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5.9 Directional dependence test
During the test, the transducer is fastened to a turntable which can rotate along two axes which are perpendicular to one another. Standardised light source A is used for the test. A collimated beam with a divergence of less than 1° is used for the measurement. The transducer is set so that the turntable’s axis passes through the centre of the transducer’s sensitive surface and is perpendicular to the optical axis of the photometric bench. Directional dependence index f₂ is measured on two orthogonal planes. Directional dependence is measured within a range ε from 5° to 85° at increments of 5° or less, according to the manufacturer’s requirements.
The directional dependence index f₂ of lux metres with a planar transducer is calculated based on relation (9) and must correspond to the parameters specified in Article 2.3 during the test.
(9)
in which
Y(ε, φ) is the output signal in dependence on the angle of incident,
ε is the angle measured in relation to a normal/perpendicular measurement surface or in relation to the optical axis,
φ is the azimuth angle.



Figure 4 – Coordinates for defining function f₂ (ε, φ)
5.10 Tests of resistance to external effects
5.10.1 Test of resistance to limit temperatures for storage and transportation
The entire lux metre in an inoperative state (switched off, if relevant) must be placed in a climatised chamber for a period of three hours at both boundary storage temperatures according to the technical conditions specified by the manufacturer.
The lux metre is immediately inspected for changes in appearance upon concluding the test. There may be no change in the measurement instrument’s appearance; the material and surface may not be frosted or blistered and may not exhibit a change in colour.
The lux metre must meet the requirements specified in Article 2.3 at the reference temperature once two hours have elapsed as of the test’s completion.