ILLUMINATOR COMPRISING BICONVEX LENS WITH TIR TEETH

1 . A lens comprising:

a first surface and a second surface opposite the first surface, the first surface including a first convex central refractive portion and a total internal reflection (TIR) portion peripheral to the first convex central portion, the second surface including a second convex central refractive portion and a peripheral refractive portion having a curvature different from a curvature of the second convex central refractive portion,

the first convex central refractive portion and the second convex central refractive portion being shaped to collimate or partially collimate light via refraction at the first convex central portion followed by refraction at the second convex central portion,

the TIR portion and the peripheral refractive portion being shaped to collimate or partially collimate light by total internal reflection at the TIR portion followed by refraction at the peripheral refractive portion.

2 . The lens of claim 1 , wherein:

a central axis of the lens extends through a center of the first convex central refractive portion and a center of the second convex refractive central portion; and

the TIR portion has a cross-section, taken in a plane that includes the central axis, that includes a plurality of serrations.

3 . The lens of claim 2 , wherein:

each serration includes an apex and a pair of opposing sides that each extend from the apex toward the second surface of the lens;

the pair of opposing sides is angled such that light that enters the lens via refraction at a first side of the pair of opposing sides is directed toward the refractive peripheral portion via total internal reflection at a second side of the pair of opposing sides and refracted out of the lens by the peripheral refractive portion.

4 . The lens of claim 2 , wherein the plurality of serrations includes apexes that lie on a virtual surface that is concave when viewed in the cross-section.

5 . The lens of claim 2 , wherein the plurality of serrations includes apexes that lie on a virtual surface that is generally planar when viewed in the cross-section.

6 . The lens of claim 1 , wherein:

the lens is circular;

the TIR portion surrounds the first convex central refractive portion; and

and the peripheral refractive portion surrounds the second convex central refractive portion.

7 . The lens of claim 1 , wherein the lens is rotationally symmetric about a central axis that extends through a center of the first convex central refractive portion and a center of the second convex refractive central portion.

8 . The lens of claim 1 , wherein:

the first convex central refractive portion has a radius of curvature between about 0.5 mm and about 3.0 mm and has a conic constant less than or equal to −0.5; and

the second convex central portion has a radius of curvature between about 0.5 mm and about 3.0 mm and has a conic constant less than or equal to −0.5.

9 . An illumination system comprising:

an array of LEDs or pcLEDs; and

the lens of claim 1 arranged with its first surface facing the array to collimate or partially collimate light emitted by the array.

10 . The illumination system of claim 9 , wherein the LEDs or pcLEDs are independently controllable.

11 . The illumination system of claim 9 , wherein each LED or pcLED is a segment of a monolithic structure.

12 . The illumination system of claim 11 , wherein each LED or pcLED is or comprises a microLED.

13 . The illumination system of claim 9 , wherein each LED or pcLED has a largest dimension in the plane of the array of less than or equal to 500 microns.

14 . The illumination system of claim 9 , wherein each LED or pcLED has a largest dimension in the plane of the array of less than or equal to 100 microns.

15 . The illumination system of claim 9 , wherein each LED or pcLED has a largest dimension in the plane of the array of less than or equal to 50 microns.

16 . The illumination system of claim 9 , comprising a controller configured to power the LEDs or pcLEDs.

17 . A mobile device comprising:

a camera;

a flash illumination system comprising:

a monolithic array of independently controllable LEDs or pcLEDs;

the lens of claim 1 arranged with its first surface facing the array to collimate or partially collimate light emitted by the array; and

a controller configured to operate the LEDs or pcLEDs to adapt light emitted by the flash illumination system to a field of view of the camera.

18 . The mobile device of claim 17 , wherein the controller is configured to operate the LEDs or pcLEDs to match a field of view of the flash illumination system to a field of view of the camera.

19 . The mobile device of claim 17 , wherein each LED or pcLED has a largest dimension in the plane of the array of less than or equal to 100 microns.

20 . The mobile device of claim 17 , wherein each LED or pcLED is or comprises a microLED.