Apparatus comprising flash light circuitry

1. An apparatus comprising:

flash light circuitry configured to emit a flash of light;

an image sensor;

an optically transparent window, shared by the flash light circuitry and the image sensor, overlying the flash light circuitry and the image sensor, configured to transmit externally an emitted flash of light from the flash light circuitry; and

at least one filter configured to reduce total internal reflection of the flash of light within the optically transparent window, wherein the at least one filter is configured to control an angle of incidence of the emitted flash of light at the optically transparent window.

2. An apparatus as claimed in claim 1 , wherein the at least one filter is configured to control an angle of incidence of the emitted flash of light at the optically transparent window to be less than the critical angle for transmission from the optically transparent window to air.

3. An apparatus as claimed in claim 1 , wherein the at least one filter comprises a plurality of parallel optical channels.

4. An apparatus as claimed in claim 3 , wherein the plurality of parallel optical channels is arranged with respect to the optically transparent window to reduce total internal reflection of the flash of light within the optically transparent window.

5. An apparatus as claimed in claim 1 , wherein the optically transparent window has a continuous smooth exterior face without a physical aperture.

6. An apparatus as claimed in claim 1 , wherein the optically transparent window forms a continuous external face of the apparatus.

7. An apparatus as claimed in claim 1 , wherein the optically transparent window comprises black paint on an interior surface and an aperture in the black paint provides a flash output aperture to transmit a flash of light emitted from the flash light circuitry.

8. An apparatus as claimed in claim 1 , wherein the at least one filter is adhered to the optically transparent window.

9. An apparatus as claimed in claim 1 , wherein a Fresnel lens is positioned between the flash light circuitry and the optically transparent window.

10. An apparatus as claimed in claim 1 , wherein the at least one filter comprises a plurality of louvers configured to control an angle of incidence of the flash of light at the optically transparent window.

11. An apparatus as claimed in claim 1 , wherein the at least one filter comprises a first filter component and an overlapping second filter component, wherein the first filter component comprises a first plurality of parallel louvers extending in a first direction and wherein the second filter component comprises a second plurality of parallel louvers extending in a second direction different from the first direction.

12. An apparatus as claimed in claim 11 , wherein the first direction and the second direction are orthogonal and wherein the first plurality of parallel louvers and the second plurality of parallel louvers have a common louver angle.

13. An apparatus as claimed in claim 1 , wherein the at least one filter comprises a plurality of concentric parallel louvers.

14. An apparatus as claimed in claim 1 , wherein the filter overlies the flash circuitry only.

15. An apparatus as claimed in claim 1 , wherein the optically transparent window is formed without an aperture.

16. An apparatus comprising:

flash light circuitry;

an image sensor;

an optically transparent window, shared by the flash light circuitry and the image sensor, overlying the flash light circuitry and the image sensor, configured to transmit a flash of light from the flash light circuitry; and

at least one filter comprising a plurality of optical channels configured to control an angle of incidence of the flash of light at the optically transparent window.

17. An apparatus as claimed in claim 16 , wherein the at least one filter comprises a plurality of parallel optical channels, wherein the plurality of parallel optical channels is arranged with respect to the optically transparent window to reduce total internal reflection of the flash of light within the optically transparent window by controlling an angle of incidence of the emitted flash of light at the optically transparent window to be less than the critical angle for transmission from the optically transparent window to air.

18. An apparatus as claimed in claim 17 wherein the optically transparent window has a continuous smooth exterior face without a physical aperture.

19. An apparatus as claimed in claim 18 , wherein the optically transparent window forms a continuous external face of the apparatus.

20. An apparatus as claimed in claim 16 , wherein the at least one filter comprises a first filter component and an overlapping second filter component, wherein the first filter component comprises a first plurality of parallel louvers extending in a first direction and wherein the second filter component comprises a second plurality of parallel louvers extending in a second direction different from the first direction, wherein the first direction and the second direction are orthogonal and wherein the first plurality of parallel louvers and the second plurality of parallel louvers have a common louver angle.