Light source having a variable focal length
View Patent ↗A variable focal length light source is constructed using a tunable focus length lens which can be adjusted in synchronization to the focal length of a camera lens. In one embodiment, a deformable lens is used in conjunction with an LED light source to provide the tunable focal length required for a camera flash device.
1. A light source having a variable focal length, the light source comprising:
a substrate;
an enclosure mounted on the substrate, the enclosure containing at least two liquids selected to form a liquid-to-liquid interface inside the enclosure, the liquid-to-liquid interface constituting a tunable lens; and
an LED mounted on the substrate inside the enclosure and immersed in one of the two liquids.
2. The light source of claim 1 , further comprising:
an isolative layer located between the LED and the substrate for isolating and protecting a junction of the LED from the one of two liquids.
3. The light source of claim 1 , further comprising:
a voltage source coupled to the light source and operable to apply a voltage for varying a curvature of the liquid-to-liquid interface.
4. The light source of claim 1 , wherein light emitted by the LED is transmitted through the liquid-to-liquid interface and out of a top cover of the enclosure.
5. The light source of claim 4 , wherein the enclosure comprises a reflective side wall for reflecting light emitted by the LED towards the liquid-to-liquid interface.
6. The light source of claim 1 , wherein the LED is a surface mount device mounted on a top surface of the substrate.
7. The light source of claim 1 , wherein the two liquids are water and oil, and wherein the LED is immersed in water.
8. The light source of claim 1 , wherein the two liquids are a water soluble formulation and an oil based formulation, and wherein the LED is immersed in the water soluble formulation.
9. A light source having a variable focal length, the light source comprising:
a substrate;
a lens;
an enclosure mounted on the substrate with the lens mounted inside the enclosure on a top cover of the enclosure, the enclosure at least partially filled with liquid crystal material thereby forming a liquid crystal-to-lens interface inside the enclosure, the liquid crystal-to-lens interface constituting a tunable lens; and
an LED mounted on the substrate inside the enclosure and immersed in the liquid crystal material.
10. The light source of claim 9 , further comprising:
an isolative layer located between the LED and the substrate for isolating and protecting a junction of the LED from the liquid crystal material.
11. The light source of claim 9 , further comprising:
a voltage source coupled to the light source and operable to apply a voltage for varying a curvature of the liquid crystal-to-lens interface.
12. The light source of claim 9 , wherein the LED is positioned for directing light out of a top cover of the enclosure after propagating through the liquid crystal-to-lens interface and the lens.
13. The light source of claim 12 , wherein the enclosure comprises a reflective side wall for reflecting light emitted by the LED towards the liquid crystal-to-lens interface.
14. The light source of claim 9 , wherein the LED is a surface mount device mounted on a top surface of the substrate.
15. A method of constructing a light source having a variable focal length, the method comprising:
providing a substrate;
mounting an LED on the substrate;
mounting an enclosure on the substrate, the enclosure positioned to enclose the LED; and
immersing the LED in one of a) a liquid or b) a liquid crystal material by filling the enclosure with one of a) at least two liquids or b) liquid crystal material, respectively.
16. The method of claim 15 , further comprising:
providing an isolative layer between the LED and the substrate for isolating and protecting a junction of the LED from the one of a) the liquid or b) the liquid crystal material.
17. The method of claim 15 , further comprising:
upon immersing the LED in liquid crystal material, mounting a lens on a top cover of the enclosure thereby forming a liquid crystal-to-lens interface inside the enclosure.
18. The method of claim 17 , wherein the lens is a camera lens.
19. The method of claim 15 , wherein the at least two liquids are selected for forming a liquid-to-liquid interface inside the enclosure.
20. The method of claim 19 , wherein the at least two liquids are water and oil, and wherein immersing the LED in the liquid comprises immersing the LED in water.