An optical device is a device that manipulates light in order to create an image, detect light, or measure its properties. Common optical devices include prisms, lasers, lenses, bifocals, and scopes. A PRISM is a transparent optical element with flat, polished surfaces that refracts light. A LASER is a device that emits a beam of coherent light through an optical amplification process. A LENS is a curved piece of transparent material that refracts light in order to form an image. Bifocals are eyeglasses with two distinct optical powers in each LENS, designed to correct both near and far vision. A SCOPE is an optical instrument used to magnify distant objects.