GLOBAL CHALLENGES

Nanotech Could Strengthen Infrared Imaging

Rebecca Kutzer-Rice | Date: 06-02-10 | Comments

Researchers from Rensselaer Polytechnic Institute have used nanotechnology to make infrared imaging up to 20 times stronger. This technique could greatly enhance satellites, cameras and other devices that employ infrared imaging.

Infrared imaging technology has a wide range of uses, from satellite cameras to night vision goggles to meteorology. Using nanotechnology, researchers from Rensselaer Polytechnic Institute (RPI) have developed a �microlens� that uses gold to amplify the power of infrared imaging.

Current infrared imaging uses photodetectors based on mercury-cadmium-telluride technology (MCT). While MCT provides a strong signal, it has many disadvantages, such as the need for a long exposure time. In creating the microlens, researchers have developed a new type of photodetector, called �quantum dot infrared photodetectors� (QDIP). These new photodetectors are flat structures that contain billions of tiny holes. Each hole is lined with nanoscopic gold. The microlens uses the gold to focus incoming light and concentrate it more effectively, a technique that enhances detectivity by up to 20 times.

The new nanotech microlens uses gold to �squeeze� light into the tiny holes on its surface.

Over the past decade, the main problem with infrared research has been noise. Most developments that have increased infrared detectivity have also increased noise, which can negatively impact a device�s response time. Innovatively, the new nanotech microlens adds no noise to the overall device.

According to the researchers, lining each hole with gold is as effective as covering it with an individual lens. The gold adds no extra weight, however, and is much less complicated and less expensive than an individual lens, which must be installed and calibrated.

Shawn-Yu Lin, the project manager at RPI, is very excited about the possible directions his research could take. �Infrared detection is a big priority right now,� he says, �as more effective infrared satellite imaging technology holds the potential to benefit everything from homeland security to monitoring climate change and deforestation.�

The study�s results, which have been published online, are forthcoming in the journal Nano Letters. Co-authors of the paper are Rensselaer Senior Research Scientist James Bur, graduate student Chun-Chieh Chang, and Research Associate Yong-Sung Kim; Yagya D. Sharma, Rajeev V. Shenoi, and Sanjay Krishna of the Center for High Technology Materials at the University of New Mexico, Albuquerque; and Danhong Huang of the Space Vehicles Directorate at the Air Force Research Laboratory, Kirtland Air Force Base.