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Researchers develop inexpensive, fast method to make freeform optics

Researchers who set out to find a simple method for fabricating high quality freeform optics that don’t rely on mechanical processing or expensive infrastructure have exceeded their goal.

The four-man team from Technion – Israel Institute of Technology have developed a way to create freeform optical components by shaping a volume of curable liquid polymer.

The new method is poised to enable faster prototyping of customised optical components for several applications, including corrective lenses, augmented and virtual reality, autonomous vehicles, medical imaging and astronomy.

 

The research team leader Mr Moran Bercovici said their approach to making freeform optics achieves extremely smooth surfaces and can be implemented using basic equipment that can be found in most labs.

“This makes the technology very accessible, even in low resource settings,” he said.

In the paper published in Optica, Optica Publishing Group’s journal for high-impact research, Bercovici and colleagues show their new technique can be used to fabricate freeform components with sub-nanometer surface roughness within minutes.

Unlike other prototyping methods such as 3D printing, they say the fabrication time remains short even if the volume of the manufactured component increases.

“Currently, optical engineers pay tens of thousands of dollars for specially designed freeform components and wait months for them to arrive,” Mr Omer Luria, one of the contributors to the paper, said.

“Our technology is poised to radically decrease both the waiting time and the cost of complex optical prototypes, which could greatly speed up the development of new optical designs.”

The researchers decided to develop the new method after learning that 2.5 billion people around the world don’t have access to corrective eyewear.

“We set out to find a simple method for fabricating high quality optical components that does not rely on mechanical processing or complex and expensive infrastructure,” Mr Valeri Frumkin, who first developed the method in Bercovici’s lab, said.

“We then discovered that we could expand our method to produce much more complex and interesting optical topographies.”

One of the primary challenges in making optics by curing a liquid polymer is that for optics larger than about two millimetres, gravity dominates over surface forces, which causes the liquid to flatten into a puddle. To overcome this, the researchers developed a way to fabricate lenses using liquid polymer that is submerged in another liquid. The buoyancy counteracts gravity, allowing surface tension to dominate.

The paper’s lead author Mr Mor Elgarisi said the research team identified an infinite range of possible optical topographies that can be fabricated using their approach.

“The method can be used to make 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,” he said.

The researchers are now working to automate the fabrication process so that various optical topographies can be made in a precise and repeatable way. They are also experimenting with various optical polymers to find out which ones produce the best optical components.

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