How do you know your imager is giving you good data? Are there steps or procedures that should be used to ensure the quality of data you are collecting?

There is a process that should be completed before, during, and after the inspection to ensure that your equipment is in working order.

We refer to this process as a functionality check. The functionality check should ideally be completed each time the imager is powered on. Here is the process:

1. Set the range to the lowest range that will allow measurement of a human face.
2. Set the emissivity to 0.98.
3. Set the background temperature to the ambient air temp. Some may ask why this value is used. If you’ve attended Level I you should already know this, but with an emissivity setting as high as 0.98, the background correction factor has very little influence in the temperature calculation performed by the camera, as long as the actual background isn’t something extremely hot or cold.
4. Set the transmission value to 100% or turn the external optic off.
5. At a distance of about 3 ft. (Frame somebodies face in the view screen trying to fill the screen).
6. Obtain a highly focused image centering the measurement cursor on the tear duct. To ensure you’re measuring the hottest part of the tear duct, narrow the span to and adjust the level so the hottest part of the tear duct is apparent. Alternately one could use an area measurement tool and select it to show the maximum measured temperature within it, and center the area marker on the tear duct.
7. Should get a reading of the tear duct between 93° to 97°F (~34° to~36°C).

Try to use the same person each day (your escort/assistant works great for this). If the reading is not ok recheck the settings, if there is still a discrepancy there may be an issue with the imager. At this point there are a few options. We can conduct an ice bath check and/or use boiling water. The ice bath check is where we fill a medium sized bowl with ice, add enough water to float the ice, stir for 5 minutes then remove the ice leaving the water in the bowl. Immediately measure the temperature of the water (should be right at 32°F/0°C).

Another check uses boiling water, bring water to the boiling point, remove from the heat source and measure the surface of the water (212°F/100°C at sea level ). *Note: be careful with the steam and condensation over the lens.

Keep in mind the tolerance of the imager +/- 2% or +/-2°C @ 30°C. Note: this is a common value of accuracy, could be different for other IR cameras. If the readings are still out of the specifications the only way to correct it is to send the imager along with all lenses and filters back to the manufacturer for calibration.

This is one of simplest ways to check if your imager is gathering good data.