OPTICAL DEVICE AND MOBILE TERMINAL COMPRISING SAME

Provided is an optical device for reducing the time for auto focusing (AF) performed by a contrast detection system, the optical device comprising: a liquid lens having a curvature that varies on the basis of an applied electrical signal; an image sensor for converting, into an electrical signal, light having passed through the liquid lens; an image processing unit for calculating a focal point value through the electrical signal received from the image sensor; a diopter driving unit for changing the curvature of the liquid lens; a memory for storing, in correspondence to the gradient ratio of the focal point value, a first curvature state of the liquid lens and a second curvature state corresponding to the distance of a subject after AF; and a control unit for calculating the gradient ratio of the focal point value in the first curvature state, and controlling the diopter driving unit such that the diopter driving unit performs AF in the second curvature state through the gradient ratio of the focal point value, wherein the gradient ratio of the focal point value, in the first curvature state, is the gradient ratio of a focal point value to the curvature change of the liquid lens formed between a first region and a second region of the liquid lens according to the distance of the subject.