THERMOGRAPHY AT LONG DISTNACE

[ferchuvicente]

HI, I WOULD LIKE TO KNOW IF I CAN TO PERFORM A THERMOGRAPHY ANALYSIS AT 60MTS WITH A COMMON CAMERA FLIR E 25WITH LENS OF 9.2MM

BEST REGARDS AT ALL

FERNANDO

 

[IRstuff]

What is 60MTS?

TTFN

 

[ferchuvicente]

60 mts= 60 meters of distance,ok?sorry

 

[IRstuff]

Sure, you just can't accurately determine the temperature of anything less than 0.326 m in size, because the object would underfill the detector and the flux on the detector would be incorrect.

TTFN

 

[electricpete]

Just to provide some more detail:

http://www.flirthermography.com/cameras/camera/1084/

(click on specifiction)

"Spot size ratio (with 12° lens) 300:1"
That corresponds to IFOV which is roughly the size of a pixel. It is the minimum size object at that you can distinguish a temperature difference (but not necessarily determine temperature)

60/300 ~0.2m corresponds to the the IFOV at this distance.

Depending on your application, you may want to estimate the temperautre. MFOV is the minimum size that you can reliably estimate temperature.

MFOV is not listed in the specs but for most cameras it is one third of IFOV (I have an article link somewhere that discusses that). In this case I suspect 100:1 would be your MFOV.

Also note that your camera can have telephoto lens attachment which will let you examine smaller objects better.

If you are performing thermography surveys as part of your job, you might want to consider taking thermography training since there are a lot of factors that can affect your measurement that you probably won't be aware of unless you have had training.

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[electricpete]

I forgot to say that 60/100 ~0.6m would correspond to MFOV (minimum target size for estimating tempearature at 60m)

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[IRstuff]

The focal length given, 9.2 mm, is for an extremely wide field of view and appears, for a 50 um pixel and 160x120 array, to correspond to the 45º FOV listed in the camera specifications. The instantaneous field of view (IFOV) should therefore be about 50 um/9.2 mm = 5.4 mrad and covers about 0.333 m at 60 m.

TTFN