Patent ID: 8792168
Filing Date: 2014-07-29
Classification: G02B

Abstract:
1. An optical system comprising: plural lens groups; a negative lens included in a specific lens group among the plural lens groups and formed of a first medium; a diffractive grating formed on at least one lens surface of the negative lens of the same first medium, said diffractive grating being in contact with a second medium different from the first medium; and a positive lens included in the specific lens group and formed of a third medium different from the first medium and the second medium, wherein the first medium satisfies the following conditions: where ndA represents a refractive index of the first medium for a d-line, and vdA represents an Abbe number of the first medium for the d-line, and wherein the third medium satisfies the following conditions: where ndC represents a refractive index of the third medium for the d-line, and vdC represents an Abbe number of the third medium for the d-line.