An optical touch system includes: a coordinate processor; a display device; and an optical element. The optical element is configured to emit light towards the display device and provide information about reflected light corresponding to a portion of the emitted light to the coordinate processor. The display device includes: a display panel configured to display an image, a touch substrate disposed on the display panel, the touch substrate including optical recesses each configured to reflect respectively different amounts of incident light, and a protective layer disposed on the touch substrate. The coordinate processor is configured to determine a touch or near-touch coordinate based on the information received from the optical element.