Multiple-polarization cloaking for projected and writing surface view screens
A system includes a view screen with polarized output. The view screen may include a projected view screen or writing-surface view screen. A window capable of blocking the polarized output at least in part cloaks the view screen to frustrate viewing of the view screen through the window. In some cases, the window includes an array of panels capable of blocking multiple polarizations. The array may disrupt multiple different polarized view screen outputs while maintaining transparency to unpolarized light. In some cases, the window capable of blocking polarized output may be paired with view screen cover that converts view screen output in an unblocked polarization to one of the one or more polarizations blocked by the window.
1. A method of manufacture including:
designating a set of one or more cloaking markers;
providing a writing-surface view screen including:
a backlight;
a view screen polarizer layer oriented to polarize output of the backlight in view-screen-output polarization; and
a markable front surface formed by a view-screen-mountable waveplate oriented to convert the view-screen-output polarization to a specific polarization, where, when the writing-surface view screen is placed within a line-of-sight of a polarizer window through the view-screen-mountable waveplate, the polarizer window filters the specific polarization to obscure cloaking markings, from a cloaking marker in the set of one or more cloaking markers, on the markable front surface.
2. The method of manufacture of claim 1 , where the view-screen- mountable waveplate includes an adhesive layer.
3. The method of manufacture of claim 1 , where non-cloaking markings, when present on the markable front surface, light in another polarization different from the view-screen-output polarization responsive to the output of the backlight.
4. The method of manufacture of claim 1 , where the writing-surface view screen further includes a diffusive layer between the backlight and the view screen polarizer layer.
5. The method of manufacture of claim 1 , where the writing-surface view screen further includes an absorptive background behind the view screen polarizer layer, the absorptive background configured to cause the writing-surface view screen to appear black when:
the backlight is off; or
the output from the backlight is cloaked.
6. The method of manufacture of claim 1 , where the set of one or more cloaking markers includes a non-fluorescing marker.
7. A system including:
a writing-surface view screen; and
a polarizer window,
the writing-surface view screen including:
a backlight;
a view screen polarizer layer oriented to polarize output of the backlight in view- screen-output polarization; and
a markable front surface formed by a view-screen-mountable waveplate oriented to convert the view-screen-output polarization to a specific polarization;
a designation specifying a set of one or more cloaking markers; and
the polarizer window configured to filter the specific polarization to obscure cloaking markings, from a cloaking marker in the set of one or more cloaking markers, on the markable front surface when within a line-of-sight of the markable front surface.
8. The system of claim 7 , where the view-screen-mountable waveplate includes an adhesive layer.
9. The system of claim 7 , where non-cloaking markings, when present on the markable front surface, light in another polarization different from the view-screen-output polarization responsive to the output of the backlight.
10. The system of claim 7 , where the writing-surface view screen further includes a diffusive layer between the backlight and the view screen polarizer layer.
11. The system of claim 7 , where the writing-surface view screen further includes an absorptive background behind the view screen polarizer layer, the absorptive background configured to cause the writing-surface view screen to appear black when:
the backlight is off; or
the output from the backlight is cloaked.
12. A system including:
a writing-surface view screen including:
a backlight;
a polarizer layer oriented to polarize output of the backlight in a first polarization; and
a markable front surface;
a designation specifying a set of one or more cloaking markers;
first regions placed to render unintelligible a cloaking marking, from a cloaking marker in the set of one or more cloaking markers, when displayed on the markable front surface, the first regions obstructive to the first polarization and transmissive to a second polarization different than the first polarization; and
second regions interlaced with the first regions, the second regions placed to render unintelligible view screen output in the second polarization.
13. The system of claim 12 , where the first and second regions are arranged in a checkered pattern, crossing line pattern, diagonal crossing line pattern, a fractal pattern, a multi-scale pattern, a repeated ring pattern, a constrained randomized pattern, a letter pattern, a repeated triangle pattern, an aperiodic tiling pattern, or any combination thereof.
14. The system of claim 12 , where the first and second regions overlap at least in part.
15. The system of claim 12 , where the writing-surface view screen includes a whiteboard.
16. The system of claim 12 , where the markable front surface is further configured to receive a non-cloaking marking when engaged with a non-cloaking marker.
17. The system of claim 16 , where neither the first regions nor the second regions are placed to render unintelligible the non-cloaking marking when displayed on the markable front surface.
18. The system of claim 14 , where an outer surface of the polarizer layer forms the markable front surface.
19. The system of claim 14 , where the set of one or more cloaking markers includes non-fluorescing markers.
20. The system of claim 14 , further including another designation specifying a set of non-cloaking markers.