Emissivity value required!
-
The NCIR has a MLX90614 sensor on it. https://docs.m5stack.com/en/unit/ncir links the datasheet.
The measurement principe is similar to a thermal camera with just one pixel. It measures the infrared (heat-)radiation that comes from an object. Unfortunately this radiation depends on the surface material where some are good radiators and some are not. To compensate this, the sensor needs to know the emissivity of the measured object.In the datasheet they say: As a standard, the MLX90614 is calibrated for an object emissivity of 1. It can be easily customized by the customer for
any other emissivity in the range 0.1…1.0 without the need of recalibration with a black body.
This means: If your object has an emissivity of 1, then you get correct readings. If your object has for example a emissivity of 0.7 then your reading is wrong as long as you not tell the sensor to calculate with 0.7.Conclusion: To measure with a IR unit (NCIR or a thermal camera) it requires to know the emissivity of the surface. See: https://en.wikipedia.org/wiki/Emissivity for more information and a table of common materials.
-
this should go as reply to https://community.m5stack.com/topic/1838/ncir-unit-weird-values
accidentally posted as new topic. -
H holofloh referenced this topic