  Glass is increasingly desired as a material for manufacturing complex
microscopic geometries, from the micro-optics in compact consumer products to
microfluidic systems for chemical synthesis and biological analyses. As the
size, geometric, surface roughness, and mechanical strength requirements of
glass evolve, conventional processing methods are challenged. We introduce
microscale computed axial lithography (micro-CAL) of fused silica components,
by tomographically illuminating a photopolymer-silica nanocomposite which is
then sintered. We fabricated 3D microfluidics with internal diameters of 150
micrometers, freeform micro-optical elements with surface roughness of 6 nm,
and complex high-strength trusses and lattice structures with minimum feature
sizes of 50 micrometers. As a high-speed, layer-free digital light
manufacturing process, micro-CAL can process extremely viscous nanocomposites
with high geometric freedom, enabling new device structures and applications.
