Manufacture of complex optical components from fluids – for glasses, cameras and telescopes

The researchers used their new method to fabricate optical components with various geometries – including toroidal and trefoil shapes – and sizes up to 200mm as well as free-form surfaces. The lenses exhibited surface qualities similar to the best polishing technologies available while being orders of magnitude faster and easier to manufacture. Credit: Technion – Israel Institute of Technology

A fast and inexpensive method of fabricating free-form optics could benefit telescope applications.

Researchers have developed a way to create free-form optical components by shaping a volume of curable liquid polymer. The new method is poised to enable faster prototyping of custom optical components for a variety of applications, including corrective lenses, augmented and virtual reality, autonomous vehicles, medical imaging and astronomy.

Common devices such as glasses or cameras rely on lenses – optical components with spherical or cylindrical surfaces, or slight deviations from these shapes. However, more advanced optical functionality can be obtained from surfaces with complex topographies. Currently, the manufacture of such freeform optics is very difficult and expensive due to the specialized equipment required to mechanically treat and polish their surfaces.

“Our approach to fabricating free-form optics results in extremely smooth surfaces and can be implemented using basic equipment that can be found in most laboratories,” said the chief. by the Moran Bercovici research team at Technion – Israel Institute of Technology. “This makes the technology very accessible, even in low-resource environments. “

In optical, the Optica Publishing Group journal for high-impact research, Bercovici and colleagues show that their new technique can be used to fabricate free-form components with sub-nanometer surface roughness in just a few minutes. Unlike other prototyping methods like 3D printing, manufacturing time is kept short even as the volume of the manufactured component increases.

Free-form optical components

Free-form optical components with less than nanometer surface roughness are fabricated in minutes by shaping volumes of liquid. Credit: Technion – Israel Institute of Technology

“Currently, optical engineers pay tens of thousands of dollars for specially designed free-form components and wait months for them to arrive,” said Omer Luria, one of the document’s contributors. “Our technology is poised to dramatically reduce both the wait time and the cost of complex optical prototypes, which could dramatically accelerate the development of new optical designs.”

Glasses with complex optics

The researchers decided to develop the new method after learning that 2.5 billion people worldwide do not have access to corrective glasses. “We looked for a simple method to manufacture high-quality optical components that does not rely on mechanical processing or complex and expensive infrastructure,” said Valeri Frumkin, who first developed the method in the Bercovici lab. “Then we discovered that we could extend our method to produce much more complex and interesting optical topographies. “

One of the main challenges of making optics by curing a liquid polymer is that for optics larger than about 2 millimeters gravity dominates the surface forces, causing the liquid to flatten into a puddle. of water. To overcome this, researchers have developed a way to make lenses using a liquid polymer that is submerged in another liquid. Buoyancy counteracts gravity, allowing surface tension to dominate.

With gravity out of the image, researchers could fabricate smooth optical surfaces by controlling the liquid surface topography of the lens. This involves injecting the lens liquid into a support frame so that the lens liquid wets the interior of the frame and then expands into a stable configuration. Once the required topography is reached, the lens liquid can be solidified by exposure to UV or other methods to complete the manufacturing process.

After using the liquid manufacturing method to make simple spherical lenses, researchers expanded to optical components with various geometries – including torus and trefoil shapes – and sizes up to 200mm. They show that the resulting lenses exhibited surface qualities similar to the best polishing technologies available while being orders of magnitude faster and easier to manufacture. In the work published in optical, they further expanded the method to create free-form surfaces, changing the shape of the support frame.

Endless possibilities

“We have identified an endless array of possible optical topographies that can be fabricated using our approach,” said Mor Elgarisi, the lead author of the article. “The method can be used to fabricate components of any size, and because liquid surfaces are naturally smooth, no polishing is required. The approach is also compatible with any liquid that can be solidified and has the advantage of not producing any waste.

Researchers are now working to automate the manufacturing process so that various optical topographies can be made in an accurate and reproducible manner. They are also experimenting with various optical polymers to determine which ones produce the best optical components.

Reference: “Manufacture of free-form optical components by fluidic shaping” by M. Elgarisi, V. Frumkin, O. Luria, M. Bercovici, November 18, 2021, optical.
DOI: 10.1364 / OPTICA.438763

Source link

Richard V. Johnson