| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens having a high zoom ratio, having various aberrations satisfactorily corrected over an entire area from a visible area to a near infrared light area, and having high optical performance.SOLUTION: A zoom lens comprises, in order from an object side to an image side, first, second, third lens groups having positive, negative, and positive refractive power. The second lens group moves to the image side during zooming from a wide angle end to a telephoto end. Distances between adjacent lens groups change during zooming. The first lens group includes a pair of lens part LB1 composed of a positive lens LP1 and a negative lens LN1 that are disposed adjacent to each other. The zoom lens individually and appropriately sets: a refractive index N400 of a material at a wavelength of 400 nm; a refractive index N1050 of the material at a wavelength of 1050 nm; a refractive index N1700 of the material at a wavelength of 1700 nm; an Abbe number νIR of the material and a partial dispersion ratio θIR of the material; an Abbe number νIRP1 of a material of the positive lens LP1 and a partial dispersion ratio θIRP1 of the material; and an Abbe number νIRN1 of a material of the negative lens LN1 and a partial dispersion ratio θIRN1 of the material.SELECTED DRAWING: Figure 1 |
