Electro-optic windows

Patent metadata

Field	Value
Publication number	US-2017191308-A1
Application number	US-201515314652-A
Country	US
Kind code	A1
Filing date	Feb 2, 2015
Priority date	Jun 12, 2014
Publication date	Jul 6, 2017
Grant date	—

Abstract

An electro-optic window is provided, together with a method of manufacturing the window. The window ( 3 ) is made of a material substantially transparent to at least one of infra-red, visible and UV radiation and treated to have reduced RF/MI-CROWAVE transmission characteristics by the provision of a grid ( 1 ) set into at least one surface ( 2 ) thereof. The grid ( 1 ) is formed of a material selected to be either reflective or absorptive to RF/MICROWAVE radiation.

First claim

What is claimed is:

1 . An electro-optic window having reduced Rf and microwave transmission, the window comprising:
a window made of a material that is substantially transparent to at least one of infra-red, visible and UV radiation; and a grid set into a surface of the window, the grid being formed of a material selected to be one of reflective and absorptive to RF/MICROWAVE radiation.

2 . The electro-optic window according to claim 1 , wherein the grid is set into channels in the window whereby to fill the channels no more than substantially flush with the said surface of the window.

3 . The electro-optic window according to claim 1 , further comprising including a capping layer covering the grid and attached to the said window surface.

4 . The electro-optic window according to claim 3 , wherein said capping layer is fusion bonded to the surface of the window.

5 . The electro-optic window according to claim 3 , wherein said capping layer is formed on the surface of the window.

6 . The electro-optic window according to claim 5 , wherein said capping layer is spun coated onto the surface of the window.

7 . The electro-optic window according to claim 5 , wherein said capping layer is spray coated onto the surface of the window.

8 . The electro-optic window according to claim 1 , wherein the grid is at least partly formed of a liquid.

9 . The electro-optic window according to claim 8 , wherein the grid includes a closable port that is adapted to allow passage of the liquid, when the port is open, into and out of the grid during an operational life of the window.

10 . A method of making an electro-optic window having reduced RF and microwave transmission characteristics, the method comprising:
providing a window that is formed from a material that is substantially transparent to at least one of infra-red, visible and UV radiation; forming on a surface of the window a grid of channels; creating a corresponding grid pattern of a material having one of electrically conductive and dielectric properties within the channels, thereby rendering the window non transmissive to RF/MICROWAVE radiation; and treating the material as required to render the grid usable to reduce the RF/MICROWAVE transmission characteristics of the window.

11 . The method according to claim 10 , wherein the material is a liquid.

12 . The method according to claim 11 , wherein the step of treating the material as required to render the grid usable to reduce the RF/MICROWAVE transmission characteristics of the window comprises solidifying the liquid.

13 . The method according to claim 11 , wherein the liquid is colloidal, having particles therein to render the window non transmissive to RF/MICROWAVE radiation, and wherein the step of treating the material as required to render the grid usable to reduce the RF/MICROWAVE transmission characteristics of the window includes evaporating off the liquid to leave the said particles within the channels.

14 . The method according to claim 13 , wherein the step of evaporating off the liquid comprises:
sealing the colloidal liquid within the channels of the grid; forming a port for evaporation having a size less than a particulate size of the particles; and then evaporating off the liquid through the port.

15 . The method according to claim 11 , wherein the step of treating the material as required to render the grid usable to reduce the RF/MICROWAVE transmission characteristics of the window comprises:
covering the channels of the grid; and confining the liquid within the covered channels.

16 . The method according to claim 15 , wherein the step of confining the liquid within the channels comprises:
confining an electroless plating solution within the channels; and electrolessly plating the channels with a metal contained in the solution.

17 . The method according to claim 15 , wherein the step of covering the channels of the grid includes growing a layer of protective material over the grid.

18 . The method according to claim 15 , wherein the step of covering the channels of the grid includes attaching a protective layer to the surface of the window.

19 . The method according to claim 15 , wherein the step of causing a liquid having one of electrically conductive and dielectric properties to RF/MICROWAVE radiation substantially to fill the channels is carried out after the channels of the grid have been covered.

20 . The method according to claim 19 , wherein the step of causing the liquid to substantially fill the channels of the grid comprises:
introducing the liquid to the grid; and at least one of:
continuously making the liquid available to the grid while capillary action draws the liquid throughout the grid; and
applying suction to the grid to draw the liquid therethrough.

21 . The method according to claim 11 , wherein the step of causing a material having one of electrically conductive and dielectric properties to RF/MICROWAVE radiation substantially to fill the channels comprises:
covering the surface of the window defining the grid with a layer of the liquid to substantially fill the channels of the grid; and wiping the surface of the window whereby to remove the liquid from the surface while leaving the channels of the grid substantially filled with the liquid.

22 . The method according to claim 11 , wherein the step of causing a material having one of electrically conductive and dielectric properties to RF/MICROWAVE radiation substantially to fill the channels comprises:
covering the surface of the window defining the grid with a layer of liquid metal to substantially fill the channels of the grid; allowing the liquid metal to solidify; and polishing the surface of the window whereby to remove the metal from the surface while leaving the channels of the grid substantially filled with the metal.

23 . The method according to claim 11 , wherein the step of causing a material having one of electrically conductive and dielectric properties to RF/MICROWAVE radiation substantially to fill the channels comprises:
sputtering over the surface of the window defining the grid a layer of metal to substantially fill the channels of the grid; and selectively etching the surface of the window whereby to remove the sputtered metal from the surface while leaving the channels of the grid substantially filled with the metal.

24 . The method according to claim 10 , wherein the step of forming on a surface of the window a grid of channels comprises forming the grid of channels by laser etching the window material.

25 . The method according to claim 10 , wherein the step of forming on a surface of the window a grid of channels comprises forming the grid of channels by chemically etching the window material.

26 . The method according to claim 10 , wherein the step of forming on a surface of the window a grid of channels comprises:
forming a mould in the shape of an EO window, the mould defining a positive grid formation whereby to impart to a moulded window a negative grid formation on one surface of the window; forming a sol of a material suitable for sintering and pouring the sol into the mould; converting the sol to a gel by the application of heat; drying the gel whereby to impart to the gel a permanent shape corresponding to that of the mould; and vitrifying the gel by sintering whereby to form a sintered EO

Assignees

• Bae Systems Plc

Inventors

• Haq Sajad
• Dyke Hazel Anne
• Dunleavy Michael
• Finn Harry John

Classifications

• H01Q5/22

  RF wavebands combined with non-RF wavebands, e.g. infrared or optical · CPC title

• H01Q17/00

  Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems · CPC title

• G02B5/20 Primary

  Filters (polarising elements G02B5/30) · CPC title

• H01Q15/0013

  said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective · CPC title

• B32B17/10403

  for radiation shielding · CPC title