| 摘要 |
A far-infrared lens is a lens system used in a far-infrared zone, is composed of two single lenses of a first lens and a second lens in order from the object side, and satisfies a conditional expression: 3.6<TL/f<5.7 (where TL is the total length of the far-infrared lens (in the case of air-equivalent back focus) and f is the focal length of the entire system of the far-infrared lens). |
