Doctoral Thesis: Volumetric Additive Manufacturing of Polymer Structures by Holographically Projected Light Fields

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Event Speaker: 

Maxim Shusteff

Event Location: 

38-466, Jackson Room

Event Date/Time: 

Monday, July 10, 2017 - 1:30pm

Abstract: 

As additive manufacturing technologies proliferate and mature, overcoming some of their process limitations becomes increasingly important for the continued expansion of practical applications.  Two such limitations that arise from layer-based fabrication are slow speed and geometric constraints (which include poor surface quality and challenges fabricating span, cantilever, and overhang elements).  Moving beyond point-by-point and layer-by-layer approaches, the ability to generate a complex 3D volume as a unit operation has the potential to overcome these limitations.

Since holography has been extensively studied as a means for storage and retrieval of 3D geometrical information, this dissertation explores the use of holographically-shaped light fields for producing three-dimensional structures in a “volume at once” approach.  Leveraging advances in spatial light modulator (SLM) technology, phase-controlled light fields are projected into photopolymer resin to cure a desired geometry.  By overlapping multiple sub-regions of a single light field within the target volume, the successful fabrication of non-periodic complex 3D geometries is demonstrated by single exposures on timescales of seconds.    

A suitable hardware configuration that makes this approach possible is presented, along with the computational algorithms necessary to calculate and optimize the required optical fields.  A study of the photopolymerization kinetics is also carried out, to determine the boundaries of usable process parameters such as resin absorbance and available light intensity.  The results indicate that low-absorbing resins containing ~0.1% photoinitiator, illuminated at modest powers (~10-100 mW) may be used to build full structures with 1-10 second exposures. 
 
Thesis Supervisor(s): Nicholas Xuanlai Fang (MechE)
Committee members:  Karl Berggren, Jeff Lang, Chris Spadaccini (LLNL)