Patent ID: 8785339

Claim:
An optical glass comprising, by mass %, 12 to 40% of SiO 2 , 15% or more but less than 42% of Nb 2 O 5 , 2% or more but less than 12% of TiO 2 , (provided that Nb 2 O 5 /TiO 2 is equal to or more than 3.49), 0.1 to 20% of Li 2 O, 0.1 to 15% of Na 2 O, and 0.1 to 25% of K 2 O, the optical glass having an Abbe's number νd of 20 to 30, a refractive index nd of 1.87 to 1.90, ΔPg,F of 0.016 or less and a liquidus temperature of 1,200° C. or lower.