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When Darwin Quiroz first started working with optics as an undergraduate, he was developing atomic magnetometers. That experience sparked a growing curiosity about how light interacts with matter, an interest that has now led him to a new technique in optical imaging.

Quiroz, a Ph.D. student in the Department of Electrical, Computer and Energy Engineering at the University of Colorado Boulder, is co-first author of a new study that demonstrates how a fluid-based optical device known as an electrowetting prism can be used to steer lasers at high speeds for advanced imaging applications.

The work, in Optics Express, conducted along with mechanical engineering Ph.D. graduate Eduardo Miscles and Mo Zohrabi, senior research associate, opens the door to new technologies in microscopy, LiDAR, optical communications and even brain imaging.

"Most laser scanners today use mechanical mirrors to steer beams of light," Quiroz said. "Our approach replaces that with a transmissive, non-mechanical device that's smaller, lower-power and potentially easier to scale down into miniature imaging systems."

Traditional laser scanning microscopy works by directing a focused beam of light across a sample like a grid one line at a time. This method provides powerful, high-resolution images of cells and neurons, but it requires fast, precise steering of the laser beam.

That's where the electrowetting prism comes in. Unlike solid mirrors, the prism uses a thin layer of fluid whose surface can be precisely controlled with voltage. By altering the liquid's shape, researchers can bend and steer light beams without moving mechanical parts.

Previous work with electrowetting prisms was limited to slow scanning speeds or one-dimensional beam steering.

Quiroz and Miscles pushed the technology further, demonstrating two-dimensional scanning at speeds from 25–75 Hz, a milestone toward making the devices practical for real-world imaging.

"A big challenge was learning how to drive the device in a way that produces linear, predictable scanning without distortion," Quiroz said. "We discovered that the prism has resonant modes like standing waves that we could actually leverage for scanning at higher speeds."

The promise of this technology extends far beyond the lab. Since electrowetting prisms are compact and energy efficient, they could be integrated into miniature microscopes small enough to sit on top of a mouse's head.

"Imagine being able to watch brain activity in real-time while an animal runs through a maze," said Quiroz. "That's the kind of in-vivo imaging this technology could enable and it could transform how we study neurological conditions like PTSD or Alzheimer's disease."

The project builds on earlier work in the Gopinath and Bright labs, where former Ph.D. student Omkar Supekar first integrated an electrowetting prism into a microscope system for one-dimensional scanning.

By extending the technique into two dimensions and higher speeds, Quiroz and Miscles established a framework for calibrating and characterizing electrowetting scanners for a wide range of applications.

Looking ahead, Quiroz hopes this research not only improves imaging systems but also inspires future collaborations across fields.

"This work shows what's possible when you combine physics and engineering approaches," Quiroz said. "The ultimate goal is to build tools that help us see and understand the brain in ways we couldn't before."