Calibration of FLIR Lepton using Raspberry PI

[robert hyde]

Using the Lepton and a raspberry pi for a university project, need to detect temperatures of a face; has anyone been able to calibrate the lepton with a pi?

[Martijn Wolbrink]

To do this you need to sign an nda with flir to get the formula and procedure to do callibration.

[Rafael Bayareh]

Hello Martijn,

What do you mean with sign an nda?

[Kurt Kiefer]

You should get a radiometric Lepton if you want absolute temperature measurement, that's what FLIR made it for, no calibration required.

If you search, this topic is discussed ad nauseam. Some users on the board have set up their own calibration coefficients, compensating values based on the internal temperature of the Lepton, but it isn't a very easy (or necessary precise) road to go down.

[Rafael Bayareh]

I’m not agree with that. Every sensor needs to be calibrated for a specific purpose. In the world of the thermal cameras, it is important to know the material that will be measure; even if two materials have the same temperature, the thermal camera will show different temperatures, that’s the reason that this sensor needs to be calibrated.

I’m I right?

On Jan 26, 2017, at 3:25 PM, Kurt Kiefer <keki...@gmail.com> wrote:

You should get a radiometric Lepton if you want absolute temperature measurement, that's what FLIR made it for, no calibration required.

If you search, this topic is discussed ad nauseam. Some users on the board have set up their own calibration coefficients, compensating values based on the internal temperature of the Lepton, but it isn't a very easy (or necessary precise) road to go down.

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[Kurt Kiefer]

You are right that every thermal camera needs calibration. So FLIR calibrate the Radiometric Lepton 2.5's against black body sources at their factory. The calibration coefficients are stored in non-volatile memory of the sensor itself. So when you get one of these it is plug and play. Out of the box, the VOSPI stream of the Lepton 2.5 outputs temperature data in Kelvin according to that calibration and compensated by the FPA temperature.

[Rafael Bayareh]

The Lepton 2.5 simplifies the job. I am working with the dev kit (https://www.sparkfun.com/products/13233), and as you say, it is not a very easy task. I guess the best way to calibrate is using the internal temperature as reference, which is given by the value 8192.

I hope this information helps with the cause. 

On Jan 30, 2017, at 10:58 AM, Kurt Kiefer <keki...@gmail.com> wrote:

You are right that every thermal camera needs calibration. So FLIR calibrate the Radiometric Lepton 2.5's against black body sources at their factory. The calibration coefficients are stored in non-volatile memory of the sensor itself. So when you get one of these it is plug and play. Out of the box, the VOSPI stream of the Lepton 2.5 outputs temperature data in Kelvin according to that calibration and compensated by the FPA temperature.

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[Kurt Kiefer]

Yes that is the same breakout Pure Engineering designed for GroupGets. If you want a 2.5 sensor, it will still work with that board: https://groupgets.com/manufacturers/flir/products/radiometric-lepton-2-5

[elviana arisaputri]

how to calibrate flir lepton 2.5 using breakout board and raspberry pi? please give the answer if you know, thanks

[Rafael Bayareh]

With a blackbody and probably with thermocouples. Once you get the 14-bit data raw of your Lepton 2.5, you can match the data with the calibrated thermocouples. Then you can do the math and obtain an equation. 

However, Lepton 2.5 is a radiometric device. As far is my experience, this 14-bit data can be divided by 100 and it is equivalent to the temperature in Celsius scale.