Title:
OPTICAL SYSTEM AND IMAGING DEVICE
Document Type and Number:
Japanese Patent JP2023061272
Kind Code:
A
Abstract:
To provide an optical system which is bright and lightweight, and with which a change of an optical performance due to temperature changes is small.SOLUTION: An optical system OL comprises a plurality of lenses L that includes at least one positive lens and at least one negative lens and a final negative lens Gn which is closest to an image side. A refractive index of a material of the final negative lens in a d ray is defined to be Ndn, and a temperature change coefficient of the refractive index Ndn at 20°C is defined to be dn_n/dt. A refractive index of a material of a specific positive lens included in the plurality of lenses in a d ray is defined to be Ndp, and a temperature change coefficient of the refractive index Ndp at 20°C is defined to be dn_p/dt. In this case, conditional expressions 1.40≤Ndn≤1.80, -300×10-6≤dn_n/dt≤-50×10-6, 1.75≤Ndp≤2.40, -15.0×10-6≤dn_p/dt≤2.0×10-6 are satisfied.SELECTED DRAWING: Figure 1
Inventors:
FUJISAKI TOYOKATSU
Application Number:
JP2021171172A
Publication Date:
May 01, 2023
Filing Date:
October 19, 2021
Export Citation:
Assignee:
CANON KK
International Classes:
G02B13/00
Attorney, Agent or Firm:
Ryosuke Fujimoto
Atsuya Mizumoto
Tomoya Hirayama
Atsuya Mizumoto
Tomoya Hirayama