Femtosecond camera

You can say the answer first. On April 19, 2020, Chinese scientists captured the trajectory of photons, which was shot with a high-speed camera, about 4 trillion frames per second. Still have to boast that China's scientific research ability is constantly strengthening, thanks to the hard work of those researchers, after all, shooting photon trajectories is really not a thing. You know, the speed of light traveling in a vacuum is 299,792,458 meters per second, which is the limit of the motion of all objects with static mass in the universe, and nothing can exceed this limit. You know, the speed of photons is so fast that it is special for scientists to catch up with it. Now the dream has come true.

First of all, we must understand the working principle of the camera. A camera can record an image by receiving the reflection of a subject through a film or a sensor. About the difficulty of photon shooting, you can say so. Generally speaking, the object to be photographed must be able to reflect or refract light. You know, light is an electromagnetic wave, and light does not have the characteristics of reflected light. The two beams of light will only pass through each other after they meet, so it is really not a simple matter to take a picture of Guangde through the camera. In addition, photon is the smallest unit of light propagation, and the camera can only record the instantaneous motion of photon, but there is no way to record the continuous motion of photon.

Scientists in China have actually adopted compressed sampling technology to overcome this difficulty, and images can be saved by overlapping areas of CCD. The great thing about this technology is that the camera can take a photo at 260 femtoseconds, and then it can superimpose these continuous recording moments through technical means, thus shooting the trajectory of photon movement.

This technological breakthrough is indeed a milestone in the scientific community. Thanks again to the researchers for their persistence and efforts. Because of you, we saw the trajectory of photons.