Systems for photocuring liquid resin with reduced heat generation

A vat polymerization printer, comprising:

• a tank configured for containing a photo-curable liquid resin;
• a light source configured to emit a light beam;
• a mask having pixels configurable to be individually transparent or opaque to portions of the light beam, wherein a diameter of a cross section of the light beam is greater than a cross-sectional dimension of each of the respective pixels;
• a beam scanner configured to scan the light beam across the mask;
• and
• a controller comprising a memory and a processor, the memory storing instructions that, when executed, cause the processor to control the vat polymerization printer to print a cross section of a three-dimensional object by:
• controlling, during an exposure time duration, a first subset of the pixels of the mask to be transparent at locations corresponding to the cross section of the three-dimensional object, and a second subset of the pixels of the mask to be opaque at locations not corresponding to the cross section of the three-dimensional object, wherein, during the exposure time duration, and as a result of the control of the first and second subset of the pixels, (i) a first region of the mask includes at least some pixels that are controlled to be transparent, the first region of the mask being surrounded by a first border with pixels that are controlled to be opaque, (ii) a second region of the mask includes only pixels that are controlled to be opaque, and (iii) a third region of the mask includes at least some pixels that are controlled to be transparent;
• and
• controlling, during the exposure time duration, the beam scanner to repeatedly scan the light beam across the first region of the mask, to turn off the light source while the beam scanner repositions the light beam between the first region of the mask that includes at least some pixels that are controlled to be transparent to the third region of the mask that includes at least some pixels that are controlled to be transparent, the third region of the mask being separated from the first region of the mask by the second region of the mask that includes only pixels that are controlled to be opaque,
• wherein the first border is illuminated by the light beam, and
• wherein at most ten percent of the pixels that are controlled to be opaque are scanned by the light beam during the printing of the cross section of the three-dimensional object.