Abstract Y0Tad?iC
An optical glass comprising in mass %: 1 P.sub.2O.sub.5 25%-less than 45% B.sub.2O.sub.3 6-20% BaO 24%-less than 40% ZnO 3-14% MgO 0-15% CaO 0-15% SrO 0-15% Li.sub.2O 0-5% Na.sub.2O 0-5% K.sub.2O 0-5% WO.sub.3 0-5% and Al.sub.2O.sub.3 0-5%. The optical glass should preferably contain 0.1-5% WO.sub.3, 3.6-15% MgO, 0.1-5% Li.sub.2O+Na.sub.2O+K.sub.2O, 0--less than 0.5% and Sb.sub.2O.sub.3+As.sub.2O.sub.3 with the mass ratio of ZnO/BaO being 0.12--less than 0.50. The optical glass should preferably have refractive index (nd) within a range from 1.54 to 1.65 and Abbe number (.nu.d) within a range exceeding 57 up to 69 and liquid phase temperature within a range from 870.degree. C. to 930.degree. C. There is provided an optical glass having high resistance to devitrification and medium refractive index and low dispersion characteristics which is free of ingredients such as Ta.sub.2O.sub.5 having a high cost of raw material and therefore can be manufactured at a relatively low cost of raw materials. b*Q3j}c Z
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Inventors: Mori, Yoshio; (Yokohama-shi, JP) ; Onozawa, Masahiro; (Sagamihara-shi, JP) s1E 0atT
Correspondence Name and Address: HEDMAN & COSTIGAN P.C. Yj'9|4%+|
1185 AVENUE OF THE AMERICAS (uDAdE5
NEW YORK (3K3)0fy
NY N,Z*d
10036 Z.&/,UU:4
US W+GC3W
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Assignee Name and Adress: Kabushiki Kaisha Ohara z"T+J?V/
1-15-30 Oyama Sagamihara-shi OPzudO
Kanagawa-ken &TY74w*
JP !d<R=L
229-1186 4BUG\~eI3
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Serial No.: 504112 8HFCmY#
Series Code: 10 kc0MQ TJU
Filed: August 10, 2004 <$yA*
PCT Filed: January 29, 2003 Wlxmp['Bh
PCT NO: PCT/JP03/00839 U#cGd\b
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U.S. Current Class: 359/883 " >.tPn
U.S. Class at Publication: 359/883 D{s87h
Intern'l Class: G02B 005/08 ^utOVi
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Foreign Application Data ~CT]&({
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Date Code Application Number 41Z@_J|&
Feb 20, 2002 JP 2002-04342 =]]1x_GB
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Claims !p/SX>NJ
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1. An optical glass comprising in mass %: l>K+4
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6 P.sub.2O.sub.5 25% -less than 45% B.sub.2O.sub.3 6-20% BaO 24%-less than 40% ZnO 3-14% MgO 0-15% CaO 0-15% SrO 0-15% Li.sub.2O 0-5% Na.sub.2O 0-5% K.sub.2O 0-5% WO.sub.3 0-5% Al.sub.2O.sub.3 0-5% and being free of Ta.sub.2O.sub.5. ':fp|m)M
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2. An optical glass as defined in claim 1 comprising, in mass %, 0.1-5% WO.sub.3. (ne[a2%>
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3. An optical glass as defined in claim 1 comprising, in mass %, 3.6-15% MgO. L4Zt4Yuw
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4. An optical glass as defined in claim 1 comprising, in masst %, 0.1-5% Li.sub.2O+Na.sub.2O+K.sub.2O. ~*7$aj
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5. An optical glass as defined in claim 1 wherein mass ratio of ZnO/BaO is within a range from 0.12 to less than 0.50. g}v](Q
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6. An optical glass as defined in claim 1 comprising, in mass %, 0-- less than 0.5% Sb.sub.2O.sub.3+As.sub.2O.sub.3. F<