Wire grid polarizer with phosphonate protective coating

1. A wire grid polarizer (WGP) comprising:

a. ribs located over a surface of a transparent substrate, wherein the ribs are elongated and arranged in a substantially parallel array;

b. gaps between at least a portion of the ribs;

c. a conformal-coating located over the ribs, wherein the conformal-coating includes a phosphonate chemical;

wherein:

i. each R 1 independently includes a hydrophobic group;

ii. Z is a bond to the ribs;

iii. R 5 is a phosphonate-reactive-group, R 1 , R 6 , or Z;

iv. the phosphonate-reactive-group is —Cl, —OR 6 , —OCOR 6 , or —OH;

v. each R 6 is independently an alkyl group, an aryl group, or combinations thereof.

2. The WGP of claim 1 , wherein R 5 is —OCH 3 or —OCH 2 CH 3 .

3. The WGP of claim 1 , wherein Z is —O-Metal, where Metal is a metal atom.

4. The WGP of claim 1 , wherein the hydrophobic group includes a carbon chain.

5. The WGP of claim 4 , wherein the carbon chain includes a perfluorinated group including at least 1 and less than 30 carbon atoms.

6. The WGP of claim 1 , wherein each hydrophobic group is independently CF 3 (CF 2 ) n (CH 2 ) m , where n and m are integers within the boundaries of: 0≦n≦20 and 0≦m≦5.

7. The WGP of claim 1 , wherein each hydrophobic group is independently CF 3 (CF 2 ) n (CH 2 ) m , where n and m are integers within the boundaries of: 4≦≦10 and 2≦m≦5.

8. The WGP of claim 1 , wherein a water contact angle is greater than 120°.

9. The WGP of claim 1 , further comprising a proximal conformal-coating that is distinct from the ribs, and wherein:

a. the conformal-coating is a distal conformal-coating;

b. the proximal conformal-coating is located between the distal conformal-coating and the ribs;

c. the proximal conformal-coating includes a metal oxide; and

d. a material of an exterior surface of the ribs has a solubility in water of at least 0.5 grams per liter at 25° C.

10. The WGP of claim 9 , wherein the material of the exterior of the rib includes germanium oxide.

11. The WGP of claim 9 , further comprising a middle conformal-coating located between the proximal conformal-coating and the distal conformal-coating, and wherein:

a. the proximal conformal-coating includes aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or combinations thereof; and

b. the middle conformal-coating includes hafnium oxide, zirconium oxide, or combinations thereof.

12. The WGP of claim 1 , wherein the WGP forms part of an image projector, the image projector comprising:

a. a light source capable of emitting a beam of light;

b. color-splitting optics:

i. located to receive at least part of the beam of light; and

ii. capable of splitting the beam of light into multiple, differently-colored light beams (colored beams);

c. color-combining optics located to receive and capable of recombining at least some of the colored beams into a combined beam;

d. a projection lens system located to receive the combined beam and capable of projecting a colored image onto a screen;

e. a spatial light modulator:

i. located to receive, in a light path between the color-splitting optics and the color-combining optics, at least one of the colored beams; and

ii. having a plurality of pixels, each pixel capable of receiving a signal and transmitting incident light without causing a change in polarization, or rotating a polarization of incident light, based on the signal;

f. the WGP located in at least one of the colored beams prior to entering the spatial light modulator, after exiting the spatial light modulator, or both.

13. The WGP of claim 11 , wherein the WGP forms part of an image projector, the image projector comprising:

a. a light source capable of sequentially emitting multiple, differently-colored light beams (colored beams);

b. a projection lens system located to receive the colored beams and capable of projecting a colored image onto a screen;

c. a spatial light modulator:

i. located to receive, in a light path between the light source and the projection lens system, one of the colored beams; and

ii. having a plurality of pixels, each pixel capable of receiving a signal and transmitting incident light without causing a change in polarization, or rotating a polarization of incident light, based on the signal;

d. the WGP located in the colored beams prior to entering the spatial light modulator and exiting the spatial light modulator.

14. A method of making a wire grid polarizer (WGP), the method comprising:

a. obtaining ribs located over a surface of a transparent substrate, wherein the ribs are elongated and arranged in a substantially parallel array with gaps between at least a portion of the ribs; and

b. exposing the WGP by vapor-deposition to a phosphonate chemical to form a conformal-coating over the ribs, the phosphonate chemical including (R 1 ) i PO(R 4 ) j (R 5 ) k , where:

i. i is 1 or 2, j is 1 or 2, k is 0 or 1, and i+j+k=3;

ii. each R 1 is independently a hydrophobic group;

iii. R 4 is a phosphonate-reactive-group;

iv. each phosphonate-reactive-group is independently selected from: —Cl, —OR 6 , —OCOR 6 , and —OH;

v. each R 6 is independently an alkyl group, an aryl group, or combinations thereof;

vi. each R 5 , if any, is independently any chemical element or group.

15. The method of claim 14 , further comprising the exposing the WGP to a gas before the step of exposing the WGP to a chemical to form a conformal-coating over the ribs, wherein the gas includes water vapor and the water vapor has a pressure of less than 100 Torr.

16. The method of claim 14 , further comprising baking the WGP after the step of exposing the WGP to a chemical to form a conformal-coating over the ribs, wherein the baking the WGP occurs at a temperature between 100° C. and 320° C. for between 5 and 90 minutes.

17. The method of claim 14 , wherein:

a. a material of an exterior surface of the ribs has a solubility in water of at least 0.015 grams per liter at 25° C.;

b. the conformal-coating is a distal conformal-coating; and

c. the method further comprises applying a proximal conformal-coating by atomic layer deposition before applying the distal conformal-coating, where the proximal conformal-coating includes hafnium oxide, zirconium oxide, aluminum oxide, silicon oxide, silicon nitride, silicon oxynitride, or combinations thereof.

18. The method of claim 14 , further comprising at least one of the following before applying the conformal-coating:

a. plasma cleaning the WGP, wherein the plasma cleaning, is performed at a temperature between 140° C. and 200° C.;

b. exposing the WGP to ultraviolet light;

c. exposing the WGP to ozone.