What is a Parabolic Mirror?

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Parabolic mirror

A Parabolic Mirror (reflector or dish) is a reflective device used to collect energy such as light, sound or radio waves. Its shape is that of a circular paraboloid , that is the surface generated by a parabola (conic section, which is a curve obtained by intersecting a cone with any flat 2 dimensional surface) revolving around its axis. A paraboloid is a particular kind of 3 dimensional surface. The parabolic mirror transforms an incoming plane (constant frequency) wave traveling along the axis into a spherical wave and focuses it to a single point.  A spherical wave is any wave for which the surface of constant phase is sphere.


What is the historical background of Parabolic Mirrors?

The principle of parabolic mirror has been known since the 3rd century BC when You do not have access to view this node, a Greek mathematician studied paraboloids as part of his study of hydrostatic equilibrium. Parabolic mirrors were also studied by the physicict, Ibn Sahl, in the 10th century. One of the earliest uses of the parabolic mirror was in Issac Newton’s reflecting telescope of the 17th century. Light houses also commonly used parabolic mirrors to collimate a point of light from the lantern into a beam, before being replaced by more efficient Fresnel lenses (a type of lenses) in the 19th century.


What are parabolic Mirrors made of?

Parabolic mirrors are usually made of a low expansion glass, similar to Pyrex glass. The mirrors are kept as fine as possible to reduce distortion in the image. The processes used to produce extremely high-end parabolic mirrors can take months and cost thousands of dollars.


What is the theory behind Parabolic Mirrors?

Parabolic reflectors are used to collect energy from a distant source (for instance, sound waves) and bring it to common focal point. The parabolic reflector or mirror functions due to the geometric properties of the paraboloid shape: if the angle of incidence to the inner surface of the collector equals the angle of reflection, then any incoming ray that is parallel to the axis of the dish will be reflected to a central point. Since many types of energy can be reflected in this way, parabolic reflectors can be used to collect and concentrate energy entering the reflector at a particular angle. Similarly, energy radiating from the “focus” to the dish can be transmitted outward in a beam that is parallel to the axis of the dish. However, with the use of parabolic mirrors, some other problems are created. This includes a problem called ‘coma’, which exists in all telescopes using parabolic mirrors to collect focus and light. Coma causes any objects viewed through the telescopes which are not at the center of the field of vision to look slightly wedge-shaped. The further outside the field they are, the more imprecise they appear.


How does a parabolic mirror work with optical illusion look like?

Many people have interacted with a parabolic mirror in the form of popular optical illusion toy. Optical illusions is any instance where the information gathered by the human eye is translated in the brain in such a  way that a visual illusion of some type of results. An optical illusion may be used in a number of different applications including toys which uses the visual illusion of some type of results in brain. The small pan  has 2 parabolic mirrors attached to one another and a hole on top to allow placement of a small object. When an object is placed between the 2 parabolic mirrors, it appears that the object is in fact resting in the air a few inches above where it is actually is. 


What are the Applications of parabolic Mirror?

  • The most common modern applications of the parabolic reflector are in satellite dishes, reflecting telescopes, radio telescopes, parabolic microphones and many lighting devices such as spot lights and car headlights.
  • The Olympic Flame has been lit using a parabolic reflector concentrating sunlight.
  • Parabolic reflectors are a popular alternative for increasing wireless signal strength. Even with the simple ones, users have reported more gains.
  • A most likely fictional tradition has it that parabolic mirrors have been used in the past as a way of gathering sunlight to spontaneously ignite enemy ships, or heat up the armor of the enemy to a point where they were forced to remove it
  • Parabolic reflectors are also used in solar cookers and water heaters, as they are very expensive to manufacture and need very little by way of maintenance. 


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