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 )

RAINBOW: Dispersion of he white light in raindrops

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

RESCUE: To free from danger, harm or confinement.

RESIDUAL STRESS: Macroscopic stresses that are set up within a metal as the result of no uniform 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 ).

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%.

SAFETY: Freedom from danger

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 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.

STRAIN: Deformation produced on a body by an outside force.

STRESS: Deforming force to which a body is subjected or the resistance which the body offers to deformation by the force.

SURVEILLANCE: Close watch. Supervision

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.

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.

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.

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

VISIBLE LIGHT: Electromagnetic radiation at wavelengths which the human eye can see.

WAVELENGH: The length of distance between cycles on a repetitive event.

WAVENUMBER: The reciprocal of wavelength 1/ ? cm ­ ¹

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.

YIELD POINT: The load per unit of original cross section at which, 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.