US Patent 11789239 Optical imaging system

An optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens sequentially disposed in numerical order along an optical axis of the optical imaging system from an object side of the optical imaging system toward an imaging plane of the optical imaging system, wherein the optical imaging system satisfies 1<|f134567−f|/f, where f134567 is a composite focal length of the first to seventh lenses calculated with an index of refraction of the second lens set to 1.0, f is an overall focal length of the optical imaging system, and f134567 and f are expressed in a same unit of measurement.