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Forward-looking infrared (FLIR) cameras, typically used on military and civilian aircraft, use a
thermographic camera Infrared thermography (IRT), thermal video and/or thermal imaging, is a process where a thermal camera captures and creates an image of an object by using infrared radiation emitted from the object in a process, which are examples of infrared ...
that senses
infrared radiation Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
. The sensors installed in forward-looking infrared cameras, as well as those of other thermal imaging cameras, use detection of infrared radiation, typically emitted from a
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...
source (
thermal radiation Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) i ...
), to create an image assembled for
video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syst ...
output. They can be used to help pilots and drivers steer their vehicles at night and in fog, or to detect warm objects against a cooler background. The
wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...
of infrared that thermal imaging cameras detect is 3 to 12  μm and differs significantly from that of night vision, which operates in the visible light and
near-infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
ranges (0.4 to 1.0  μm).


Design

Infrared light Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from arou ...
falls into two basic ranges: ''long-wave'' and ''medium-wave''. Long-wave infrared (LWIR) cameras, sometimes called "far-infrared", operate at 8 to 12 μm and can see heat sources, such as hot engine parts or human body heat, several kilometers away. Longer-distance viewing is made more difficult with LWIR because the infrared light is absorbed, scattered, and
refracted In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomeno ...
by air and by water vapor. Some long-wave cameras require their detector to be cryogenically cooled, typically for several minutes before use, although some moderately sensitive infrared cameras do not require this. Many thermal imagers, including some forward-looking infrared cameras (such as some LWIR enhanced vision systems (EVS)) are also uncooled. ''Medium-wave'' (MWIR) cameras operate in the 3–5 μm range. These can see almost as well, since those frequencies are less affected by water-vapor absorption, but generally require a more expensive sensor array, along with cryogenic cooling. Many camera systems use
digital image processing Digital image processing is the use of a digital computer to process digital images through an algorithm. As a subcategory or field of digital signal processing, digital image processing has many advantages over analog image processing. It allo ...
to improve the image quality. Infrared imaging sensor arrays often have wildly inconsistent sensitivities from
pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the ...
to pixel, due to limitations in the manufacturing process. To remedy this, the response of each pixel is measured at the factory, and a transform, most often linear, maps the measured input signal to an output level. Some companies offer advanced "fusion" technologies that blend a visible-spectrum image with an infrared-spectrum image to produce better results than a single-spectrum image alone.


Properties

Thermal imaging cameras, such as the Raytheon AN/AAQ-26, are used in a variety of applications, including
naval vessels A naval ship is a military ship (or sometimes boat, depending on classification) used by a navy. Naval ships are differentiated from civilian ships by construction and purpose. Generally, naval ships are damage resilient and armed with w ...
, fixed-wing
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engine ...
,
helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...
s, armored fighting vehicles, and military-grade smartphones. In warfare, they have three distinct advantages over other imaging technologies: # The imager itself is nearly impossible to detect for the enemy, as it detects energy emitted from the target rather than sending out energy that is reflected from the target, as with
radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...
or
sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging), communicate with or detect objects on o ...
. # It sees radiation in the infrared spectrum, which is difficult to
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
. # These camera systems can see through smoke, fog, haze, and other atmospheric obscurants better than a
visible light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...
camera can.


Etymology

The term "forward-looking" is used to distinguish fixed forward-looking thermal imaging systems from sideways-tracking infrared systems, also known as " push broom" imagers, and other thermal imaging systems such as gimbal-mounted imaging systems, handheld imaging systems and the like. Pushbroom systems typically have been used on aircraft and satellites. Sideways-tracking imagers normally involve a one-dimensional (1D) array of pixels, which uses the motion of the aircraft or satellite to move the view of the 1D array across the ground to build up a 2D image over time. Such systems cannot be used for real-time imaging and must look perpendicular to the direction of travel.


History

In 1956,
Texas Instruments Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globa ...
began research on
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
technology that led to several line scanner contracts and, with the addition of a second scan mirror, the invention of the first forward-looking infrared camera in 1963, with production beginning in 1966. In 1972, TI invented the Common Module concept, greatly reducing cost and allowing reuse of common components.


Uses

*Traffic video detection and monitoring * Surveillance and/or capture of
mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...
**e.g. Detection of
illegal immigrants Illegal immigration is the migration of people into a country in violation of the immigration laws of that country or the continued residence without the legal right to live in that country. Illegal immigration tends to be financially upwa ...
hidden in lorries/trucks **Warning drivers about sudden road obstructions caused by deer **Location through smoke and/or haze * Search and rescue operations for missing persons especially in wooded areas or water *Target acquisition and tracking by military or civil
aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engine ...
*
Drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...
temperature monitoring and monitoring wild game habitats *Detection of energy loss or consumption, or insulation defects **e.g. insulation level mapping (pipes, walls, joints etc.) in order to reduce HVAC energy consumption **Quality control for especially electrical installations (a picture can reveal if loads are higher than expected, or show bad and potentially failing joints) **Search for drug labs and/or indoor
cannabis ''Cannabis'' () is a genus of flowering plants in the family Cannabaceae. The number of species within the genus is disputed. Three species may be recognized: '' Cannabis sativa'', '' C. indica'', and '' C. ruderalis''. Alternative ...
producers (especially at night) *Piloting of aircraft in low visibility ( IMC) conditions *Pinpoint sources of ignition during firefighting operations *Monitoring active volcanoes *Detecting faulty or overheating electrical joints, connections and components *Night driving *Identification or visual acquirement of hostile armour in
tanks A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful engi ...


Cost

The cost of thermal imaging equipment in general has fallen dramatically after inexpensive portable and fixed infrared detectors and systems based on microelectromechanical technology were designed and manufactured for commercial, industrial and military application. Also, older camera designs used rotating mirrors to scan the image to a small sensor. More modern cameras no longer use this method; the simplification helps reduce cost. Uncooled technology available in many EVS products have reduced the costs to fractions of the price of older cooled technology, with similar performance. EVS is rapidly becoming mainstream on many fixed wing and rotary wing operators from
Cirrus Cirrus may refer to: Science *Cirrus (biology), any of various thin, thread-like structures on the body of an animal *Cirrus (botany), a tendril * Infrared cirrus, in astronomy, filamentary structures seen in infrared light *Cirrus cloud, a typ ...
and Cessna aircraft to large business jets.


Police actions

In 2001, the
United States Supreme Court The Supreme Court of the United States (SCOTUS) is the highest court in the federal judiciary of the United States. It has ultimate appellate jurisdiction over all U.S. federal court cases, and over state court cases that involve a point o ...
decided in '' Kyllo v. United States'' that performing surveillance of private property (ostensibly to detect high emission
grow light A grow light is an electric light to help plants grow. Grow lights either attempt to provide a light spectrum similar to that of the sun, or to provide a spectrum that is more tailored to the needs of the plants being cultivated (typically a varyi ...
s used in clandestine cannabis farming) using thermal imaging cameras without a
search warrant A search warrant is a court order that a magistrate or judge issues to authorize law enforcement officers to conduct a search of a person, location, or vehicle for evidence of a crime and to confiscate any evidence they find. In most countries, ...
by law enforcement violates the Fourth Amendment's protection from unreasonable searches and seizures. In the 2004 '' R. v. Tessling'' judgment, the Supreme Court of Canada determined that the use of airborne FLIR in surveillance by police was permitted without requiring a search warrant. The Court determined that the general nature of the data gathered by FLIR did not reveal personal information of the occupants and therefore was not in violation of Tessling's Section 8 rights afforded under the
Charter of Rights and Freedoms The ''Canadian Charter of Rights and Freedoms'' (french: Charte canadienne des droits et libertés), often simply referred to as the ''Charter'' in Canada, is a bill of rights entrenched in the Constitution of Canada, forming the first part o ...
(1982).
Ian Binnie William Ian Corneil Binnie (born April 14, 1939) is a former puisne justice of the Supreme Court of Canada, serving from January 8, 1998 to October 27, 2011. Of the justices appointed to the Supreme Court in recent years, he is one of the few app ...
distinguished the Canadian law with respect to the Kyllo judgment, by agreeing with the Kyllo minority that public officials should not have to avert their senses or their equipment from detecting emissions in the public domain such as excessive heat, traces of smoke, suspicious odors, odorless gases, airborne particulates, or radioactive emissions, any of which could identify hazards to the community. In June 2014, the Canadian National Aerial Surveillance Program DHC-8M-100 aircraft mounted with
infrared sensor Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
s was instrumental in the search for Justin Bourque, a fugitive who had killed three
Royal Canadian Mounted Police The Royal Canadian Mounted Police (RCMP; french: Gendarmerie royale du Canada; french: GRC, label=none), commonly known in English as the Mounties (and colloquially in French as ) is the federal police, federal and national police service of ...
members in Moncton. The plane's crew used its advanced heat-sensing camera to discover Bourque's heat signature in the deep brushwoods at midnight. During
2015 Baltimore protests On April 12, 2015, Baltimore Police Department officers arrested Freddie Gray, a 25-year-old African American resident of Baltimore, Maryland. Gray's neck and spine were injured while he was in a police vehicle and he went into a coma. On Ap ...
, the
FBI The Federal Bureau of Investigation (FBI) is the domestic intelligence and security service of the United States and its principal federal law enforcement agency. Operating under the jurisdiction of the United States Department of Justice, t ...
conducted 10 aerial surveillance missions between April 29 and May 3, which included "infrared and day color, full-motion FLIR video evidence" collection, according to FBI spokesman Christopher Allen.FBI spy planes used thermal imaging tech in flights over Baltimore after Freddie Gray unrest
The Washington Post, October 30, 2015
A FLIR Talon multi-sensor camera system equipped with an infrared laser pointer (which is invisible to casual observers) for illumination purposes was used to gather data at night. The
American Civil Liberties Union The American Civil Liberties Union (ACLU) is a nonprofit organization founded in 1920 "to defend and preserve the individual rights and liberties guaranteed to every person in this country by the Constitution and laws of the United States". T ...
raised concerns over the fact that new surveillance technology is implemented without judicial guidance and public discussion.FBI Documents Reveal New Information on Baltimore Surveillance Flights
ACLU, October 30, 2015 According to Nathan Wessler, an ACLU attorney, "this is a dynamic we see again and again when it comes to advances in surveillance. By the time details leak out, programs are firmly entrenched, and it’s all but impossible to roll them back – and very hard to put in place restrictions and oversight."


See also

*
Automotive night vision An automotive night vision system uses a thermographic camera to increase a driver's perception and seeing distance in darkness or poor weather beyond the reach of the vehicle's headlights. Such systems are offered as optional equipment on certa ...
*
Electro-optical targeting system An electro-optical targeting system (EOTS), is a system employed to track and locate targets in aerial warfare. It can use charge-coupled device TV cameras, laser rangefinders and laser designators. See also *Forward looking infrared *Infra-r ...
*
Infra-red search and track An infrared search and track (IRST) system (sometimes known as infrared sighting and tracking) is a method for detecting and tracking objects which give off infrared radiation, such as the infrared signatures of jet aircraft and helicopters. ...


References


External links


Electro-Optical Systems

Thermal Imaging Sensors (Defence Today)


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