Smartphones to produce high-resolution 3D images

Want a quick 3-D copy of an object? It may be as simple as taking a snapshot from your smartphone!
Researchers have developed a cheap and highly accurate imager that may be incorporated in smartphones to help produce a 3D replica of an object within minutes.
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.
The new compact device known as a nanophotonic coherent imager (NCI) promises to change that.
Using an inexpensive silicon chip less than a millimetre square in size, the NCI provides the highest depth-measurement accuracy of any such nanophotonic 3-D imaging device.

"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 frequency of the signal in addition to the intensity," said Ali Hajimiri from the California Institute of Technology.

The new chip utilises an established detection and ranging technology called LIDAR, in which a target object is illuminated with scanning laser beams.
The light that reflects off of the object is then analysed based on the wavelength of the laser light used, and the LIDAR can gather information about the object's size and its distance from the laser to create an image of its surroundings.

"By having an array of tiny LIDARs on our coherent imager, we can simultaneously image different parts of an object or a scene without the need for any mechanical movements within the imager," Hajimiri said.
Such high-resolution images and information provided by the NCI are made possible because of an optical concept known as coherence.
If two light waves are coherent, the waves have the same frequency, and the peaks and troughs of light waves are exactly aligned with one another. In the NCI, the object is illuminated with this coherent light.
The light that is reflected off of the object is then picked up by on-chip detectors, called grating couplers, that serve as "pixels," as the light detected from each coupler represents one pixel on the 3-D image.

"The small size and high quality of this new chip-based imager will result in significant cost reductions, which will enable thousands new uses for such systems by incorporating them into personal devices such as smartphones," Hajimiri said.
The study was published in the journal Optics Express.