US Patent 10365453 Optical device and optical apparatus having the same

An optical device including first and second optical elements formed of mutually different materials, and a bonding member bonding the first and second optical elements to each other, wherein the following conditional expression is satisfied:0.14<Log(te/tc)×Log(E1×E2/Ec2)<5.0where tc is a thickness in an optical axis direction of the bonding member on an optical axis, te is a thickness in the optical axis direction of the bonding member in a maximum diameter of interfaces between the first and second optical elements and the bonding member, and E1, E2, and Ec are respective Young's moduli of the first and second optical elements and the bonding member.