1. A system comprising, in combination: an artificial light source for illuminating an optical pattern, which pattern encodes binary data; the pattern; and apparatus adapted for altering the direction of light rays from the pattern in such a way that the light rays travel to a camera and pass through a lens of the camera, and a focused image of at least a part of the pattern is captured by the camera at a time that the camera is focused at a depth other than the depth of the apparatus; wherein the system is separate from and not part of a unified structure with the camera.