Techniques of additive fabrication using an aspheric lens and related systems and methods
According to some aspects, an additive fabrication device for forming solid objects within a build region is provided, the device comprising a laser source, an aspheric lens configured to receive light emitted by the laser source and to produce a light beam having a circular cross section at at least one position inside the build region, and at least one mirror configured to be actuated to reflect the light beam toward a selected position within the build region.
1. An additive fabrication device for forming solid objects within a build region, the device comprising:
a laser source;
an aspheric lens configured to:
receive light emitted by the laser source; and
output a light beam having an ellipticity that changes with distance from the aspheric lens according at least in part to said distance, such that the light beam has a circular cross section at at least one position inside the build region and a non-circular cross section at at least one position outside of the build region; and
at least one mirror configured to be actuated to reflect the light beam toward a selected position within the build region.
2. The additive fabrication device of claim 1 , wherein the light beam produced by the aspheric lens has an elliptical cross section at at least one position outside the build region.
3. The additive fabrication device of claim 1 , wherein the aspheric lens is configured to produce the light beam such that it has an elliptical cross section at the at least one mirror.
4. The additive fabrication device of claim 3 , wherein, at all positions inside the build region to which the light beam may be directed, an ellipticity of a cross section of the light beam is no less than 0.8 and no more than 1.2.
5. The additive fabrication device of claim 1 , wherein an ellipticity of a cross section of the light beam at the at least one mirror is less than 0.6 or greater than 1.6.
6. The additive fabrication device of claim 1 , wherein the laser source comprises a single-mode laser diode.
7. The additive fabrication device of claim 6 , wherein the laser source emits light with a wavelength between 380 nm and 430 nm.
8. The additive fabrication device of claim 1 , wherein an effective focal length of the aspheric lens is less than 5 mm.
9. The additive fabrication device of claim 1 , wherein a distance from the laser source to the aspheric lens is less than 3 mm.
10. The additive fabrication device of claim 1 , wherein a path length of the light beam from the aspheric lens to the build region is between 350 mm and 450 mm.
11. The additive fabrication device of claim 1 , wherein a diameter of the circular cross section is between 50 μm and 200 μm.
12. The additive fabrication device of claim 1 , wherein the aspheric lens comprises glass and includes an anti-reflective coating.
13. The additive fabrication device of claim 1 , wherein the additive fabrication device is configured to form solid objects by curing a liquid photopolymer within the build region using the light beam.
14. The additive fabrication device of claim 1 , wherein the additive fabrication device is configured to form solid objects by sintering powdered material within the build region using the light beam.
15. The additive fabrication device of claim 1 , wherein the circular cross section of the light beam has an ellipticity of 1 and wherein the non-circular cross section of the light beam has an ellipticity greater than 1 or less than 1.
16. The additive fabrication device of claim 1 , wherein the circular cross section is a cross section through the light beam at an angle perpendicular to the light beam's axis.
17. A method of forming a solid object via additive fabrication within a build region, the method comprising:
directing light from a laser source to an aspheric lens such that the lens outputs a light beam having an ellipticity that changes with distance from the aspheric lens according at least in part to said distance, such that the light beam has a circular cross section between a first distance and a second distance from the lens along a path of the light beam and a non-circular cross section at at least one position closer to the lens than the first distance; and
directing, using at least one mirror, the light beam toward the build region such that the light beam intersects the build region between the first distance and the second distance from the lens along the path of the light beam.
18. The method of claim 17 , further comprising directing, using the at least one mirror, the light beam toward a plurality of positions in the build region, thereby forming a layer of the object.
19. The method of claim 17 , wherein the circular cross section of the light beam has an ellipticity of no less than 0.8 and no more than 1.2.
20. The method of claim 19 , wherein a difference between the first and second distances from the lens is at least 2 mm and no more than 40 mm.
21. The method of claim 19 , wherein the circular cross section of the light beam has an ellipticity of no less than 0.9 and no more than 1.1.
22. The method of claim 21 , wherein the circular cross section of the light beam has an ellipticity of no less than 0.95 and no more than 1.05.
23. The method of claim 17 , further comprising curing at least a portion of a photopolymer within the build region using the light beam.
24. The method of claim 17 , wherein a diameter of the circular cross section is between 100 μm and 200 μm.
25. The method of claim 17 , wherein the circular cross section is a cross section through the light beam at an angle perpendicular to the light beam's axis.