Caustic (optics)
In optics, a caustic or caustic network is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface. The caustic is a curve or surface to which each of the light rays is tangent, defining a boundary of an envelope of rays as a curve of concentrated light. Therefore in the image to the right, the caustics can be the patches of light or their bright edges. These shapes often have cusp singularities.
Explanation
Concentration of light, especially sunlight, can burn. The word caustic, in fact, comes from the Greek καυστός, burnt, via the Latin causticus, burning. A common situation where caustics are visible is when light shines on a drinking glass. The glass casts a shadow, but also produces a curved region of bright light. In ideal circumstances (including perfectly parallel rays, as if from a point source at infinity), a nephroid-shaped patch of light can be produced. Rippling caustics are commonly formed when light shines through waves on a body of water.
Optics
Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.
Most optical phenomena can be accounted for using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be accounted for in geometric optics. Historically, the ray-based model of light was developed first, followed by the wave model of light. Progress in electromagnetic theory in the 19th century led to the discovery that light waves were in fact electromagnetic radiation.
Optical 88
Optical 88 (Chinese: 眼鏡88) is one of the famous eyewear stores in Hong Kong. It was established in 1984, as a member of Stelux Group of Companies, who owns largest professional optical retail network in Hong Kong.
Areas served
Optical 88's headquarters is located in Hong Kong (dispersed all over Hong Kong Island, Kowloon and the New Territories) while overseas stores are located at various countries and cities including Macau, Guangzhou, Singapore, Thailand and Malaysia etc.
Products and Services
Optical 88's key products are eyeglasses, including sunglasses and the frames and lenses of these glasses. They mainly provide customers eyeglasses-making services and Eye examination services.
See also
References
External links
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