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 as MEF = 1.22 ∑ λ = 380 780 SPD ( λ ) m ( λ ) Δλ ∑ λ = 380 780 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.
1. A light indicator for use in evaluating melanopsin active radiation of light, the light indicator comprising a first light indicator element comprising a first light reflective element and a second light indicator element comprising a second light reflective element, the light reflecting elements having different wavelength dependencies of the spectral reflectivity, wherein the light reflecting elements are selected to provide the same intensity ratio of reflected light of two or more different types of light irradiating on the light indicator elements, wherein the two or more different types of light have different spectral power distributions in the visible wavelength range but have the same ratios of the melanopic flux to the luminous flux, wherein the ratio of the melanopic flux to the luminous flux of light is defined as
MEF
=
1.22
∑
λ
=
380
780
SPD
(
λ
)
m
(
λ
)
Δλ
∑
λ
=
380
780
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 V(λ) is the photopic sensitivity, and wherein the light reflecting elements are further selected to provide a different intensity ratio of reflected light of two or more different types of light irradiating on the light indicator elements, wherein the two or more different types of light have different ratios of the melanopic flux to the luminous flux.
2. The light indicator ( 100 ) according to claim 1 , wherein the at least two light reflecting elements are selected to provide also the same color point of the reflected light of the two or more different types of light.
3. The light indicator according to claim 1 , wherein the at least two light reflecting elements have different wavelength dependencies of the spectral reflectivity at least within the wavelength range of 380-550 nm.
4. The light indicator according to claim 1 , wherein the at least two light reflecting elements have different wavelength dependencies of the spectral reflectivity at least within the wavelength ranges of 380-470 nm, 470-500 nm, and 500-550 nm.
5. The light indicator according to claim 1 , wherein,
the first light indicator element comprising a first sensing area, wherein the first light reflecting element being configured to reflect at least part of light illuminating the first sensing area having one or more wavelengths selected from the wavelength range of an absorption band of melanopsin in the visible wavelength range and configured to absorb at least part of light illuminating the first sensing area having one or more wavelengths in the visible wavelength range outside the wavelength range of the absorption band of melanopsin in the visible wavelength range;
the second light indicator element comprising a second sensing area, wherein the second light reflecting element being configured to reflect at least part of light illuminating the second sensing area having one or more wavelengths selected from the wavelength range of an absorption band of melanopsin in the visible wavelength range and configured to absorb at least part of light illuminating the second sensing area having one or more wavelengths in the visible wavelength range outside the wavelength range of the absorption band of melanopsin in the visible wavelength range;
wherein
first light indicator element and the second light indicator element are chosen such that:
(i) under illumination with first light with a predefined first spectral power distribution, including first spectral power in the wavelength range of an absorption band of melanopsin in the visible wavelength range, the intensities of the reflections of the first light from the first sensing area and the second sensing area are the same;
(ii) under illumination with second light, including second spectral power in the wavelength range of an absorption band of melanopsin in the visible wavelength range, wherein the second spectral power is larger than the first spectral power, the intensity of the reflection of the second light from the first sensing area is larger than from the second sensing area; and
(iii) under illumination with third light, including third spectral power in the wavelength range of an absorption band of melanopsin in the visible wavelength range, wherein the third spectral power is smaller than the first spectral power, the intensity of the reflection of the third light from the first sensing area is smaller than from the second sensing area.
6. The indicator according to claim 5 , wherein (i) the first light reflecting element is (ia) configured to reflect at least part of light illuminating the first sensing area having one or more wavelengths selected from the wavelength range of 440-530 nm and (ib) configured to absorb at least part of light illuminating the first sensing area having one or more wavelengths in the visible wavelength range outside the wavelength range of 440-530 nm, (ii) the second light reflecting element is (iia) configured to reflect at least part of light illuminating the second sensing area having one or more wavelengths selected from the wavelength range of 440-530 nm and (iib) configured to absorb part of light illuminating the second sensing area having one or more wavelengths in the visible wavelength range outside the wavelength range of 440-530 nm.
7. The light indicator according to claim 5 , wherein (i) a reflection of visible light at the first sensing area in the wavelength range of the absorption band of melanopsin is in average at least two times higher than in average the reflection at the other wavelengths in the visible wavelength range, and (ii) a reflection of visible light at the second sensing area in the wavelength ranges of 380-470 nm and 500-550 nm is in average at least two times higher than in average the reflection at the other wavelengths in the visible wavelength range.
8. The light indicator according to claim 1 , wherein the first light reflecting element comprises a first pigment and wherein the second light reflecting element comprise a second pigment, wherein (i) the first light reflecting element comprises a light transmissive material, wherein the first pigment is embedded in the light transmissive material, and (ii) wherein the second light reflecting element comprises a light transmissive material, wherein the second pigment is embedded in the light transmissive material.
9. A kit of parts comprising:
a light indicator for use in evaluating melanopsin active radiation of light, the light indicator comprising a first light indicator element comprising a first light reflective element and a second light indicator element comprising a second light reflective element, the light reflecting elements having different wavelength dependencies of the spectral reflectivity, wherein the light reflecting elements are selected to provide the same intensity ratio of reflected light of two or more different types of light irradiating on the light indicator elements, wherein the two or more different types of light have different spectral power distributions in the visible wavelength range but have the same ratios of the melanopic flux to the luminous flux, wherein the ratio of the melanopic flux to the luminous flux of light is defined as
MEF=1.22(Σ(λ=380){circumflex over ( )}780 SPD(λ) m (λ)Δλ)/(Σ(λ=380){circumflex over ( )}780 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 V(λ) is the photopic sensitivity, and wherein the light reflecting elements are further selected to provide a different intensity ratio of reflected light of two or more different types of light irradiating on the light indicator elements, wherein the two or more different types of light have different ratios of the melanopic flux to the luminous flux; and
reference information or a reference to such reference information which is available on one or more of the light indicator, a data carrier, and another tangible element, and wherein the reference information contains information allowing one or more of a qualitative analysis and a quantitative analysis of a ratio of the melanopic flux and the luminous flux of light on the light indicator elements, of the light indicator.
10. The kit of parts according to claim 9 , wherein the reference information contains information instructing a user how to perform the one or more of the qualitative analysis and the quantitative analysis by using a camera, and wherein the other tangible element is selected from the group consisting of a manual of the light indicator, a package of the light indicator, a manual of a lighting device, and a package of a lighting device.
11. The kit of parts according to claim 9 , wherein the tangible element is a portable device having a camera and wherein the reference information contains information instructing a user how to perform the one or more of the qualitative analysis and the quantitative analysis by using said camera.
12. A method of evaluating a melanopsin active radiation of light, using a light indicator,
wherein the light indicator is for use in evaluating melanopsin active radiation of light, the light indicator comprising a first light indicator element comprising a first light reflective element and a second light indicator element comprising a second light reflective element, the light reflecting elements having different wavelength dependencies of the spectral reflectivity, wherein the light reflecting elements are selected to provide the same intensity ratio of reflected light of two or more different types of light irradiating on the light indicator elements, wherein the two or more different types of light have different spectral power distributions in the visible wavelength range but have the same ratios of the melanopic flux to the luminous flux, wherein the ratio of the melanopic flux to the luminous flux of light is defined as
MEF=1.22(Σ(λ=380){circumflex over ( )}780 SPD(λ) m (λ)Δλ)/(Σ(λ=380){circumflex over ( )}780 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 V(λ) is the photopic sensitivity, and wherein the light reflecting elements are further selected to provide a different intensity ratio of reflected light of two or more different types of light irradiating on the light indicator elements, wherein the two or more different types of light have different ratios of the melanopic flux to the luminous flux,
wherein the method comprises: illuminating the light indicator with light from a light source and evaluating on the basis of the intensities of light emanating from the first light indicator element and from the second light indicator element the ratio of the melanopic flux to the luminous flux of the light source.
13. The method according to claim 12 , comprising evaluating with an optical sensor, wherein the optical sensor is an optical sensor of a portable device.
14. The method according to claim 13 , wherein the optical sensor is an image capturing device and the method further comprising:
taking an image of the light indicator when being illuminated by the light source,
calculating the value of the melanopic DER from the intensities of light emanating from the first light indicator element ( 110 ) and the second light indicator element using the formula:
melanopic
DER
=
k
(
m
1
R
m
+
m
2
G
m
+
m
3
B
m
p
1
R
p
+
p
2
G
p
+
p
3
B
p
)
n
(
Eq
.
9
)
wherein:
R m , G m , B m : mean R, G, B values for the first light reflective element,
R p , G p , B p : mean R, G, B values for the second light reflective element,
k, m 1 , m 2 , m 3 , p 1 , p 2 , p 3 , n: regression parameters.
15. A computer program product when running on a processor is capable of carrying out a method of evaluating a melanopsin active radiation of light, wherein the method comprises the steps of:
taking an image of a light indicator when being illuminated with the light,
wherein the light indicator is for use in evaluating melanopsin active radiation of light, the light indicator comprising a first light indicator element comprising a first light reflective element and a second light indicator element comprising a second light reflective element, the light reflecting elements having different wavelength dependencies of the spectral reflectivity, wherein the light reflecting elements are selected to provide the same intensity ratio of reflected light of two or more different types of light irradiating on the light indicator elements, wherein the two or more different types of light have different spectral power distributions in the visible wavelength range but have the same ratios of the melanopic flux to the luminous flux, wherein the ratio of the melanopic flux to the luminous flux of light is defined as
MEF=1.22(Σ(λ=380){circumflex over ( )}780 SPD(λ) m (λ)Δλ)/(Σ(λ=380){circumflex over ( )}780 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 V(λ) is the photopic sensitivity, and wherein the light reflecting elements are further selected to provide a different intensity ratio of reflected light of two or more different types of light irradiating on the light indicator elements, wherein the two or more different types of light have different ratios of the melanopic flux to the luminous flux,
calculating the value of the melanopic DER from the intensities of light emanating from the first light indicator element and the second light indicator element using the formula:
melanopic
DER
=
k
(
m
1
R
m
+
m
2
G
m
+
m
3
B
m
p
1
R
p
+
p
2
G
p
+
p
3
B
p
)
n
(
Eq
.
9
)
wherein:
R m , G m , B m : mean R, G, B values for the first light reflective element,
R p , G p , B p : mean R, G, B values for the second light reflective element,
k, m 1 , m 2 , m 3 , p 1 , p 2 , p 3 , n: regression parameters.