‘Light rays’ explores the idea that light is something that propagates in a straight line from the object to the viewer. Alhazen, in the 9th century, modified the understanding of light rays by proposing that objects are illuminated by rays from the sun, which are then scattered towards the observer. Particles of light, called photons, move along these rays and possess the properties of reflection and refraction. These properties can result in two-dimensional images being produced on lenses. The development of optical instruments, the limits to imaging, the strange refractive properties of metamaterials, and super lenses are also discussed.