Jadak Photo Research SpectraScan PR-7 Series, User Manual

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Chapter 3
– Theory of Operation
31
For the PR-735 and PR-745, a Mercury Argon spectral line source is used. The calibration lines are 404.7 nm,
435.8 nm, 546.1 nm, 696.5 nm, 763.51 nm, 811.53 nm, 912.3 nm and 1013.97 nm.
Next, spectral correction factors are established using a continuous source with known intensities at each
wavelength. These factors ensure that the proper spectral power distribution (SPD) of the target is determined
following a measurement and that calculated values such as CIE Chromaticity, based on the measured spectral
quantities, are accurately reported. Lastly, a scaling factor (photometric factor) is applied ensuring the proper
photometric levels such as luminance or illuminance are displayed.
Calculations
The corrected spectral data is then used to calculate CIE photometric and colorimetric values including
luminance, CIE 1931 x, y and 1976 u’, v’ chromaticity coordinates, correlated color temperature in Kelvins and
dominant wavelength. Following are some of the basic calculations used to generate photometric and
colorimetric parameters:
FIGURE 20 - CIE 1931 TRISTIMULUS FUNCTIONS