New Fiber Optics Design Measures NIF Beamline Performance

Dylan Beckman’s route to NIF began when he first toured the University of Rochester’s optical engineering building and knew he wanted to work with lasers.

"I’d never seen anything as cool as an optical lab table," he said. "It just looked like something so futuristic and science fiction-like to me. I came in thinking I was going to do chemical engineering. That went straight out the window as soon as I saw the optics lab."

Beckman, 20, is one of this year’s NIF & Photon Science summer scholars, helping to design from scratch new ways for optical fiber cables to transport ultraviolet light from inside the Target Chamber to external diagnostic instruments. His designs may eventually be used for all 192 NIF beams.

His work has impressed his mentors, Abe Handler and Leyden Chang of the NIF Laser Diagnostics Group, and Mike Messerly, Fiber Laser Group leader.

Beckman’s designs for a more complex optical lens system that takes load off the fiber "has been a big help to us," Messerly said. "We think going forward, his designs are going to make our lives easier and everybody happier."

Beckman will soon start his senior year as an optical engineering major. At NIF, Handler said he challenged the intern with "developing and designing this optical system, which simplifies, reduces costs, and gives new capabilities to NIF."

Using the FRED optical engineering software platform, Beckman looked at ways to pick off portions of light from beams to perform measurements. Only a fraction of the facility’s beams has such measurement devices, Handler said.

Beckman was tasked with taking a system originally designed in the 1990s, "wiping that clean and starting with a fresh, empty box," Handler said.

At present, power is measured only in a quarter of NIF’s beamlines, with computer modeling filling in the rest of the information. Beckman is developing a system that could be built for all 192 beamlines, which would reduce the uncertainty in the measurements and to give scientists, engineers and other users greater confidence in laser performance.

Improving Understanding

This would be an upgrade that NIF needs for the future. "The more information you know about each beamline, the more you can characterize your system," Handler said. "The better you understand it, the more energetic you can go with it."

Beckman is working on physical prototypes, which he hopes to finish before returning to school.

"We’re looking at doing this as cheaply as possible, so that’s very challenging," Handler said. "The bigger picture is that this helps everybody who runs the facility and uses NIF."

The private telecommunications industry widely uses fiber optic cables to transmit voice and data over long distance. But NIF requires custom fiber optics to transmit the ultraviolet (UV) light produced when its laser beams approach the Target Chamber, Messerly said.

"It’s not an off-the-shelf thing," he said. "Carrying the UV light is difficult. And having the fiber that can tolerate a high-radiation environment is tough, too.

We’ve come up with designs that greatly simplify what this fiber is going to need to do," Messerly said. "And if we’re going to put fiber on every one of these beamlines, we can make enough to populate those beamlines in a reasonable amount of time."

Admittedly, NIF "can be daunting to people that work here, let alone someone who’s coming here as an intern," Handler said. "It’s a huge undertaking, it’s a huge task. It has to work in lots of different scenarios. So, we gave him a set of requirements, gave him a blank slate and we just left it up to him."

Beckman jumped in with both feet and "showed a high degree of skill right away," Handler said.

To be sure, Beckman was properly in awe of NIF.

"The scale of NIF never ceases to amaze me," Beckman said. "Every time I get a tour, go into the Target Bay room and you see that giant Death Star-looking thing, it’s crazy, it looks really awesome. It’s so impressive to me that there’s so much working together in one giant well-oiled machine."

Was he excited or scared?

"A bit of both," he acknowledged. "I thought it was really cool that as an intern, I got a project of this scope. I’ve heard stories about other interns at other places just doing busy work. But to get thrust right into a role where I’m actually doing optical design, and I’m doing it on such a big scale on the world’s largest laser, I was mostly in awe at first."

But once he immersed himself in the project and talked to his mentors, "it definitely didn’t seem so daunting," he said. "It’s nice to have really smart people to work with to help me through it.

"I’m hoping it’s something that can actually be integrated into NIF," Beckman said. "That’d be really awesome, to have my name on something that was put into the world’s largest laser. "