A new imaging technique (holographic camera) might one day help physicians peer into human tissue and behind bones, let mechanics inspect moving machinery such as airplane turbines for tiny defects, or enable automated vehicles to see through dense fog or around blind corners. A new study shows how the process, called synthetic wavelength holography, can capture detailed and nearly instant snapshots of objects hidden from view.
Light scatters when it bounces around a corner or travels through a cloudy material. To see what lies on the other side of such obstacles, you need to undo the scattering and resolve the (hidden) structures with very high resolution. The holographic camera technique overcomes those challenges at frame rates fast enough for video.
The process involves firing laser beams with slightly different wavelengths past obstructions – be it off a wall or through some translucent material – to strike a hidden target. The wavelengths that reflect back are captured and superimposed to produce an interference pattern that reveals the distances of objects hidden from direct view.