Techniques for application of light in additive fabrication and related systems and methods

A method of additive fabrication, the method comprising:

• moving, within an additive fabrication device, a movable stage beneath a container having an interior bottom surface extending in a first direction and a second direction, perpendicular to the first direction, wherein the interior bottom surface of the container is formed, at least in part, from a suspended film, the container holding a liquid photopolymer, and the movable stage configured to move in the first direction, the movable stage being arranged beneath the container and comprising a plurality of light sources offset from one another along the second direction and operable to direct light through the interior bottom surface of the container, and a plurality of leveling elements configured to contact the suspended film while the movable stage moves in the first direction, the plurality of leveling elements including leveling elements arranged on either side of the plurality of light sources along the first direction that apply an upward force on the suspended film to produce a flat region of the suspended film between the leveling elements arranged on either side of the plurality of light sources as the movable stage moves in the first direction;
• and
• directing actinic radiation from at least some of the plurality of light sources through the flat region of the suspended film to the liquid photopolymer held by the container, thereby forming a layer of solid material that contacts the interior bottom surface in addition to the surface of a build platform and/or to a previously formed layer of material.