Patent ID: 8773772
Filing Date: 2014-07-08
Classification: G02B

Abstract:
1. A lens optical system comprising first, second, third, and fourth lenses that are arranged between an object and an image sensor where an image of the object is formed, in order from an object side, wherein the first lens has a positive (+) refractive power and an incident surface that is convex toward the object, the second lens has a negative (−) refractive power and both surfaces of which are concave, the third lens has a positive (+) refractive power and a meniscus shape that is convex toward the image sensor, and the fourth lens has a negative (−) refractive power and at least one of an incident surface and an exit surface of which is an aspherical surface, wherein the lens optical system satisfies the following inequalities, wherein TTL is a distance from the incident surface of the first lens to the image sensor, BL is a distance from the exit surface of the fourth lens to the image sensor, RL4 is an effective radius of the exit surface of the fourth lens, and f is a focal length of the lens optical system.