Electrochromic filtering in a camera

1. A lens assembly configured to focus light on a sensor array of an optical device, comprising:

one or more optical lenses; and

an electrochromic layer positioned between the one or more optical lenses and the sensor array, the electrochromic layer having one or more optical properties that are responsive to voltage applied to the layer, including:

a first optical property related to optical transmissivity having:

a first state corresponding to a Day mode, responsive to a first applied voltage, in which the layer is substantially opaque to a predefined band of IR wavelengths; and

a second state corresponding to a Night mode, responsive to a second applied voltage distinct from the first applied voltage, in which the layer is substantially transparent to the predefined band of IR wavelengths and visible wavelengths;

wherein the optical device is configured to, in the Night mode:

determine whether ambient light incident on the optical device is due to other than an IR light source;

detect an ambient light level;

based on a determination that the ambient light due to other than the IR light source and that the ambient light level exceeds a first lux threshold, initiate a mode change of the optical device to the Day mode; and

based on a determination that the ambient light is due to other than the IR light source and that the ambient light threshold does not exceed the first lux threshold, maintain the optical device in the Night mode.

2. The lens assembly of claim 1 , wherein the electrochromic layer includes an electrolyte layer, a first electrode, and a counter electrode.

3. The lens assembly of claim 2 , wherein the first applied voltage and the second applied voltage are applied on the first electrode.

4. The lens assembly of claim 2 , wherein the first electrode includes a layer of indium tin oxide (ITO) nanocrystals in glass made out of niobium oxide.

5. The lens assembly of claim 4 , wherein the ITO nanocrystals are combined with niobium-containing ions (also called polyoxometalate (POM) clusters) in solution, and the first electrode is formed when the solution covers a surface of the electrochromic layer.

6. The lens assembly of claim 1 , wherein the optical device further includes a controller, and the first applied voltage and the second applied voltage are supplied by the controller.

7. The lens assembly of claim 1 , wherein the sensor array includes a plurality of sensor elements and is configured to capture images or video clips.

8. An optical device including a plurality of modes of operation, the optical device comprising:

a controller;

a sensor array; and

a lens assembly that is configured to focus light on the sensor array, wherein the lens assembly includes one or more optical lenses and an electrochromic layer positioned between the one or more optical lenses and the sensor array, the electrochromic layer having one or more optical properties that are responsive to voltage applied to the layer, including:

a first optical property related to optical transmissivity having:

a first state corresponding to a Day mode, responsive to a first applied voltage supplied by the controller, in which the layer is substantially opaque to a predefined band of IR wavelengths in ambient light; and

a second state corresponding to a Night mode, responsive to a second applied voltage supplied by the controller, in which the layer is substantially transparent to the predefined band of IR wavelengths and visible wavelengths;

wherein the plurality of modes includes a third mode; and

in accordance with a determination that the optical device is in the third mode, the controller supplies a third voltage that is substantially larger than the first voltage, the third voltage is applied on the electrochromic layer to cause the electrochromic layer to remove a substantial portion of the predefined band of IR wavelengths in ambient light incident on the optical device and reduce the intensity of visible wavelengths in the ambient light to a first visible light intensity, thereby exposing the sensor array to the visible wavelengths of the ambient light having the first visible light intensity.

9. The optical device of claim 8 , wherein:

the controller is configured to, in accordance with a determination to transition the optical device to the Day mode, supply the first voltage that is applied to the electrochromic layer; and

the electrochromic layer is configured to, in response to the first voltage, exhibit the first state by removing a substantial portion of the predefined band of IR wavelengths in ambient light incident on the optical device and simultaneously passing a substantial portion of visible wavelengths in the ambient light, thereby exposing the sensor array to the substantial portion of the visible wavelengths of the ambient light via the lens assembly.

10. The optical device of claim 9 , further comprising: one or more infrared light emitting diodes that are powered on to illuminate a field of view in accordance with the determination to transition the optical device to the Night mode of operation.

11. The optical device of claim 8 , wherein the third mode includes a high dynamic range (HDR) mode, and the optical device is configured to:

capture a first image when the first voltage is applied on the electrochromic layer;

capture a second image when the third voltage is applied on the electrochromic layer; and

combine at least the first and second images to obtain a HDR image.

12. The optical device of claim 8 , wherein the third mode includes a high dynamic range (HDR) mode, and the optical device is configured for:

supplying by the controller a fourth voltage that is distinct from the third voltage;

applying the fourth voltage on the electrochromic layer;

in response to the fourth voltage, removing by the electrochromic layer a substantial portion of the predefined band of the wavelengths while reducing the intensity of the visible wavelengths in the ambient light to a second visible light intensity;

capturing a first image when the third voltage is applied on the electrochromic layer;

capturing a second image when the fourth voltage is applied on the electrochromic layer; and

combining at least the first and second images to obtain a HDR image.

13. The optical device of claim 9 , wherein the optical device is configured for:

in the Night mode:

determining whether the ambient light is due to other than an IR light source;

detecting an ambient light level;

based on a determination that the ambient light that is not filtered by the electrochromic layer is due to other than the IR light source and that the ambient light level exceeds a first lux threshold, initiating a mode change of the optical device to the Day mode;

based on a determination that the ambient light is due to other than the IR light source and that the ambient light threshold does not exceed the first lux threshold, maintaining the optical device in the Night mode.

14. The optical device of claim 13 , wherein the sensor array includes a plurality of sensor elements, the sensor elements include first, second and third pixels, each having respective peak responses at different respective visible light frequencies, and determining whether the ambient light is due to other than the IR light source further includes:

detecting a first light component of the ambient light by averaging output signals from the first pixels;

detecting a second light component of the ambient light by averaging output signals from the second pixels;

detecting a third light component of the ambient light by averaging output signals from the third pixels; and

determining based on respective values of the first, second and third light components whether the ambient light is due to other than the IR light source.

15. A method performed

at an optical device having a controller, a sensor array, and a lens assembly that is configured to focus light on the sensor array, wherein the optical device includes a plurality of modes of operation, the modes of operation including a Day mode, a Night mode, and a third mode, and wherein the lens assembly includes one or more optical lenses and an electrochromic layer positioned between the one or more optical lenses and the sensor array, the electrochromic layer having one or more optical properties that are responsive to voltage applied to the layer, including a first optical property related to optical transmissivity, the method comprising:

responsive to an instruction to initiate the Day mode of operation:

supplying by the controller a first voltage; and

applying the first voltage to the electrochromic layer to cause the electrochromic layer to exhibit a first state of the first optical property, in which the layer is substantially opaque to a predefined band of IR wavelengths in ambient light;

responsive to an instruction to initiate the Night mode of operation:

supplying by the controller a second voltage; and

applying the second voltage to the electrochromic layer to cause the electrochromic layer to exhibit a second state of the first optical property, in which the layer is substantially transparent to the predefined band of IR wavelengths and visible wavelengths; and

in accordance with a determination that the optical device is in the third mode:

supplying by the controller a third voltage that is substantially larger than the first voltage, the third voltage is applied on the electrochromic layer to cause the electrochromic layer to remove a substantial portion of the predefined band of IR wavelengths in ambient light incident on the optical device and reduce the intensity of visible wavelengths in the ambient light to a first visible light intensity, thereby exposing the sensor array to the visible wavelengths of the ambient light having the first visible light intensity.

16. The method of claim 15 , wherein

the first applied voltage causes the electrochromic layer to exhibit the first state by removing a substantial portion of the predefined band of IR wavelengths in ambient light incident on the optical device and simultaneously passing a substantial portion of visible wavelengths in the ambient light, thereby exposing the sensor array to the substantial portion of the visible wavelengths of the ambient light via the lens assembly.

17. The method of claim 15 , wherein

the second applied voltage causes the electrochromic layer to exhibit the second state by becoming substantially transparent to the predefined band of IR wavelengths, thereby exposing the sensor array to both the predefined band of IR wavelengths and a substantial portion of the visible wavelengths of the ambient light via the lens assembly.

18. The method of claim 15 , wherein the first applied voltage has a magnitude not greater than 5 V and the second applied voltage is substantially equal to zero.