Coloured and Neutral Density filters

An optical filter is a device which selectively transmits light having certain properties (often, a particular range of wavelengths, that is, range of colours of light), while blocking the remainder. They are commonly used in photography, in many optical instruments, and to colour stage lighting. Various coloured and ND filters; photo by User:DrBob File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Various coloured and ND filters; photo by User:DrBob File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... In telecommunications, transmission is the act of transmitting electrical messages (and the associated phenomena of radiant energy that passes through media). ... The wavelength is the distance between repeating units of a wave pattern. ... Color is an important part of the visual arts. ... This article does not cite any references or sources. ... In photography, a filter is a camera accessory consisting of an optical filter that can be inserted in the optical path. ... See also list of optical topics. ... This is a current Stagecraft collaboration! Please help improve it to good article standard. ...

Absorptive

Absorptive filters are usually made from glass to which various inorganic or organic compounds have been added. These compounds absorb some wavelengths of light while transmitting others. The compounds can also be added to plastic (often polycarbonate or acrylic) to produce gel filters, which are lighter and cheaper than glass-based filters. Glass can be made transparent and flat, or into other shapes and colors as shown in this sphere from the Verrerie of Brehat in Brittany. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ... Organic chemistry is a specific discipline within chemistry which involves the scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of chemical compounds consisting of primarily carbon and hydrogen, which may contain any number of other elements, including nitrogen, oxygen, halogens as well... Absorption, in optics, is the process by which the energy of a photon is taken up by another entity, for example, by an atom whose valence electrons make a transition between two electronic energy levels. ... This article or section does not cite any references or sources. ... Polycarbonates are a particular group of thermoplastic polyesters. ... Structure of methyl methacrylate, the monomer that makes up PMMA Polymethyl methacrylate (PMMA) or poly(methyl 2-methylpropenoate) is the synthetic polymer of methyl methacrylate. ... A color gel or color filter (US color gel or color filter), or a lighting gel or simply gel, is a transparent colored material that is used in theatre, event production, photography, videography and cinematography to colour light and for color correction. ...

Dichroic filter

Alternately, dichroic filters (also called "reflective" or "thin film" filters) can be made by coating a glass substrate with a series of optical coatings. Dichroic filters usually reflect the unwanted portion of the light and transmit the remainder. Dichroic filters A dichroic filter or thin-film filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. ... An optical coating is a thin layer of material placed on an optical component such as a lens or mirror which alters the way in which the optic reflects and transmits light. ...

Dichroic filters are particularly suited for precise scientific work, since their exact color range can be controlled by the thickness and sequence of the coatings. They are usually much more expensive and delicate than absorption filters.

They can be used in devices such as the dichroic prism of a camera to separate a beam of light into different coloured components. A dichroic prism is a prism that splits light into two beams of differing wavelength (colour). ... Large format camera lens. ...

Dichroic filters' films form a sequential series of reflective cavities that resonate with the desired wave lengths. Other wavelengths destructively cancel or reflect as the peaks and troughs of the waves overlap.

The basic scientific instrument of this type is a Fabry-Pérot interferometer. It uses two mirrors to establish a resonating cavity. It passes wavelengths that are a multiple of the cavity's resonant frequency. In optics, a Fabry-Pérot interferometer or etalon is typically made of a transparent plate with two reflecting surfaces, or two parallel highly reflecting mirrors. ...

Etalons are another variation: transparent cubes or fibers whose polished ends form mirrors tuned to resonate with specific wavelengths. These are often used to separate channels in telecommunications networks that use wavelength division multiplexing on long-haul optic fibers. In optics, a Fabry-Perot interferometer or etalon is typically made of a transparent plate with two reflecting surfaces, or two parallel highly-reflecting mirrors. ... Telecommunication involves the transmission of signals over a distance for the purpose of communication. ... // Look up network in Wiktionary, the free dictionary. ... In telecommunications wavelength division multiplexing (WDM) is a technology which multiplexes several optical carrier signals on a single optical fibre by using different wavelengths (colours) of laser light to carry different signals. ... Fiber Optic strands An optical fiber in American English or fibre in British English is a transparent thin fiber for transmitting light. ...

Monochromatic

Monochromatic filters only allow a narrow range of wavelengths (that is, a single colour) to pass. A photograph of a sign in grayscale The same photograph in black and white Monochrome comes from the two Greek words mono (μωνο, meaning one), and chroma (χρωμα, meaning surface or the color of the skin). A monochromatic object has a single color. ...

Infrared

Infrared (IR) or heat-absorbing filters are designed to block mid-infrared wavelengths but pass visible light. They are often used in devices with bright incandescent light bulbs (such as slide and overhead projectors) to prevent unwanted heating. There are also near-infrared filters which are used in solid state video cameras to compensate for the high sensitivity of many camera sensors to near-infrared light. Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ... An incandescent lamp bulb and its glowing filament. ... [carousel slide projector, the most common form of projector] A slide projector is an opto-mechanical device to view photographic slides. ... An overhead projector is a display system that is used to display images to an audience. ... In electronics, solid state circuits are those that do not contain vacuum tubes. ... A specially developed CCD used for ultraviolet imaging in a wire bonded package. ...

Ultraviolet

Advanced Image Quality Space-Qualified Ultraviolet Interference Filter (Courtesy-NASA/JPL/Caltech)

Ultraviolet (UV) filters block ultraviolet radiation, but let visible light through. Because photographic film and digital sensors are sensitive to ultraviolet (which is abundant in skylight) but the human eye is not, such light would, if not filtered out, make photographs look different from the scene that the photographer saw. This causes images of distant mountains to appear hazy. By attaching a filter to remove ultraviolet, photographers can produce pictures that more closely resemble the scene as seen by a human eye. ImageMetadata File history File links Under a Small Business Innovation Research (SBIR) contract to Jet Propulsion Laboratory, Barr Associates developed advanced image quality space-qualified ultraviolet (UV) interference filters. ... ImageMetadata File history File links Under a Small Business Innovation Research (SBIR) contract to Jet Propulsion Laboratory, Barr Associates developed advanced image quality space-qualified ultraviolet (UV) interference filters. ...

Neutral density

Neutral density (ND) filters have a constant attenuation across the range of visible wavelengths, and are used to reduce the intensity of light by reflecting or absorbing a portion of it. They are specified by the optical density (OD) of the filter, which is the negative of the common logarithm of the transmission coefficient. They are useful for making photographic exposures longer. A practical example is making a waterfall look blurry when it's photographed in bright light. Alternatively, the photographer might want to use a larger aperture (so as to limit the depth of field); adding an ND filter permits this. ND filters can be reflective (in which case they look like partially-reflective mirrors) or absorptive (appearing grey or black). In photography and optics, a neutral density filter or ND filter is a grey filter;. In theory, a neutral density filter reduces light of all wavelengths or colors equally, much like inexpensive sunglasses. ... Optical density is the absorbance of an optical element for a given wavelength λ per unit distance: Where: = the distance that light travels through the sample (i. ... Logarithms to various bases: is to base e, is to base 10, and is to base 1. ... This article is about the transmission coefficient in optics. ... In optics, particularly film and photography, the depth of field (DOF) is the distance in front of and beyond the subject that appears to be in focus. ...

Longpass

A longpass (LP) Filter is an optical interference or coloured glass filter that attenuates shorter wavelengths and transmits (passes) longer wavelengths over the active range of the target spectrum (ultraviolet, visible, or infrared). Longpass filters, which can have a very sharp slope (referred to as edge filters), are described by the cut-on wavelength at 50 percent of peak transmission. In fluorescence microscopy, longpass filters are frequently utilized in dichroic mirrors and barrier (emission) filters. Use of the older term of highpass to describe longpass filters is now discouraged because it more accurately refers to frequency rather than wavelength.

Shortpass

A shortpass (SP) Filter is an optical interference or coloured glass filter that attenuates longer wavelengths and transmits (passes) shorter wavelengths over the active range of the target spectrum (usually the ultraviolet and visible region). In fluorescence microscopy, shortpass filters are frequently employed in dichromatic mirrors and excitation filters.

Bandpass

If we combine a LP filter and a SP filter we will get a Bandpass (BP) filter. These filters have usually lower transmittance values than SP and LP filters, and block all wavelengths outside of a selected interval, which can be wide or narrow, depending on the number of layers of the filter. In the fields of optics and spectroscopy, transmittance is the fraction of incident light at a specified wavelength that passes through a sample. ...

Polarizer

Another kind of optical filter is a polarizer or polarization filter, which blocks or transmits light according to its polarization. They are often made of materials such as Polaroid and are used for sunglasses and photography. Reflections, especially from water and wet road surfaces, are partially polarized, and polarized sunglasses will block some of this reflected light, allowing an angler to better view below the surface of the water and better vision for a driver. Light from a clear blue sky is also polarized, and adjustable filters are used in colour photography to darken the appearance of the sky without introducing colours to other objects, and in both colour and black-and-white photography to control specular reflections from objects and water. A polarizer is a device that converts an unpolarized or mixed-polarization beam of electromagnetic waves (e. ... In electrodynamics, polarization (also spelled polarisation) is the property of electromagnetic waves, such as light, that describes the direction of their transverse electric field. ... Polaroid is the name of a type of synthetic plastic sheet which is used to polarise light. ... Ray-Ban Wayfarer sunglasses (RB2132 901L) Sunglasses are a visual aid, variously termed spectacles or glasses, which feature lenses that are coloured or darkened to prevent strong light from reaching the eyes. ... Photography [fәtɑgrәfi:],[foʊtɑgrәfi:] is the process of recording pictures by means of capturing light on a light-sensitive medium, such as a film or sensor. ... Angling is a method of fishing, specifically the practice of catching fish by means of an angle (hook). ... Diagram of specular reflection Specular reflection is the perfect, mirror-like reflection of light from a surface, in which light from a single incoming direction is reflected onto a single outgoing direction. ...

Polarized filters are also used to view certain types of stereograms, so that each eye will see a distinct image from a single source. The Lake Palanskoye in northern Kamchatka was formed when a large landslide disrupted the drainage pattern, forming a natural dam. ...

See also

• Filter (photography)
• Filter (signal processing)
• Filter fluorometer
• Lyot filter
• Dichroic filter
• Dichroic prism
• Atomic line filter
• Warm filter

In photography, a filter is a camera accessory consisting of an optical filter that can be inserted in the optical path. ... In electronics and signal processing, a filter is a device or process that modifies a signal. ... A filter fluorometer is a type of fluorometer that may be employed in fluorescence spectroscopy. ... A Lyot filter, named for its inventor Bernard Lyot, is a type of optical filter that uses birefringence to produce a narrow passband of transmitted wavelengths. ... Dichroic filters A dichroic filter or thin-film filter is a very-accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. ... A dichroic prism is a prism that splits light into two beams of differing wavelength (colour). ... An atomic line filter, or ALF, (sometimes atomic resonance filter or ARF) is a class of optical band-pass filters used in the physical sciences for filtering light with great precision, accuracy and efficiency. ... A warm filter is a Photographic filter. ...

References