What is Hologram? Difference Between Hologram and Normal Photography

The difference between the two: ordinary photography can only store the spatial distribution of the light intensity of the photographed object, which cannot meet the requirements of people who want to perceive the real 3D scene in a specific environment; Holographic photography is to record the interference fringes of the object light wave and the corresponding reference light wave irradiating the object, so as to record all the light field information including the object amplitude (light intensity) and phase, so it is called "holographic".

The fields of application of holography are wide.

The application of holographic technology to the field of photography is far superior to ordinary photography, ordinary photography is based on the principle of lens imaging, the three-dimensional scene is "projected" onto the plane photosensitive base plate, forming a light intensity distribution, and there is no three-dimensional sense of recording, because the image obtained from various angles is exactly the same.

Holographic photography reproduces an exact replica of the object light wave, and when we "see" at this object light wave, we can observe different sides of the reproduced stereo image from various perspectives, as if we were seeing a realistic object, with depth of field and parallax. If we photograph two models of Mercedes-Benz cars side by side, the covered part of the latter car will be revealed when we change the direction of the observer. No wonder people were excited at the exhibition for a hologram of a "Mercedes" car:

Seeing the reproduction of the car, it seems that you can sit on the 'Mercedes-Benz' as soon as you pull the car door, which is so exciting! A hologram is equivalent to many ordinary ** taken from multiple angles and focused, and the amount of information in this sense is equivalent to 100 or 1000 ordinary**.

On the surface of the hologram with a high-powered microscope, you can see complex stripes, and you can't see the image of the object at all, these stripes are the object light waves emitted by laser illumination and the standard light waves (reference light waves) interference, which are recorded on the plane photosensitive bottom plate, that is, the object light waves are "frozen" by the coding method. Once the finger hole is irradiated by an illumination light wave similar to a reference light wave, an imaging light wave is diffracted as if the original light wave was re-released. Therefore, the principle of hologram can be expressed in eight words:

Interference recording, diffraction reproduction".

1. What does holographic photography mean.

2. Why is holographic photography called holographic?

3. What does hologram mean.

4. What does hologram mean.

1.Hologram is a photographic method that records and reproduces three-dimensional (stereoscopic) images of objects without lenses.

2.It is a technology that records information about the amplitude and phase of the wavefront of a light wave from an object, and reproduces this light wave when needed.

3.Light wave is a type of electromagnetic wave that carries information about amplitude and phase in its propagation.

4.Ordinary photography uses photosensitive materials (such as photographic negatives) as the recording medium, and lens imaging systems (such as cameras) are used to image objects on photosensitive materials.

5.It records only a picture of the intensity distribution of the light wave from the object, i.e., information about the amplitude, and does not include information about the phase.

6.Therefore, ordinary photography can only capture two-dimensional (flat) images.

7.In order to record the amplitude and phase of the Song Chong light wave at the same time, the phase difference between the two light waves can be determined with the help of a coherent reference light, and the field Zheng Jian optical path difference between the object light and the reference light can be used.

8.Thus, with the help of a reference light, information on the amplitude and phase of the light wave from the object can be recorded.

Holographic cameras belong to a special type of camera that uses holography to record the interference and scattering of light in order to capture three-dimensional information about an object. Unlike traditional photographic cameras, which use optical lenses and interchangeable films, holographic cameras use holographic plates to record information about the phase and amplitude of light.

The function of the holographic camera is to record and visualize the information of the three-dimensional object code silver, so that the observer can get the same three-dimensional image as the real thing. This kind of camera is often used in scientific research, Iwago's art creation, and other fields.

Holographic cameras are relatively rare in practical applications due to their high technical difficulty and high production costs. However, the application of coarse mold rock in some fields is still of great significance, such as three-dimensional imaging in industrial testing, medicine, security monitoring and other fields.

According to your question First of all, we should first understand hologram: hologram is to superimpose a suitable coherent reference wave with the scattered wave of an object, and the amplitude and phase distribution of this scattered wave can be recorded on the photosensitive plate in the form of an interference pattern, and the recorded interference pattern is called a hologram. The hologram is then illuminated with coherent light, and a very realistic 3D image is finally reproduced.

1. Instruments used in holographic photography (1) Holographic experimental bench, including optical elements on the table. (2) He-NE lasers. (3) Timer.

4) Darkroom equipment. 2. The principle of holographic photography uses the electromagnetic waves emitted by the object, and the electromagnetic waves have amplitude distribution and phase distribution. Holograms, on the other hand, use the interferometric method to record the amplitude and phase of the light wave when the object arrives at the camera negative.

Because it does not record the geometric image of the object, the noisy wheel image of the object is generally not visible on the holographic **, and the original reference light must be illuminated to obtain the stereoscopic image of the original object, which is called the reproduction of the holographic negative. From the above knowledge, we can summarize the experience as: to understand the conditions required for holographic photography, it must be coherent light, and there is one point to add, that is, in the specific operation, the teacher also emphasized the necessity of the stable system, one of the differences from other experiments, is that the working environment of our experiment is more quiet, which is also one of the key points of the success of hologram.

When taking pictures, we need to pay attention to the photoelectric needs generated by the all-reflective mirror and beam splitter near the coherent light source.

Holographic photography can reproduce the three-dimensional image of an object and has a series of unique advantages, both in terms of shooting and observation methods, as well as basic principles, which are fundamentally different from ordinary photography.

Hologram is a two-step holographic recording and reproduction.

Holographic recording: In order to ensure that a hologram is taken well, holographic photography needs to be carried out on a holographic laboratory table. The holographic table top is generally a thick steel plate weighing tens of kilograms to hundreds of kilograms (specifications vary according to the requirements of use), which is placed flat on a solid cement table or table frame.

Since holograms actually record some very fine interference fringes, any slight vibration and interference during the photography process will blur the interference fringes or even fail to record. In order to prevent the interference of ground vibration and maintain the maximum stability of the holographic table, a seismic isolation system composed of various elastic materials or shock-absorbing devices is used between the steel plate and its supports, and all the optical components used in the experiment are firmly fixed to the holographic stage with magnetic materials or other methods. A good coherent light source is a must for holographic recording, and a high-power laser generator is used here.

The usual photographic method is to divide the beam output by the laser into two beams, one of which is projected onto the photosensitive plate, which is called the reference beam; The other beam is projected onto the object, and after being reflected or transmitted by the object, the resulting object beam is also shot to the photosensitive plate, and the two beams are coherently superimposed on the photosensitive plate to form interference fringes, which is a hologram, that is, the interference pattern map. Observe the holographic negative directly with the naked eye, it is just a gray **, and cannot directly display any image of the photographed object.

However, holograms have subtly recorded all the light information of each point on the object through the method of interference, including amplitude and phase, which is holographic recording.

Holographic reproduction: A hologram is illuminated with a beam of light that is exactly the same wavelength and propagation direction as the reference beam, and a very realistic stereoscopic image of the original can be observed with the eye. When you move your eyes to look at it from different angles, you can see different aspects of it as if you were looking at the original.

What's even more interesting is that if you block a part of the hologram, through the exposed part, the reproduced image of the object is still intact and not mutilated. Even a small piece of a broken holographic negative can still reproduce the entire original.

The characteristic of holography is that it is based on the laws of wave optics such as interference and diffraction. The hologram records all the light information of each point of the object, including amplitude and phase; Each part of the hologram contains light information from each point of the object, so that each part of the holographic negative can be observed as a very realistic stereoscopic image.

In addition, the recording and reproduction of holograms require a highly coherent strong light source, and lasers are widely used at present.

Holograms have a wide range of applications, but many are currently in the experimental stage. Such as holographic movies and holographic TV, which can make film and television comprehensive three-dimensional; Holographic microscopy technology, holographic interference technology, holographic storage technology, as well as infrared microwave and ultrasound holographic technology, etc., will occupy an important position in many fields of the national economy and make breakthroughs and achievements.