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5.7 Test of sensitivity to UV and infrared radiation
Sensitivity to UV and infrared radiation is a critical factor for measurements in which it is expected that infrared and/or UV radiation will be present, such as in daylight or with certain vacuum tubes or light bulbs. Lux metres should not be sensitive to UV and infrared light.
Sensitivity to UV radiation is determined by irradiating the lux metre with a source of UV radiation which primarily emits irradiation within the UV spectral range. The ratio of illuminance in the spectral range of visible radiation to the intensity of radiation in the UV spectral range should be 35 lx∙(W ∙ m^-2)^-1. The radiation source should have a spectral characteristic similar to that in Figure 1. Sensitivity is defined as the ratio of the lux metre’s signal Y_uv when irradiated by a UV source in combination with a UV filter and the lux metre’s signal Y when irradiated by the same radiation source without a filter, according to relation (6). The recommended characteristic of the filter is specified on the graph in Figure 2.
(6)

Figure 1 – Recommended spectral characteristic of the UV radiation source


Figure 2 – Recommended characteristic of the UV filter

Sensitivity to infrared light is determined by irradiating the lux metre with a lamp (CIE standardised source A). Sensitivity is defined as the ratio of the lux metre’s signal Y_IČ when irradiated by source A in combination with an infrared filter and the lux metre’s signal Y when irradiated by the same radiation source without a filter, according to relation (7). The recommended characteristic of the filter is specified on the graph in Figure 3.

(7)

Figure 3 – Recommended characteristic of the infrared filter
5.8 Temperature dependence test
The photometric transducer is placed into a suitable climatic chamber on the moveable carriage of the photometric bench. A photometric lamp is switched on in the chamber at a stable temperature of 5 °C (generally after one hour) and the illuminance values are measured for 5 different distances of the photometric transducer.
Afterward, the temperature in the climatic chamber is increased to 40 °C and the photometric lamp is switched back on after a stabilisation period (generally one hour) and the illuminance values are measured for 5 different distances of the photometric transducer.
The illuminance values are also measured at a reference temperature of T₀ = 25 °C. The temperature dependence index f₆ is calculated based on relation (8) and must correspond to the parameters specified in Article 2.3 during the test.
(8)
in which
Y(T) is the output signal at temperature T,
T₀ = 25 °C; T₁ = 5 °C; T₂ = 40 °C; T = 10 °C.