For drivers, the blind spot has always been a very dangerous problem.However, a research team from Northwestern University in the United States has just unveiled a new holographic camera technology.By reconstructing scattered light waves to observe corners invisible to the naked eye, this system can find fast-moving targets, such as cars or pedestrians, more quickly.
(From:Northwestern University）
It is reported that when light hits an object, it is scattered. Some of this light reaches our retina (or camera sensor) and eventually forms an object that we can see.
But because of this, we cannot see targets that are blocked by other objects, much less through dispersal media such as fog. To solve this embarrassment, one feasible method is to use light scattering from multiple objects.
Research Image 1: SWH Schematic Diagram of NLoS Images
For example, by placing the mirror in the right place, we can see objects in the corner. But even if there is no mirror, this principle still applies; it’s just that there is too much light scattered from the secondary objects, making it impossible for us to easily reconstruct the target object.
Non-line-of-sight (NLoS) imaging technology used by Northwestern University researchers can better perform target detection in blind areas by actively emitting light, waiting for it to hit an object, and transmitting it back to the sensor.
Research Image-2: SWH Demonstration Experiment / Resolution Evaluation
Obviously, this requires a set of special algorithms to inversely derive the image of the object at the corner of the blind spot. Similar technical solutions exist before, but their resolution is usually low or requires a lot of processing time.
In contrast, Northwestern University’s NLoS program is not only fast and convenient, it also works well at night or when it is foggy.
Research Image 3: SWH Scattering Medium Imaging Demonstration
To improve on both problems, the researchers used so-called synthetic wavelength holography technology. Its working principle is to combine the light waves from the two lasers and emit them together to produce a three-dimensional “holographic” image near the corner (or behind other scattering media).
The first study, Florian Willomitzer, said: “If you can capture the light field of the entire object in a hologram, you can completely reconstruct the 3D shape of the object.”
Research Image 4: Demonstration of Synthetic Pulse Holographic Experiment
Compared to ordinary light waves, synthetic light waves can effectively make holographic images of targets in corners (or through scattered objects).
In addition, this system can not only capture the fine details of lurking objects in a wide-angle field of view, but also has a very fast response speed, usually within 46 milliseconds.
Research Image-5: Demonstration of Wavefront Detection Experiment
Through continuous improvement in many aspects, the NLoS solution enables cars to detect rapidly approaching cars or pedestrians in time, which is a huge improvement over other early NLoS systems that take more than an hour to calculate .
Florian Willomitzer laughed and said that this technology turns the wall into a mirror and can work at night or in fog.
Research Image-6: Key Attributes of SWH and Possible Future Applications
Finally, in addition to the on-board collision warning system, they also intend to use it to improve endoscope technology in the medical and industrial industries. That way, the camera doesn’t need to work hard to bypass the curved tube (or gut), but it can perform blind spot observation in the corner by emitting synthetic light and watching it fold back.
Details of this research have been published in the recently published “Nature Communications” (Communications from nature) In the magazine, the original title is “Fast images without line of sight with high resolution and wide field of vision using synthetic wavelength holography”.
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