LIGHT MELANOPIC ACTIVITY INDICATOR

The invention provides a light indicator (100) for use in evaluating melanopsin active radiation in a flux of light, the light indicator (100) comprising a first light indicator element (110) comprising a first light reflective element (112) and a second light indicator element (120) comprising a second light reflective element (122), the light reflecting elements (112,122) having different wavelength dependencies of the spectral reflectivity, wherein the light reflecting elements (112,122) are selected to provide the same intensity of reflected light of two or more different types of light irradiating on the light indicator elements (110,120), wherein the two or more different types of light have different spectral power distributions in the visible wavelength range but having the same ratios of the melanopic flux and the luminous flux, wherein the ratio of the melanopic flux and the luminous flux of light is defined asMEF=1.22∑λ=380780⁢SPD⁡(λ)⁢m⁡(λ)⁢Δλ∑λ=380780⁢SPD⁡(λ)⁢V⁡(λ)⁢Δλ(Eq.1)wherein SPD(λ) is the spectral power distribution of the light, m(λ) is the melanopic sensitivity function, and the V(λ) is the photopic sensitivity.