How was the camera invented?

As early as the15th century, European painters made pinhole drawing camera boxes in order to draw landscapes quickly. Based on the principle of pinhole imaging, the real image is displayed on the frosted glass screen of the camera box, and semi-transparent paper is pasted on it to describe the picture. In the19th century, pinholes were replaced by convex lenses, so that clearer images could be obtained. 1839, the French painter Daguerre discovered a kind of thin slice that was easily exposed to light after repeated research. After dilution and restoration, he finally got a clear photo. His improved camera case became the first real optical camera in the world.

At present, the structure and function of the camera have made great progress, but the basic working principle of photography has not changed much. The principle of convex lens imaging is still the basic principle of photography.

With the progress of science and technology, some new photography techniques have appeared in recent years, such as stereoscopic photography, infrared photography and laser photography. There are also digital cameras that use photosensitive chips instead of film, without negative film and development. Their photosensitive principle is different from ordinary photography.

However, the basic working principle of the optical camera commonly used in our family has not changed, but advanced technologies such as computer autofocus have been adopted to make it easier to take pictures.

digital camera

Holography records not the focused image of the object recorded by the traditional camera, but the interference image formed by the light wave emitted by the photographed object and the reference light wave, or the ordinary camera records the light intensity, while holography records the phase of the light wave.

The basic step of making a hologram is to use a partially reflective glass plate to split the light emitted by the laser into two beams. One beam of light shines on the basement membrane, and the other beam scatters from the object. Some scattered light is also irradiated on the substrate, which interferes with the directly irradiated light. In this way, the light and dark stripes of the interference pattern appear on the negative. After the negative is developed, the interference pattern can be reproduced by putting it into a laser beam. When you look at the negative film taken in this way, the interference image will produce the image of the subject. But this is a virtual image, because it is produced by illusion, and it relies on the observer's eyes to gather the light from the negative. This illusion faithfully preserves the parallax and depth of field of the original object. In this way, the hologram looks three-dimensional.

In the cultural relics department, because many collections are precious, some have only one copy, which will cause irreparable losses after being lost. Therefore, people use holographic technology to take these collections into holographic photos, and then use special lenses to enlarge them, so that people can watch the original three-dimensional images as realistic as the real thing.

Old camera