Innovative Engineering and Consulting is a leading provider of thermal imaging and infrared imaging equipment for use in surveillance and tracking. As a service to our site visitors, the following glossary provides common definitions for the thermal imaging industry.

S T U V W X Y Z
A-I, J-R, S-Z

K

Kelvin: A temperature unit in the SI system based on absolute zero.  One degree Kelvin is equal to one degree Celsius.

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L

Level: Functionally similar to ‘brightness’ in a visual system, level sets the median thermal intensity in a given scene.

Level I, II, III Certification: Guidelines set by the American Society for Nondestructive Testing (ASNT) allow for professional certification of infrared thermographers.

Liquid Nitrogen: Cryogenic (77 K) liquid used for cooling some detectors.

Long Wave Infrared (LWIR): The spectral region from about 7-14 microns where some imaging systems operate.

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M

Minimum Resolvable Temperature Difference (MRTD): A measure of the minimum difference in energy (expressed in units of blackbody temperature) required to thermally discriminate a target from the background.

Measuring IFOV: The smallest target whose temperature can be accurately measured.

MerCadTel (HgCdTe, Mercury-Cadmium-Telluride): A detector element used in both long wave and mid wave systems.

Mid Wave Infrared (MWIR): The spectral region from about 2-5 microns where some imaging systems operate.

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N

Narcissus Effect: The effect where the detector images itself through reflection off a window in front of it.

Near Infrared (NIR): The spectral region from about 0.8 to 2 microns where some imaging systems operate.

Noise Equivalent Temperature Difference (NRDT): A measure of the minimum difference in energy (expressed in units of blackbody temperature) required to thermally discriminate a target from the background.

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P

Photoconductive Detector: A detector with a constant bias voltage across it, which, when it absorbs a photon, the bulk resistance changes, causing a change in the current.  The current change is monitored in an external circuit, and compared to calibration values to render radiometric temperature data.

Photovoltaic Detector: A detector in which absorbed photons cause a voltage potential that is measured in an external circuit, and compared to calibration values to render radiometric temperature data.

Planks’ Law: This relation describes the way in which all objects emit thermal radiation as a function of temperature and wavelength.

Platinum Silicide (PtSi): Detector material used in some shortwave, cooled detectors.

Predictive/Preventive Maintenance: Periodic testing and monitoring of equipment to assure that the design life of the equipment can be achieved.

Pyroelectric Detector: A detector that detects changes in temperature.  These systems typically have a rotating ‘chopper’ to produce a changing scene between the lens system and the detector.

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Q

Quantum Well Infrared Photodetector (QWIP): Detector based on Gallium Arsenide (GaAs), used in both mid wave and long wave detectors.

Quantum Efficiency (QE): A measure of how well a detector converts incoming photons into a measurable signal that can be calibrated.

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R

Radiation: The transfer of electro-magnetic energy, generally (in the context of imaging systems) in the form of light of any wavelength.

Rankine: A temperature unit in the English system based on absolute zero. One degree Rankine is equal to one degree Farenheit.

Resolution: A general term, often casually used to describe the performance of a thermal camera, meaning “the smallest detail that can be perceived”. Two broad categories of resolution are thermal resolution and spatial resolution (defined separately).

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