By Tom Dinki, BA ’16

On a list of the innovations that helped NASA send astronauts to the moon, schlieren photography belongs near the top.

This longstanding aerodynamics technique, which uses light rays and mirrors inside a wind tunnel to photograph the flow of air around an object, also helped prove the existence of shock waves and produced some of the earliest clear images of a bullet in flight.

And yet Joshua Weisberger, PhD ’20, MS ’15, BS ’12, found a way to make it better. A lot better.

Together with colleague Brett Bathel, Weisberger, a research engineer at NASA’s Langley Research Center in Virginia, developed a new version of schlieren photography that reduces setup time from weeks to minutes and realignment time from days to seconds. Their self-aligned focusing schlieren (SAFS) system takes advantage of retroreflective film—the same material used in traffic signs—to send light back along the exact path it came from, eliminating the painstaking process of realigning optical components and preventing misalignment caused by vibration.

SAFS was named a co-winner of NASA’s 2025 Government Invention of the Year award and received a coveted R&D 100 Award. It’s quickly becoming the gold standard for schlieren photography.

In my line of work, you’re often just trying to solve a particular problem you’re facing, and you think maybe someone else will find it useful at some point down the line,” Weisberger says. “You never expect your solution will immediately be embraced all over the world.”

The memory still haunts Weisberger.

It was an undergraduate engineering course taught by Kemper Lewis, MBA ’03, now dean of the School of Engineering and Applied Sciences. Lewis asked the class to estimate the number of soccer balls that could be packed into their Knox lecture hall.

Weisberger diligently calculated an answer, but ended up being off by an order of magnitude, or perhaps several. “Dr. Lewis announced the lowest estimate and the highest estimate from the class. I was one of the two,” he says. It was a tough way to learn to always do a sanity check—a quick cross-check of one’s math to rule out clearly illogical answers.

“It’s like the scene from ‘The Office’ where Michael’s GPS is telling him to turn right and Dwight is yelling at him not to turn because there’s a lake there,’” Weisberger says. “The sanity check would be Dwight and I was Michael, driving straight into the lake.”

Now, working in NASA’s Advanced Measurements and Data Systems Branch, Weisberger says he does a sanity check on all his calculations. It’s just one of the many ways that UB shaped the engineer he is today.

A native of Denmark who grew up in New Jersey, Weisberger remembers coming away from his tour of the engineering school impressed by the robotics lab and 3D printers. But what really sold him was the opportunity for immediate hands-on learning. “Nobody was saying, ‘You don't know enough and you have to wait until your junior or senior year.’ It was like, ‘Hey, you’re here. You’re interested. You can get involved,’” Weisberger says.

He took full advantage, designing and flying drones with the UB chapter of the American Institute of Aeronautics and Astronautics (AIAA) and conducting experiments in the hyper-velocity wind tunnels at Cheektowaga- based CUBRC, a defense contractor. He also worked in several engineering labs, including that of Paul DesJardin, BS ’93, who would become his advisor.

“Josh was instrumental in measuring a lot of the biomass systems we were doing in my lab, and he did some really interesting measurements over at CUBRC,” says DesJardin, professor of mechanical and aerospace engineering. “It’s been great to see how his career has just flourished since then.”

CUBRC was where Weisberger met a visiting NASA researcher who connected him with Bathel, leading to an internship in 2017. A NASA Pathways internship the following year led to full-time employment after he received his PhD in 2020.

Invented in 1864 by a German physicist, schlieren photography was refined in the mid-1900s to isolate a narrow depth of field. Called focusing schlieren, this version provided better results but was notoriously cumbersome. Weisberger’s first exposure to the technique came when a university research group visited Langley to conduct some tests.

“It took so much time to set up. It was very finicky. It didn’t make me want to ever do focusing schlieren photography,” Weisberger says.

When work at Langley slowed down during the COVID-19 pandemic, it was Bathel who began brainstorming ways to improve focusing schlieren. He realized that retroreflective film could work if combined with a Rochon prism—a crystal made of two fused materials that bends only the returning

beam after its polarization has been flipped.

Once back in the lab, Weisberger helped Bathel to refine the system. When their quartz-quartz Rochon prism wasn’t behaving correctly, Weisberger dug into the research and discovered a quartz-glass Rochon prism—where one half of the prism is made of quartz and the other half of an index-matched isotropic glass—described in a 1968 study. “We asked our manufacturer to fabricate the prism. Then we tested it and it worked amazingly,” Weisberger says.

His NASA supervisors called the system a “game-changer” when he and Bathel reported their initial results. Three NASA centers, as well as the Air Force Research Laboratory and Lawrence Livermore National Laboratory, now utilize it. About a dozen universities are using it under a no-cost research license, while several companies have also licensed it for commercial use.

As for what’s next, Weisberger says he misses his adopted home of Buffalo, and part of him would like to return one day. He met his wife at UB—she graduated from the School of Dental Medicine—and he still follows the Bills and Sabres, even when they cause him torment. But for now his current situation at NASA is too good to pass up.

Whatever his future holds, he says he will never forget how his 10+ years at UB transformed him from a kid who loved airplanes to a NASA research engineer who makes sure that every mission stays on course.