Laser beams can be used to accurately measure the position or speed of an object. But for this it is usual
Scientists from Utrecht University and TU Wienwere able to obtain measurements of a given accuracy even in such difficult conditions. They specifically modified the laser beam so that it delivered the desired information in a disordered environment.
“The maximum possible measurement accuracy isa central element of all natural sciences,” says Stefan Rotter from TU Wien. “For example, in the huge LIGO facility, which is used to detect gravitational waves, laser beams are sent to a mirror, and changes in the distance between the laser and the mirror are measured with extreme precision.”
It only works so well because the laser beam passes through an ultra-high vacuum.
“But let's imagine a glass panel, notperfectly transparent, but rough and unpolished like a bathroom window, ”continues Allard Mosk of Utrecht University. “Light, of course, passes, but refracts. Light waves change and scatter, so we cannot accurately see the object on the other side of the window with the naked eye. " A similar situation occurs when it is necessary to examine tiny objects inside biological tissue: a disordered environment interferes with the light beam. Then a simple, regular, straight laser beam turns into a complex wave structure that deflects in all directions.
But if you know exactly what the interfering environment does withlight beam, the situation can be changed by creating a complex wave pattern instead of a simple direct laser beam, which is converted into exactly the desired shape. because of the riots and shocks exactly where you want the best result. “To achieve this, you don't even need to know exactly what these violations are,” explains Dorian Boucher, the study's first author. "It is enough to first send a series of test waves through the system to study how they change by the system."
The method was confirmed experimentally inUtrecht University: laser beams were directed through a disordered medium in the form of a cloudy plate. The researchers then calculated the optimal waves to analyze the object outside the plate - this was done with nanometer precision.
Scientists were able to show that the method is not onlyworks, but it is also optimal in the physical sense: "The accuracy of our method is limited only by the so-called quantum noise," explains Allard Mosk. "This noise comes from the fact that light is made of photons - nothing can be done about it."
See also:
Saturn's moon Titan is remarkably similar to Earth. What plans does humanity have for it?
Large numbers of gray whales start starving and dying in the Pacific
A third of those who have recovered from COVID-19 return to the hospital. Every eighth - dies