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SAVI Camera uses a Synthetic Aperture to capture Telephoto Shots without a Telephoto Lens

Credit: Jason Holloway/Rice University
Credit: Jason Holloway/Rice University

Telephoto lenses are expensive. Now imagine that you can capture images from a distance without using a telephoto lens.

This is what the wizards (engineers) at Rice and Northwestern universities have done with the SAVI Camera which uses a single laser beam, multiple images (moving the camera for each shot), techniques borrowed from holography, microscopy and bullet time, and sophisticated software to capture detailed images from a distance.

SAVI — which stands for “Synthetic Apertures for long-range, subdiffraction-limited Visible Imaging” — doesn’t need a long lens to take a picture of a faraway object. It fires a laser at a spot and captures the “speckle” pattern with a camera sensor. Raw data from dozens of camera positions is fed to a computer program that interprets it and constructs a high-resolution image.

Though the current prototype works only with coherent illumination sources such as lasers, the engineers have set their long range sight toward developing a SAVI camera that uses visible light.

Credit: Jeff Fitlow/Rice University

Credit: Jeff Fitlow/Rice University

Ashok Veeraraghavan, a Rice assistant professor of electrical and computer engineering, explains that “with a traditional camera, the larger the physical size of the aperture, the better the resolution. If you want an aperture that’s half a foot, you may need 30 glass surfaces to remove aberrations and create a focused spot. This makes your lens very big and bulky.”

Oliver Cossairt, an assistant professor of electrical engineering and computer science at Northwestern’s McCormick School of Engineering, explains how “by moving aberration estimation and correction out to computation, we can create a compact device that gives us the same surface area as the lens we want without the size, weight, volume and cost.”

Jason Holloway, a Rice alumnus who is now a postdoctoral researcher at Columbia University, suggested that to eliminate the need of moving the camera, all the data needed could be captured using an array of inexpensive sensors and plastic lenses that cost a few dollars each.

Credit: Jason Holloway/Rice University

Credit: Jason Holloway/Rice University

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