Long-wave infrared: 8 to 12, or 7 to 14 µm.The "thermal imaging" region, in which sensors can obtain a completely passive image of objects only slightly higher in temperature than room temperature - for example, the human body - based on thermal emissions only and requiring no illumination such as the sun, moon, or infrared illuminator. This region is also called the "thermal infrared". Product example >>>

3 to 5 µm (defined by the atmospheric window and covered by Indium antimonide [InSb] and HgCdTe and partially by lead selenide [PbSe]).
Quanhom MWIR lenses, mounted on an MWIR camera, are the perfect choice for a variety of applications, including imaging through the fog, high-speed thermal imaging, thermography, R&D (MWIR range), non-destructive testing. Product example >>>

Mostly be used for magnify 0.4-0.6 inch OLED. An eyepiece consists of several "lens elements" in a housing, with a "barrel" on one end. The barrel is shaped to fit in a special opening of the instrument to which it is attached. The image can be focused by moving the eyepiece nearer and further from the objective. .Elements are the individual lenses, which may come as simple lenses or "singlets" and cemented doublets or (rarely) triplets.  Product example >>>