Most sensations of color are only triggered by electromagnetic radiation in the range of wavelengths between 380 nm and 780 nm (light) when the intensity of this radiation is sufficient to permit daylight vision. In this case, the cones are responsible for color sensation. Night vision, which uses rod receptors, is colorless. The spectral brightness response for daytime vision (cones, >10 cd/m²) is described by the V(λ) function, and is the function used most often. The spectral brightness response for night vision (rods, <0.001 cd/m²) is described with the V’(λ) function. Practical applications for the scotopic function are rare.
The specifications of the sensor play an important part in the quality classes that exist for photometers. DIN 5032 Part 7 and CIE Publ. No. 69 distinguish quality classes L, A, B and C, where L represents the highest level. The quality classes are meant provide the user with information on the maximum uncertainty of measurement of his photometer. But many light measurement qualifications refer blindly to these DIN classes. The total error is composed of a very wide range of differentiated evaluation criteria. For each criterion there is a maximum permitted tolerance that must be maintained regardless of the total tolerance. The conformance of the detector head to the given V(λ) and/or V’(λ) functions is a primary qualification feature within the context of this classification.
Information for this application can be found under:
Additional information from our Products section: Scotopic Illuminance Light Detector: VL-3705 Possible Optometer: P-9710
Additional information from our Products section: 