The Mind-Bending Mirrors Of Sophisticated Technology
The European Space Observatory (ESO) is currently erecting the world’s largest optical telescope atop a mountain in Chile’s bone-dry Atacama Desert.
The Extremely Large Telescope, or ELT, was named without delay.
Instead, a lot of effort has gone into planning and creating “the world’s biggest eye on the sky,” which will begin gathering photographs in 2028 and is quite likely to increase our understanding of the universe.
None of this would be feasible without some of the most advanced mirrors ever developed.
Dr. Elise Vernet is an adaptive optics specialist at ESO who has been in charge of developing the five huge mirrors that will collect and redirect light to the telescope’s measuring equipment.
Each of the ELT’s unique mirrors is a masterpiece of optical design.
The 14-foot (4.25-meter) convex M2 mirror is described as “a piece of art” by Dr. Vernet.
However, the M1 and M4 mirrors may best capture the level of complexity and precision required.
The M1 is the largest mirror ever built for an optical telescope.
“It’s 39 m [128 ft] in diameter, made up of [798] hexagonal mirror segments, aligned so that it behaves as a perfect monolithic mirror,” states Vernet.
M1 will capture 100 million times more light than the human eye and must preserve position and shape with 10,000 times the precision of a human hair.
The M4 is the largest deformable mirror ever created, with the ability to change shape 1,000 times per second to compensate for atmospheric turbulence and telescope vibrations that would otherwise distort vision.
Its flexible surface is composed of six petals of a glass-ceramic substance that is less than 2 mm (0.075 in) thick.
Schott created the petals in Mainz, Germany, and delivered them to Safran Reosc, an engineering firm just outside Paris, where they were polished and assembled into the entire mirror.
All five mirrors are nearly finished and will soon be transported to Chile for installation.
While these massive mirrors will be utilized to collect cosmic light, ESO’s neighbors in Garching, the Max Planck Institute for Quantum Optics, have developed a quantum mirror that can function at the smallest sizes imaginable.
In 2020, a research team was able to create a single layer of 200 aligned atoms that act collectively to reflect light, effectively generating a mirror so small that it cannot be seen with the human eye.
In 2023, they succeeded in inserting a single microscopically controlled atom in the center of the array, resulting in a “quantum switch” that can be used to control whether the atoms are transparent or reflecting.
While these massive mirrors will be utilized to collect cosmic light, ESO’s neighbors in Garching, the Max Planck Institute for Quantum Optics, have developed a quantum mirror that can function at the smallest sizes imaginable.
In 2020, a research team was able to create a single layer of 200 aligned atoms that act collectively to reflect light, effectively generating a mirror so small that it cannot be seen with the human eye.
In 2023, they succeeded in inserting a single microscopically controlled atom in the center of the array, resulting in a “quantum switch” that can be used to control whether the atoms are transparent or reflecting.
“What theorists predicted and we observed experimentally is that in these ordered structures, once a photon is absorbed and re-emitted, it is actually emitted [in one predictable] direction.
which is what makes it a mirror,” says Dr Pascal Weckesser, a postdoctoral researcher at the institute.
This capacity to regulate the direction of atom-reflected light may have potential uses in a variety of quantum technologies, including hack-proof quantum networks for storing and sending information.
Zeiss manufactures mirrors with another extreme characteristic to the north-west, in Oberkochen near Stuttgart.
The optics company spent years inventing an ultra-flat mirror, which is now a vital component in machines that print computer chips known as extreme ultraviolet lithography machines, or EUVs.
ASML, a Dutch business, is the world’s leading manufacturer of EUVs, and Zeiss mirrors are an integral component of them.
Zeiss’ EUV mirrors can reflect light at very short wavelengths, allowing for image clarity on a microscopic scale and increasing the number of transistors that can be produced on the same area of silicon wafer.
Dr. Frank Rohmund, president of semiconductor manufacturing optics at Zeiss, provides a topographical analogy to describe the mirrors’ flatness.
“If you took a household mirror and enlarged it to the size of Germany, the tallest point would be 5 meters. On a space mirror [such as the James Webb Space Telescope], it would be 2cm [0.75in]. “On an EUV mirror, it would be 0.1mm,” he says.
This ultra-smooth mirror surface, along with Zeiss-made systems that manage the mirror’s placement, achieves an accuracy level comparable to bouncing light off an EUV mirror on Earth’s surface and identifying a golf ball on the moon.
While those mirrors may appear severe, Zeiss has plans to upgrade them in order to aid in the development of even more powerful computer chips.
“We have ideas on how to further develop EUV. By 2030, the goal is for a microchip to include one trillion transistors. Today, we may be at one hundred billion.”
That aim was closer with Zeiss’s latest technology, which allows for the printing of almost three times more structures on the same surface than the current generation of chip manufacturing machines.
“The semiconductor industry has a dominant, robust roadmap that serves as a drumbeat for all stakeholders involved in the solution. With this, we are able to make advancements in microchip fabrication, which now enables for things like artificial intelligence that were unfathomable even ten years ago,” explains Dr. Rohmund.
What humanity will understand and be capable of in ten years’ hence remains to be seen, but mirrors will undoubtedly be key to the technology that will transport us there.
