GLOSSARY OF IMPORTANT TERMS
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ACCURACY: A measure of the similarity of an instrument reading to the actual value for that reading. Instrument drift cause by: environment, temperature, time, operator expertise, emissivity etc. (only radiometric camera)
ACTINIC: With respect to radiation, the characteristic that indicates capability to produce chemical change, as in the photographic activity of light. Electromagnetic energy that is capable of producing photochemical activity
AGING :Spontaneous change in the physical properties of some metals, which occurs on standing, at atmospheric temperatures after final cold working or after a final heat treatment. Frequently synonymous with the term “ Age-Hardening.”
AMBIENT TEMPERATURE: This parameter is used to compensate for the radiation reflected in the object and the radiation emitted from the atmosphere between the camera and the object. Sometimes call background temperature. The background temperature creates the radiation level available as reflected energy.
ANNEALING:A heating and cooling operation implying usually a relatively slow cooling. Annealing is a comprehensive term. The process of such a heat treatment may be: to remove stresses; to induce softness; to alter ductility; toughness; electrical magnetic, or other physical properties; to refine the crystalline structure; to remove gases; to produce a definite micro-structure. In annealing, the temperature of the operation and the rate of cooling depend upon the material being heat treated and the purpose of the treatment
AREA COVERAGE RATE: Amount of image area per unit time collected by the system at the given resolution
ATMOSPHERIC TEMPERATURE: Is the temperature of the atmosphere between the object and the scanner. Some of the radiation that reaches the scanner emanates from the object and some from atmosphere that it is not perfectly transparent to the infrared radiation and therefore also radiates and absorb.
ATMOSPHERIC TURBULENCE: Refers to the density fluctuations arising from atmospheric temperature fluctuations. (Not fluid dynamics turbulence)
ATMOSPHERIC WINDOWS: Spectral radiation regions not absorbed by atmospheric gasses. These windows are transparent to radiation at those wavelengths. The most obvious window is the visible light window - If the smog is not too bad we can see through the atmosphere forever.
ASTM: Abbreviation for American Society for Testing Material. An organization for issuing standard specifications on materials, including metals and alloys.
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BINOCULAR: Designating any instrument in which both eyes can be used to view the image to achieve a stereoscopic effect, or merely to facilitate observation. A pair of telescopes with prismatically erected images, mounted side by side with the eyepieces at the interocular distance of the observer.
BRIGHTNESS: A term to indicate the relative amount of light intensity available. Brighter is more light, dimmer is less light. In an infrared system, the brightness control may affect actual image intensity or it may change the temperature range displayed. Either effect will change the brightness of a given temperature.
BLACKBODY: Is defined as an object, which absorbs all radiation that impinges on it at any wavelength.
BONDERIZING : The coating of steel with a film composed largely of zinc phosphate in order to develop better bonding surface for paint or lacquer.
BORON : (Chemical Symbol B)- Element No. 5 of the periodic system. Atomic weight 10.82. It is gray in color, ignites at about 1112°F. and burns with a brilliant green flame, but its melting point in a non-oxidizing atmosphere is about 4000°F. Boron is used in steel in minute quantities for one purpose only - to increase the hardenability as in case hardening and to increase strength and hardness penetration.
BRITTEL MATERIALS: Materials that experience little, if any, plastic deformation before the onset of fracture
BSI: British Standards Institution-- United Kingdom (London)
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CAPSTAN:
vertical (could be horizontal) drum
which do
rotated and around which wire is turned .The capstan
CARBON: (Chemical symbol C) - Element No. 6 of the periodic system; atomic weight 12.01; has three allotropic modifications, all non-metallic. Carbon is preset in practically all ferrous alloys, and has tremendous effect on the properties of the resultant metal. Carbon is also an essential compound of the cemented carbides. Its metallurgical use, in the form of coke, for reduction of oxides, is very extensive
CARBON RANGE: In steel specifications, the carbon range is the difference between the minimum and maximum amount of carbon acceptable.
CARBON STEEL: Common or ordinary steel as contrasted with special or alloy steels, which contain other alloying metals in addition to the usual constituents of steel in their common percentages.
CATARACT:
A cataract is a cloud or film that can form on the lens of a person's eye. The
presence of a cataract can degrade the quality of one's vision by blocking and
scattering light as it enters the eye. It is often associated with chronic exposure
to ultraviolet radiation.
CELCIUS º C (Centigrade): A scale for measuring temperature where absolute cold is -273.2 °C, the melting point of water (ice point) is 0 º C, and the boiling point of water is 100° C.
CELL FILL FACTOR: Is the fraction of detector cell area occupied by the zone actively involved in the generation of signal radiance.
CONDUCTION: The transfer of energy through a solid without motion of the conducting solid as a whole. Steady-State conduction calls if the temperature at each point is independent of time. Unsteady or transient conduction situations changes with time (time dependant).
CONVECTION: The transfer of energy through a liquid or gas due to the motion of the medium.
COPANT: Comision Panamericana de Normas. Pan-American Commission of Technical Standards. Regional Organization integrated by the organisms of normalization of 18 countries of the American continent and to which they stick the national organisms of normalization from Spain, France, Italy and Portugal. Their artificial headquarters are in Buenos Aires.(Argentina)
CONVECTION: The transfer of energy through a liquid or gas due to the motion of the medium.
CORONA : A non-directional electrical discharge into the atmosphere usually around very high-voltage connections and insulators as the result of local ionization of atmospheric gases.
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DALTONISM: Related with vision that are color- blindness
DIE: small device that shape or finish the wire to new diameter. (plastic deformation occurs)
DIFFUSE REFLECTION (surface scatter): The reflection from a rough surface that emerges at almost any angle
DIN: Deutsches Institut für Normung --Germany (Berlin) / German Standard Institute
DISLOCATIONS: linear defects in a crystal.
DUCTILITY: The property of metals that enables them to be mechanically deformed when cold, without fracture. In steel, ductility is usually measured by elongation and reduction of area as determined in a tensile test. Brittle materials experience little or no plastic deformation.
DYNAMIC RANGE: Is the ratio of the maximum signal radiance and the minimum signal radiance that can be controllably projected.
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ELASTIC LIMIT: Maximum stress that a material will stand before permanent deformation occurs.
ELECTROMAGNETIC RADIATION: The field effects given off by accelerating a charged particle in a magnetic field. Depending on field strength and speed of acceleration, many types of electromagnetic radiation are created.
EMISSIVITY: The ability of an object to radiate and absorb energy from its surroundings measured as a ratio of the actual object emission to the blackbody equivalent emission
ELECTROMAGNETIC RADIATION: The field effects given off by accelerating a charged particle in a magnetic field. Depending on field strength and speed of acceleration, many types of electromagnetic radiation are created.
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FACE CENTERED: (Concerning cubic space lattices) - Having equivalent points at the corners of the unit cell and at the centers of its six faces. A face-centered cubic space lattice is characteristic of one of the close-packed arrangements of equal hard spheres.
FAHRENHEIT: A temperature measurement scale which defines the ice point of water as 32° F and the boiling point of water as 212° F. Absolute zero is - 459.7° F.
FIELD OF VIEW (FOV): The total field measured in angle within which objects can be imaged or measured and displayed by an infrared system.
FILTER (optical): An optical device, which modifies the characteristics of radiation, which is passed through it. Usually filters either attenuate all wavelengths of radiation a certain controlled amount or modify the optical pass band of the radiation - eliminating selected wavelengths or bands while allowing others to pass.
FOCAL PLANE ARRAY (FPA): A group of sensor (pixels) organized into a rectangular array of elements located in the focal plane of an optical system.
FRAME RATE: Is the rate at which an entire scene is change when every pixel is commanded to project a new value of signal radiance
FREQUENCY (υ): A property of a wave that describes how many wave patterns or cycles passes by in a period of time. Frequency is often measured in Hertz (Hz), where a wave with a frequency of 1 Hz will pass by at 1 cycle per second
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GALVANIZING : Coating steel with zinc and tin (principally zinc) for rustproofing purposes. Formerly for the purpose of galvanizing, cut length steel sheets were passed singly through a bath of the molten metal. Today’s galvanizing processing method consists of uncoiling and passing the continuous length of successive coils either through a molten bath of the metal termed Hot Dipped Galvanizing or by continuously zinc coating the uncoiled sheet electrolytically - termed Electro-Galvanizing.
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HARD DRAWING : drawing metal wire through a die to reduce cross section and increase tensile strength.
HARD DRAWN :Wire or tubing drawn to high tensile strength by a high degree of cold work.
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IEC : International Electric Commission
INFRARED (IR): Electromagnetic radiation which occupies the band from 0.7 microns to 100 microns. Infrared radiation is between the visible spectrum and microwave radiation. Emission of energy as electromagnetic waves in the portion of the spectrum just beyond the limit of the red portion of visible radiation
INSTANTANEOUS FIELD OF VIEW (IFOV): The angle in milliradians derived by dividing the active detector element's size by the system's effective focal length.
IONIZING RADIATION: Generally, any radiation that can form ions, either directly or indirectly, while traveling through a substance. Above visible light and starting in the ultra-violet frequencies, ionizing radiation has sufficient capacity to break a chemical bond and thereby destabilize an atom.
IRAM: Instituto Argentino de Nomalizacion--Argentina ( Buenos Aires) / Argentinean Normalization Standards Institute (Standards)
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KELVIN: (Lord Kelvin---1824 - 1907) Thermodynamic temperature scale. The zero Kelvin is - 273,16 ºC (Celsius or centigrade) or - 459,7 ºF (Fahrenheit). A temperature scale often used in sciences such as astronomy.
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LASER: Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. It's a device that produces a coherent beam of optical radiation by stimulating electronic, ionic, or molecular transitions to higher levels so that when they return to lower energy levels they emit energy.
LOW CARBON STEELS : Contain from 0.10 to 0.30% carbon and less than 0.60% manganese. ( The product of Basic Oxygen, Bessemer, Open Hearth or Electric Processes.)
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MECHANICAL PROPERTIES: Those properties of a material that reveal the elastic and inelastic reaction when force is applied, or that involve the relationship between stress and strain; for example, the modulus of elasticity, tensile strength and fatigue limit. These properties have often been designated as “physical properties,” but the term “mechanical properties” is much to be preferred. The mechanical properties of steel are dependent on its microstructure.
MEDIUM-CARBON STEEL: Contains from 0.30% to 0.60% carbon and less than 1.00% manganese. May be made by any of the standard processes.
MERCOSUR: Standard for the common market of the south --CMN (Mercosur Committee of Normalization), Regional Organization of normalization of the Mercosur, integrated by the national organisms of normalization of the countries belonging to the common market: ABNT for the Brazil, INTN for the Paraguay, UNIT for the Uruguay and IRAM for the Argentina. Also, they recently have adhered to the respective organisms from Chile and from Bolivia.
MESOPIC: Intensities of light under which both rods and cones operate
MICROBOLOMETER:
Focal Plane Array Detector materials that measure radiant power by changing
resistance at each pixel (thermoelectric detectors)
MICRON (m): A measurement of length in the metric system appropriate for measuring infrared radiation wavelengths. 1,000,000 microns equals one meter
MICROWAVE: Electromagnetic radiation which has a long wavelength (between 1 mm and 30 cm). Microwaves can be used to study the Universe, communicate with satellites in Earth orbit, and cook popcorn.
MID INFRARED (MWIR): The middle infrared spectrum, (window) usually from 2.4 to 7.0 microns.
MILLIRADIANS: A measure of small angles. Two thousand-pi milliradians can be measured in a complete circle. There are 17.4 mrads per degree of angle.
MODTRAN: Transmission model. It is most widely used atmospheric absorption.
MODULUS OF ELASTICITY (Tension): Force which would be required to stretch a substance to double its normal length, on the assumption that it would remain perfectly elastic, i.e., obey Hooke’s Law throughout the test. The ratio of stress to strain within the perfectly elastic range.
MRTD: Minimum resolvable temperature difference.
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NANOMETER: Is a unit of measurement of light wavelength. A nanometer is one millionth of a millimeter.
NETD: Noise Equivalent Temperature Difference
NOISE: The random fluctuations that are always associated with a measurement that is repeated many times over. These fluctuations do not represent any real sources of infrared radiation of target, but rather are caused by the imperfections of the system.
NOISE EQUIVALENT TEMPERATURE DIFFERENCE (NEDT): Is the temperature difference at which the signal amplitude equals the total noise. That it is when SNR = 1.
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OPAQUE: Transmittance (τ) equals zero
OZONE: Ozone is a molecule consisting of three Oxygen atoms that is can be created in electrical discharges in air.It has a pungent, acrid odor and is often associated with corona discharges around high voltage electrical power lines and equipment. A layer of Ozone exists in the upper atmosphere and shields the earth's surface from most of the harmful ultraviolet (UV) radiation from the Sun, because it is a strong absorber of UV radiation.
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PASSIVE INFRARED: The normal form of infrared system in use commercially. A passive system does not generate a thermal source to illuminate the scene, it is only acted upon. A passive system monitors the flux of photons already being generated by the scene within its field of view.
PATENTING : Treatment of steel, usually in wire form, in which the metal is gradually heated to about 1830°F, with subsequent cooling, usually in air, in a bath of molten lead, or in a fused salt mixture held between 800°F and 1050°F.
PELTIER EFFECT: The ability for two dissimilar metals and metal/semiconductors to create a thermal difference when current flows across the dissimilar junction.
PERIODIC
TABLE (of The Elements): The Periodic table is a chart listing all of the
known elements arrayed usually in order of their atomic charge number.
PHOTOGRAPHY: Technique of producing permanent images on sensitized surfaces by means of the photochemical action of light or other forms of radiant energy.
PHOTOPIC: Bright light conditions where only the cones are functional
PHOTOSYNTHESIS: The fundamental chemical process in which green plants (and blue-green algae) utilize the energy of sunlight or other light to convert carbon dioxide and water into carbohydrates, with the green pigment chlorophyll acting as the energy converter. This process releases oxygen and is the chief source of atmospheric oxygen
PIXEL : The smallest single individual image element of detection on
a focal plane array sensor, either thermal infrared or visible.
PLASTICITY : The ability of a metal to be deformed extensively without rupture. Plastic deformation is the elongation that occurs that not will be recovered with the removal of the load.
PYROMETER: An instrument of various types used for measuring temperatures
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QUANTITATIVE ANALYSIS: An analysis of objects or processes, which is concerned with measuring temperatures or radiant energy levels by assigning numerical values to the characteristics of the displayed scene.
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RAINBOW: Dispersion of he white light by water vapor or raindrops
RADAR: Electronic system, used to locate objects beyond the range of vision, and to determine their distance by projecting radio waves against them.
RADIATION: Energy radiated in the form of waves or particles; photons.
RADIOSITY: Accounts for all of the radiant energy leaving a surface. Target exitance --- (We + Wr + Wt )
RECRYSTALLIZATION : A process whereby a distorted grain structure of cold worked metals is replaced by a new, stress-free grain structure as a result of annealing above a specific minimum temperature for a specific time.
RENDERING: Process in which two-dimensional image it is obtaining from three-dimensional target
RESIDUAL STRESS : Macroscopic stresses that are set up within a metal as the result of no nuniform plastic deformation. This deformation may be caused by cold working or by drastic gradients of temperature from quenching or welding.
RESOLUTION: Defines the smallest resolvable object in the target plane at a given range-to-target, atmospheric condition and target signal level ability of a telescope to differentiate between two objects in the sky which are separated by a small angular distance
ROOM TEMPERATURE: At or near 74 º F (24 º C).
RESCUE: To free from danger, harm or confinement.
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SAE: Abbreviation for Society of Automotive Engineers. This organization has specified common and alloy steels and copper base alloys in accordance with a numerical index system allowing approximation of the composition of the metal. The last two digits indicate the carbon content, usually within 0.05%.
SCOTOPIC: Dim light conditions where only rods are functional
SENSITIVITY: Defines the smallest signal detectable in the presence of systems noise
SIGNAL-TO-NOISE RATIO: (SNR) Is the ratio of the signal amplitude to the total noise
SPECTRAL COVERAGE: The number of spectral bands and their associated spectral resolution needed to faithfully extract target information.
SPECULAR REFLECTION: (Lambertian surface) Reflection from smooth surface in which angle of incidence is equal to angle of reflection. The surface radiance it is independent of the angle.
SPEED OF LIGHT: The speed at which electromagnetic radiation propagates in a vacuum; it is defined as 299 792 458 m/s (~186,000 miles/second).
STEEL: Iron, malleable in at least one rang of temperature below its melting point without special heat treatment substantially free from slag, and containing carbon more than about 0.05% and less than about 2.00%. Other alloying elements may be present in significant quantities, but all steels contain at least small amounts of manganese and silicon, and usually as undesirable constituents, also sulfur and phosphorus.
STRAIN: Deformation produced on a body by an outside force.
STRAIN AGING: Aging induced by cold working.
STRAIN HARDENING: An increase in hardness and strength caused by plastic deformation at temperatures lower than the recrystallization range.
STRESS: Deforming force to which a body is subjected or the resistance which the body offers to deformation by the force.
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TARGET: An object in the object plane, which the system can focus on and analyze.
TEMPERATURE: An expression of thermal energy density. How hot or cold an object is.
THERMAL CONDUCTIVITY: A property of materials, which measures the ability of a material to conduct heat. It can be expressed as power per degree length (watts/meter-°C). Metals have a high thermal conductivity (conduct well) while air fibers and plastics have much poorer conductivities.
THERMOGRAM: A two-dimensional hard copy record of the apparent scene temperatures displayed on an IR system.
TENSILE STRENGTH : (Also called ultimate strength) - Breaking strength of a material when subjected to a tensile (stretching) force. Usually measured by placing a standard test piece in the jaws of a tensile machine, gradually separating the jaws, and measuring the stretching force necessary to break the test piece. Tensile strength is commonly expressed as pounds (or tons) per square inch of original cross section.
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ULTRAVIOLET: Electromagnetic radiation at wavelengths shorter than the violet end of visible light
UNI:
Ente Nazionale Italiano di Unificazione --Italy (Milano) /Italian
National Entity for Unification.
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VISIBLE LIGHT: Electromagnetic radiation at wavelengths which the human eye can see.
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WAVELENGTH: The length of distance between cycles on a repetitive event.
WAVENUMBER: The reciprocal of wavelength 1/ λ cm
WELDING
: A
process used to join metals by the application of heat. Fusion welding, which
includes gas, arc, and resistance welding, requires that the parent metals be
melted. This distinguishes fusion welding from brazing. In pressure welding
joining is accomplished by the use of heat and pressure without melting. The
parts that are being welded are pressed together and heated simultaneously, so
that recrystalization occurs across the interface.
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YIELD POINT: The load per unit of original cross section atwhich, in soft steel, a marked increase in deformation occurs without increase in load.
YIELD STRENGTH (YS) :The stress (load/area) at which the metal changes from elastic to plastic in behavior, i.e., takes a permanent set.
YOUNG’S MODULUS :The coefficient of elasticity of stretching. For a stretched wire, Young’s Modulus is the ratio of stretching force per unit cross-sectional area to the elongation per unit length. The values of Young’s Modulus for metals are of the order 10 12 dynes per square cm.
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Special thanks to Andres Esteban Rozlosnik for contributing the glossary listed above.
Last Updated on 14 August 2001
By R. B. Dinwiddie