Powerful lasers are now used in many fields from manufacturing to space communications. With the development of this field, even more powerful devices are needed, which leads to the need to change the design and create optical components that can withstand and pass large amounts of energy. And recently, a team of scientists and engineers from Harvard University created a new type of mirror using the world’s hardest material, diamond, that can withstand motion without damaging it and displays a powerful laser beam that can pierce steel barriers.

The new mirror was created to solve specific problems when creating powerful laser systems that can operate continuously. Previously used high-quality mirrors, the main component of any laser, are made of several layers of materials with different optical properties. And if there is a very small flaw in any of these layers, the mirror burns there and loses its function.

Therefore, the scientists decided to use a single material for the entire structure of the mirror, which reduces the possibility of defects. The scientists took a high-quality diamond crystal 3 x 3 millimeters in size and used the ion beam to create tiny nanostructures on its surface, similar to structures commonly used in quantum optics and communications. The presence of an ordered array of structures of a certain shape, which can be seen in one of the pictures given here, gives the surface of the diamond crystal high reflective properties, while the value of the reflection coefficient is 98.9 percent.

“Of course you can create a mirror with 99.999 percent reflectivity,” says lead researcher Neil Sinclair. “But such a mirror would consist of 10 to 20 different layers.” Moreover, such a mirror can only be used in low-power lasers, it cannot withstand the effects of a huge amount of light falling on it.

The scientists conducted a test by placing a diamond mirror in the beam of a 10 kW military laser focused on a point with a diameter of 750 microns. Despite the fact that such a laser was quite easy to burn steel targets at such a distance, the mirror lasted and remained intact. Using a single material to make the entire mirror, this approach avoids the problem of different materials having different coefficients of thermal expansion that cause mechanical stress when heated. Source