| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared fixed-focus lens of which lens components are made of germanium having low chromatic dispersion, and which has no diffraction optical element face.SOLUTION: The infrared fixed-focus lens comprises, in order form an object side, a negative first lens in which an object-side face r1 has a convex face toward the object side and a positive second lens in which an image-side face r4 has a convex face toward an image side. Both the first and second lenses are made of germanium, attaining the full field angle of 24 to 55 degrees. |
