{"id":212412,"date":"2017-01-24T11:03:54","date_gmt":"2017-01-24T16:03:54","guid":{"rendered":"http:\/\/www.rochester.edu\/newscenter\/?p=212412"},"modified":"2017-01-31T13:01:36","modified_gmt":"2017-01-31T18:01:36","slug":"new-needle-pulse-beam-pattern-packs-a-punch-212412","status":"publish","type":"post","link":"https:\/\/www.rochester.edu\/newscenter\/new-needle-pulse-beam-pattern-packs-a-punch-212412\/","title":{"rendered":"New ‘needle pulse’ beam pattern packs a punch"},"content":{"rendered":"
\"Kevin
Miguel Alonso, professor of optics, (right) and Kevin Parker, the William F. May Professor of Engineering, illustrate the “analytically beautiful mathematical solution” Alonso devised for the new beam pattern they describe in a recent paper. (University photo \/ J. Adam Fenster)<\/figcaption><\/figure>\n

A new beam pattern devised by University of Rochester researchers could bring unprecedented sharpness to ultrasound and radar images, burn precise holes in manufactured materials at a nano scale\u2014even etch new properties onto their surfaces.<\/p>\n

These are just a few of the items on the \u201cChristmas tree\u201d of possible applications for the beam pattern that Miguel Alonso, professor of optics, and Kevin Parker, the William F. May Professor of Engineering, describe in a recent paper in Optics Express<\/em><\/a><\/strong>.<\/p>\n

The pattern results from what Parker calls \u201can analytically beautiful mathematical solution\u201d that Alonso devised. It causes a light or sound wave to collapse inward, forming\u2014during a mere nanosecond or less\u2014an incredibly thin, intense beam before the wave expands outward again.<\/p>\n

\u201cAll the energy fits together in time and space so it comes together\u2014BAM!\u2014like a crescendo,\u201d says Parker, explosively clapping his hands for emphasis. \u201cIt can be done with an optical light wave, with ultrasound, radar, sonar \u2013 it will work for all of them.\u201d<\/p>\n

\"animated
A representation of the ‘needle pulse’ beam, showing how the circular wave fronts collapse into a needle-like thin power distribution with no side lobes.<\/figcaption><\/figure>\n

Most traditional beam patterns maintain a persistent shape as long as the source is operating. However, they are not as intense as the beam created by Parker and Alonso, which the researchers call a \u201cneedle pulse beam.\u201d \u201cIt is very localized, with no extensions or side lobes that would carry energy away from the main beam,\u201d says Alonso.<\/p>\n

Side lobes, radiating off a beam like the halos sometimes seen around a car headlight, are especially problematic in ultrasound. \u201cSide lobes are the enemy,\u201d Alonso says. \u201cYou 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\u2019re also getting a diffusion of waves elsewhere, it blurs the image.\u201d<\/p>\n

Because it is incredibly narrow, the new beam \u201cmakes it possible to resolve things at exquisite resolutions, where you need to separate tiny things that are close together,\u201d Parker says, adding that the beam could have applications not only for ultrasound, but microscopy, radar, and sonar.<\/p>\n

According to Alonso, industrial applications might include any form of laser materials processing that involves putting as much light as possible on a given line.<\/p>\n

The idea for the needle pulse beam originated with Parker, an expert in ultrasound, who for inspiration often peruses mathematical functions from a century or more ago in the \u201cancient texts.\u201d<\/p>\n

\u201cI could see a general form of the solution; but I couldn\u2019t get past the equation,\u201d he says. \u201cSo I went to the person (Alonso) who I consider the world\u2019s leading expert on optical theory and mathematics.\u201d<\/p>\n

They came up with various expressions that were \u201cmathematically correct,\u201d Alonso says, but corresponded to beams requiring an infinite amount of energy. The solution\u2014\u201ca particular mathematical trick\u201d that could apply to a beam with finite energy\u2014came to him while swimming with his wife in Lake Ontario.<\/p>\n

\u201cMany of the ideas I have do not happen at my desk,\u201d Alonso says. \u201cIt happens while I\u2019m riding my bicycle, or in the shower, or swimming, or doing something else\u2014away from all the paperwork.\u201d<\/p>\n

Parker says this discovery continues an international quest that began at the University of Rochester. In 1986\u2014in the face of worldwide skepticism\u2014a University team including Joseph Eberly, the Andrew Carnegie Professor of Physics and professor of optics, offered evidence of an unexpected new, diffraction-free light form. The so-called Bessel beam is now widely used.<\/p>\n