reflector

A reflector is a surface or device designed to redirect electromagnetic, acoustic, or optical radiation by reflection. Reflectors are used to control the distribution of light, sound, or radio energy, improve efficiency, or create specific imaging and sensing effects. They can be passive components in lamps and antennas or independent devices in optical or RF systems.

Optical reflectors include mirrors and the reflectors used in telescopes, projectors, and illumination fixtures. A common type is the parabolic reflector, which focuses incoming parallel rays to a focal point, or a dish-shaped reflector that directs energy into a feed. In radio and radar, reflector designs such as parabolic dishes and corner reflectors serve to concentrate signals or to enhance detectability by reflecting signals back toward the source. Acoustic reflectors shape sound fields in rooms and in ultrasonic or sonar contexts, where reflective surfaces influence imaging and measurement.

The performance of a reflector depends on geometry, surface quality, and coating. The law of reflection governs the direction of specular reflection, while diffuse reflectors scatter light in many directions. Reflective coatings—silver or aluminum on glass for optical mirrors, or metal platings for RF reflectors—raise reflectivity across wavelength ranges; dielectric coatings can tailor spectral response. Material choice and finish determine reflectivity, durability, and environmental resistance.

Historically, reflectors range from polished metals in ancient times to silvered glass mirrors in the 19th century. Today, reflectors are integral to lighting fixtures, automotive headlights, satellite dishes, radio telescopes, and radar systems. In summary, a reflector redirects energy through reflection to achieve desired optical, acoustic, or RF performance.