Message Board Thread - "Optical resolution of E45"

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Optical resolution of E45 Shaibal Ghosh 8/1/2007
As per the Flir ThermaCAM E45 brochure Optical resolution, for 36 mm lens, as 300:1

Now as per my understanding : The Optical resolution is (IFOV/Spot Size) : (Distance)

Taking into consideration the lens data sheet and taking IFOV as Spot size, the above value become 1000:1

I have made the Calculation as below:
Distance: 1.2 M (1200 mm).
IFOV: 1.17 mm.
IFOV @ 1000 mm = (1.17 / 1200) x 1000 = .975 mm (i.e approx: 1).

So as per above calculation Optical resolution for 17 mm becomes: 1000:1 which is no where near 300:1

There may be two things either my way of correlating the same may be wrong or there is different way of calculating so all are requested to put in their comments ASAP.

Best Regards,
Shaibal Ghosh
Mobile: 09830202043
Re:Optical resolution of E45 Doctir bob 8/1/2007
The Measurement Field of View (MFOV) is 3 to 4 times the Instantaneous Field of View (IFOV) due to optical effects. The IFOV has typically 50% response on a given detector element. For measurement one needs close to 100% response.

Usually, you can detect a thermal anomaly for targets that subtend one IFOV, but you cannot measure them until they are large enough to subtend one MFOV.

As you can see from your calculation, there is a factor of 3.3 between MFOV and IFOV.

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