| 摘要 |
PURPOSE:To eliminate the need to use glass of a high refractive index by enabling five-group six-element constitution to meet prescribed requirements. CONSTITUTION:Six elements L1-L6 in five groups are used while the 4th group consists of negative and positive lenses as connected lenses. Now, formula I is satisfied, where the focal length of the whole system is denoted as f, the radiuses of curvature of the 6th, 7th, 8th, 10th, and 11th surfaces as r6, r7, r8, r10, and r11, the composite focal length of the 1st group as f1, the composite focal length of the air lens composed of the 4th and 5th surfaces as f45*, the composite focal length of the 4th group at f45, refractive indexes of the 1st, 2nd and 3rd groups, connected lenses L4 and L5 of the 4th group, and the glass of the lens of the 5th group as N1, N2, N3, N4, N5, and N6 and the dispersion factors of glass to negative lens L4 of connected lenses of the 3rd and 4th groups as nu3 and nu4. Consequently, the lens with less distortion aberration is obtained by using glass of a high refractive index. |
