Unfortunately, hardware-based adaptive optics are complicated, tedious to align and extremely expensive. They can only focus on one focal plane at a time, so for tomography 3-D models constructed from sectional images as in a CT scan, for example the mirrors have to be adjusted and a new image scanned for each focal plane. In addition, complex corrective systems are impractical for handheld or portable devices, such as surgical probes or retinal scanners.
Therefore, instead of using hardware to correct a light profile before it enters the lens, the Illinois team uses computer software to find and correct aberrations after the image is taken. Boppart's group teamed up with with Scott Carney, a professor of electrical and computer engineering and the head of the Optical Science Group at the Beckman Institute, to develop the technique, called computational adaptive optics. They demonstrated the technique in gel-based phantoms laced with microparticles as well as in rat lung tissue. They scan a tissue sample with an interferometric microscope, which is an optical imaging device using two beams of light. The computer collects all of the data and then corrects the images at all depths within the volume. Blurry streaks become sharp points, features emerge from noise, and users can change parameters with the click of a mouse.
"Being able to correct aberrations of the entire volume helps us to get a high-resolution image anywhere in that volume," said Adie. "Now you can see tissue structures that previously were not very clear at all."
Computed adaptive optics can be applied to any type of interferometric imaging, such as optical coherence tomography, and the computations can be performed on an ordinary desktop computer, making it accessible for many hospitals and clinics.
Next, the researchers are working to refine the algorithms and explore applications. They are
|Contact: Liz Ahlberg|
University of Illinois at Urbana-Champaign