Light engines for photo-curing of liquid polymers to form three-dimensional objects
Three-dimensional objects are formed by photo-curing a liquid polymer by exposure to a radiation, which radiation (e.g., at 410 nm) is provided by a collimated light source composed of an array of light emitting diode (LED) sources, an array of baffles, and an array of lenses. The baffles limit beam widths of each individual LED source in the array of LED sources, and the array of lenses is located one focal length from said array of LED sources.
1. An apparatus for forming three-dimensional objects by photo-curing a photo-curing liquid polymer by exposure to a radiation, comprising a tank for containing the liquid polymer, and a collimated light source to emit said radiation by which said photo-curing liquid polymer undergoes curing through a radiation-transparent opening in said tank, wherein said collimated light source comprises:
a plurality of light emitting diode (LED) groups, and, corresponding to each of the LED groups,
(i) a baffle configured to constrain and direct a first beam of electromagnetic radiation propagating from the LED group; and
(ii) a lens arrangement configured to receive the first beam of electromagnetic radiation, and project a second beam of electromagnetic radiation, said second beam of electromagnetic radiation being characterized by substantially parallel light rays,
wherein the lens arrangement comprises a first lens configured to receive the first beam of electromagnetic radiation, and project an intermediate beam of electromagnetic radiation; and a second lens configured to receive the intermediate beam from the first lens, and project the second beam of electromagnetic radiation towards the photo-curing liquid polymer.
2. The apparatus for forming three-dimensional objects according to claim 1 , wherein each of the plurality of LED groups comprises more than one LED.
3. The apparatus for forming three-dimensional objects according to claim 1 , wherein the second lens has six side surfaces.
4. The apparatus of claim 1 , wherein the baffle corresponding to each of the LED groups has a circular cross-section.
5. The apparatus of claim 1 , wherein the second lenses of each of the LED groups are arranged in a honeycomb pattern with respect to one another.
6. The apparatus of claim 1 , wherein a cladding surrounds side surfaces of the second lenses corresponding to each of the LED groups and the cladding substantially absorbs electromagnetic radiation.
7. The apparatus of claim 6 , wherein the second lenses corresponding to each of the LED groups are affixed to one another by an opaque glue, and wherein the opaque glue forms the cladding.
8. The apparatus of claim 1 , wherein for each of the LED groups, a portion of the first lens is disposed within the baffle.
9. The apparatus of claim 1 , wherein each of the LED groups are arranged at respective centers of hexagonal-shaped cells of a honeycomb lattice.
10. The apparatus of claim 1 , wherein for each of the LED groups, the first lens is a plano-convex lens.
11. The apparatus of claim 1 , wherein for each of the LED groups, the first lens is circular shaped.
12. The apparatus of claim 1 , wherein for each of the LED groups, the second lens is a plano-convex lens.
13. The apparatus of claim 1 , further comprising:
a first supporting plate configured to support the plurality of LEDs; and
a second supporting plate separated by a distance from the first supporting plate and configured to support the first lenses.
14. The apparatus of claim 13 , wherein the baffles are formed as cutouts in the second supporting plate.