Melanopsin blocker
Methods and devices are described that relate to spectral filters and associated eyewear that are specifically designed to block emissions of circadian-active blue light to reach the observer. An example wearable device includes one or more windows positioned to allow light from a light source to propagate toward a position of a wearer's eyes, and a spectral filter that comprises a coating positioned on one or more sections of the one or more windows. The spectral filter includes a multi-layer stack of dielectric material. The number and thicknesses of the layers are selected to provide designed transmission and blocking characteristics. The designed characteristics include a contiguous blocking region that blocks 98-100% of the circadian-active spectra and two contiguous transmission regions that transmit 80%-100% of the spectral content outside of the circadian-active spectra.
1 . A wearable device, comprising:
one or more windows positioned to allow light from a light source to propagate toward a position of a wearer's eyes; and
a spectral filter that comprises a coating positioned on one or more sections of the one or more windows,
wherein the spectral filter includes a multi-layer stack of dielectric material with alternate high and low indices of refraction such that a layer having a high index of refraction is positioned above or below a layer having a low index of refraction, and a layer having a high index of refraction is positioned above or below a layer having a low index of refraction,
wherein a number of the layers and a thickness of each layer are selected to provide designed transmission and blocking characteristics to block circadian-active spectra while allowing spectral content outside of the circadian-active spectra to pass through the spectral filter,
wherein the designed transmission and blocking characteristics include a contiguous blocking region within 455-495 nm band of wavelengths with a tolerance to within at least ±5 nm, and two contiguous transmission regions, a first one of the contiguous transmission regions extending below 455 nm and a second one of the contiguous transmission regions extending above 495 nm,
wherein the spectral filter is configured to block 98-100% of the spectral content in the contiguous blocking region, and transmit 80%-100% of the spectral content in the contiguous transmission regions, and
wherein the contiguous blocking region extends from 455 nm to 495 nm, the first contiguous transmission region extends from 300 nm to 455 nm, and the second contiguous transmission region extends from 495 nm to at least 700 nm, all with a ±5 nm tolerance.
2 . The wearable device of claim 1 , wherein each layer with the high index of refraction includes titanium dioxide (TiO 2 ) and has a 2.35 index of refraction, each layer with the low index of refraction includes silicon dioxide (SiO 2 ) and has a 1.45 index of refraction, and the multi-layer stack includes 81 layers.
3 . The wearable device of claim 1 , wherein the contiguous blocking region extends from 455 nm to 495 nm, the first contiguous transmission region extends from 300 nm to 455 nm, and the second contiguous transmission region extends from 495 nm to at least 700 nm, all with a ±2 nm tolerance.
4 . The wearable device of claim 3 , wherein each layer with the high index of refraction includes titanium dioxide (TiO 2 ) and has a 2.35 index of refraction, each layer with the low index of refraction includes silicon dioxide (SiO 2 ) and has a 1.45 index of refraction, and the multi-layer stack includes 121 layers.
5 . The wearable device of claim 1 , wherein the one or more windows include two lenses, and the spectral filter is formed as the coating on each of the lenses.
6 . The wearable device of claim 1 , wherein the wearable device is a pair of goggles, the one or more windows forms a unitary window, and the spectral filter is formed as the coating on the unitary window.
7 . The wearable device of claim 1 , wherein the wearable device is a pair of goggles, the one or more windows forms a unitary window, and the spectral filter is formed as the coating on two or more sections of the unitary window.
8 . The wearable device of claim 1 , wherein the one or more windows are made of glass or plastic.
9 . The wearable device of claim 1 , wherein the spectral filter is removably attached to the one or more windows.
10 . The wearable device of claim 1 , the light source is one or more of: an atmospheric light source, a light emitting diode (LED), a halogen lamp, or a fluorescent lamp.
11 . The wearable device of claim 1 , further including an anti-reflection coating positioned on one side of the one or more windows.
12 . The wearable device of claim 1 , wherein the wearable device is a pair of goggles, the one or more windows form a unitary window, the spectral filter is formed as the coating on two or more sections of the unitary window, and locations and areal extents of the two or more sections of the unitary window are selected to allow light propagating at normal angles to pass through the spectral filter and reach the position of the wearer's eyes.
13 . The wearable device of claim 12 , wherein the locations and areal extents of the two or more sections of the unitary window are selected to allow light propagating at inclined angles to pass through the spectral filter and reach the position of the wearer's eyes.
14 . The wearable device of claim 12 , wherein the goggles include opaque side shields positioned to prevent side illumination from reaching the position of the wearer's eyes.
15 . The wearable device of claim 1 , wherein a number of layers is greater than or equal to 81.
16 . A spectral filter for use in an eyewear for restoring circadian rhythm, comprising:
a multi-layer stack coating on a substrate, the multi-layer stack including a plurality of layers of dielectric material with alternate high and low indices of refraction such that a layer having a high index of refraction is positioned above or below a layer having a low index of refraction, and a layer having a high index of refraction is positioned above or below a layer having a low index of refraction,
wherein a number of the layers and a thickness of each layer are selected to provide designed transmission and blocking characteristics to block circadian-active spectra to be transmitted through the spectral filter,
wherein the designed transmission and blocking characteristics include a contiguous blocking region within 455-495 nm band of wavelengths to within at least ±5, and two contiguous transmission regions, a first one of the contiguous transmission regions extending below 455 nm and a second one of the contiguous transmission regions extending above 495 nm,
wherein the spectral filter is configured to block 98-100% of spectral content in the contiguous blocking region, and transmit 80%-100% of the spectral content in the contiguous transmission regions, and
wherein the contiguous blocking region extends from 455 nm to 495 nm, the first contiguous transmission region extends from 300 nm to 455 nm, and the second contiguous transmission region extends from 495 nm to at least 700 nm, all with a ±5 nm tolerance.
17 . The spectral filter of claim 16 , wherein:
each layer with the high index of refraction includes titanium dioxide (TiO 2 ) and has a 2.35 index of refraction, each layer with the low index of refraction includes silicon dioxide (SiO 2 ) and has a 1.45 index of refraction, and the multi-layer stack includes 81 layers.
18 . The spectral filter of claim 16 , wherein:
the contiguous blocking region extends from 455 nm to 495 nm, the first contiguous transmission region extends from 300 nm to 455 nm, and the second contiguous transmission region extends from 495 nm to at least 700 nm, all with a ±2 nm tolerance, and
each layer with the high index of refraction includes titanium dioxide (TiO 2 ) and has a 2.35 index of refraction, each layer with the low index of refraction includes silicon dioxide (SiO 2 ) and has a 1.45 index of refraction, and the multi-layer stack includes 121 layers.
19 . The spectral filter of claim 16 , configured to receive input illumination from one or more light sources including an atmospheric light source, a light emitting diode (LED), a halogen lamp, or a fluorescent lamp.
20 . The spectral filter of claim 16 , wherein the spectral filter does not include a dye-based or a pigment-based material.