What is holography?

Holography, also known as holography, is a very attractive technology in optics. We all have the experience that the oil film spilled on the road will show many colors in the sun, and the same will be seen on the soap bubbles blown out. The reason is that the reflected light on both sides of soap bubbles interferes, which is called thin film interference of light. Light is the life of photography, and it has many characteristics, such as dispersion and scattering. Experienced photographers can make full use of these phenomena and turn harm into benefit, thus adding some novel effects to their works. A camera lens is composed of multiple groups of lenses. In order to avoid the reflection loss of light on the lens surface, people invented the coating technology of the lens, so that the light with a certain wavelength can cancel each other when reflected, thus increasing the light entering the lens and making the image clearer. Similarly, people have developed holographic photography technology with stereoscopic effect by using the interference characteristics of light waves. Holography used to be a patented technology for scientists to carry out scientific research, but now ordinary people can master it after a certain amount of learning. For example, fake cards commonly used in credit cards or book covers are three-dimensional imaging things that show colored reflected light in the sun.

We will be familiar with the word "hologram", which is associated with the human body hologram in the ear acupuncture. The human ear is the epitome of the human body, corresponding to various organs of the human body. From here, people further study that any part of the human body has the whole body information, so it is called hologram, and it is easy to understand hologram.

The difference between holographic photography and ordinary photography

Classification holography general photography

Optical lens imaging of object beam and reference beam in recording mode (object beam)

Record the intensity and phase information of scattered light from the content object, the scene itself or the intensity of reflected light.

The recorded imaging medium is called holographic (full gray tone) photographic film.

The general way of image observation is to restore direct vision with the help of laser.

Color represents color interference fringe image color object image.

The image is characterized by a three-dimensional scene, with only scattered light and no real plane object image.

1. What is the phenomenon of light interference?

In the mechanics of physics class, we have done the interference experiment of water waves. According to the wave characteristics of light, people have successfully observed the interference and diffraction of light waves. In order to get two beams of light with the same frequency, let the light shoot from a slit to two small holes in the second screen at the same time, and interference fringes appear behind the screen. Fringe appears because the peaks and valleys of two beams of light will be strengthened by superposition (in-phase) light, and when they cancel each other (in-phase), the light will be weakened. This phenomenon made Stephen Benton, a physicist at Massachusetts Institute of Technology, discover that there is a high-tech hidden behind it, so as to do further research on this technology.

Second, the characteristics of holographic images

The principle of holography was put forward by British physicist Dennis Gabor in 1947, and the scientist himself won the Nobel Prize. When taking a holographic image, the relative phases of the light wave itself and the two beams are recorded. The phase is caused by the position difference between the object (blue light in the figure) and the reference light (red light in the figure). We can't see the imaging of the object from the interference fringes on the hologram. 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. A man named Banton later discovered a simpler method to restore images by using white light, thus making this technology gradually move towards the practical stage. When National Geographic magazine first used the white hologram on its cover, its sales volume increased from10 million to16 million after reprinting. This technology was later spread from the United States to Europe and other countries, and was widely used in counterfeit technologies such as credit cards. Laser holography is also popular around the world.

Holography is a photographic technology that records and reproduces images through the interference of laser light waves. It is completely different from the general stereo photo technology. We can observe all aspects around it, but we can't touch real objects. Its remarkable features and advantages are as follows:

1. The reconstructed stereoscopic image is beneficial to the preservation and collection of precious artworks.

2. When shooting, every point is recorded on any point of the hologram. Once the photo is damaged, it doesn't matter much.

3. Holograms have strong stereoscopic impression and vivid images, and can be displayed in various exhibitions with the help of lasers, which will get very good results.