Researchers develop a new lens manufacturing technique

Researchers at Washington State University and the state of Ohio have developed a simple, inexpensive way to make custom lenses that could help manufacturers avoid expensive molds needed for optical fabrication.

Under the guidance of Lei Li, an assistant professor in the School of Mechanical Engineering and Materials, and graduate student Mojtaba Falahati, the researchers developed a liquid mold from droplets that they can handle at the university. Using magnets to create lenses of varying shapes and sizes. Their work is featured on the cover of the newspaper, Applied Physics Letters.

High quality lenses are increasingly used in cameras, autonomous cars and almost all robotics, but the traditional casting and casting processes used in their manufacture require sophisticated and expensive metal molds. Manufacturers are therefore generally limited to mass production of a type of lens.

"The molds are finished precisely and are difficult to manufacture," said Li. "It's not worth making a mold for low-volume production."

The researchers discovered the problem by seeking goals for their work in order to develop a portable lab reader on a phone.

They first tried to make their own lenses using 3D printing, but they struggled to control the shape of the lens. They then had the idea of ​​using magnets and the surface tension of liquids to create free-flowing molds.

They placed tiny magnetic iron particles in liquid droplets and built a device to surround the droplets of magnets. They then poured the plastic material used in the lenses onto the droplet. By applying a magnetic field, the droplet took a conical lens shape, creating a mold for the plastic lens material. Once the plastic has hardened, it hardens and has the same optical properties and imaging quality as a commercially purchased lens. The drop of liquid remains separate and can be reused.

The magnets can be moved to modify the magnetic field, the shape of the mold and the resulting lens. Researchers also used larger or smaller droplets to create lenses of different sizes.

"We introduced the concept of interfacial tension in the field of optics by introducing an innovative controllable liquid mold," said Mr. Li. "This new process allowed us to regulate the shape of a drop magnetic and create lenses without having to make expensive molds. "