The LPPHOT01 probe measures illuminance (lux) defined as the ratio between the luminous flux (lumen) passing through a surface and the surface area (m2).
The spectral response curve of a photometric probe is equal to the one of the human eye, known as standard photopic curve V(λ). The difference in spectral response between LPPHOT01 and the standard photopic curve V(λ) is calculated by means of the error f1'.
The calibration of the probe is performed by comparing it to a luxmeter calibrated by a Primary Metrological Institute. All calibration procedures follow the CIE publication No 69 (1987) “Method of Characterizing Illuminance Meters and Luminance Meters”.
The calibration is carried out byilluminating the probe with a standard illuminant A.