Scientists at Caltech have developed a new lensless camera that doesn’t require any lenses. They have replaced the curved glass with something that does the same job computationally: an ultra-thin optical phased array.
In digital cameras, the lenses are used to focus the light onto a digital sensor. The optical phased array has a group of light receivers that adds a minute delay to the light as it is captured. This allows the camera to switch focus and look in different directions using nothing but electronic trickery.
The phased arrays work by using a selection of stationary transmitters sending out the same signal from the transmitter that then interferes with each other. In some areas, it cancels out the signal, and in other areas, it amplifies the signal. By adding a small delay to some of the transmitters, the focus of the amplified signal can be moved around – electronically steering the signal.
This new lensless camera is made from thin, light-sensitive silicon components integrated into a silicon chip. Light waves are received by each light-sensitive element in the array and destructively interfere from all but one of the directions. In that direction, the waves amplify each other to create a focused “gaze” that can be electronically controlled.
Ali Hajimiri from Caltech said, “With our new system, you can selectively look in the desired direction and at a very small part of the picture in front of you at any given time, by controlling the timing with femtosecond, a quadrillionth of a second, precision.”
Lead researcher Reza Fatemi said, “What the camera does is similar to looking through a thin straw and scanning it across the field of view. We can form an image at an incredibly fast speed by manipulating the light instead of moving a mechanical object.”
Currently, the camera consists of 64 light receivers in an eight-by-eight-pixel array, and the images it creates are a world away from what is currently captured by your smartphone. The ability to control all the optical properties of a camera electronically using a paper-thin layer of low-cost silicon photonics without any mechanical movement, lenses, or mirrors.
- Fatemi, Reza, Behrooz Abiri, and Ali Hajimiri. 2017. “An 8×8 Heterodyne Lens-less OPA Camera”. In Conference on Lasers and Electro-optics, Art. No. JW2A.9. San Jose, CA: Optical Society of America (OSA). Cleo_2017_2D_OPA_V7