The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 14, 2020
Filed:
May. 11, 2017
Canon Kabushiki Kaisha, Tokyo, JP;
Masatsugu Nakano, Utsonomiya, JP;
CANON KABUSHIKI KAISHA, Tokyo, JP;
Abstract
Provided is an optical system including, in order from an object side to an image side, a first lens unit having a negative refractive power, an aperture stop, and a second lens unit having a positive refractive power, in which an average value θIR(G)of partial dispersion ratios of materials of positive lenses included in the second lens unit and an average value θIR(G)of partial dispersion ratios of materials of negative lenses included in the second lens unit are appropriately set, provided that BF and F are a backfocus and a focal length of the optical system at a wavelength of 1050 nm, respectively, and a partial dispersion ratio of a material is θ=(Ns−Nm)/(Ns−Nl), where Ns, Nm, and Nl are refractive indices of the material at wavelengths of 400 nm, 1050 nm, and 1700 nm, respectively.