What properties of light does pinhole imaging use?

The principle of pinhole imaging is that light travels along a straight line.

Analysis: Because light travels in a straight line in the same medium, when the light passes through the small hole, the upper and lower parts of the light source exchange, but the imaging shape remains unchanged, just like the light source.

Aperture imaging, about 24,500 years ago, China scholar-Mo Zhai (Mozi) and his students made the world's first pinhole inverted image experiment, explained the reasons of pinhole inverted image, and pointed out the essence of direct light. This is the first scientific explanation for the straight-line propagation of light.

Blocking a plate with a small hole between a wall and an object will form the reflection of the object on the wall. We call this phenomenon pinhole imaging. Moving the middle board back and forth will change the size of the image on the wall, which shows the nature of light propagating along a straight line.

Extended data:

Property application

1, the linear propagation of light has been widely used in ancient astronomical calendars in China. Our ancestors made standard watches and sundials and measured the length and direction of shadows to determine the time, winter solstice and summer solstice. Install peepholes on astronomical instruments to observe the sky and measure the positions of stars.

2. Our country has already invented shadow play by using this characteristic of light. In the early Han Dynasty, people and things cut by Qi Shaoweng were performed behind a white screen, and the images of people and things were reflected on the white screen with light, so people outside the screen could see the performance of the images. Shadow play was very popular in the Song Dynasty, and later spread to the West, causing a sensation.

3. Now some cameras and camcorders use the principle of pinhole imaging-the lens is pinhole (most of them are equipped with convex lens to ensure the imaging distance of light), the scene enters the darkroom through pinhole, and the image is left on the film by some special chemicals (such as developer) (digital cameras and camcorders store the image in the memory card through some photosensitive elements).

References:

Baidu encyclopedia-pinhole imaging