Prof. Moran Bercovici and Dr. Valeri Frumkin have developed cheap technology for manufacturing optical lenses, and it is possible to produce spectacles for many developing countries where spectacles are not available. Now, NASA says it can be used to make space telescopes
Science usually advances in small steps. A small piece of information is added to each new experiment. It is rare that a simple idea that appears in the brain of a scientist leads to a major breakthrough without using any technology. But this is what happened to two Israeli engineers who developed a new method of manufacturing optical lenses.
The system is simple, cheap and accurate, and could have a huge impact on up to one-third of the world’s population. It may also change the face of space research. In order to design it, the researchers only need a white board, a marker, an eraser and a little luck.
Professor Moran Bercovici and Dr. Valeri Frumkin from the Mechanical Engineering Department of the Technion-Israel Institute of Technology in Haifa specialize in fluid mechanics, not optics. But a year and a half ago, at the World Laureate Forum in Shanghai, Berkovic happened to sit with David Ziberman, an Israeli economist.
Zilberman is a Wolf Prize winner, and now at the University of California, Berkeley, he talked about his research in developing countries. Bercovici described his fluid experiment. Then Ziberman asked a simple question: “Can you use this to make glasses?”
“When you think of developing countries, you usually think of malaria, war, hunger,” Berkovic said. “But Ziberman said something I don’t know at all-2.5 billion people in the world need glasses but cannot get them. This is an amazing number.”
Bercovici returned home and found that a report from the World Economic Forum confirmed this number. Although it only costs a few dollars to make a simple pair of glasses, cheap glasses are neither manufactured nor sold in most parts of the world.
The impact is huge, ranging from children who cannot see the blackboard in school to adults whose eyesight deteriorates so much that they lose their jobs. In addition to harming people’s quality of life, the cost of the global economy is estimated to be as high as US$3 trillion per year.
After the conversation, Berkovic could not sleep at night. When he arrived at Technion, he discussed this issue with Frumkin, who was a postdoctoral researcher in his laboratory at the time.
“We drew a shot on the whiteboard and looked at it,” he recalled. “We know instinctively that we cannot create this shape with our fluid control technology, and we want to find out why.”
The spherical shape is the basis of optics because the lens is made of them. In theory, Bercovici and Frumkin knew that they could make a round dome from a polymer (a liquid that had solidified) to make a lens. But liquids can only remain spherical in small volumes. When they are larger, gravity will squash them into puddles.
“So what we have to do is get rid of gravity,” Bercovici explained. And this is exactly what he and Frumkin did. After studying their whiteboard, Frumkin came up with a very simple idea, but it is not clear why no one had thought of it before-if the lens is placed in a liquid chamber, the effect of gravity can be eliminated. All you have to do is to make sure that the liquid in the chamber (called the buoyant liquid) has the same density as the polymer from which the lens is made, and then the polymer will float.
Another important thing is to use two immiscible fluids, which means they will not mix with each other, such as oil and water. “Most polymers are more like oils, so our’singular’ buoyant liquid is water,” Bercovici said.
But because water has a lower density than polymers, its density must be increased a bit so that the polymer will float. To this end, the researchers also used less exotic materials-salt, sugar or glycerin. Bercovici said that the final component of the process is a rigid frame into which polymer is injected so that its form can be controlled.
When the polymer reaches its final form, it is cured using ultraviolet radiation and becomes a solid lens. To make the frame, the researchers used a simple sewage pipe, cut into a ring, or a petri dish cut from the bottom. “Any child can make them at home, and my daughters and I made some at home,” Bercovici said. “Over the years, we have done a lot of things in the laboratory, some of which are very complicated, but there is no doubt that this is the simplest and easiest thing we have done. Perhaps the most important.”
Frumkin created his first shot on the same day he thought of the solution. “He sent me a photo on WhatsApp,” Berkovic recalled. “In retrospect, this was a very small and ugly lens, but we were very happy.” Frumkin continued to study this new invention. “The equation shows that once you remove gravity, it doesn’t matter whether the frame is one centimeter or one kilometer; depending on the amount of material, you will always get the same shape.”
The two researchers continued to experiment with the second-generation secret ingredient, the mop bucket, and used it to create a lens with a diameter of 20 cm that is suitable for telescopes. The cost of the lens increases exponentially with the diameter, but with this new method, regardless of size, all you need is cheap polymer, water, salt (or glycerin), and a ring mold.
The ingredient list marks a huge shift in traditional lens manufacturing methods that have remained almost unchanged for 300 years. In the initial stage of the traditional process, a glass or plastic plate is mechanically ground. For example, when manufacturing spectacle lenses, about 80% of the material is wasted. Using the method designed by Bercovici and Frumkin, instead of grinding solid materials, liquid is injected into the frame, so that the lens can be manufactured in a completely waste-free process. This method also does not require polishing, because the surface tension of the fluid can ensure an extremely smooth surface.
Haaretz visited Technion’s laboratory, where doctoral student Mor Elgarisi demonstrated the process. He injected polymer into a ring in a small liquid chamber, irradiated it with a UV lamp, and handed me a pair of surgical gloves two minutes later. I very carefully dipped my hand in the water and pulled out the lens. “That’s it, the processing is over,” Berkovic shouted.
The lenses are absolutely smooth to the touch. This is not just a subjective feeling: Bercovici says that even without polishing, the surface roughness of a lens made using a polymer method is less than one nanometer (one billionth of a meter). “The forces of nature create extraordinary qualities on their own, and they are free,” he said. In contrast, optical glass is polished to 100 nanometers, while the mirrors of NASA’s flagship James Webb Space Telescope are polished to 20 nanometers.
But not everyone believes that this elegant method will be the saviour of billions of people around the world. Professor Ady Arie from Tel Aviv University’s School of Electrical Engineering pointed out that Bercovici and Frumkin’s method requires a circular mold into which liquid polymer is injected, the polymer itself and an ultraviolet lamp.
“These are not available in Indian villages,” he pointed out. Another issue raised by SPO Precision Optics founder and vice president of R&D Niv Adut and the company’s chief scientist Dr. Doron Sturlesi (both familiar with Bercovici’s work) is that replacing the grinding process with plastic castings will make it difficult to adapt the lens to the needs. Its people.
Berkovic did not panic. “Criticism is a fundamental part of science, and our rapid development over the past year is largely due to experts pushing us to the corner,” he said. Regarding the feasibility of manufacturing in remote areas, he added: “The infrastructure required to manufacture glasses using traditional methods is huge; you need factories, machines, and technicians, and we only need the minimum infrastructure.”
Bercovici showed us two ultraviolet radiation lamps in his laboratory: “This one is from Amazon and costs $4, and the other is from AliExpress and costs $1.70. If you don’t have them, you can always use Sunshine,” he explained. What about polymers? “A 250-ml bottle sells for $16 on Amazon. The average lens requires 5 to 10 ml, so the cost of the polymer is not a real factor either.”
He emphasized that his method does not require the use of unique molds for each lens number, as critics claim. A simple mold is suitable for each lens number, he explained: “The difference is the amount of polymer injected, and to make a cylinder for the glasses, all that is required is to stretch the mold a little bit.”
Bercovici said that the only expensive part of the process is the automation of polymer injection, which must be done precisely according to the number of lenses required.
“Our dream is to have an impact in the country with the fewest resources,” Bercovici said. Although cheap glasses can be brought to poor villages-although this has not been completed-his plan is much bigger. “Just like that famous proverb, I don’t want to give them fish, I want to teach them how to fish. In this way, people will be able to make their own glasses,” he said. “Will it succeed? Only time will give the answer.”
Bercovici and Frumkin described this process in an article about six months ago in the first edition of Flow, a journal of fluid mechanics applications published by the University of Cambridge. But the team does not intend to stay on simple optical lenses. Another paper published in Optica magazine a few weeks ago described a new method for manufacturing complex optical components in the field of free-form optics. These optical components are neither convex nor concave, but are molded into a topographic surface, and light is irradiated to the surface of different areas to achieve the desired effect. These components can be found in multifocal glasses, pilot helmets, advanced projector systems, virtual and augmented reality systems, and other places.
Manufacturing free-form components using sustainable methods is complicated and expensive because it is difficult to grind and polish their surface area. Therefore, these components currently have limited uses. “There have been academic publications on the possible uses of such surfaces, but this has not yet been reflected in practical applications,” Bercovici explained. In this new paper, the laboratory team led by Elgarisi showed how to control the surface form created when polymer liquid is injected by controlling the form of the frame. The frame can be created using a 3D printer. “We don’t do things with a mop bucket anymore, but it’s still very simple,” Bercovici said.
Omer Luria, a research engineer at the laboratory, pointed out that this new technology can quickly produce particularly smooth lenses with unique terrain. “We hope it can significantly reduce the cost and production time of complex optical components,” he said.
Professor Arie is one of Optica’s editors, but did not participate in the review of the article. “This is a very good job,” Ali said of the research. “In order to produce aspheric optical surfaces, current methods use molds or 3D printing, but both methods are difficult to create sufficiently smooth and large surfaces within a reasonable time frame.” Arie believes that the new method will help create freedom Prototype of formal components. “For industrial production of large numbers of parts, it is best to prepare molds, but in order to quickly test new ideas, this is an interesting and elegant method,” he said.
SPO is one of Israel’s leading companies in the field of free-form surfaces. According to Adut and Sturlesi, the new method has advantages and disadvantages. They say that the use of plastics limits possibilities because they are not durable at extreme temperatures and their ability to achieve sufficient quality across the entire color range is limited. As for the advantages, they pointed out that the technology has the potential to significantly reduce the production cost of complex plastic lenses, which are used in all mobile phones.
Adut and Sturlesi added that with traditional manufacturing methods, the diameter of plastic lenses is limited because the larger they are, the less precise they become. They said that, according to Bercovici’s method, manufacturing lenses in liquid can prevent distortion, which can create very powerful optical components-whether in the field of spherical lenses or free-form lenses.
The most unexpected project of the Technion team was choosing to produce a large lens. Here, it all started with an accidental conversation and a naive question. “It’s all about people,” Berkovic said. When he asked Berkovic, he was telling Dr. Edward Baraban, a NASA research scientist, that he knew his project at Stanford University, and he knew him at Stanford University: “You think you can Do you make such a lens for a space telescope?”
“It sounded like a crazy idea,” Berkovic recalled, “but it was deeply imprinted in my mind.” After the laboratory test was successfully completed, Israeli researchers realized that the method could be used in It works the same way in space. After all, you can achieve microgravity conditions there without the need for buoyant liquids. “I called Edward and I told him, it works!”
Space telescopes have great advantages over ground-based telescopes because they are not affected by atmospheric or light pollution. The biggest problem with the development of space telescopes is that their size is limited by the size of the launcher. On Earth, telescopes currently have a diameter of up to 40 meters. The Hubble Space Telescope has a 2.4-meter-diameter mirror, while the James Webb Telescope has a 6.5-meter-diameter mirror — it took scientists 25 years to achieve this achievement, costing 9 billion U.S. dollars, partly because A system needs to be developed that can launch the telescope in a folded position and then automatically open it in space.
On the other hand, Liquid is already in a “folded” state. For example, you can fill the transmitter with liquid metal, add an injection mechanism and expansion ring, and then make a mirror in space. “This is an illusion,” Berkovic admitted. “My mother asked me,’When will you be ready? I told her,’Maybe in about 20 years. She said she didn’t have time to wait.”
If this dream comes true, it may change the future of space research. Today, Berkovic pointed out that humans do not have the ability to directly observe exoplanets-planets outside the solar system, because doing so requires an Earth telescope 10 times larger than existing telescopes-which is completely impossible with existing technology.
On the other hand, Bercovici added that the Falcon Heavy, currently the largest space launcher SpaceX, can carry 20 cubic meters of liquid. He explained that in theory, Falcon Heavy could be used to launch a liquid to an orbital point, where the liquid could be used to make a 75-meter-diameter mirror—the surface area and collected light would be 100 times larger than the latter. James Webb telescope.
This is a dream, and it will take a long time to realize it. But NASA is taking it seriously. Together with a team of engineers and scientists from NASA’s Ames Research Center, led by Balaban, the technology is being tried for the first time.
In late December, a system developed by the Bercovici laboratory team will be sent to the International Space Station, where a series of experiments will be conducted to enable astronauts to manufacture and cure lenses in space. Before that, experiments will be conducted in Florida this weekend to test the feasibility of producing high-quality lenses under microgravity without the need for any buoyant liquid.
The Fluid Telescope Experiment (FLUTE) was carried out on a reduced-gravity aircraft-all seats of this aircraft were removed for training astronauts and shooting zero-gravity scenes in movies. By maneuvering in the form of an antiparabola-ascending and then falling freely-microgravity conditions are created in the aircraft for a short period of time. “It’s called a’vomit comet’ for good reason,” Berkovic said with a smile. The free fall lasts for about 20 seconds, in which the gravity of the aircraft is close to zero. During this period, the researchers will try to make a liquid lens and make measurements to prove that the quality of the lens is good enough, then the plane becomes straight, the gravity is fully restored, and the lens becomes a puddle.
The experiment is scheduled for two flights on Thursday and Friday, each with 30 parabolas. Bercovici and most members of the laboratory team, including Elgarisi and Luria, and Frumkin from the Massachusetts Institute of Technology will be present.
During my visit to the Technion laboratory, the excitement was overwhelming. There are 60 cardboard boxes on the floor, which contain 60 self-made small kits for experiments. Luria is making final and last-minute improvements to the computerized experimental system he developed to measure lens performance.
At the same time, the team is conducting timing exercises before critical moments. One team stood there with a stopwatch, and the others had 20 seconds to make a shot. On the aircraft itself, the conditions will be even worse, especially after several free falls and upward lifts under increased gravity.
It’s not just the Technion team that is excited. Baraban, the lead researcher of NASA’s Flute Experiment, told Haaretz, “The fluid shaping method may result in powerful space telescopes with apertures of tens or even hundreds of meters. For example, such telescopes can directly observe the surroundings of other stars. Planet, facilitates high-resolution analysis of its atmosphere, and may even identify large-scale surface features. This method may also lead to other space applications, such as high-quality optical components for energy harvesting and transmission, scientific instruments, and medical equipment Space manufacturing-thus playing an important role in the emerging space economy.”
Shortly before boarding the plane and embarking on the adventure of his life, Berkovic paused for a moment in surprise. “I keep asking myself why no one thought of this before,” he said. “Every time I go to a conference, I am afraid that someone will stand up and say that some Russian researchers did this 60 years ago. After all, it is such a simple method.”
Post time: Dec-21-2021