ELECTRICALLY RESPONSIVE LIGHT FILTER

• US 3,692,388 A
• Filed: 11/28/1969
• Issued: 09/19/1972
• Est. Priority Date: 11/28/1969
• Status: Expired due to Term

• Current Assignee: John A. Hall Jr, John J. Mccann
• Original Assignee: John A. Hall Jr, John J. Mccann
• Inventors: Hall, John A. Jr., McCann, John J.
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Kosmer, Toby H.
• Application Number:
  US04/880,796
• Time in Patent Office: 1,026 Days
• Field of Search: 350/160,312,285,269,288
• US Class Current: 359/275
• CPC Class Codes: G02F 1/1503 caused by oxidation-reduction reactions in organic liquid solutions, e.g. viologen solutions
• CPC Class Codes: G02F 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices

Abstract

A controllable light filtering element having an electrolytic cell in which is an electrode having a specularly reflecting surface. The electrode is positioned to reflect light entering the electrolyte through an entrance window toward an exit window. The electrolyte contains a redox agent. Electrode polarity and potential are selected to cause a light absorbing layer to form adjacent the electrode'"'"''"'"'s reflecting surface. Light transmission through the filter is regulated by controlling the current and voltage.

Claims

1. Apparatus for selectively filtering light passing along an optical path comprising:

a first electrode;

mirror means situated within said optical path for specularly reflecting said light and for functioning as a second electrode; and

means for forming, in said optical path, an optical filtering layer, from electrolyte means, adjacent said mirror means by the presence of a select electric potential between said electrodes having a predetermined polarity.

2. The apparatus as described in claim 1 further comprising:

means for imposing said select electric potential having a predetermined polarity on said filter layer forming means.

3. The apparatus as described in claim 2 wherein said filter layer forming means includes a redox indicator dye.

4. The apparatus of claim 3 wherein said mirror means further comprises electrode means for making electrical contact with said electrolyte means.

5. Apparatus for selectively filtering light passing along an optical path comprising:

reflector means situated in said optical path for specularly reflecting said light;

electrolyte means, contacting said reflector means, for forming a light absorbing layer in said optical path adjacent said reflector means, said electrolyte means characterized in forming saiD light absorbing layer in the presence of an electric potential of select value having a predetermined polarity, the optical density of said absorbing layer being functionally related to said electric potential value; and

electrode means, including the specularly reflecting surface of said reflector means, for making electrical contact with said electrolyte and between which said electric potential can be established.

6. The apparatus as described in claim 5 further comprising means for imposing said select electric potential on said electrode means and thereby through said electrolyte to cause formation of said absorbing layer at said reflector means.

7. The apparatus as described in claim 6 wherein said means for imposing said select potential further comprises means for controlling said select electric potential.

8. The apparatus as described in claim 5 wherein said electrolyte contains a redox indicator dye.

9. The apparatus as described in claim 8 wherein said redox indicator dye is methyl viologen.

10. An apparatus for selectively filtering light passing along an optical path comprising:

at least one electrode having a specularly reflecting conducting surface situated within said optical path to reflect said light;

another electrode spaced apart from said reflecting electrode;

means for imposing select electric potential having predetermined polarity between said reflecting electrode and said other electrode; and

a transparent electrolytic solution, in said optical path, in which said reflecting electrode and said other electrode are immersed forming an electrically conductive path therebetween, said electrolytic solution being characterized in forming a light absorbing layer in said optical path adjacent to said specularly reflecting conducting surface in the presence of a select electric potential value having said light absorbing layer being functionally related to said electric potential value.

11. The apparatus of claim 10 wherein said other electrode is spaced apart from said reflecting electrode and positioned substantially outside of said optical path.

12. The apparatus as described in claim 10 including means for controlling said select electric potential.

13. The apparatus of claim 10 wherein said electrolytic solution contains a redox indicator dye which changes its optical properties on being alternately reduced and oxidized.

14. The apparatus described in claim 13 wherein said redox agent is methyl viologen.

15. The apparatus described in claim 10 wherein said electrolytic solution is gelatinous.

16. An electrically responsive controllable light filter as in claim 10 wherein said electrolyte has viscosity greater than 50 centipoises at 20* C.

17. Apparatus for selectively filtering light passing along an optical path comprising:

a container enclosing a portion of said optical path;

a solution, situated so as to fill said optical path within said container, capable of changing its light absorption properties in response to an electric current;

an entrance window in said container for admitting said light into said electrolyte;

an exit window in said container through which said light can leave;

at least one electrode having a specularly reflecting conducting surface immersed in said electrolyte and situated to reflect said light entering through said entrance window along said optic path toward said exit window;

another electrode immersed in said electrolyte spaced apart from said reflecting electrode and positioned substantially outside of said optical path;

means for imposing select electrical potential, having predetermined polarity, between said reflecting electrode and said other electrode across said optical path; and

said electrodes contacting said solution.

18. The apparatus described in claim 17 wherein said solution contains an electrolyte and a redox indicator dye.

19. The apparatus described in claim 17 wherein said solutiOn contains methyl viologen.

20. An image forming optical system having an optic axis and including an electrically responsive light filtering element to control the amount of light transmitted through said system comprising:

at least one electrode having a specularly reflecting conducting surface positioned to reflect light passing along said optic axis;

another electrode spaced apart from said reflecting electrode;

means for imposing select electric potentials having predetermined polarity between said reflecting electrode and said other electrode; and

a transparent electrolytic solution contacting said electrodes and forming an electrically conductive path therebetween, said electrolytic solution being characterized in forming a light absorbing layer in an optical path defined by said optic axis and adjacent said specularly reflecting conducting surface in the presence of a select electric potential having said predetermined polarity, the optical density of said light absorbing layer being functionally related to the value of said electric potential.