The test starts from a controlled temperature of 25 degC, then ramps up to 70 degC and then down again to 25 degC. The chamber temperature is then lowered to -35 degC, and then up again to the initial temperature value.
The measured temperature profiles are displayed in Figure 1. Data is logged with a frequency of 25 Hz in this case. The FSI-based measurements follow closely the measurements provided by the PT100 sensor, not showing a time-delay when the temperature changes, even if the fibre optics is protected by the PEEK tube. Influence of humidity is not considered in this case, given the strong performance of the FSI temperature sensor across the range of temperatures tested.
When looking at steady-state performance only, a calibration graph of the FSI-based measurements against the PT1000 measurements is shown in Figure 2. The FSI-based measurements are within a 1.5 degC error band with respect to the values measured by the PT1000 sensor, in fact the average difference between the two measurements is 0.9 degC.
Finally, in Figure 3 it is shown a comparison of the resolution from the two different measurement technologies used. The FSI-based measurements have a resolution of 0.005 degC, measured as standard deviation of the signal over 300 seconds, against a resolution of 0.05 degC from the PT1000 sensor.