ILLUMINATION TECHNIQUES FOR ADDITIVE FABRICATION AND METHODS
Techniques for force sensing in additive fabrication are provided. According to some aspects, an additive fabrication device may include a force sensor configured to measure a force applied to a build platform during fabrication. A length of time taken for a layer of material to separate from a surface other than the build platform to which it is adhered may be determined based on measurements from the force sensor. Subsequent additive fabrication operations, such as subsequent motion of the build platform, may be adapted based on the determined length of time.
1 . (canceled)
2 . An additive fabrication device configured to form layers of solid material on a build platform, the additive fabrication device comprising:
a container;
at least one light source arranged beneath the container; and
a parabolic mirror arranged to receive light from the at least one light source and reflect said light through the container and onto a print plane within the container, wherein light reflected from the parabolic mirror provides telecentric illumination of the print plane.
3 . The additive fabrication device of claim 2 , wherein light rays reflected from different locations on the parabolic mirror are parallel to one another.
4 . The additive fabrication device of claim 2 , wherein light rays reflected from different locations on the parabolic mirror produce light beams having the same size across the print plane.
5 . The additive fabrication device of claim 2 , wherein light rays reflected from different locations on the parabolic mirror produce light beams having the same shape across the print plane.
6 . The additive fabrication device of claim 2 , wherein the print plane extends over a first direction and a second direction, perpendicular to the first direction, and wherein the parabolic mirror is configured such that the light reflected from the parabolic mirror is normally incident on the print plane at a range of positions along the first direction and the second direction.
7 . The additive fabrication device of claim 2 , wherein light reflected from the parabolic mirror produces a telecentric flat field over the print plane
8 . The additive fabrication device of claim 2 , wherein the at least one light source comprises multiple rows of light emitting diodes (LEDs).
9 . The additive fabrication device of claim 2 , wherein the parabolic mirror has multiple different parabolic cross-sections.
10 . The additive fabrication device of claim 2 , wherein the at least one light source is configured to direct light onto a plurality of different positions on the interior surface of the parabolic mirror.