China developed a camera that could 'capture' from a distance of 45km, through fog and dust

This is a camera system capable of capturing your images from a distance of 45km.

According to Technologyreview , developed by China, this Lidar- based system can penetrate the city's smog layer to capture images of people at great distances.

Taking pictures far away on Earth is always a difficult challenge.

Taking pictures far away on Earth is always a difficult challenge. Getting enough light from an object at a distance is not easy. Next, the atmosphere can distort the image; so is pollution, which is a special problem in cities. That makes it difficult to get any kind of image taken beyond a distance of several kilometers or more (assuming the camera is mounted high enough to deal with the Earth's curvature).

But in recent years, researchers have begun exploiting "Photodetector" sets - Photodetector or optical sensors, also known as photosensors , as photon transducers of light or faithful electromagnetic radiation. electrical effect - extremely sensitive to overcome those problems. Thanks to extremely sensitive detectors, they can receive single photons and use them to put together to create images of objects with distances of up to 10 km.

However, physicists still want to improve this further. And today, Zheng-Ping Li and colleagues from Shanghai University of Science and Technology in Shanghai demonstrated how to photograph objects at distances of up to 45 km in the urban environment. The town has a lot of smoke preventing visibility . Their technique uses single photon detectors combined with a unique computational image algorithm to achieve ultra-high resolution images by knitting data points together.

This new technique is relatively simple in principle. It is based on the detection range of detectors and lasers, or launches objects with laser light and then creates images from reflected light.

The great advantage of this type of activity image is that the photons reflected from the object return to the detector in a specific time window depending on the distance. So any photon coming outside this window can be ignored.

This tool significantly reduces the noise generated by unwanted photons from elsewhere in the environment. And it allows Lidar systems to operate with high sensitivity and longer distances.

To make the new system better in urban environments, Zheng-Ping and his colleagues used a laser with a wavelength of 1550 nanometers , a repeat rate of 100 kilohertz and a modest capacity of 120 milliwatts. This wavelength makes the system safe for the human eye and allows the team to filter out solar photons that can overwhelm the detector.

The researchers sent and received these photons through the same optical device. Conventional astronomical telescopes have a 280mm aperture. The reflected photons are then detected by a commercial photon detector. To create an image, the researchers scanned the field of view using a circular control mirror that could be tilted up, down and sideways.

To create an image, the researchers scanned the field of view using a circular control mirror that could be tilted up, down and sideways.

In this way, they can create two-dimensional images. But if they change the interference time, they can receive reflected photons from different distances to build 3D images.

The last step the team took was to develop an algorithm to weave images together using single photon data. This type of computational image has grown tremendously in recent years, allowing researchers to create images from relatively small data sets.

The team installed a new camera on the 20th floor of a building on Chongming Island in Shanghai and pointed it at Pudong Civil Aviation Tower across the river, about 45km away.

The usual picture taken through a telescope shows nothing but noise. But the new technique creates images with a spatial resolution of about 60 cm, which helps to see building windows. This result shows the superior ability of the near-infrared infrared LiDAR system to detect targets through the fog.

Zheng-Ping and colleagues say that the system is also capable of further improvement: "Our system can take pictures up to hundreds of kilometers if refined. It represents an important milestone. towards Lidar technology fast, strong, far but still energy saving ".