New laser to boost imaging quality of microscopes

Researchers have developed a new semiconductor laser that can significantly improve the imaging quality of the next generation of high-tech microscopes, laser projectors, holography and biomedical imaging.
Based on a chaotic cavity laser, the technology combines the brightness of traditional lasers with the lower image corruption of light emitting diodes (LEDs), said researchers from Yale University.
"This chaotic cavity laser is a great example of basic research ultimately leading to a potentially important invention for the social good," said co-author A Douglas Stone, the Carl A Morse Professor and chair of applied physics, and professor of physics.
"All of the foundational work was primarily motivated by a desire to understand certain classes of lasers - random and chaotic - with no known applications.

"Eventually, with input from other disciplines, we discovered that these lasers are uniquely suited for a wide class of problems in imaging and microscopy," Stone said.
One of those problems is known as 'speckle'. Speckle is a random, grainy pattern, caused by high spatial coherence that can corrupt the formation of images when traditional lasers are used.

A way to avoid such distortion is by using LED light sources. The problem is, LEDs are not bright enough for high-speed imaging.
The new, electrically pumped semiconductor laser offers a different approach. It produces an intense emission, but with low spatial coherence.

Co-author Michael A Choma, assistant professor of diagnostic radiology, pediatrics, and biomedical engineering, said laser speckle is a major barrier in the development of certain classes of clinical diagnostics that use light.
Speckle-free lasers could lead to new types of clinical diagnostics, he said.
The laser is described in the Proceedings of the National Academy of Sciences.