What is the principle of holographic film shooting?

Holography uses laser as the illumination source, and divides the light emitted by the light source into two beams, one of which is directly directed at the photosensitive plate, and the other is reflected by the subject and then directed at the photosensitive plate. The superposition of two beams of light on the photosensitive plate produces interference, and the sensitivity of each point on the photosensitive plate changes not only with the intensity, but also with the phase correlation of the two beams of light. Therefore, holography not only records the reflection intensity on the object, but also records the phase information. When the human eye directly looks at this photosensitive film, it can only see interference fringes like fingerprints, but if it is irradiated by laser, the human eye can see the three-dimensional image of the original object through the film. Even if only a small part of the holographic image remains, it can still reproduce the whole scene. Holography can be applied to nondestructive testing, ultrasonic holography, holographic microscope, holographic storage, holographic film and television and many other aspects in industry. The principle of generating holograms can be traced back to 300 years ago, and some people have done experiments with poor coherent light sources, but it was not until 1960 that laser, the best coherent light source, was invented that holography developed rapidly.

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.