The key is to leave the intended hollow regions uncured. Light hardens the resin where walls should remain, while deliberately dark regions stay uncured. Washing removes that material and reveals the internal voids.[1][2]
Single-exposure holographic 3D printing designs this relationship throughout a resin volume. Instead of forming successive layers, it creates the required three-dimensional light distribution in one optical step.[2]
From light distribution to hollow structure
The photopolymer resin contains long molecular chains that crosslink under laser light. Exposed regions harden; unexposed resin can be washed away.[1]
A hollow region therefore must remain dark enough to avoid crosslinking, not merely dimmer than its surroundings. Exposure decides what becomes solid, and washing clears the intended void.[1]
The central component is an inverse-designed microstructured phase mask. Its surface is tailored to produce the target 3D light-intensity distribution, including dark regions for internal hollow features.[2]
The University of Utah reports that substrate diffraction can blur the pattern; a nanopatterned mask compensates for it. The abstract also specifies resin with controlled optical absorption, so mask and material work as one system.[1][2]
What the demonstration establishes
Earlier prints formed voids along length and width but not height. “True 3D” here means controlling internal voids in the height dimension, not merely making a thick object.[1][2]
The abstract reports millimeter-scale architectures with more than 10⁶ addressable voxels in a single 7.5-second exposure, corresponding to about 1 mm³/s or more than 10⁵ voxels/s in this demonstration.[2]
A voxel is a small volume element; “addressable” means it can be specified in the optical distribution. This count is not final-part tolerance or feature resolution. Current limits are resin kinetics and illumination geometry.[2]
The hollow cylinder and cube are proof-of-concept results, not production validation. Industrial throughput, qualified commercial materials, and repeatability were not reported. The 7.5 seconds is exposure time, not total lead time including washing, post-curing, and inspection.[1][2]
Seven checks before adoption
These are recommended engineering checks, not results reported by the study.
- Geometry: Test walls, voids, height-dependent features, and resin-drain paths.
- Material: Verify absorption, curing, removable regions, and final-use properties.
- Optics: Define mask, substrate, placement, alignment, illumination, and redesign needs.
- Post-processing: Check resin removal, residue, post-curing, and final geometry.
- Inspection: Set criteria for dimensions, void connectivity, blockage, and residue.
- Repeatability: Compare success, variation, and void formation across runs and batches.
- Total lead time: Measure setup, exposure, washing, post-curing, inspection, and rework; separate first setup from repeat production.
These checks show whether a specific application can achieve its geometry, quality, and accepted-part delivery time.
Sources:
- https://www.price.utah.edu/2026/08/12/new-holographic-printer-makes-3d-shapes-voids-and-all-in-one-shot
- https://api.crossref.org/works/10.1126/sciadv.aec3536
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