Ocean Optics OOIIrrad-C - Manual (Page 45)

4: Configuration
Irradiance Measurements Tab
The Irradiance Measurements tab on the Configure Spectrometer screen allows you to select the
desired irradiance values. Phototropic/Scotopic values are calculated over a 380 to 780 nm wavelength
range. Radiometric values require that you specify the wavelength range. Scotopic conditions are defined
when the luminance is less than some hundredths of a candela per square meter (cd/m
2 ). The difference
between this scotopic vision (low-level condition) compared to a photopic (high-level condition) affects
the calculations for Lumen, Lux, and Candela by using the V’(λ) spectral luminous efficiency curve
instead of the V(λ) curve.
► Procedure
1. Click the
Phototropic/Scotopic slide switch to select the type of values desired. Photopic is the
default selection, and is the preferred selection in most cases.
The Scotopic selection measures the sample as seen by the darkness-adapted eye (darkness
vision). Scotopic measurements can only be taken for samples emitting between 380 nm and
780 nm, the visible range of the human eye. Scotopic measurements require a level of luminance
low enough so that the retinal cones of the eye are not stimulated and color is not visible to the
eye.
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