Caltech researchers develop camera without lenses that can make smartphones slimmer

The OPA chip on a penny. Image: Caltech/Hajimiri Lab.

To make smartphones more slimmer, a group of engineers has developed a new camera design that replaces the lenses with an ultra-thin optical phased array (OPA). According to a paper presented at the Optical Society of America’s (OSA) Conference on Lasers and 

Electro-Optics (CLEO) and published online in the OSA Technical Digest, the OPA computationally manipulates incoming light to capture an image — exactly what lenses do using large pieces of glass.

“We have created a single thin layer of integrated silicon photonics that emulates the lens and sensor of a digital camera, reducing the thickness and cost of digital cameras,” said Ali Hajimiri from the California Institute of Technology. “It can mimic a regular lens, but can switch from a fish-eye to a telephoto lens instantly — with just a simple adjustment in the way the array receives light,” Hajimiri, who is also the principal investigator of a paper, added.

The OPA has a large array of light receivers, each of which can individually add a tightly controlled time delay (or phase shift) to the light it receives, enabling the camera to selectively look in different directions and focus on different things. “With our new system, you can selectively look in a desired direction and at a very small part of the picture in front of you at any given time, by controlling the timing with femto-second — quadrillionth of a second — precision,” Hajimiri mentioned.

Phased arrays, which are used in wireless communication and radar, are collections of individual transmitters, all sending out the same signal as waves. These waves interfere with each other constructively and destructively, amplifying the signal in one direction while cancelling it out elsewhere. Thus, an array can create a tightly focused beam of signal, which can be steered in different directions by staggering the timing of transmissions made at various points across the array.

A similar principle is used in reverse in an optical phased array receiver, which is the basis for the new camera.