Spectral Emissivity ftir system

Key-words: Emissivity, thermal radiation, surface temperature

The emissivity of a surface plays a role in many applications, e.g. accurate surface temperature measurement, thermal radiation heat transfer and properties of coatings and reflecting surface. The emissivity of real surfaces varies in general with wavelength and can be measured with high accuracy with a FTIR spectrometer.

Spectral intensities from blackbody and sample at known temperature are measured by Fourier Transform Infrared Spectroscopy (FTIR) spectrometer in NIR and MIR range to measure the spectral emissivity of a sample, i.e. spectral range from 1 to 25 µm. The system can be used for typical 1” samples, but can also be used for wires, heaters, shiny surfaces, etc. Contact Pyrooptic for discussion of the specific application.

Options: Installation and training


Blackbody source (left) used as reference in spectral emissivity measurements and sample mounted on Sample-heater with temperature range from ambient up to 500°C. Sample temperature is measured by ø0.5 mm diameter thermocouple.


System performance test before shipping (red curve) on customer sample “R1” at 180°C. Black curve is emissivity measurement perform with alternative FTIR laboratory set-up. FTIR spectra was collected with spectral resolution of 8 cm-1 and 200 scans (approx. 2 min. measurement time).


“Spectral emissivity of surface blackbody calibrators” by Sønnik Clausen, International Journal of Thermophysics, Vol. 28, No. 6, 2007, p. 2145-2154.