Infrared

context: Infrared radiation is used in industrial, scientific, and medical applications. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected. Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space, such as molecular clouds; detect objects such as planets, and to view highly red-shifted objects from the early days of the universe. Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatus.
qas: answers: text: active near-infrared illumination
question: What technology is used by night-vision devices?

answers: text: Infrared astronomy
question: What discipline uses infrared telescopes to see through molecular clouds?

answers: text: red
question: What color shift indicates that space objects date from the early days of the universe?

answers: text: Infrared thermal-imaging cameras
question: What devices are used to observe insulated system heat loss?

answers: text: scientific
question: Along with industrial and medical, in what applications is infrared radiation used?

context: The onset of infrared is defined (according to different standards) at various values typically between 700 nm and 800 nm, but the boundary between visible and infrared light is not precisely defined. The human eye is markedly less sensitive to light above 700 nm wavelength, so longer wavelengths make insignificant contributions to scenes illuminated by common light sources. However, particularly intense near-IR light (e.g., from IR lasers, IR LED sources, or from bright daylight with the visible light removed by colored gels) can be detected up to approximately 780 nm, and will be perceived as red light. Sources providing wavelengths as long as 1050 nm can be seen as a dull red glow in intense sources, causing some difficulty in near-IR illumination of scenes in the dark (usually this practical problem is solved by indirect illumination). Leaves are particularly bright in the near IR, and if all visible light leaks from around an IR-filter are blocked, and the eye is given a moment to adjust to the extremely dim image coming through a visually opaque IR-passing photographic filter, it is possible to see the Wood effect that consists of IR-glowing foliage.
qas: answers: text: 700 nm
question: At what wavelength does the human eye become significantly less sensitive to light?

answers: text: near-IR
question: What sort of light is generated by IR lasers?

answers: text: 780 nm
question: Up to what wavelength does the human eye perceive IR LED sources as red?

answers: text: 1050 nm
question: Up to what wavelength does the human eye perceive certain intense lights as being dull red in color?

answers: text: Leaves
question: What objects are notably bright in near IR?

context: The concept of emissivity is important in understanding the infrared emissions of objects. This is a property of a surface that describes how its thermal emissions deviate from the ideal of a black body. To further explain, two objects at the same physical temperature will not show the same infrared image if they have differing emissivity. For example, for any pre-set emissivity value, objects with higher emissivity will appear hotter, and those with a lower emissivity will appear cooler. For that reason, incorrect selection of emissivity will give inaccurate results when using infrared cameras and pyrometers.
qas: answers: text: emissivity
question: What is the term for the property that describes how a surface's thermal emissions deviate from the ideal of a black body?

answers: text: hotter
question: How will the infrared image of an object with a higher emissivity appear in relation to one with lower emissivity?

answers: text: infrared cameras
question: Along with pyrometers, what devices can receive inaccurate results if emissivity is not set correctly?

context: Infrared vibrational spectroscopy (see also near-infrared spectroscopy) is a technique that can be used to identify molecules by analysis of their constituent bonds. Each chemical bond in a molecule vibrates at a frequency characteristic of that bond. A group of atoms in a molecule (e.g., CH2) may have multiple modes of oscillation caused by the stretching and bending motions of the group as a whole. If an oscillation leads to a change in dipole in the molecule then it will absorb a photon that has the same frequency. The vibrational frequencies of most molecules correspond to the frequencies of infrared light. Typically, the technique is used to study organic compounds using light radiation from 4000–400 cm−1, the mid-infrared. A spectrum of all the frequencies of absorption in a sample is recorded. This can be used to gain information about the sample composition in terms of chemical groups present and also its purity (for example, a wet sample will show a broad O-H absorption around 3200 cm−1).
qas: answers: text: Infrared vibrational spectroscopy
question: What is the technique that analyzes the constituent bonds of molecules to identify them?

answers: text: it will absorb a photon that has the same frequency
question: What happens to a molecule if an oscillation results in a dipole being changed?

answers: text: the frequencies of infrared light
question: What do the vibrational frequencies of molecules usually correspond to?

answers: text: the mid-infrared
question: What is the term for light radiation in the 4000–400 cm−1 spectrum?

context: In infrared photography, infrared filters are used to capture the near-infrared spectrum. Digital cameras often use infrared blockers. Cheaper digital cameras and camera phones have less effective filters and can "see" intense near-infrared, appearing as a bright purple-white color. This is especially pronounced when taking pictures of subjects near IR-bright areas (such as near a lamp), where the resulting infrared interference can wash out the image. There is also a technique called 'T-ray' imaging, which is imaging using far-infrared or terahertz radiation. Lack of bright sources can make terahertz photography more challenging than most other infrared imaging techniques. Recently T-ray imaging has been of considerable interest due to a number of new developments such as terahertz time-domain spectroscopy.
qas: answers: text: infrared filters
question: What is used in infrared photography to capture the near-infrared spectrum?

answers: text: Digital cameras
question: What devices are often equipped with infrared blockers?

answers: text: 'T-ray' imaging
question: What is the technique that involves imaging with terahertz radiation?

answers: text: far-infrared
question: What is another name for terahertz radiation?

answers: text: terahertz time-domain spectroscopy
question: What is a notable recent development in T-ray imaging?

context: Infrared reflectography (fr; it; es), as called by art conservators, can be applied to paintings to reveal underlying layers in a completely non-destructive manner, in particular the underdrawing or outline drawn by the artist as a guide. This often reveals the artist's use of carbon black, which shows up well in reflectograms, as long as it has not also been used in the ground underlying the whole painting. Art conservators are looking to see whether the visible layers of paint differ from the underdrawing or layers in between – such alterations are called pentimenti when made by the original artist. This is very useful information in deciding whether a painting is the prime version by the original artist or a copy, and whether it has been altered by over-enthusiastic restoration work. In general, the more pentimenti the more likely a painting is to be the prime version. It also gives useful insights into working practices.
qas: answers: text: Infrared reflectography
question: What technique is used in art to examine underlying layers of a painting without damaging it?

answers: text: carbon black
question: What shows up particularly well in reflectograms?

answers: text: pentimenti
question: What is the term for differences in the painting and underdrawing made by the original artist?

context: The discovery of infrared radiation is ascribed to William Herschel, the astronomer, in the early 19th century. Herschel published his results in 1800 before the Royal Society of London. Herschel used a prism to refract light from the sun and detected the infrared, beyond the red part of the spectrum, through an increase in the temperature recorded on a thermometer. He was surprised at the result and called them "Calorific Rays". The term 'Infrared' did not appear until late in the 19th century.
qas: answers: text: William Herschel
question: Who discovered infrared radiation?

answers: text: the Royal Society of London
question: To whom did Herschel present his work on infrared radiation?

answers: text: 1800
question: In what year did Herschel publish his work on infrared radiation?

answers: text: a prism
question: What device did Herschel use to discover the infrared?

answers: text: Calorific Rays
question: What did Herschel call the infrared spectrum?

context: Infrared radiation is popularly known as "heat radiation"[citation needed], but light and electromagnetic waves of any frequency will heat surfaces that absorb them. Infrared light from the Sun accounts for 49% of the heating of Earth, with the rest being caused by visible light that is absorbed then re-radiated at longer wavelengths. Visible light or ultraviolet-emitting lasers can char paper and incandescently hot objects emit visible radiation. Objects at room temperature will emit radiation concentrated mostly in the 8 to 25 µm band, but this is not distinct from the emission of visible light by incandescent objects and ultraviolet by even hotter objects (see black body and Wien's displacement law).
qas: answers: text: heat radiation
question: What is a commonly used term for infrared radiation?

answers: text: 49%
question: What percentage of the Earth's heat is derived from the Sun's infrared light?

answers: text: 8 to 25
question: What is the common range of emitted radiation of room temperature objects, in micrometers? 

answers: text: visible
question: Other than infrared light, what type of light is responsible for heating the Earth?

context: Infrared tracking, also known as infrared homing, refers to a passive missile guidance system, which uses the emission from a target of electromagnetic radiation in the infrared part of the spectrum to track it. Missiles that use infrared seeking are often referred to as "heat-seekers", since infrared (IR) is just below the visible spectrum of light in frequency and is radiated strongly by hot bodies. Many objects such as people, vehicle engines, and aircraft generate and retain heat, and as such, are especially visible in the infrared wavelengths of light compared to objects in the background.
qas: answers: text: Infrared tracking
question: What is another term for infrared homing?

answers: text: Missiles
question: What devices make use of infrared homing?

answers: text: heat-seekers
question: What is a common name for missiles that make use of infrared seeking?

answers: text: vehicle engines
question: Along with aircraft and people, what objects notably create and retain heat?

answers: text: infrared
question: What does IR stand for?

context: High, cold ice clouds such as Cirrus or Cumulonimbus show up bright white, lower warmer clouds such as Stratus or Stratocumulus show up as grey with intermediate clouds shaded accordingly. Hot land surfaces will show up as dark-grey or black. One disadvantage of infrared imagery is that low cloud such as stratus or fog can be a similar temperature to the surrounding land or sea surface and does not show up. However, using the difference in brightness of the IR4 channel (10.3–11.5 µm) and the near-infrared channel (1.58–1.64 µm), low cloud can be distinguished, producing a fog satellite picture. The main advantage of infrared is that images can be produced at night, allowing a continuous sequence of weather to be studied.
qas: answers: text: Cumulonimbus
question: Along with Cirrus, what types of clouds are cold and high?

answers: text: white
question: What color do Cirrus clouds appear in infrared?

answers: text: Stratocumulus
question: Along with Stratus, what clouds are lower and warmer?

answers: text: grey
question: What color are Strarus clouds in infrared?

answers: text: 1.58–1.64
question: What is the range of the near-infrared channel in micrometers?

context: The sensitivity of Earth-based infrared telescopes is significantly limited by water vapor in the atmosphere, which absorbs a portion of the infrared radiation arriving from space outside of selected atmospheric windows. This limitation can be partially alleviated by placing the telescope observatory at a high altitude, or by carrying the telescope aloft with a balloon or an aircraft. Space telescopes do not suffer from this handicap, and so outer space is considered the ideal location for infrared astronomy.
qas: answers: text: water vapor in the atmosphere
question: What limits the sensitivity of infrared telescopes on Earth?

answers: text: at a high altitude
question: To somewhat avoid the water vapor in the atmosphere, where can an observatory be sited?

answers: text: balloon
question: Along with aircraft, what object can be used to carry a telescope aloft?

answers: text: Space telescopes
question: What sorts of telescopes completely avoid water vapor in Earth's atmosphere?

context: Near-infrared is the region closest in wavelength to the radiation detectable by the human eye, mid- and far-infrared are progressively further from the visible spectrum. Other definitions follow different physical mechanisms (emission peaks, vs. bands, water absorption) and the newest follow technical reasons (the common silicon detectors are sensitive to about 1,050 nm, while InGaAs's sensitivity starts around 950 nm and ends between 1,700 and 2,600 nm, depending on the specific configuration). Unfortunately, international standards for these specifications are not currently available.
qas: answers: text: Near-infrared
question: What is the nearest wavelength to the radiation that a human eye can see?

answers: text: water absorption
question: Along with the emission peaks and vs. bands mechanisms, what other physical mechanism is used to define near-infrared?

answers: text: 1,050
question: In micrometers, when do common silicon detectors cease to be sensitive?

answers: text: 950
question: What is the lowest level of sensitivity, in micrometers, for InGaAs?

context: Heat is energy in transit that flows due to temperature difference. Unlike heat transmitted by thermal conduction or thermal convection, thermal radiation can propagate through a vacuum. Thermal radiation is characterized by a particular spectrum of many wavelengths that is associated with emission from an object, due to the vibration of its molecules at a given temperature. Thermal radiation can be emitted from objects at any wavelength, and at very high temperatures such radiations are associated with spectra far above the infrared, extending into visible, ultraviolet, and even X-ray regions (i.e., the solar corona). Thus, the popular association of infrared radiation with thermal radiation is only a coincidence based on typical (comparatively low) temperatures often found near the surface of planet Earth.
qas: answers: text: Heat
question: What is the term for transit energy flowing as a result of differences in temperature?

answers: text: thermal radiation
question: What type of heat transmission can propagate through a vacuum?

answers: text: the solar corona
question: What object emits thermal radiation in the X-ray spectrum?

answers: text: infrared
question: The visible, ultraviolet and X-ray spectra are all above what spectrum?

context: Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 μm) and produce images of that radiation. Since infrared radiation is emitted by all objects based on their temperatures, according to the black body radiation law, thermography makes it possible to "see" one's environment with or without visible illumination. The amount of radiation emitted by an object increases with temperature, therefore thermography allows one to see variations in temperature (hence the name).
qas: answers: text: 0.9–14
question: What is the range of the electromagnetic spectrum in micrometers?

answers: text: 900–14,000
question: In nanometers, what is the electromagnetic spectrum's range?

answers: text: the black body radiation law
question: What law states that infrared radiation is emitted by objects based on temperature?

answers: text: increases
question: What happens to the amount of radiation an object emits as temperature increases?

answers: text: Thermographic
question: What type of cameras see infrared radiation?

context: The infrared portion of the spectrum has several useful benefits for astronomers. Cold, dark molecular clouds of gas and dust in our galaxy will glow with radiated heat as they are irradiated by imbedded stars. Infrared can also be used to detect protostars before they begin to emit visible light. Stars emit a smaller portion of their energy in the infrared spectrum, so nearby cool objects such as planets can be more readily detected. (In the visible light spectrum, the glare from the star will drown out the reflected light from a planet.)
qas: answers: text: imbedded stars
question: What irradiates clouds of gas in the galaxy and makes them glow?

answers: text: protostars
question: What can be detected via infrared prior to their emitting visible light?

answers: text: Stars
question: What objects emit less of their energy as infrared light versus visible light?

context: Infrared is used in night vision equipment when there is insufficient visible light to see. Night vision devices operate through a process involving the conversion of ambient light photons into electrons that are then amplified by a chemical and electrical process and then converted back into visible light. Infrared light sources can be used to augment the available ambient light for conversion by night vision devices, increasing in-the-dark visibility without actually using a visible light source.
qas: answers: text: night vision
question: What sort of equipment uses the infrared spectrum in the absence of sufficient visible light?

answers: text: electrons
question: What do night vision devices convert ambient light photons into?

answers: text: electrical
question: Along with a chemical process, what type of process is used by night vision devices to convert infrared into visible light?

context: IR data transmission is also employed in short-range communication among computer peripherals and personal digital assistants. These devices usually conform to standards published by IrDA, the Infrared Data Association. Remote controls and IrDA devices use infrared light-emitting diodes (LEDs) to emit infrared radiation that is focused by a plastic lens into a narrow beam. The beam is modulated, i.e. switched on and off, to encode the data. The receiver uses a silicon photodiode to convert the infrared radiation to an electric current. It responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly changing infrared radiation from ambient light. Infrared communications are useful for indoor use in areas of high population density. IR does not penetrate walls and so does not interfere with other devices in adjoining rooms. Infrared is the most common way for remote controls to command appliances. Infrared remote control protocols like RC-5, SIRC, are used to communicate with infrared.
qas: answers: text: the Infrared Data Association
question: What is the IrDA?

answers: text: light-emitting diodes
question: What does the acronym LEDs stand for?

answers: text: modulated
question: What is a term for when something is switched on and off?

answers: text: silicon photodiode
question: What device is used to transform infrared radiation into an electric current?

answers: text: IR does not penetrate walls
question: Why does infrared not cause trouble for devices in adjacent rooms?

context: In the semiconductor industry, infrared light can be used to characterize materials such as thin films and periodic trench structures. By measuring the reflectance of light from the surface of a semiconductor wafer, the index of refraction (n) and the extinction Coefficient (k) can be determined via the Forouhi-Bloomer dispersion equations. The reflectance from the infrared light can also be used to determine the critical dimension, depth, and sidewall angle of high aspect ratio trench structures.
qas: answers: text: n
question: What letter represents the index of refraction?

answers: text: k
question: What letter represents the extinction Coefficient?

answers: text: Forouhi-Bloomer dispersion
question: What equations are used to figure out the index of refraction and extinction Coefficient?

answers: text: sidewall angle
question: Along with critical dimension and depth, what can the infrared light reflectance be used to determine in regard to high aspect ratio trench structures?

answers: text: light
question: What reflectance is measured from a semiconductor wafer's surface to determine the index of refraction?

context: Infrared cleaning is a technique used by some Motion picture film scanner, film scanners and flatbed scanners to reduce or remove the effect of dust and scratches upon the finished scan. It works by collecting an additional infrared channel from the scan at the same position and resolution as the three visible color channels (red, green, and blue). The infrared channel, in combination with the other channels, is used to detect the location of scratches and dust. Once located, those defects can be corrected by scaling or replaced by inpainting.
qas: answers: text: Infrared cleaning
question: What is the name of the technique used in scanners to minimize the effects of dust and scratches?

answers: text: green
question: Along with red and blue, what is the third visible color channel?

answers: text: scaling
question: Along with replacement via inpainting, what procedure is used in infrared cleaning to remove the effect of scratches and dust?

answers: text: infrared
question: Along with the visible light channels, what channel is used to locate scratches and dust in scanners?

context: Earth's surface and the clouds absorb visible and invisible radiation from the sun and re-emit much of the energy as infrared back to atmosphere. Certain substances in the atmosphere, chiefly cloud droplets and water vapor, but also carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, and chlorofluorocarbons, absorb this infrared, and re-radiate it in all directions including back to Earth. Thus, the greenhouse effect keeps the atmosphere and surface much warmer than if the infrared absorbers were absent from the atmosphere.
qas: answers: text: clouds
question: Along with the surface of the Earth, what objects absorb radiation from the sun?

answers: text: infrared
question: After Earth surface's absorbs radiation, in what spectrum is much of it re-emitted?

answers: text: cloud droplets
question: Along with water vapor, what atmospheric substance primarily absorbs the infrared emitted by the Earth?

answers: text: greenhouse
question: What notable warming effect does the presence of infrared absorbers contribute to?