Unknown Variables and Values for Calculated Temperature

[eric-hedengren]

In the equation that calculates temperature from wavelength data is found on the bottom right of page 5 in this paper.

One variable remains unknown: αn. I'm not sure what type of data it will hold or what it represents.

The current constant value being used for Gage Factor (FG) is for 22 degrees Celsius. It uses 0.807 currently. Will this be the same? If not, how is the new number calculated with a provided temperature?

What is the correct metal and it's constant for: αΛ?

Finally, what area is being measured for the initial temperature (T0)?

T = (λp −λ0) / (λpFG(αΛ +αn)) + T0

[APMonitor]

The initial temperature is 82.8 degF. The constant αn is much larger than αΛ. I assume (αΛ +αn) = 3.70556 micro-strain/degF. micro-strain = 1e6 * (λp −λ0) / (λpFG)