Methods and devices for reducing actual and perceived glare
Partially transparent devices and methods that reduce actual and/or perceived glare by incorporating absorbing materials are described. Actual and/or perceived glare can be reduced by multi-path absorption in the device. Perceived glare is further reduced by accounting for the psychophysics of human visual perception as a function of wavelength, orientation, and field illuminance.
1. A device through which or from which an object is viewed, the device comprising:
semi-transparent material;
a reflective opaque object or region adjacent to the semi-transparent material; and
an optical absorber disposed in the semi-transparent material having greater absorption for optical wavelengths between approximately 380 nm and approximately 450 nm than for optical wavelengths between approximately 500 nm and 700 nm, wherein a first ratio of actual glare intensity to primary image intensity, integrated over all visible wavelengths, for the object viewed in transmission through or reflection from the device is less than a second ratio of actual glare to primary image intensity for the object viewed in transmission through or reflection from the device when the optical absorber is not disposed in the semi-transparent material.
2. The device of claim 1 , wherein the object viewed from the device is viewed in reflection.
3. The device of claim 1 , wherein the transparency of the semi-transparent material extends through the semi-transparent material and terminates on the reflective opaque object or region.
4. The device of claim 3 , wherein the reflective opaque object or region is partially reflective or partially opaque.
5. The device of claim 1 , wherein an angle of incidence measured from a normal to a front surface of the semi-transparent material for a ray travelling from the object to a point where the object is viewed is between 0 degrees and 75 degrees.
6. The device of claim 1 , wherein the semi-transparent material comprises a glass.
7. The device of claim 1 , wherein the absorber comprises an organic dye.
8. The device of claim 1 , wherein the absorber comprises a metallic dopant.
9. The device of claim 1 , wherein the absorber is distributed non-uniformly in the semi-transparent material.
10. The device of claim 1 , wherein at least 85% of the primary image intensity is transmitted through the semi-transparent material and optical absorber at normal incidence.
11. The device of claim 1 , wherein a first hue or first chroma of a glare image viewed through or from the device is shifted compared to a corresponding second hue or second chroma of a primary image viewed through or from the device.
12. The device of claim 1 , wherein an average color distortion of a primary image as measured by an average shift in the L*a*b* uniform color space coordinates of the 1269 Munsell color tiles in daylight illumination is between 1 JND and 10 JND.
13. The device of claim 12 , wherein the average color distortion of a first glare image as measured by the average shift in the L*a*b* uniform color space coordinates of the 1269 Munsell color tiles in daylight illumination shifts by at least 3 JND more than the shift in average color distortion of the primary image.
14. The device of claim 1 , wherein the semi-transparent material comprises a polymer.
15. The device of claim 1 , wherein the semi-transparent material comprises a polymer laminated between layers of a glass.
16. The device of claim 14 , wherein the polymer is polyvinylbutyral.
17. A method of making a device through which or from which an object is viewed, the method comprising:
forming semi-transparent material adjacent to a reflective opaque object or region; and
including in the semi-transparent material an optical absorber, wherein the optical absorber disposed in the semi-transparent material exhibits greater absorption for optical wavelengths between approximately 380 nm and approximately 450 nm than for optical wavelengths between approximately 500 nm and 700 nm, and wherein a first ratio of actual glare intensity to primary image intensity, integrated over all visible wavelengths, for the object viewed in transmission through or reflection from the device is less than a second ratio of actual glare to primary image intensity for the object viewed in transmission through or reflection from the device when the optical absorber is not disposed in the semi-transparent material.
18. The method of claim 17 , wherein the transparency of the semi-transparent material extends through the material and terminates on the reflective opaque object or region.
19. The method of claim 17 , wherein the reflective opaque object or region is partially reflective or partially opaque.
20. The method of claim 17 , wherein forming the semi-transparent material comprises dispersing a dye in the semi-transparent material during formation of the semi-transparent material.
21. The method of claim 17 , wherein forming the semi-transparent material comprises dispersing a metallic dopant in the semi-transparent material during formation of the semi-transparent material.
22. The method of claim 17 , further comprising forming the semi-transparent material as a windshield or windscreen for a vehicle, a window for a motorized vehicle or a dwelling, a lens for an eyeglass or goggle, a lens for a camera, or a lens for a microscope or telescope.
23. The method of claim 17 , further comprising laminating a polymer layer to a glass layer.
24. The method of claim 17 , further comprising dispersing the absorber non-uniformly in the semi-transparent material.