Cheap and fast technology for creating complex optical lenses using liquids

An original technology developed at the Technion makes it possible to produce complex and precise optical components quickly and without the need for casting and polishing

Original technology developed at the Technion makes it possible to produce complex and precise optical components quickly and without the need for casting and polishing. The article published in the journal Optica describes how liquid polymer which is in a special liquid environment is molded into complex shapes by the physical forces acting on it. After the polymer takes its final shape, it is hardened using UV radiation and becomes a solid lens.

The inventors, researchers at the Faculty of Mechanical Engineering at the Technion, estimate that the new technology will advance the rapid production of complex optical components on demand for a variety of applications, including glasses and contact lenses, virtual and augmented reality systems, panoramic imaging, solar radiation focusing, autonomous vehicles, medical imaging devices, Microscope and telescope. 

The article was led Mor Allegrisi, PhD student in Prof. Moran Berkovich's lab, and Dr. Valery Frumkin who started the fluid design project while he was a postdoctoral fellow in the Berkovich lab (he is now a postdoctoral fellow at MIT). The idea behind the technology arose when Dr. Frumkin and Prof. Berkovic were exposed to a report by the World Economic Forum, where it was claimed that 2.5 billion people currently do not have access to eyeglasses, mainly in developing countries that are not equipped with the necessary infrastructure to manufacture optics, but it quickly became clear For them, visual aids are only one of the potential applications of the invention.

"Our technology is expected to dramatically reduce both the production time of complex optical components and their price," says Omar Luria, a research engineer at the laboratory, who co-authored the scientific article. "The technology we have developed enables the rapid creation of extremely smooth lenses, with complex and unique topographies, without the need for casting and polishing or sophisticated equipment. Unlike other production methods such as XNUMXD printing, the production time remains short even when the volume of the requested component increases."

Most of the optical lenses we are familiar with are spherical or approximately spherical, however the progress of science, technology and medicine requires more complex and less symmetrical lenses. The creation of such lenses is a lengthy and expensive process due to the dedicated equipment required for the casting process and surface polishing. Technologies such as engraving and lithography allow the creation of complex lenses, but they are limited in the size of the product. Another relevant technology is XNUMXD printing, but since it is based on layer printing it does not provide the surface required for advanced optical devices. Furthermore, the duration of printing increases as the volume of the component increases.

The innovative technology developed by Technion researchers Completely different and as mentioned based on the design of a liquid polymer inside another liquid. One of the biggest challenges in this approach stems from the fact that for optics larger than about 2 millimeters in diameter, the force of gravity overshadows the force of the surface, and the result is the flattening of the upper part of the lens in its liquid state. This problem was solved by the researchers by adjusting the properties of the polymer and the surrounding liquid so that the force of buoyancy offsets the force of gravity.

In the method developed by the Technion researchers, the liquid polymer is injected into the primary liquid and forms within it under the influence of the interplay between the surface tension of the liquids, the hydrostatic forces acting on them and the force of gravity, with the help of a rigid frame that encloses the perimeter of the liquid polymer. When the polymer reaches its final form, UV radiation is applied to it which hardens it and turns it into a solid lens.

After using the new method to create simple spherical lenses, the researchers demonstrated its effectiveness in the production of optical components with complex geometry known as Freeform optics. In an article in Optica they show that the resulting lenses are characterized by a surface quality similar to that of lenses processed with the best polishing technologies available today. In the article they present a "roughness level" of less than 1 nanometer, which is achieved in a quick and simple process.

According to Prof. Berkovich, "Our method makes it possible to produce components in a huge range of sizes and shapes from any liquid that can be hardened, and there is also an environmental value here - it is a process that does not produce waste."

The researchers estimate that in addition to the production of rigid lenses, the innovative technology will also be used to create liquid lenses, that is, lenses that will be used as optical components in their liquid state. In this way, the dynamism of the lens will be achieved, since it will be possible to change it as needed by injecting an additional liquid polymer or by changing the density of the initial liquid in which the lens is formed.

for the article in the journal Optica 

For a video explaining the research click here