| 摘要 |
This far-infrared lens is a lens system used in the far-infrared band. The lens is formed of two single lenses, namely, a first lens and a second lens in this order from the object side, satisfies the conditional expression 0.52 < fB/f < 0.97 (fB: the air-equivalent distance between the image-side face of the second lens and the image plane; f: the focal length of the entire far-infrared lens system), and has a half angle of view greater than 30°. |
