NETD Parameter in Thermal Imaging.pdf

Darkness becomes risky for soldiers. With MKU’s thermal weapon sight, one can detect their enemies & objects in darkness. This is made by the NETD parameter that measures how well a thermal imaging detector can distinguish between tiny differences.

1. NETD Parameter in
Thermal Imaging
The escape from enemies in the darkness becomes risky for soldiers.
With MKU’s thermal weapon sight, the user can detect their enemies &
objects in total darkness and very diverse weather condition. This is
made by the NETD parameter that measures how well a thermal
imaging detector can distinguish between tiny differences in thermal
radiation in the image.

2. NETD Parameter in Thermal Imaging
Theescapefromenemiesinthedarknessbecomesriskyforsoldiers.WithMKU’sthermalweaponsight,the
usercandetecttheirenemies&objectsintotaldarknessandverydiverseweathercondition.Thisismadeby
theNETDparameterthatmeasureshowwellathermalimagingdetectorcandistinguishbetweentiny
differencesinthermalradiationintheimage.Whenthenoiseisequivalenttothesmallestmeasurable
temperaturedifference,thedetectorhasreachedthelimitofitsabilitytoresolveausefulthermalsignal.The
lowertheNETDvalue,thehigherthesensitivity,therebyproducingamoredetailedimage.Toknowmore
aboutit,clickhere.

3. NETD Parameter in Thermal Imaging
Inmilitaryapplications,thermalimagingdevicesarewidelyusedfor
nightsurveillance,liveobjectdetectioninrescueoperations,targeting
andrangeidentification,andthermalmapping.Thermalimagerscanbe
usedforobjectidentificationinworstday-nightconditionslikehigh
humidity,foggyandhazyconditionswhereastheimageintensification
technologyworksonlyinalowlightenvironment.Militarythermal
imagersaredevelopedwiththeabilitytoimageatnightwithout
additionalilluminators.
WhatisNETD&Howisitmeasured?
Thermaldevicesfacilitatenon-destructivetemperaturemonitoringof
multipleobjectsinasingleframe.Thesensitivityofthethermaldetector
determinestheminimumtemperaturedifferencebetweenthe
backgroundandtheobjectthatcanbedistinguished.

4. Curvature and Coverings in Hard Body Armour
NETD Parameter in Thermal Imaging
NoiseEquivalentTemperatureDifference(NETD)determinesthelevelofthermal
sensitivityofathermaldevice.ThelowertheNETDvalue,thehigherthe
sensitivity,producingamoredetailedimage.NETDhelpsindeterminingtheeffect
ofsystemnoiseonthethermalresponseofthedevice.Thisisthekeyparameter
usedtotestthemeritofathermaldevice.
Itisthesignal-to-noisefigurethatrepresentsthetemperaturedifferencebetween
objectandbackground,whichwouldproducesignalvoltageequaltothecamera’s
effectivetemporalnoise.NETDexpressesthetemperaturedifferencerequiredto
getasignal-to-noiseratioofunity.It,therefore,representsapproximatelythe
leasttemperaturedifferenceatwhichthecameracanworkout.

5. NETD Parameter in Thermal Imaging
Figure1depictsthestateofasystem’snoisevoltageandsignal
voltages.
Figure 1. Illustration of SNR and NETD using system signal and noise voltages.

6. Curvature and Coverings in Hard Body Armour
NETD Parameter in Thermal Imaging
The successful operation of a thermal Imagers requires minimum radiative power that could
induce temperature difference (ΔT) in a scene for which Vs (rms) > Vn(rms), or ΔT > NETD.
NETD is calculated by dividing the temporal noise by the responsivity of the sensor and usually
expressed in units of milli-Kelvins (mK), for military applications preferred choice of NETD is up to
50 mK.The value is a function of the camera’s f/number, signal integration time, and the
temperature at which the measurement is made.
How does NETD affect the quality of an image?
The images below show the same scene recorded by two different cameras. One camera has a
NETD of 40 mKand the other 80 mK.The low-temperature background of an image taken by
larger value (80 mK) NETD camera shows lesser thermal contrast or lesser clarity between the
human target and the background whereas, the image was taken by the lower value of NETD i.e.
40 mKis showing higher thermal contrast or more celerity between human target and the
background. However, here the net 40 mKthe difference doesn’t seem like much, but it has a
huge impact on the image quality and measurement accuracy.

7. Curvature and Coverings in Hard Body Armour
NETD Parameter in Thermal Imaging
In brief, the lower NETD value promise the;
•Good image –simple to understand and easy to focus on the camera.
•Higher efficiency with a better image.
•Ease of identifying the objects in a thermal image.
•More professional-looking reports with better images.
Figure 2. Comparative illustration of thermal images captured by the thermal Night Vision Scope of different NETD
values.

8. Curvature and Coverings in Hard Body Armour
NETD Parameter in Thermal Imaging
Thermal imaging devices use advanced optics and sensors that digitally process the inputs from
the optics of the device to deliver digital raster images of the target and its surroundings. They
can detect minute temperature differences to deliver images and identify hidden objects in
adverse conditions.
To know more about Thermal Imaging Devices by MKU click here

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