By Mark Dwortzan
For 15 years, Professor Thomas Bifano (ME, MSE) has developed deformable mirrors that are widely used to compensate for optical aberrations in telescopes and microscopes. His “adaptive optics” technique leverages micro-electro-mechanical systems (MEMS) technology—electrostatic actuators and flexible layers of silicon—to shape the mirrors precisely and thus bring images of everything from retinal cells to planets into sharper focus.
On April 9, Bifano traced the evolution of his trailblazing work on deformable mirrors at Boston University and Boston Micromachines Corporation (where he’s the founder and CTO) in the 2013 College of Engineering Distinguished Scholar Lecture, “Shaping Light with Deformable Mirrors.” Speaking from the podium of the Colloquium Room at the Boston University Photonics Center that he directs, he addressed students, faculty and researchers from throughout the BU academic community and beyond.
Bifano described a deformable mirror (DM) as an integrated system of two main parts—an array of electrostatic actuators and a compliant mirror that is connected by posts to the actuator array.
“The whole idea is that if you apply a voltage to [the electrostatic actuator], it pulls down on the posts, and that deforms the mirror,” he explained. “And voila, you have a deformable mirror.”
Bifano observed that in comparison to other DMs, these MEMS-driven mirrors are smaller in size, weight and power; easily scalable to large arrays; faster, more predictable and reliable; and much less expensive.
Developing these mirrors at both BU and Boston Micromachines has allowed him to aim his academic research at technology translation, resulting in state-of-the-art telescopes, retinal imaging systems and microscopes. During the lecture he highlighted three recent developments:
- When deployed in Chile in October on the eight-meter-diameter Gemini telescope, a next-generation adaptive optics instrument called the Gemini Planet Imager will rely on a 4000-actuator DM from Boston Micromachines to directly detect light from extrasolar planets. These observations will be the most sensitive ever made, and will allow scientists to determine if those planets possess the chemical building blocks of life.
- A prototype scanning laser ophthalmoscope from Boston Micromachines uses deformable mirrors to compensate for optical aberrations of the eye, yielding unprecedented cell-scale, in vivo images of the retina to track disease progression and evaluate the effectiveness of clinical treatments. Joslin Diabetes Center is using the instrument in clinical trials aimed at improving treatments for diabetic retinopathy, a progressive retinal disease common to people with long-term diabetes.
- Bifano is collaborating with Professor Jerome Mertz (BME) to develop DM-based microscopes that can obtain sharp images of biological structures through media that strongly scatter light, such as the brain and other organs with nearly opaque tissue.
A Quarter Century of Achievement
Bifano has served as a BU professor of mechanical engineering for 25 years, chair of the Manufacturing Engineering Department from 1999 to 2006, and chair of the University Research Council from 2008 to 2011. As director of the Photonics Center since 2006, he has led programs for education, research and development of advanced photonic device prototypes for commercial and military applications.
“As the second director of the Photonics Center, his impact has been absolutely transformational,” said Dean Kenneth R. Lutchen in introductory remarks. “It’s Tom’s leadership and vision that made the center such an enjoyable and enabling research and educational amplifier not only for engineering, but also for chemistry, physics, astronomy, and medicine. The center is now one of the most powerful magnets for excellent faculty and graduate students; it’s nothing short of the pride and joy of faculty and administrators throughout Boston University.”
A member of the U.S. Army Science Board, Bifano has served as conference technical session chair for five professional societies; member of the Board of Directors of the American Society for Precision Engineering; and associate editor of International Journal of Manufacturing Science and Production and Society of Manufacturing Engineers Journal of Manufacturing Processes. Since receiving a PhD in mechanical engineering from North Carolina State University, he has authored or co-authored more than 120 peer-reviewed journal articles and conference publications.
Bifano’s ability to transition fundamental research into useful and widely used technologies is reflected in his six patents, three R&D 100 Awards and the 2009 Bepi Colombo Prize for his work in “micro-deformable mirrors for astronomical telescopes.”
Initiated in 2008, the annual Distinguished Scholar Lecture Series honors a senior faculty member engaged in outstanding, high-impact research at the College of Engineering. The previous four recipients are Professors H. Steven Colburn (BME), Theodore Moustakas (ECE), Irving Bigio (BME), John Baillieul (ME) and Malvin Teich (ECE).