End the “ghost probe”: the holographic camera can find the blind area objects in the corner within a few milliseconds

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it is reported that when light shines on an object, scattering will occur. Some of these rays reach our retinas (or camera sensors) and eventually form objects that we can see

but because of this, we can’t see the target obscured by other objects, let alone through scattering media such as fog. In order to resolve this embarrassment, a feasible method is to use the light scattering of multiple objects

for example, put the mirror in the right position, and we can see the object at the corner. But even without a mirror, this principle still applies – except that there is too much scattered light from the secondary object to easily reconstruct the target object

the non line of sight (NLOS) imaging technology scheme used by researchers at Northwestern University can better realize blind area target detection by actively emitting light, waiting for it to touch an object and transmitting it back to the sensor

research drawing – 2: SWH demonstration experiment / resolution evaluation

obviously, this requires the help of a special algorithm to inverse the object image at the corner of the blind area. There have been similar technical solutions before, but they usually have low resolution or require a lot of processing time

in contrast, the NLOS program of Northwestern University is not only fast and convenient, but also can work well at night or in foggy weather

research matching – 3: SWH scattering medium imaging demonstration

in order to improve two problems, researchers used the so-called synthetic wavelength holographic technology. Its working principle is to combine the light waves from two lasers and then emit them to produce a three-dimensional “holographic” image near the corner (or behind other scattering media)

Florian willomitzer, a research work, said: “if you can capture the light field of the whole object in the hologram, you can completely reconstruct the 3D shape of the object”

research picture – 4: experimental demonstration of synthetic pulse holography

compared with ordinary light wave, synthetic light wave can effectively holographic image the target at the corner (or through scattering objects)

in addition, this system can not only capture the fine details of objects lurking in a large angle of view, but also respond very quickly – usually within 46 milliseconds

research diagram – 5: wavefront sensing experiment demonstration

through various continuous improvements, the NLOS scheme allows the car to find fast approaching cars or pedestrians in time, which is a great improvement over other early NLOS systems that often take more than an hour to calculate

Florian willomitzer laughs that this technology turns the wall into a mirror and can work at night or in foggy weather

research figure-6: key attributes and potential future applications of SWH

finally, in addition to the on-board collision warning system, they also intend to use it to improve endoscopic technology in the industrial and medical industries. In that way, the camera does not have to work hard to bypass the curved pipe (or intestinal tract), but can observe the blind area of the corner by emitting synthetic light and observing how they turn back