What is laser holography?

Laser holography is a brand-new technology, which is known as the miracle of the 20th century. Its principle was discovered by Hungarian British physicist dennis gabor in 1947, which is completely different from ordinary photography. It was not until 10 years later that American physicists Rafe and Rupert Nyx invented the laser and holography was put into practical application. It can be said that holography is a combination of information storage and laser technology. Laser holography includes two steps: recording and copying. 1. The holographic recording process is: the laser beam is divided into two beams; A laser beam is directly projected on the photosensitive film, which is called reference beam; Another laser beam is projected on an object, and after being reflected or transmitted by the object, it carries the relevant information of the object, which is called object beam. After processing, the object beam is also projected to the same area of the photosensitive film. On the photosensitive film, the object beam and the reference beam are coherently superimposed to form interference fringes, thus completing the hologram. 2. The method of holographic reconstruction is to irradiate the hologram with a laser beam. The frequency and propagation direction of the laser beam should be exactly the same as the reference beam, so that the three-dimensional image of the object can be reproduced. People can see different sides of the object from different angles, just like seeing the real thing, but they can't touch the real thing. The difference between holographic photography and ordinary photography: in ordinary photography, the scene shot by the camera only records the intensity of the reflected light, that is, the amplitude information of the reflected light, but cannot record the three-dimensional information of the scene. Holographic technology can record the amplitude and phase of reflected light from the scene. When shooting a holographic image, the relative phase of the light wave itself and two beams of light is recorded, which is caused by the position difference between the object and the reference light. We can't see the imaging of the object from the interference fringes on the hologram, so we must use cohesive laser to accurately aim at the target to illuminate the hologram in order to reproduce all the information of the object light.