The detection of touch on an optical touch-sensitive device is disclosed. For example, one disclosed embodiment comprises a touch-sensitive device including a display screen, a laser, and a scanning mirror configured to scan light from the laser across the screen. The touch-sensitive device also includes a position-sensitive device and optics configured to form an image of at least a portion of the screen on the position-sensitive device. A location of an object relative to the screen may be determined by detecting a location on the position-sensitive device of laser light reflected by the object.