Lens optical system

본 발명은 NA가 높으면서도 광학계의 전장을 최소화할 수 있는 4매 렌즈 광학계에 관한 것으로, 물체측으로부터 상측으로 제1 렌즈, 제2 렌즈, 제3 렌즈, 및 제4 렌즈가 순차로 배열되고, 광학계의 앞쪽에 연달아 배치되는 제1 렌즈와 제2 렌즈가 각각 양의 굴절능을 가지도록 구성된 렌즈 광학계에 관한 것이다. A four-lens optical system is provided which is capable of minimizing a total length of an optical system while having a high numerical aperture (NA), and, more particularly, to an optical system including a first lens, a second lens, a third lens, and a fourth lens that are sequentially arranged from an object side to an image side of the four-lens optical system, in which the first lens and the second lens continuously disposed in front of the optical system are each configured to have positive refractive power and in which the first lens is a lens is made of a plastic material, and the fourth lens is a lens made of a glass material.