PASCO SE-7183 Spectrometer - Manual (Page 11)

9
A BOUT THE MEASUREMENTS
Rel. Irradiance
Relative irradiance is a comparison of the fraction of energy a light source emits
and the energy the spectrometer collects from a reference lamp with a
blackbody energy distribution (normalized to 1 at the energy maximum).
To measure the relative irradiance of a sample, you must save the reference scan
using a lamp of known color temperature and enter the color temperature in the
Spectrometer Properties screen (see “Editing the spectrometer properties”
above).
SPARK calculates relative irradiance with this equation:
Where:
B
λ
= Relative energy of the reference (calculated from the color temperature) at
wavelength λ
S
λ
= Sample intensity at wavelength λ
D
λ
= Dark intensity at wavelength λ
R
λ
= Reference intensity at wavelength λ
I

B

S

D

–
R

D

–
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 
=