Have you ever needed an ultrasound only to see an image that makes absolutely no sense to the average viewer? Of course, doctors and clinicians can read them without issue (thankfully), but even so, a clearer view is always better.
Researchers from the University of Rochester have created a new beam pattern that could provide extraordinary sharpness to ultrasound and radar images as well as nanoscale laser etching abilities.
Ultrasounds, radar, and lasers are all based on wave properties. A traditional beam is created that maintains the same shape and pattern as it approaches its target image. The challenge has always remained in “side lobes” that radiate off of a beam. These side lobes dissipate some of the beam energy laterally so not all energy is focused within the beam. This is what creates a blurry ultrasound image for example.
“Side lobes are the enemy,” Miguel Alonso, professor of optics, says. “You want to direct all of your ultrasound wave to the one thing you want to image, so then, whatever is reflected back will tell you about that one thing. If you’re also getting a diffusion of waves elsewhere, it blurs the image.”
Alonso and Kevin Parker, the William F. May Professor of Engineering, devised a solution, called a “needle pulse.” This new beam pattern is able to maintain all of its energy within the beam, creating extremely high resolution imaging. The new pattern is the result of mathematical equations, causing a light or sound wave to collapse inward on itself for a nanosecond before expanding out again. This narrowing pattern creates a tremendously intense beam in that moment.
“All the energy fits together in time and space so it comes together—BAM!—like a crescendo,” says Parker. “It can be done with an optical light wave, with ultrasound, radar, sonar – it will work for all of them.”
The first iterations of the mathematical equations Alonso and Parker worked on would work in theory but were impractical as they required an infinite amount of energy to create the beam. They finally stumbled upon a particular trick that changed the equation to allow a precise beam to be sourced by finite energy.
Because the new beam pattern is so narrow and precise, it opens up new possibilities to applications in ultrasound, microscopy, radar, lasers and even sonar. The math applies equally to all of these waves.
“It had been decades since anyone formulated a new type of beam,” Parker says. “Then, as soon as the Bessel beam was announced [in 1986], people were thinking there may be other new beams out there. The race was on. Finding a new beam pattern is a like finding a new element. It doesn’t happen very often.”