| 摘要 |
PROBLEM TO BE SOLVED: To shorten an entire length of an optical system.SOLUTION: An infrared zoom lens is configured by arranging, in order from an object side, a first lens group G1 having a focus function and a positive refractive power as a whole, a second lens group G2 moving on an optical axis upon zooming and having a function of varying a magnification and having a positive refractive power as a whole, a third lens group G3 moving on the optical axis upon the zooming and having a function of compensating for a focus position varied by the zooming and having a positive refractive power as a whole, and a fourth lens group G4 having a function of forming an image on a detector surface I and having a positive refractive power as a whole. The infrared zoom lens forms an intermediate image, and re-images the intermediate image on the detector surface I. |
