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:
Feb. 17, 2015
Filed:
Oct. 14, 2011
Yosuke Miyazaki, Ichihara, JP;
Yosuke Miyazaki, Ichihara, JP;
Nikon Vision Co., Ltd., Tokyo, JP;
Abstract
Provided are an ocular zoom optical system which has a wide apparent field of view even on a low power side and in which aberrations are favorably corrected while a sufficient eye relief is secured over the entire zoom range, and an optical instrument including the ocular zoom optical system. The ocular zoom optical systemincludes, in order from the object side: a first lens group Ghaving a negative refractive power; a second lens group Ghaving a positive refractive power; and a third lens group Ghaving a positive refractive power and at least one aspheric surface. An intermediate image I' is formed between the first lens group Gand the second lens group G. During zooming, the third lens group Gis fixed on the optical axis, and the first lens group Gand the second lens group Gare moved in directions opposite to each other with the intermediate image I′ interposed therebetween. The second lens group Gincludes, in order from the object side: a positive single lens Lhaving a higher positive refractive power on the lens surface on the eye-point side than that on the lens surface on the object side; and a positive cemented lens CLincluding a positive lens Land a negative lens L