Optical light weight glass

• US 4,812,423 A
• Filed: 07/17/1985
• Issued: 03/14/1989
• Est. Priority Date: 01/27/1984
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Kodama, Hiroyuki, Ichimura, Takeo, Mangyo, Katsumi
• Primary Examiner(s): BELL, MARK LEE
• Application Number:
  US06/758,645
• Time in Patent Office: 1,336 Days
• Field of Search: 501/903, 501/55, 501/63, 501/65, 501/66, 501/67, 501/68, 501/69, 501/70, 501/72
• US Class Current: 501/55
• CPC Class Codes: C03C 3/076 with 40% to 90% silica, by weight C03C3/045 takes precedence
• CPC Class Codes: C03C 3/083 containing aluminium oxide or an iron compound
• CPC Class Codes: C03C 3/087 containing calcium oxide, e.g. common sheet or container glass
• CPC Class Codes: C03C 3/089 containing boron
• CPC Class Codes: Y10S 501/903 having refractive index less than 1.8 and ABBE number less than 70

Abstract

This specification discloses optical light-weight glass having a composition of SiO₂ 47--70, Li₂ O 5.5-21, K₂ O 2-30, Na₂ O 0-30 (Li₂ O+Na₂ O+K₂ O 21-50), TiO₂ 9.5-24, B₂ O₃ 0-20, CaO 0-20, MgO+SrO+BaO+ZnO 0-4, Al₂ O₃ 0-5 and ZrO₂ +La₂ O₃ +Ta₂ O₅ +WO₃ 0-3, all being in % by weight, and having a refractive index (n_d) of 1.58-1.65, an Abbe number (γ_d) of 35-50 and a specific gravity of 2.69 or less. This optical glass is light in weight, high in transparency and low in dispersion, and is particularly suitable for spectacle lenses, but can also be utilized for photographic lenses.

Claims

1. Optical lens of light-weight glass consisting essentially of the following composition in % by weight and having a refractive index (n_d) of 1.58 through 1.65, and Abbe number (ν

_d) of 35 through 50 and a specific gravity of 2.69 or less;

space="preserve" listing-type="tabular">______________________________________ SiO.sub.2 47-70 Li.sub.2 O 5.5-21 K.sub.2 O 2-30 Li.sub.2 O + K.sub.2 O 21-50 TiO.sub.2 9.5-24 CaO 0-20 MgO + SrO + BaO + ZnO 0-4 Al.sub.2 O.sub.3 0-5 ZrO.sub.2 + La.sub.2 O.sub.3 + Ta.sub.2 O.sub.5 + WO.sub.3 0-3. ______________________________________

2. The lens of claim 1, wherein the proportions of two of the components are as follows in % by weight, n_d is within the range 1.58 through 1.64, ν

_d is within the range of 39 through 50 and specific gravity is 2.59 or less;

space="preserve" listing-type="tabular">______________________________________ TiO.sub.2 9.5-20 CaO 0-4. ______________________________________