Extended Data Fig. 5: Printing resolution note 1: blurring of the upconverted voxel in the printing resin.

Cartoon depiction (not to scale) of the blurring that occurs between the shape of the upconverted voxel and the photoinitiation in resin caused by absorption of the upconverted light. Although upconverted light generates light in nanocapsules that emits isotropically from a focal point, this light must subsequently be absorbed by the photoinitiator to cause polymerization. This emission and reabsorption introduce a blurring function to the print that is dependent on the Beer–Lambert law for the distance that the light travels before reabsorption.