| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens system capable of obtaining a sharp image in the wavelength band of infrared rays.SOLUTION: A lens system 10 comprises, in order from an object side 10a to an image side 10b, a first lens L1 made of germanium, not moved when varying power, a second lens L2 made of germanium, moved when varying power, a third lens L3 made of germanium, moved when varying power, a fourth lens L4 made of germanium, not moved when varying power, a fifth lens L5 made of chalcogenide, moved when varying power, and a sixth lens L6 made of chalcogenide, not moved when varying power. |
