Optical filter with color enhancement
View Patent ↗An eyewear lens is described that provides polarization filtering and spectral filtering using polarization interference. The lens produces enhanced saturation and colorfulness, increasing enjoyment when observing commonly encountered imagery. The lens can be configured to optimize accuracy/efficiency when performing a task involving colored imagery, and can improve performance in sports. The lens can further be helpful for color discrimination by those with certain types of color vision deficiency.
1. An optical filter, comprising:
a polarization interference filter (PIF), including at least:
an input polarizer;
one or more retarders; and
an output polarizer;
wherein the PIF has a transmission across the 400 nm to 700 nm spectrum that is substantially sinusoidal having minimums and maximums, and with a single maximum in the 610 nm to 680 nm range, a single maximum in the 520 nm to 555 nm range, and at least one maximum in the 455 nm to 480 nm range, and with a single minimum in the 485 nm to 515 nm range, a single minimum in the 565 nm to 590 nm range, and at least one minimum in the 400 nm to 450 nm range.
2. An optical filter, including:
an input polarizer;
an input chromatic retarder;
an output chromatic retarder;
a neutral Polarization Control Unit (PCU) therebetween, including:
one or more zero-order half-wave uniaxial retarders, wherein the polarization transformation by the PCU creates a net chromatic retardation that is substantially independent of angle-of-incidence; and
an output polarizer;
wherein the filter has a transmission across the 400 nm to 700 nm spectrum with a single maximum in the 610 nm to 680 nm range, a single maximum in the 520 nm to 555 nm range, and at least one maximum in the 455 nm to 480 nm range, and with a single minimum in the 485 nm to 515 nm range, a single minimum in the 565 nm to 590 nm range, and at least one minimum in the 400 nm to 450 nm range.
3. An optical filter as defined in claim 2 , wherein the input and output polarizers have parallel axes of polarization;
wherein the chromatic retarders are composed of polycarbonate and each have a retardance (Γ) of 2.25 waves in the 505 nm to 555 nm range; and
wherein the PCU provides rotation about an axis in the range of −19 to −24 degrees and an axis in the range of +19 to +24 degrees.
4. An optical filter as defined in claim 2 , wherein the PCU includes an odd number of half-wave retarders.
5. An optical filter as defined in claim 4 , wherein the PCU is a single half-wave retarder with the slow and fast axes of the retarder aligned at 0 degrees and 90 degrees with the orientation of a polarization axis of the input polarizer.
6. An optical filter as defined in claim 4 , wherein the PCU is a compound half-wave retarder with three retarder layers and with the fast axis of: a first of the three retarder layers oriented at −30 degrees with an orientation of a polarization axis of the input polarizer, a second of the three retarder layers oriented at +30 degrees with the orientation of the polarization axis of the input polarizer, and a third of the three retarder layers oriented at −30 degrees with the orientation of the polarization axis of the input polarizer.
7. An optical filter, comprising:
a polarization interference filter (PIF), including at least:
an input polarizer;
a retarder stack that generates only two output impulses from a polarized impulse input; and
an output polarizer;
wherein the PIF has a transmission across the 400 nm to 700 nm spectrum with a single maximum in the 610 nm to 680 nm range, a single maximum in the 520 nm to 555 nm range, and at least one maximum in the 455 nm to 480 nm range, and with a single minimum in the 485 nm to 515 nm range, a single minimum in the 565 nm to 590 nm range, and at least one minimum in the 400 nm to 450 nm range.
8. An optical filter as defined in claim 7 , wherein a substantially neutral white-point is achieved.
9. An optical filter as defined in claim 7 , wherein each of the minimums in the transmission spectrum is less than 20% of each of maximums.
10. An optical filter as defined in claim 7 , wherein there is at least one minimum in the 700 nm to 1400 nm range.
11. An optical filter as defined in claim 7 , wherein at least one retarder in the retarder stack includes solvent bonded retarder films.
12. An optical filter as defined in claim 7 , wherein at least one retarder in the retarder stack includes at least one uniaxial stretched retarder film.
13. An optical filter as defined in claim 12 , wherein the film includes polycarbonate.
14. An optical filter as defined in claim 12 , wherein the film includes polyolefin.
15. An optical filter as defined in claim 7 , wherein at least one of the polarizers include a chromatic dye that controls a color balance and overall hue of the optical filter.
16. An optical filter as defined in claim 7 , wherein the optical filter is arranged as a laminated stack of layers.
17. An optical filter as defined in claim 16 , wherein the polarizers include polyvinyl alcohol.
18. An optical filter as defined in claim 16 , wherein the retarder stack is formed on glass.
19. An optical filter as defined in claim 16 , wherein the retarder stack is formed on isotropic plastic.
20. An optical filter as defined in claim 16 , wherein each of the layers of the laminated stack lie substantially in their own plane.
21. An optical filter as defined in claim 16 , wherein each of the layers of the laminated stack is curved.
22. An optical filter as defined in claim 7 , wherein each of the components of the optical filter is thermoformed.
23. An optical filter as defined in claim 7 , wherein the optical filter is arranged for use by a person having color vision deficiency.
24. An optical filter as defined in claim 7 , wherein the optical filter is arranged for use as a sunglass lens.
25. An optical filter as defined in claim 7 , wherein the optical filter is arranged for filtering light before it is captured electronically.
26. An optical filter as defined in claim 7 , wherein the optical filter is arranged as part of a display that displays images.
27. An optical filter as defined in claim 7 , wherein the optical filter is arranged for filtering light provided to a human performing an activity.