Blurred tomography: 3D printing process for microlenses

Canadian researchers have developed a new 3D printing process called “blurred tomography” that can be used to quickly produce commercially available optical-quality microlenses. The new method could make it easier and faster to design and manufacture a variety of optical devices.

“We purposely added optical blurring to the beams of light used for this 3D printing method to manufacture precision optical components,” said Daniel Webber from the National Research Council of Canada. “This enables production of optically smooth surfaces.”

In a study published in the journal Optica, the researchers demonstrate the new method by fabricating a millimeter-sized plano-convex optical lens with image performance equivalent to a commercially available glass lens. They also show that the method can produce optical components in just 30 minutes.

“We anticipate this method to be valuable for cost-effective and swift prototyping of optical components due to the affordability of the tomographic 3D printer and the materials used,” said Webber. “Also, the inherent freeform nature of tomographic 3D printing could enable optical designers to simplify designs by replacing multiple standard optics with printed optics that have complex shapes.”

Tomographic volumetric additive manufacturing, a relatively new approach, uses projected light to solidify photosensitive resin in specific areas. This makes it possible to print an entire part at once without support structures. However, existing tomographic methods cannot print imaging lenses directly, as the pin-like beams cause streaks that result in small edges on the surface of the part.

“Fabrication of optical components is costly due to the stringent technical specifications needed for a functioning lens, as well as the complex and time-consuming process of manufacturing,” said Dr. Webber. “Blurred tomography can be used to make freeform designs in a low-cost manner. As the technology matures, it could allow much quicker prototyping for new optical devices, which would be useful for anyone from commercial manufacturers to garage-based inventors.”

The researchers first created a simple plano-convex lens and showed that it had an image resolution comparable to a commercial glass lens. They also demonstrated a micrometer-sized shape error, sub-nanometer surface roughness and a point spread function similar to glass.

They also fabricated a 3×3 array of microlenses using blurred tomography and compared it to an array printed using conventional tomographic 3D printing. The conventionally printed array could not image a business card due to high surface roughness, but the blurred tomography printed array could.

The researchers are now working on improving the accuracy of the components by optimizing the light patterning method and incorporating material parameters into the printing process. They also plan to automate the printing time to make the system robust enough for commercial use.

“Tomographic 3D printing is a rapidly maturing field that is finding use in many application areas,” said Webber. “Here, we leverage the intrinsic advantages of this 3D printing method to fabricate millimeter-sized optical components. In doing so, we have added to the repertoire of optical manufacturing techniques a rapid and low-cost alternative that could potentially have an impact in future technologies.”