Panasonic research and development of high ranging precision remote TOF image sensor can be used in vehicle remote imaging and other fields

Posted 2021-10-11 00:00:00 +0000 UTC

According to foreign media reports, on February 18 local time, Panasonic announced that it had developed a time-of-flight image sensor. Using avalanche photodiode (APD) pixels, the sensor can obtain high-precision 3D information according to the position of the object (up to 200m), which can be applied to many fields such as vehicle remote imaging and wide area monitoring. (image source: Panasonic company) the newly developed TOF image sensor reduces the APD pixel area through the vertical stacking structure and electronic storage of the electronic multiplier, so that it can integrate 1 million pixels. Panasonic launched the TOF image sensor with APD pixels in June 2018, and the new sensor is based on this technology. In addition, in addition to the long-range high-resolution 3D long-range imaging technology developed by Panasonic, the sensor also has high ranging accuracy, which is very difficult to achieve for the previous TOF sensor and lidar. The new sensor can also accurately detect people and objects in the distance. The new sensor has the following advantages: 1 It is a TOF image sensor with high resolution and high sensitivity. It uses APD of 1 million pixels, which is 4 times the number of pixels of Panasonic traditional sensor. Traditional TOF sensor and other image sensors will convert a single photon that has entered its pixel into an electron. Therefore, because of the sensitivity of signal light to noise, when the signal light is weak to near the level of single photon, it will appear sensitive The problem of low degree. The traditional APD sensor is called SPAD (single photon avalanche diode). It multiplies electrons in a pixel and has a large pixel area, so it is difficult to miniaturize. The newly developed vertical stack APD (vpad) reduces the area by stacking the photoelectric converter, electronic multiplier and signal memory vertically. So as to form a pixel spacing of 6 μ M. Thus, the sensitivity signal of the image sensor can be magnified 10000 times to achieve a high resolution of 1 million pixels. 2. Using TOF to acquire 3D Remote Image with high ranging accuracy, even in the range of 10-100 meters, it is possible to realize 10 cm spacing sensor, which is 15 times of the ranging accuracy of Panasonic traditional sensor. Generally speaking, TOF ranging calculates the distance by measuring the flight time of photons emitted from the light source to the object, reflected and returned. Panasonic has previously developed a 3D long-range imaging technology that uses a unique short pulse TOF method with a ranging accuracy of 1.5m intervals and a maximum distance of 250m. This technology is based on the weak light detection technology. By building a unique integrated circuit in all APD pixels, the weak signal of a single photon can be reliably captured, so that the number of incident photons can be calculated according to the probability. Panasonic has developed a new indirect TOF technology of photon accumulation and time division, which can convert the number of incident photons into an integrated signal, and apply indirect TOF calculation in a short distance, so that 3D remote imaging with ranging accuracy of 10 cm can be realized in a long distance range (10 to 100 meters), which is difficult to achieve by traditional TOF sensors and lidar. The sensor has not only high resolution, but also high ranging accuracy. Even in a long distance, it can obtain 3D remote image, which can recognize the position and shape of people and small objects.

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