A team of scientists at Rochester Institute of Technology is designing and developing an imaging detector that will read individual beams of light, greatly enhancing imaging quality and application.
The centerpiece of this work is the design of a quantum limited, zero-noise detector for the future Thirty Meter Telescope. Expected to be operational in the next decade, the telescope’s light-collecting power will be 10 times that of the largest telescopes now in operation.
The detector’s new sensing technology promises to penetrate the darkness of space with the greatest sensitivity ever. It could also have applications on Earth improving everything from cell phone cameras to securing communications and surveillance systems.
“You could effectively quadruple the collecting power of a telescope just by using this detector,” says Donald Figer, director of the Rochester Imaging Detector Laboratory at RIT’s Chester F. Carlson Center for Imaging Science and leader of the research team. “Or you can do the same thing by making a telescope twice the size, but then we’re talking a cost of billions of dollars and taking on a monumental engineering challenge.”
Imaging sensors produce their own “noisy” signal that often degrades images, especially under low-light conditions. The noise can sometimes be seen as the grainy, salt-and-pepper speckling found in pictures snapped in a dark room. In applications like astrophysics, that noise can do more than ruin a picture; it can mean the difference between making a discovery or not.
Designing a quantum-limited detector using a digital photon counter to detect every single photon, or unit of light, coming from a target can circumvent the problem. According to Figer, the zero-noise detector employed with the Thirty Meter Telescope will have the same sensitivity as a combination of today’s detectors and a 60-meter telescope for probing the farthest reaches of the universe.
Figer’s team, which includes scientists from Massachusetts Institute of Technology’s Lincoln Laboratory, is currently testing the new detector at cryogenic temperatures in the Rochester Imaging Detector Laboratory. Cooling the device to lower temperatures will freeze its dark current, another potential source of noise, and keep it stuck in the crystal lattice like flies on flypaper and away from the conduction band.
In the second phase of the project, Figer’s team will adapt the detector technology to infrared applications, replacing silicon, a material sensitive only in optical light, with the semiconductor material Indium Gallium Arsenide. The infrared version of the detector will give astrophysicists the ability to peer through cosmic dust and also to detect stars in the early universe.
“If you want to look back into the early universe, you have to look back into the infrared,” Figer says.
The Thirty Meter Telescope is a joint collaboration of California Institute of Technology, the University of California and the Association of Canadian Universities for Research in Astronomy. The RIT portion of the project is being funded through a grant from the Gordon and Betty Moore Foundation.
A broader description of Figer’s research is presented in the 2009 Spring/Summer issue of Research at RIT. To view the issue, visit http://www.rit.edu/research.