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Letter - I
IEC International Electrotechnical Commission

A European organization that coordinates and sets related standards among the European Community.


A standard developed by Hewlett-Packard Corporation and adopted by the IEEE for digital interface between programmable instrumentation. It uses a 16-bit bus to interconnect up to 15 instruments. The standard comprises hardware and protocol options. It is also called the Hewlett-Packard Interface Bus (HPIB)  or General Purpose Interface Bus (GPIB). The present standard is ANSI/IEEE-4881-1987.

IFOV (Instantaneous Field of View)

Instantaneous Field of View is the angular resolution of an imaging Field of View) instrument that is determined by the size of the detector and the lens. For a point Instrument the IFOV and FOV are the same.

Image processing

Converting an image to a digital form and further enhancing the image to prepare it for computer or visual analysis. In the case of an infrared image or thermogram, this could include temperature scaling, spot temperature measurements, and thermal profiles, as well as image addition, subtraction, averaging, filtering, and storage.

Indium Antimonide (InSb)

A material used to construct photon detectors that are sensitive in the spectral region from 2.0 to 5.5 µm and used in infrared scanners and imagers. These detectors require cryogenic cooling.

Infrared or Optical Filter

See Spectral Filter or Neutral Density Filter.

Infrared Radiation (IR)

Radiation within the portion of the electromagnetic spectrum which extends from 0.75 to 1000 µm.

Infrared Thermometer

An instrument that determines the temperature of an object by means of detecting and quantifying the infrared radiation emitted therefrom. types include total power, wide band, narrow band, and multiple wavelengths.

Insulation Resistance

Measuring electrical resistance between two electrical wires.


The ability for a head sensor to be interchanged with another of the same type without the need to recalibrate the system (also referred to as Universal Electronics). Some monitors support the interchangeability of different types of heads.

Intrinsically Safe

A standard for preventing explosions in hazardous areas by limiting the electrical energy available to levels that are insufficient to cause ignition of explosive atmospheres during normal operation of an Instrument.

IP Designation

Grades of intrinsic safety protection pertaining to enclosures per the British Standard 4752. The type of protection is defined by two digits, the first relating to accessibility and the second to environmental protection. The two numbers are preceded by the letters IP.

Isolated Inputs, Outputs

Inputs, outputs and power supply lines that are electrically insulated or Power Supplies from each other, whereby arbitrary grounding of these lines cannot affect the performance of the instrument such as generate ground-loops or short out internal resistors.


A continuous line (not necessarily straight or smooth) on a surface (or chart) comprising points of equal or constant temperature.

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