Apr 2, 2018 | By David

An exciting new breakthrough in the field of 3D printed optics was recently achieved by a team of researchers based at California’s Lawrence Livermore National Laboratory (LLNL). Scientists and engineers that worked on the optics project developed a new 3D printing technique that made use of special inks, which were extruded from a customized printer. They successfully printed small test pieces that had high-level optical properties, on par with many commercially available glass products. A patent has now been filed for the innovative 3D printing process.

We reported before on the 3D printed optics work of LLNL. Many 3D printed optics techniques have been tried in the past, by such names as the Fraunhofer IOF and Micron3DP, often making use of glass filaments and advanced SLA processes. Researchers at LLNL were among the first to suggest the use of customized 3D printing inks to improve the FDM deposition technique for making glass.

A difficulty with printing optics that perform effectively is that the refractive index of glass is sensitive to its thermal history. To deal with this issue, the researchers chose to deposit a special LLNL-developed material in paste form, and then heat the entire print to form it properly. This meant that the glass was capable of maintaining a uniform refractive index, thus eliminating any optical distortion which could lead to degradation in the optical function.

The custom 3D printing inks were formed of a slurry of different silica and silica-titania particles. They were fine-tuned in order to enable the printing of glasses that had specific thermal and mechanical properties as well as high optical performance.

"Components printed from molten glass often show texture from the 3D-printing process, and even if you were to polish the surface, you would still see evidence of the printing process within the bulk material,” said LLNL chemical engineer Rebecca Dylla-Spears, the project’s principal investigator. “This approach allows us to obtain the index homogeneity that is needed for optics. Now we can take these components and do something interesting.”

The initial test pieces that were printed were small, but now the technique has been proven, many possible applications are open for testing. Optics can be made with geometric structures and compositional changes that were unattainable with more conventional manufacturing methods. For example, the 3D printing technique could be used to make gradient refractive index lenses that could be polished flat, which would replace more expensive polishing techniques used for traditional curved lenses.

LLNL researchers involved in this study included Nikola Dudukovic, Michael Johnson, Du Nguyen, Timothy Yee, Garth Egan, April Sawvel, William Steele, Lana Wong, Paul Ehrmann, Theodore Baumann, Eric Duoss, and Tayyab Suratwala. Their work was detailed in a paper entitled ‘3D Printed Optical Quality Silica and Silica–Titania Glasses from Sol–Gel Feedstocks’, published in the journal Advanced Materials Technologies.

“Additive manufacturing gives us a new degree of freedom to combine optical materials in ways we could not do before,” Dylla-Spears said. “It opens up a new design space that hasn’t existed in the past, allowing for design of both the optic shape and the optical properties within the material.”

 

 

Posted in 3D Printing Applications

 

 

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