Finding focus: These three pictures were taken, from left to right, after 0.007, 0.020, and 0.033 seconds. The focal point of the lens changes as the sound waves alter the shape of the droplet. The researchers suggest that a camera using this liquid lens could take tens of pictures at the press of a button and let software sort out the one that’s most in focus.
In tests, Hirsa’s liquid-lens camera was able to take 250 images per second, at varying focal lengths. He envisions a camera that could instantly capture tens of images with different focal lengths, and then use simple image-analysis software to determine the most in-focus image. “Say you capture 60 frames per second,” he says. “Just take the one that’s the sharpest.”
Stein Kuiper, the Philips researcher who developed the electrowetting technique, notes that the researchers’ ideas seem original, but he sees drawbacks to the approach. Since the lens is continuously moving, this means that “a significant amount of light is lost, as most of the time the object is out of focus.”
Additionally, these early results are not high resolution, notes Yuhwa Lo, a professor of electrical engineering at the University of California, San Diego. “Even the low-end cameras have a pretty strict resolution requirement,” he says. However, he says that at this stage, the lens could be good for other optical applications, such as simply focusing beams of light instead of taking high-quality pictures.
Hirsa says that his team is looking to improve the resolution, possibly with different types of fluid, such as those that change shape in response to magnetic fields. He’s also exploring the possibility of working with electronics manufacturers and says that Samsung has expressed interest in the lens.