Absolute Zero:
The temperature at which no heat energy remains in an object. This falls at approximately -273.15°C.
Blackbody:
An object which is entirely non-reflective. All radiation emitted from a blackbody is due to its own temperature.
Emissivity:
A measure of the amount of radiation discharged from an object, compared with that of a blackbody. This measure is a number from 0 (perfect reflector) to 1 (perfect blackbody).
Emittance:
The amount of energy emitted from the surface of a body per second per unit area.
EMR:
Electromagnetic Radiation.
FOV:
Field of View - the horizontal angle viewed through a camera lens.
IFOV:
Instantaneous Field of View - a measure of the spatial resolution of an IR camera.
IR:
Infrared - denoting EMR with a wavelength greater than the red visible light (~700 nm), but less than microwaves (~1 mm).
MFOV:
Multiple Field of View - this is larger than the IFOV and represents the minimum object size for which an IR camera can measure the temperature.
NETD:
Noise Equivalent Temperature Difference - a measure of the thermal sensitivity of the sensor. See What is NETD? for a more detailed description.
Palette:
The set of colors used to represent radiation beyond the colour spectrum in an infrared image.
Pixel:
Short for 'picture element', a pixel is a single point in a picture.
Radiance:
The amount of energy emitted from the surface of a body per second per unit area, per unit angle.
Radiation:
The process by which electromagnetic energy is emitted by an object.
Reflectivity:
A measure of the amount of incident radiation reflected by a surface. This number is a measure from 0 (no radiation reflected) to 1 (all radiation reflected).
Saturation Colour:
The areas in an IR image which are at temperatures beyond the current temperature scale are represented by saturation colours. The most pertinent of these colours are the 'overflow' colour that represents all areas beyond the maximum temperature and an 'underflow' colour that represents all areas below the minimum temperature.
Temperature Range:
The current limitation of an IR camera regarding overall temperature measurement.
Temperature Scale:
Describes the current display of an IR image image. Expressed as a maximum and minimum temperature, with all temperatures outside this range represented by the corresponding saturation colour.
Thermal Noise:
Small disturbances in an infrared image due to radiation which is not related to the object being imaged.
Thermography:
The measurement of temperature using thermal imaging.
Thermogram:
The infrared image captured through thermography. This image will have a 'fake' colour scheme applied to it in order to represent heat.
Transmissivity:
A measure of the amount of incident radiation transmitted by a surface. This number is a measure from 0 (no radiation transmitted) to 1 (all radiation transmitted).
