWIR family of sensors (IMX 990 / IMX991 / IMX992 / IMX 993) with a sensitivity of 400-1700 nm and a resolution of up to 5 megapixels are a good alternative.

For simple IR applications with 'standard' cameras, LEDs in the 870 or 950 nm range are therefore preferred. The longer wavelength is expected to reduce surface scattering and therefore improve the illumination of the target, but the sensitivity of the standard CMOS camera sensor is significantly reduced.

Longer-wave radiation is electromagnetic radiation and therefore oscillates less frequently than shorter-wave radiation and thus generates less interaction with the material.

It is therefore capable of penetrating deeper into the material and generates fewer surface reflections than short-wave light. When using IR radiation it is sometimes even possible to look through an object.

As IR radiation is invisible to the human eye, it is particularly suitable for workplaces where normal light would be particularly disturbing.