Using NIR fluorescence with visible light reflectance imaging can help surgeons pinpoint the exact location of tumors, making removal easier and safer. A dual-mode imager developed by a team from the University of Arizona and Washington University in St. Louis combines the two imaging methods into one package. The near-IR imaging detects marks cancer cells, while the visible light imaging identifies contours in the tissue. Optical and mechanical structure of the customized lens with aperture filter (left), and the assembled lens (right). Courtesy of Optics Letters. “Dual modality is the path forward because it has significant advantages over single modality,” said Rongguang Liang, associate professor of optical sciences at the University of Arizona. Traditional tumor imaging methods usually involve injecting dyes that fluoresce under near-IR light. This can be time-consuming and challenging, however, as additional, bulky devices are needed to see near-IR images and visible light is needed to see the tumors’ details. The new device incorporates a simple aperture filter that has a disk-shaped region in the middle, which lets in both near-IR and visible light, and a ring-shaped region on the outside, which only allows near-IR light. Because visible light can't penetrate the outer ring, the visible-sensitive part of the filter has a small enough aperture that the depth of field is large. The researchers are now furthering their study, in efforts to develop lightweight goggle devices and handheld instruments for surgeons to use while operating on tumors. The research was published in Optics Letters (doi: 10.1364/OL.39.003830). For more information, visit www.arizona.edu.