Cyclops' body is naturally immune to the beams' force. His mind projects a psionic field that envelops his body rendering it immune to his optic beam, allowing him to shut it off by simply closing his eyes. Scott is also immune to the power of his brother Alex (Havok) who has the ability to emit waves of energy that heat the air into plasma. Likewise Havok has demonstrated immunity to Cyclops' optic beam. Scott has been shown as being able to absorb Storm's lightning bolt, although this act caused Cyclops a great deal of pain. The ruby quartz used in his battle visor has been said to be resonate with his body's psionic field. Scott has only a limited resistance to his brother Vulcan's powers.
For all Cyclops' skill in manipulating his optic beam, it continuously projects from his eyes whenever they are open and unprotected. To prevent the destruction of any objects in his field of view, Cyclops uses a pair of ruby quartz eye glasses developed by Professor X to contain the devastating rays. In his X-Men uniform he uses a ruby quartz battle visor in place of the glasses. The crystal is said to resonate at the same frequency as the psionic field that protects Cyclops (and Havok) from their own powers. [volume & issue needed] His uniform has firing studs incorporated into his gloves and on the sides of the battle visor that control the visor's aperture. In the event that the visor has a power failure, the apertures are spring loaded to automatically close so Cyclops can at least see normally. He has also been observed using casual sunglasses and contact lenses made from the same ruby quartz as his visor lens.
Unforunately, the section on the ruby resonation has no volume/issue citation. This resonance is also referenced in SciFi.SE question. So somehow, this makes the visor also immune to the force blasts.