| 摘要 |
PROBLEM TO BE SOLVED: To provide an infrared optical system that can give a bright image and is applicable to a single focus lens from a wide angle to a middle telephotographic range.SOLUTION: The infrared optical system is composed of a first lens having a negative refractive power and a second lens having a positive refractive power, successively disposed from an object side, in which both the first lens and the second lens are made of an infrared transmitting material that transmits rays in an infrared wavelength region of 3 μm or more and 14 μm or less, and at least one lens is made of an infrared transmitting material other than germanium. |
