1.7 directional error of lux metre error caused by inaccurate evaluation of the effects of light incident on the photometric head from a non-perpendicular direction.
1.8 linearity property of a detector based on which the output variable is directly proportional to the input variable; a deviation from linearity is non-linearity.
1.9 temperature dependence change in responsivity depending on temperature is quantitatively described by the temperature coefficient.
1.10 sensitivity in UV range fUV undesired responsivity to radiation in the UV spectral range; a lux metre should not be sensitive to UV radiation; sensitivity to UV radiation may be caused by imperfect filtering of UV radiation or by fluorescent influences.
1.11 sensitivity in infrared rangefIR undesired responsivity to radiation in the infrared spectral range; a lux metre should not be sensitive to infrared radiation.
1.12 intrinsic error (of a measuring instrument) a measuring instrument’s error in measurement determined under reference conditions prior to the commencement of the electromagnetic compatibility (EMC) tests.
1.13 fatal error (during EMC tests) a state found in EMC tests in the event that the difference between the measurement error determined during the EMC tests and the intrinsic error (of the measuring instrument) is greater than:
a value of one third the value of the maximum permissible error for lux metres with digital displays,
the value of the maximum permissible error for lux metres with analogue displays.
2 Metrological requirements 2.1. Operating conditions The working conditions are defined by the lux metre manufacturer.
2.2 Measuring range The manufacturer must precisely specify the lux metre’s measuring range.
A lux metre’s basic measurement range is from 10 lx to 10 000 lx.
