When photographers zoom in on an object to see it better, they lose the wide-angle perspective -- they are forced to trade off "big picture" context for detail. But now an imaging method developed by Princeton researchers could lead to lenses that show all parts of the scene at once in the same high detail. The new method could help build more powerful microscopes and other optical devices.
"It allows you to take a closer look at an object without narrowing your field of view," said Jason Fleischer, an assistant professor of electrical engineering at Princeton who led the research. The study, co-written with graduate students Christopher Barsi and Wenjie Wan, is reported as the cover story in the April edition of Nature Photonics.
Cameras and other optical devices -- including the human eye -- are limited by the amount of light that they can collect through their lens openings, or apertures. In order for a light ray to be recorded, it has to pass through the lens and reach the device's "detector" -- such as the eye's retina or a digital camera's detector. But many light rays never make it to the detector, either because they are too weak, or because they are deflected.
This problem is particularly acute with details that are smaller than the wavelength of light. (Each color of light has a distinct wavelength -- green, for instance, has a wavelength of 530 nanometers, roughly the size of a typical bacterium's internal structure.) Light rays from such tiny features fade before they reach the lens. To capture these rays, devices have to probe very near the surface of the object, and scan it point-by-point, stitching together a full image.
"In effect, these devices suffer from 'tunnel vision,'" said Fleischer.
The new method addresses the shortcomings of small apertures by taking advantage of the unusual properties of substances called nonlinear optical materials. In conventional lens materials such as gla
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Princeton University, Engineering School