LED light converging system
An LED light converging system includes an LED light source, and first and second lens units aligned in sequence along an optical axis. The LED light source provides source light. The first lens unit has a first focal length, and is disposed forwardly of and is spaced apart from the LED light source by a first distance less than the first focal length such that a virtual image of the source light provided by the LED light source is formed rearwardly of the LED light source. The second lens unit has a second focal length, is disposed forwardly of the first lens unit, and is spaced apart from the virtual image of the source light by a second distance larger than the second focal length such that a real image of the source light provided by the LED light source is formed forwardly of the second lens unit.
1. An LED light converging system comprising an LED light source, a first lens unit and a second lens unit aligned in sequence along an optical axis, said LED light source providing source light;
wherein said first lens unit has a first focal length and is disposed forwardly of and is spaced apart from said LED light source by a first distance less than the first focal length for forming a virtual image of the source light provided by said LED light source rearward of said LED light source; and
wherein said second lens unit has a second focal length, is disposed forwardly of said first lens unit, and is spaced apart from the virtual image of the source light by a second distance larger than the second focal length for forming a real image of the source light provided by said LED light source forward of said second lens unit.
2. The LED light converging system as claimed in claim 1 , wherein said LED light source includes an array of light-emitting diodes, each capable of emitting the source light within a corresponding primary color wavelength range for producing source light of three primary colors, and a hemispherical lens that covers said light-emitting diodes.
3. The LED light converging system as claimed in claim 1 , wherein said first lens unit is a doublet converging lens.
4. The LED light converging system as claimed in claim 3 , wherein said first lens unit includes first and second positive lenses.
5. The LED light converging system as claimed in claim 4 , wherein each of said first and second positive lenses is a plano-convex lens.
6. The LED light converging system as claimed in claim 4 , wherein said second lens unit is a doublet converging lens.
7. The LED light converging system as claimed in claim 6 , wherein said second lens unit includes third and fourth positive lenses.
8. The LED light converging system as claimed in claim 7 , wherein each of said third and fourth positive lenses is a plano-convex lens.
9. The LED light converging system as claimed in claim 1 , wherein the first focal length ranges between 8.7 and 17.4 mm.
10. The LED light converging system as claimed in claim 1 , wherein the second focal length ranges between 30 and 42 mm.
11. The LED light converging system as claimed in claim 1 , wherein said second lens unit is spaced apart from said first lens unit by a third distance ranging between 13 and 26 mm.