Remarks on data acquisition |
  
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Remarks on data acquisition |
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BREIN needs absolute reflectance and transmittance spectra of the samples for correct analysis. Usually the following three measurements are required:
•the raw dark spectrum D (light source switched off or black reference sample is used)
•the raw spectrum Ref of the reference sample (no sample in case of transmittance, a reference mirror with known absolute reflectance Rabs in case of reflectance)
•the raw spectrum S of the sample
It depends very much on the stability of the spectroscopic hardware and the environment how frequently the dark and the reference spectra have to be updated.
Finally the transmittance is then given by
T = (S-D)/(Ref-D)
and in case of reflectance one gets
R = Rabs * (S-D)/(Ref-D)
The R and T values computed according to the expressions above are to be passed to BREIN.
If your spectrometer software generates R or T spectra in percent, i.e. the data range is 0 ... 100, you do not have to change the range to 0 ... 1. The required division by 100 can be taken into account when BREIN is configured for your coating line.