A laser beam hits the skin, and tissues respond with a barely audible ultrasonic echo. From that echo, doctors can see blood vessels and tumors without making a single incision. But before the picture appears on the screen, the signal has to be cleaned of noise, just as a cook skims the foam off a broth to make the soup clear.

For a long time, the only tool for this cleaning was a mathematical trick that breaks the signal down into waves of different lengths, like a prism splitting white light into a rainbow. That trick is called the Fourier transform, and it works almost everywhere: from music compression to analyzing bridge vibrations. But it comes at a cost: it is slow and can distort weak signals, especially when you need a sharp image in a hurry.

The scientists proposed a new way to clean the signal that doesn't try to fit it to a Fourier 'rainbow' but instead knows exactly how sound is born in tissues. It's like a cook who doesn't use a universal spoon to skim the foam but uses a skimmer designed specifically for that broth. The new method requires fewer computational steps and captures details more accurately — in simulations and on real recordings from devices, it outperforms Fourier and other classical approaches.

Now optoacoustic scanners can work faster and produce sharper images. That means devices will become more accessible for hospitals and even for home use, like a thermometer that shows not just temperature but also the state of blood vessels under the skin.