Abstract: Provided an optical system having a multiple curvature lens and a method for manufacturing the same. The optical system includes an image-forming lens group, an image sensor, and an image processing unit. The image-forming lens group has one or more multiple curvature lenses each having a multiple curvature surface provided on at least one refractive surface on one side of the multiple curvature lens. The multiple curvature surface includes two or more curved surfaces of different curvatures formed in a concentric circle. The image-forming lens group also has one or more single curvature lenses arranged before or after the multiple curvature lens and having a refractive surface. The refractive surface includes a continuous curved surface of a single curvature radius formed on both sides of the single curvature lens. The image sensor senses an image formed by the image-forming lens group, and the image processing unit recovers the image sensed by the image sensor.

Abstract: Disclosed is a method for determining the state of an engine speed sensor for a vehicle which can improve stability of the engine during the slow speed rotation of the engine through prompt entry into failure mode by changing a condition of the failure determination according to the state of the engine and thereby minimizing the failure determining time of the engine.