Camera chip provides superfine 3-D resolution
Imagine you need to have an almost exact copy of an object. Now imagine that you can just pull your smartphone out of your pocket, take a snapshot with its integrated 3-D imager, send it to your 3-D printer and, within minutes, you have reproduced a replica accurate to within microns of the original object. This feat may soon be possible because of a new, tiny high-resolution 3-D imager developed at Caltech.
Any time you want to make an exact copy of an object with a 3-D printer, the first step is to produce a high-resolution scan of the object with a 3-D camera that measures its height, width, and depth. Such 3-D imaging has been around for decades, but the most sensitive systems generally are too large and expensive to be used in consumer applications.
A cheap, compact yet highly accurate new device known as a nanophotonic coherent imager (NCI) promises to change that. Using an inexpensive silicon chip less than a millimeter square in size, the NCI provides the highest depth-measurement accuracy of any such nanophotonic 3-D imaging device.
The work, done in the laboratory of Ali Hajimiri, the Thomas G. Myers Professor of Electrical Engineering in the Division of Engineering and Applied Science, is described in Optics Express.
In a regular camera, each pixel represents the intensity of the light received from a specific point in the image, which could be near or far from the camera—meaning that the pixels provide no information about the relative distance of the object from the camera. In contrast, each pixel in an image created by the Caltech team’s NCI provides both the distance and intensity information. “Each pixel on the chip is an independent interferometer—an instrument that uses the interference of light waves to make precise measurements—which detects the phase and frequencyThe number of complete cycles or vibrations per unit of time. Rate of alternation in an AC current. Expressed in cycles per second or hertz (Hz). of the signal in addition to the intensity,” says Hajimiri.