PR-680/680L User Manual
2
FIGURE 47
–
PR-680/680L SPECTROMETER
The uncorrected or ‘raw’ spectrum is corrected using factors established during the factory calibration of the
instrument. These factors include wavelength accuracy correction, spectral distribution correction and
photometric correction. The wavelength calibration is performed using a helium spectral line source. The line
source provides known spectral emission lines that the software uses to map the dispersion of the grating to the
multi-element detector. The helium lines used during the wavelength calibration are 388.6 nm, 447.1 nm, 471.3
nm, 587.6 nm, 667.8 nm, 706.5 nm and 728.13 nm.
Next, the data is corrected by spectral factors. These factors insure that the spectral power distribution (SPD) of
the target is and calculated values such as CIE Chromaticity are accurately reported. Lastly, a scaling factor
(photometric factor) is applied ensuring the proper photometric levels such as luminance or illuminance are
displayed.
256 detector array
Diffracted light
Diffraction grating
Objective
lens
Aperture mirror
Optical
radiation
Eyepiece
Input Slit
Grating
Incident light