Projection two-photon lithography method and system for rapid printing of 3D structures with sub-micrometer features and porosities

A system comprising:

• a memory having instructions for a plurality of interspersed features for a 3D structure to project as a sequence of sparse images on the same plane to generate closely spaced fine features on a polymer resist;
• and
• lithography equipment configured to generate using the sequence of sparse images a plurality of patterned light sheet on the polymer resist with a temporally-focused femtosecond pulse, wherein the light sheet has patterns,
• wherein the polymer resist comprises a photoinitiator, a radical quencher, and a monomer, wherein the concentration of the photoinitiator is less than one third the concentration of the radical quencher, the radical quencher includes dissolved oxygen, and wherein the solubility threshold DOC of the resist is less than 10%.