OPA chip, changes the timing of light waves to "bend" light (via Caltech)
Have you ever seen what happens when Tony Stark answers the phone? In Iron Man, it seemed like every call he received turned into a 3D video conference that came to life through his screen. Well, researchers at Caltech have said ‘wait no more.’ The engineering team has devised a microchip that can actually turn a cellphone into a projector.
While the new microchip doesn’t exactly enable the kind of technology Iron Man enjoys,( i.e. 3D projections floating idly in space), it does “bend” light, enabling a phone placed face-up on a table to project the image on its screen onto the wall in front of it. The team of engineers that developed the chip has plans for it to eventually be able to project crisp images as large as a movie screen, all from your handheld device.
Most projectors require that a beam of light pass through a small image to shine that image on a larger surface. Hajimiri’s chip, however, relies on integrated optical phased array to project an image electronically only using a chip and a single laser diode as the light source.
The team then found a way to “bend” the light by changing the timing of the light waves. Hajimiri explains that it works a lot like waves in a swimming pool. If 20 people standing in the shallow end of a pool all slap the water at the same time in the same direction, it would create one large wave. If instead, each person slaps the water in the same direction one second after the person in front of them, the wave would still be large, but it would travel at an angle, “bending” slightly after each new slap.
The engineering team thus designed a chip that “slaps” the light, if you will, to bend it in a new direction. The light is released from phase shifters and the OPA chip can alter the timing of the waves, ultimately controlling the direction of the light beam. The chip can also apply stronger or weaker currents, changing the number of electrons within each light path, changing the timing of the light wave itself.
Each light wave is then projected onto a grid, which combines the beams into one coherent beam that is projected in a single direction. The projected image is actually a series of moving lights, but because of the rate at which the human eye processes light, it sees the moving light beam as a single, still image.
The silicon chip itself is a one-millimeter-square.. This means the images it is currently able to project are relatively simple, such as shapes and single letters, but the team is currently developing a larger chip they hope can offer improved capabilities and resolution to eventually enable the projection of videos.
The team has also recently been experimenting with the projection of infrared light. Hajimiri said that while he expects to eventually manufacture the chip for use with mobile phones, he does not want to limit its function to just phones. At its size and low-cost, the possibilities, he said, are endless. Below is one of the first tests.
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