Devices, systems, methods, and other embodiments associated with an optical movement sensor are described. In one embodiment, an optical system includes an image sensor configured to track a position of the optical system with respect to a surface. A light folding device optically folds light received from the surface by at least a first mirror that increases a focal length of the light. The system also includes a lens configured to optically focus the light from the light folding device onto the image sensor.