X-ray

X-rays are a type of electromagnetic radiation used to see through a solid object.

Medical practitioners, such as doctors or nurses, use this type of radiation to get a look at the internal anatomy of a person. This makes bones visible.

Superman has a special sight ability called x-ray vision, which is similar to x-rays but not quite as limited. Although lead still can block his vision just like regular x-rays.

The Raven used his spacecraft to blind Superman with a smokescreen of mirror-type photons, which blocked his x-rays.

External Link

 * X-ray at Wikipedia