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Interference Filter
An interference filter, dichroic filter, or thin-film filter is an optical filter that Reflection (physics), reflects some wavelengths (colors) of light and transmits others, with almost no absorption (optics), absorption for all wavelengths of interest. An interference filter may be high-pass, low-pass, bandpass, or band-rejection. They are used in scientific applications, as well as in Architectural lighting design, architectural and theatrical lighting. An interference filter consists of multiple thin layers of dielectric material having different refractive indices. There may also be metallic layers. Interference filters are wavelength-selective by virtue of the Interference (wave propagation), interference effects that take place between the incident and reflected waves at the thin-film boundaries. The principle of operation is similar to a Fabry-Perot etalon. Dichroic mirrors and dichroic reflectors are the same type of device, but are characterized by the colors of light t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interference (wave Propagation)
In physics, interference is a phenomenon in which two coherent waves are combined by adding their intensities or displacements with due consideration for their phase difference. The resultant wave may have greater amplitude (constructive interference) or lower amplitude (destructive interference) if the two waves are in phase or out of phase, respectively. Interference effects can be observed with all types of waves, for example, light, radio, acoustic, surface water waves, gravity waves, or matter waves as well as in loudspeakers as electrical waves. Etymology The word ''interference'' is derived from the Latin words ''inter'' which means "between" and ''fere'' which means "hit or strike", and was used in the context of wave superposition by Thomas Young in 1801. Mechanisms The principle of superposition of waves states that when two or more propagating waves of the same type are incident on the same point, the resultant amplitude at that point is equal to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perception
Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system, which in turn result from physical or chemical stimulation of the sensory system.Goldstein (2009) pp. 5–7 Vision involves light striking the retina of the eye; smell is mediated by odor molecules; and hearing involves pressure waves. Perception is not only the passive receipt of these signals, but it is also shaped by the recipient's learning, memory, expectation, and attention. Gregory, Richard. "Perception" in Gregory, Zangwill (1987) pp. 598–601. Sensory input is a process that transforms this low-level information to higher-level information (e.g., extracts shapes for object recognition). The following process connects a person's concepts and expectations (or knowledge) with restorative and selective mechanisms, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichroism
In optics, a dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths (colours) (not to be confused with Dispersion (optics), dispersion), or one in which light rays having different Polarization (waves), polarizations are absorbed by different amounts. In beam splitters The original meaning of ''dichroic'', from the Greek language, Greek ''dikhroos'', two-coloured, refers to any optical device which can split a beam of light into two beams with differing wavelengths. Such devices include mirrors and dichroic filter, filters, usually treated with optical coatings, which are designed to reflect light over a certain range of wavelengths and transmit light which is outside that range. An example is the dichroic prism, used in some camcorders, which uses several coatings to split light into red, green and blue components for recording on separate charge-coupled device, CCD arrays, however it is now more common to have a Ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichroic Prism
A dichroic prism is a prism (optics), prism that splits light into two beams of differing wavelength, wavelengths (colour). A trichroic prism assembly combines two dichroic prisms to split an image into 3 colours, typically as red, green and blue of the RGB colour model. They are usually constructed of one or more glass prisms with dichroism, dichroic optical coatings that selectively reflect or transmit light depending on the light's wavelength. That is, certain surfaces within the prism act as dichroic filters. These are used as beam splitters in many optical instruments. (See: Dichroism, for the etymology of the term.) Applications in camcorders or digital cameras One common application of dichroic prisms is in some camcorders and high-quality digital cameras. A ''trichroic prism assembly'' is a combination of two dichroic prisms which are used to split an image into red, green, and blue components, which can be separately detected on three charge-coupled device, CCD arrays. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Professional Video Camera
A professional video camera (often called a television camera even though its use has spread beyond television) is a high-end device for creating electronic moving images (as opposed to a movie camera, that earlier recorded the images on film). Originally developed for use in television studios or with outside broadcast trucks, they are now also used for music videos, direct-to-video movies (see digital movie camera), corporate and educational videos, wedding videos, among other uses. Since the 2000s, most professional video cameras are digital (instead of analog). The distinction between professional video cameras and movie cameras narrowed as HD digital video cameras with sensors the same size as 35mm movie cameras - plus dynamic range ( exposure latitude) and color rendition approaching film quality - were introduced in the late 2010s. Nowadays, HDTV cameras designed for broadcast television, news, sports, events and other works such as reality TV are termed as professional ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video Projector
A video projector is an image projector that receives a video signal and projects the corresponding image onto a projection screen using a lens system. Video projectors use a very bright ultra-high-performance lamp (a special mercury arc lamp), Xenon arc lamp, metal halide lamp, LED or solid state blue, RB, RGB or fiber-optic lasers to provide the illumination required to project the image. Most modern projectors can correct any curves, blurriness and other inconsistencies through manual settings. Video projectors are used for many applications such as conference room presentations, classroom training, home cinema, movie theaters, and concerts, having mostly replaced overhead, slide and conventional film projectors. In schools and other educational settings, they are sometimes connected to an interactive whiteboard. In the late 20th century, they became commonplace in home cinema. Although large LCD television screens became quite popular, video projectors are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visible Spectrum
The visible spectrum is the spectral band, band of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' (or simply light). The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well, known collectively as ''optical radiation''. A typical human eye will respond to wavelengths from about 380 to about 750 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 400–790 Terahertz (unit), terahertz. These boundaries are not sharply defined and may vary per individual. Under optimal conditions, these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared). The spectrum does not contain all the colors that the human visual system can distinguish. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fabry–Pérot Interferometer
In optics, a Fabry–Pérot interferometer (FPI) or etalon is an optical cavity made from two parallel reflecting surfaces (i.e.: thin mirrors). Optical waves can pass through the optical cavity only when they are in resonance with it. It is named after Charles Fabry and Alfred Perot, who developed the instrument in 1899. ''Etalon'' is from the French ''étalon'', meaning "measuring gauge" or "standard". Etalons are widely used in telecommunications, lasers and spectroscopy to control and measure the wavelengths of light. Recent advances in fabrication technique allow the creation of very precise tunable Fabry–Pérot interferometers. The device is technically an interferometer when the distance between the two surfaces (and with it the resonance length) can be changed, and an etalon when the distance is fixed (however, the two terms are often used interchangeably). Basic description The heart of the Fabry–Pérot interferometer is a pair of partially reflective glass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Passband
A passband is the range of frequency, frequencies or wavelengths that can pass through a Filter (signal processing), filter. For example, a radio receiver contains a bandpass filter to select the frequency of the desired radio signal out of all the radio waves picked up by its antenna. The passband of a receiver is the range of frequencies it can receive when it is tuned into the desired frequency as in a radio station or television channel. A band-pass filter, bandpass-filtered signal (that is, a signal with energy only in a passband), is known as a bandpass signal, in contrast to a baseband signal. The bandpass filter usually has two stopband, band-stop filters. Filters In telecommunications, optics, and acoustics, a passband (a band-pass filtered signal) is the portion of the frequency spectrum that is transmitted (with minimum relative loss or maximum relative Gain (electronics), gain) by some filtering device. In other words, it is a ''band'' of frequencies which ''pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency
Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light. The interval of time between events is called the period. It is the reciprocal of the frequency. For example, if a heart beats at a frequency of 120 times per minute (2 hertz), its period is one half of a second. Special definitions of frequency are used in certain contexts, such as the angular frequency in rotational or cyclical properties, when the rate of angular progress is measured. Spatial frequency is defined for properties that vary or cccur repeatedly in geometry or space. The unit of measurement of frequency in the International System of Units (SI) is the hertz, having the symbol Hz. Definitions and units For cyclical phenomena such as oscillations, waves, or for examp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Deposition
Vacuum deposition is a group of processes used to deposit layers of material atom-by-atom or molecule-by-molecule on a solid surface. These processes operate at pressures well below atmospheric pressure (i.e., vacuum). The deposited layers can range from a thickness of one atom up to millimeters, forming freestanding structures. Multiple layers of different materials can be used, for example to form optical coatings. The process can be qualified based on the vapor source; physical vapor deposition uses a liquid or solid source and chemical vapor deposition uses a chemical vapor. Description The vacuum environment may serve one or more purposes: * reducing the particle density so that the mean free path for collision is long * reducing the particle density of undesirable atoms and molecules (contaminants) * providing a low pressure plasma environment * providing a means for controlling gas and vapor composition * providing a means for mass flow control into the processing chambe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
