Optical system for endoscopes

Claim 1

An optical system for endoscopes comprising an objective lens, a field lens, a variable-magnification relay lens system, another field lens, two relay lens systems, and an eyepiece arranged in the order from the object side, said optical system for endoscopes having the following numerical data: ______________________________________ f = 1 r.sub.1 = ∞ d.sub.1 = 0.0321 n.sub.1 = 1.7880 v.sub.1 = 47.43 r.sub.2 = 0.1048 d.sub.2 = 0.1413 r.sub.3 = -1.8540 d.sub.3 = 0.1284 n.sub.2 = 1.6860 ν.sub.2 = 49.16 r.sub.4 = -0.2063 d.sub.4 = 0.2081 r.sub.5 = 5.0094 d.sub.5 = 0.1359 n.sub.3 = 1.62041 ν.sub.3 = 60.27 r.sub.6 = -0.1536 d.sub.6 = 0.0423 n.sub.4 = 1.84666 ν.sub.4 = 23.90 r.sub.7 = -0.2960 d.sub.7 = 0.3130 r.sub.8 = 1.0901 d.sub.8 = 0.6993 n.sub.5 = 1.62004 ν.sub.5 = 36.25 r.sub.9 = -1.0901 d.sub.9 = 0.99 (variable) r.sub.10 = 0.919 d.sub.10 = 0.045 n.sub.6 = 1.65830 ν.sub.6 = 57.33 r.sub.11 = 3.170 d.sub.11 = 0.008 r.sub.12 = 0.247 d.sub.12 = 0.069 n.sub.7 = 1.67790 ν.sub.7 = 55.33 r.sub.13 = 1.134 d.sub.13 = 0.031 n.sub.8 = 1.62606 ν.sub.8 = 39.10 r.sub.14 = 0.204 d.sub.14 = 0.235 r.sub.15 = -0.210 d.sub.15 = 0.031 n.sub.9 = 1.59551 ν.sub.9 = 39.21 r.sub.16 = -1.684 d.sub.16 = 0.069 n.sub.10 = 1.67790 ν.sub.10 = 55.33 r.sub.17 = -0.362 d.sub.17 = 0.006 r.sub.18 = -5.860 d.sub. 18 = 0.044 n.sub.11 = 1.65830 v.sub.11 = 57.33 r.sub.19 = -0.507 d.sub.19 = 1.88 (variable) r.sub.10 = 0.884 d.sub.20 = 0.096 n.sub.12 = 1.56883 ν.sub.12 = 56.14 r.sub.21 = 0.224 d.sub.21 = 0.192 n.sub.13 = 1.61659 ν.sub.13 = 36.63 r.sub.22 = 0.243 d.sub.22 = 0.6046 r.sub.23 = 1.6829 d.sub.23 = 0.6426 n.sub.14 = 1.62004 ν.sub.14 = 36.25 r.sub.24 = -1.6829 d.sub.24 = 0.0465 r.sub.25 = 1.4110 d.sub.25 = 3.3109 n.sub.15 = 1.62004 ν.sub.15 = 36.25 r.sub.26 = ∞ d.sub.26 = 0.1182 r.sub.27 = 1.8607 d.sub.27 = 0.1980 n.sub. 16 = 1.65160 ν.sub.16 = 58.67 r.sub.28 = -0.4708 d.sub.28 = 0.0658 n.sub.17 = 1.80610 ν.sub.17 = 40.95 r.sub.29 = -1.0354 d.sub.29 = 0.1696 r.sub.30 = ∞ d.sub.30 = 3.3109 n.sub.18 = 1.62004 ν.sub.18 = 36.25 r.sub.31 = -1.4110 d.sub.31 = 0.5190 r.sub.32 = 1.4110 d.sub.32 = 3.3109 n.sub.19 = 1.62004 ν.sub.19 = 36.25 r.sub.33 = ∞ d.sub.33 = 0.1182 r.sub.34 = 1.8607 d.sub.34 = 0.1980 n.sub.20 = 1.65160 ν.sub.20 = 58.67 r.sub.35 = -0.4708 d.sub.35 = 0.0658 n.sub.21 = 1.80610 ν.sub.21 = 40.95 r.sub.36 = -1.0354 d.sub.36 = 0.1696 r.sub.37 = ∞ d.sub.37 = 3.3109 n.sub.22 = 1.62004 ν.sub.22 = 36.25 r.sub.38 = -1.4110 d.sub.38 = 1.4141 r.sub.39 = 2.2095 d.sub.39 = 0.0642 n.sub.23 = 1.78472 ν.sub.23 = 25.7 r.sub.40 = 0.6153 d.sub.40 = 0.1605 n.sub.24 = 1.67003 ν.sub.24 = 47.3 r.sub.41 = -1.0717 ______________________________________ wherein reference symbols r 1 through r 41 respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 through d 40 respectively represent thicknesses or respective lenses and airspaces between respective lenses, reference symbols n 1 through n 24 respectively represent refractive indices of respective lenses, and reference symbols ν 1 through ν 24 respectively represent Abbe's numbers of respective lenses.