query: part_of optical filter
supports: Optical filters are devices that selectively transmit light of different wavelengths , usually implemented as plane glass or plastic devices in the optical path which are either dyed in the bulk or have interference coatings . The optical properties of filters are completely described by their frequency response , which specifies how the magnitude and phase of each frequency component of an incoming signal is modified by the filter . Filters mostly belong to one of two categories . The simplest , physically , is the absorptive filter ; then there are interference or dichroic filters . Optical filters selectively transmit light in a particular range of wavelengths , that is , colours , while blocking the remainder . They can usually pass long wavelengths only ( longpass ) , short wavelengths only ( shortpass ) , or a band of wavelengths , blocking both longer and shorter wavelengths ( bandpass ) . The passband may be narrower or wider ; the transition or cutoff between maximal and minimal transmission can be sharp or gradual . There are filters with more complex transmission characteristic , for example with two peaks rather than a single band ; these are more usually older designs traditionally used for photography ; filters with more regular characteristics are used for scientific and technical work . Optical filters are commonly used in photography ( where some special effect filters are occasionally used as well as absorptive filters ) , in many optical instruments , and to colour stage lighting . In astronomy optical filters are used to restrict light passed to the spectral band of interest , e.g. , to study infrared radiation without visible light which would affect film or sensors and overwhelm the desired infrared . Optical filters are also essential in fluorescence applications such as fluorescence microscopy and fluorescence spectroscopy . Photographic filters are a particular case of optical filters , and much of the material here applies . Photographic filters do not need the accurately controlled optical properties and precisely defined transmission curves of filters designed for scientific work , and sell in larger quantities at correspondingly lower prices than many laboratory filters . Some photographic effect filters , such as star effect filters , are not relevant to scientific work . Glass is a non-crystalline amorphous solid that is often transparent and has widespread practical, technological, and decorative usage in, for example, window panes, tableware, and optoelectronics. The most familiar, and historically the oldest, types of glass are "silicate glasses" based on the chemical compound silica (silicon dioxide, or quartz), the primary constituent of sand. The term "glass", in popular usage, is often used to refer only to this type of material, which is familiar from use as window glass and in glass bottles. Of the many silica-based glasses that exist, ordinary glazing and container glass is formed from a specific type called soda-lime glass, composed of approximately 75% silicon dioxide (SiO), sodium oxide (NaO) from sodium carbonate (NaCO), calcium oxide, also called lime (CaO), and several minor additives. Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. It is defined by size, being finer than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e. a soil containing more than 85% sand-sized particles by mass. Folded optics is an optical system in which the beam is bent in a way to make the optical path much longer than the size of the system. Prismatic binoculars are a well-known example. Quartz is the second most abundant mineral in Earth's continental crust, after feldspar. Its crystal structure is a continuous framework of SiO siliconoxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO. The path that light takes in traversing an optical is often called the optical path. The physical length of an optical device can be reduced to less than the length of the optical path by using folded optics. The optical path length as defined in optics is the length of the path multiplied by the index of refraction of the medium. A bottle is a rigid container with a neck that is narrower than the body and a mouth. By contrast, a jar has a relatively large mouth or opening which may be as wide as the overall container. Bottles are often made of glass, clay, plastic, aluminium or other impervious materials, and typically used to store liquids such as water, milk, soft drinks, beer, wine, cooking oil, medicine, shampoo, ink, and chemicals. A device applied in the bottling line to seal the mouth of a bottle is termed an external bottle cap, closure, or internal stopper. A bottle can also be sealed by a conductive "innerseal" by using induction sealing. Optoelectronics is the study and application of electronic devices and systems that source, detect and control light, usually considered a sub-field of photonics. In this context, "light" often includes invisible forms of radiation such as gamma rays, X-rays, ultraviolet and infrared, in addition to visible light. Optoelectronic devices are electrical-to-optical or optical-to-electrical transducers, or instruments that use such devices in their operation. 
  "Electro-optics" is often erroneously used as a synonym, but is a wider branch of physics that concerns all interactions between light and electric fields, whether or not they form part of an electronic device. Silicon dioxide, also known as silica (from the Latin "silex"), is a chemical compound that is an oxide of silicon with the chemical formula . It has been known since ancient times. Silica is most commonly found in nature as quartz, as well as in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing both as several minerals and being produced synthetically. Notable examples include fused quartz, crystal, fumed silica, silica gel, and aerogels. Applications range from structural materials to microelectronics to components used in the food industry. Carbon (from "coal") is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalentmaking four electrons available to form covalent chemical bonds. Three isotopes occur naturally, C and C being stable, while C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity. Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "lime" connotes calcium-containing inorganic materials, in which carbonates, oxides and hydroxides of calcium, silicon, magnesium, aluminium, and iron predominate. By contrast, "quicklime" specifically applies to the single chemical compound calcium oxide. Calcium oxide which survives processing without reacting in building products such as cement is called free lime. In condensed matter physics and materials science, an amorphous (from the Greek "a", without, "morphé", shape, form) or non-crystalline solid is a solid that lacks the long-range order that is characteristic of a crystal. In some older books, the term has been used synonymously with glass. Nowadays, "Glassy solid" or "Amorphous solid" is considered to be the overarching concept, and glass the more special case: A glass is an amorphous solid that exhibits a glass transition. Polymers are often amorphous. Other types of amorphous solids include gels, thin films, and nanostructured materials such as glass. In optics, optical path length (OPL) or optical distance is the product of the geometric length of the path light follows through the system, and the index of refraction of the medium through which it propagates. A difference in optical path length between two paths is often called the optical path difference (OPD). Optical path length is important because it determines the phase of the light and governs interference and diffraction of light as it propagates. 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. A window is an opening in a wall, door, roof or vehicle that allows the passage of light and, if not closed or sealed, air and sound. Tableware is the dishes or dishware used for setting a table, serving food and dining. It includes cutlery, glassware, serving dishes and other useful items for practical as well as decorative purposes. The quality, nature, variety and number of objects varies according to culture, religion, number of diners, cuisine and occasion. For example, Middle Eastern, Indian or Polynesian food culture and cuisine sometimes limits tableware to serving dishes, using bread or leaves as individual plates. Special occasions are usually reflected in higher quality tableware.
candidates: body building c class cooking cutlery door earth electronic food industry industry life mass may milk mouth nature optics order physics radiation rock science solid system variety vehicle wall window
answer: optics