OPTICAL ASSEMBLY WITH EVANESCENT ACTIVATION LIGHT LEAKAGE FOR DIMMING
An optical assembly is configured to receive visible scene light at the backside of the optical assembly and to direct the visible scene light on an optical path toward the eyeward side. The optical assembly includes a dimming layer disposed on the optical path and includes a photochromic material that is configured to darken in response to exposure to a range of light wavelengths. An illumination layer is also disposed on the optical path and is configured to propagate an evanescent activation light within the illumination layer. The illumination layer is also configured to leak the evanescent activation light towards the dimming layer to activate a darkening of the photochromic material of the dimming layer to dim the visible scene light.
1 . An optical assembly, comprising:
an eyeward side and a backside, wherein the optical assembly is configured to receive visible scene light at the backside of the optical assembly and to direct the visible scene light on an optical path toward the eyeward side;
a dimming layer disposed on the optical path between the eyeward side and the backside, wherein the dimming layer includes a photochromic material that is configured to darken in response to exposure to a range of light wavelengths; and
an illumination layer disposed on the optical path between the eyeward side and the dimming layer, wherein the illumination layer is configured to propagate an evanescent activation light that is within the range of light wavelengths, and wherein the illumination layer is configured to leak the evanescent activation light towards the dimming layer to activate a darkening of the photochromic material to dim the visible scene light.
2 . The optical assembly of claim 1 , wherein the illumination layer comprises:
a core layer configured to propagate the evanescent activation light, the core layer having a first surface facing the eyeward side and a second surface facing the backside; and
an eyeward side cladding layer disposed on the first surface of the core layer to promote total internal reflection of the evanescent activation light within the core layer.
3 . The optical assembly of claim 2 , wherein the second surface of the core layer is disposed directly on a surface of the dimming layer.
4 . The optical assembly of claim 2 , wherein the illumination layer further comprises:
a backside cladding layer disposed on the second surface of the core layer between the core layer and the dimming layer, wherein the backside cladding layer has a thickness that is less than a thickness of the eyeward side cladding layer.
5 . The optical assembly of claim 4 , wherein the thickness of the backside cladding layer is in the range of one to ten microns.
6 . The optical assembly of claim 2 , wherein the illumination layer further comprises:
a backside cladding layer disposed on the second surface of the core layer between the core layer and the dimming layer, wherein the backside cladding layer has a refractive index that is greater than a refractive index of the eyeward side cladding layer.
7 . The optical assembly of claim 1 , further comprising at least one absorption layer disposed on the optical path between the eyeward side and the backside to absorb the evanescent activation light.
8 . The optical assembly of claim 1 , further comprising:
at least one illuminator coupled to an edge of the illumination layer, wherein the at least one illuminator is configured to selectively emit the evanescent activation light.
9 . The optical assembly of claim 8 , further comprising a reflective coating disposed on the edge of the illumination layer, wherein the reflective coating is configured to reflect the evanescent activation light within the dimming layer.
10 . The optical assembly of claim 1 , wherein the evanescent activation light comprises non-visible light, ultraviolet light, infrared light, or violet light.
11 . The optical assembly of claim 1 , further comprising:
a display layer disposed on the optical path between the eyeward side of the optical assembly and the dimming layer, wherein the display layer is configured to direct visible display light toward the eyeward side.
12 . A head-mounted device, comprising:
a frame; and
an optical assembly secured within the frame, wherein the optical assembly is configured to receive visible scene light at a backside of the optical assembly and to direct the visible scene light on an optical path toward an eyeward side of the optical assembly, wherein the optical assembly includes:
a dimming layer disposed on the optical path between the eyeward side and the backside, wherein the dimming layer includes a photochromic material that is configured to darken in response to exposure to a range of light wavelengths; and
an illumination layer disposed on the optical path between the eyeward side and the dimming layer, wherein the illumination layer is configured to propagate an evanescent activation light that is within the range of light wavelengths, and wherein the illumination layer is configured to leak the evanescent activation light towards the dimming layer to activate a darkening of the photochromic material to dim the visible scene light.
13 . The head-mounted device of claim 12 , wherein the illumination layer comprises:
a core layer configured to propagate the evanescent activation light, the core layer having a first surface facing the eyeward side and a second surface facing the backside; and
an eyeward side cladding layer disposed on the first surface of the core layer to promote total internal reflection of the evanescent activation light within the core layer.
14 . The head-mounted device of claim 13 , wherein the second surface of the core layer is disposed directly on a surface of the dimming layer.
15 . The head-mounted device of claim 13 , wherein the illumination layer further comprises:
a backside cladding layer disposed on the second surface of the core layer between the core layer and the dimming layer, wherein the backside cladding layer has a thickness that is less than a thickness of the eyeward side cladding layer.
16 . The head-mounted device of claim 13 , wherein the illumination layer further comprises:
a backside cladding layer disposed on the second surface of the core layer between the core layer and the dimming layer, wherein the backside cladding layer has a refractive index that is greater than a refractive index of the eyeward side cladding layer.
17 . The head-mounted device of claim 12 , wherein the optical assembly further comprises:
a display layer disposed on the optical path between the eyeward side of the optical assembly and the dimming layer, wherein the display layer is configured to direct visible display light toward the eyeward side.
18 . An optical assembly, comprising:
a dimming layer that includes a photochromic material configured to darken in response to exposure to a range of light wavelengths;
an illumination layer coupled to the dimming layer, wherein the illumination layer includes:
a core layer configured to propagate an evanescent activation light that is within the range of light wavelengths; and
a first cladding layer disposed on a first surface of the core layer to promote total internal reflection of the evanescent activation light within the core layer; and
an illuminator coupled to edge of the illumination layer, wherein the illuminator is configured to selectively emit the evanescent activation light, and wherein the illumination layer is configured to leak the evanescent activation light towards the dimming layer to activate a darkening of the photochromic material.
19 . The optical assembly of claim 18 , wherein the illumination layer further comprises:
a second cladding layer disposed on a second surface of the core layer, opposite the first surface, between the core layer and the dimming layer, wherein the second cladding layer has a thickness that is less than a thickness of the first cladding layer.
20 . The optical assembly of claim 18 , wherein the illumination layer further comprises:
a second cladding layer disposed on a second surface of the core layer, opposite the first surface, between the core layer and the dimming layer, wherein the second cladding layer has a refractive index that is greater than a refractive index of the first cladding layer.