Why is the shape of the image imaged by the hole irrelevant to the shape of the hole?

I remember when we were in junior high school, the book only said that the hole of the image is smaller than the object, but it cannot be infinitely small.

Because the size of the hole determines the light transmittance, it determines the clarity and brightness of the imaging.

And the shape of the image must be fixed. You learn that this leads to asking why, which is worthy of praise.

Each point on the object is equivalent to a point light source, and the image formed by each such point light source through the small hole is the shape of the small hole (and considering the diffraction effect, even if it is a point light source, the edge of the image of the small hole is not completely defined, but will be blurred to a certain extent). ), but because the hole is small, the image is also very small; The position of the image formed by each point light source through the small hole is different, and all these images are interlaced and combined to form the contour image of the object, because the point light source, the small hole and the corresponding image are almost in the same straight line.

Because the image of an object radiates or reflects light through a small hole, the formation of the image is independent of the shape of the hole. For example, the filament of a light bulb, only the light radiated by the filament through the small holes is different from the light that passes through the small holes around it, so this difference produces the shape of the filament. The hole is only responsible for blocking the light from the vertical hole and letting other rays pass through the hole, because the other rays pass through the hole obliquely, so the imaging will rotate 180 degrees.

Aperture imaging, a Chinese scholar Mo Zhai (Mozi) and his students, did the world's first experiment of small hole inverted image, explained the reason for small hole inverted image, pointed out the nature of light along a straight line, and summarized a similar theory more than 2000 years earlier than Newton. This is the first scientific explanation of the propagation of light along a straight line.

If a plate with a small hole is used to block between the wall and the object, the reflection of the object will be formed on the wall, and we call this phenomenon the image of the hole. When the middle plate is moved back and forth, the size of the image on the wall also changes, which illustrates the nature of light propagation in a straight line.

Aperture imaging is imaging based on the principle that light travels in a straight line.

I used to make a model when I was in school.

It is quite certain that the image and the object are upside down and upside down. The light emitted from the top of the object hits the underside of the phosphor screen through a small hole.

Because what you see in the small hole image is a real image that is made up of actual light converging.

The characteristics are:1It looks like a real image.

2.The ratio of the image to the size of the object is (the distance from the hole to the imaging screen) divided by (the distance from the hole to the object).

3.The resulting image is the same as the size of the object.

4.It looks like it is upside down and upside down (symmetrical to the center of the original object)5The smaller the hole, the clearer the image, but the brightness will be smaller.

The real image can be displayed on a piece of paper.

And upside down, side down.

You draw a picture and it's clear.

Hole imaging has nothing to do with the shape of the hole, and the size of the image is related to the distance from the object to the hole and the distance from the screen to the hole.

If the distance from the hole to the screen is unchanged, the farther the object is from the hole, the smaller the image, and the closer the object is from the hole, the larger the image. If the distance between the object and the hole remains the same, the greater the distance between the hole and the screen, the larger the image, and vice versa.

For example, the light spots in the trees are circular, not the shape of the gaps in the leaves.

Light travels in a straight line in the same homogeneous substance. The closer the object is, the larger the image and the darker the brightness; The farther away the object is, the smaller and brighter the image.

It doesn't matter, the principle of small hole imaging is to use the straight line propagation of light, so the image is inverted, and the light is fluctuating, so the image has nothing to do with the shape of the hole.

Junior high school generally thinks that it doesn't matter

The principle of aperture imaging is that light travels along a straight line, and the aperture can be used to form an image of the light source on the screen, which is like an inverted and reduced real image. Therefore, the shape of the light source and the shape of the image have nothing to do with the shape of the hole.

Notice the difference between the two images below:

Note that the principle of aperture imaging is independent of the diffraction of light.

1. Aperture imaging regrets early.

The reason is that light travels in a straight line.

2. Use a plate with a small hole to block between the screen and the object, and the inverted image of the object will be formed on the screen, which we call the phenomenon of small hole imaging. Move the middle plate back and forth, and the size of the image will also change. This phenomenon reflects the nature of light rays traveling in a straight line.

3. Put a sharpened pencil and make a small hole in the center of a piece of cardboard. The diameter of the hole is about three millimeters. Try to put it upright on the table. Then close the curtains to dim the light in the room.

4. Light a candle on the stove and place it near the hole. Take a blank piece of paper and place it on the other side of the hole. This way, you will see an inverted candle flame on the white paper.

We call it the image of a candle. Move the white paper back and forth to see how the candle flame looks. When the white paper is closer to the hole, it looks small and bright; When the white paper slowly moves away from the small holes, it seems to slowly become larger and darker.

The principle of aperture imaging is that light travels in a straight line in the same homogeneous medium without being disturbed by gravity. The resulting image is an inverted real image, and the shape of the image has nothing to do with the shape of the hole.

Take a sharpened pencil and make a small hole in the center of a piece of cardboard. The small hole is about three millimeters in diameter and manages to hold it upright on the table, and then the curtains are closed to dim the light in the room.

Light a candle and place it near the hole. Take a blank piece of paper and place it on the other side of the hole. On the white paper, you will see an inverted candle flame, which is the image of a candle.

Move the mountain back and forth on the white paper, when the white paper is closer to the candle, it is small and bright; When the white paper slowly moves away from the candle, it slowly grows larger and the brightness darkens.

Change the size of the hole, and on the white paper, there will be several inverted images corresponding to the hole. They are all the same size, but the degree of clarity varies, and the larger the hole, the less clear the likeness. As long as the hole is small enough, its shape, whether it is square, round, or oblate, has no effect on the clarity of the image and the shape of the image.

Expand the information of Ja Weiye

The reasons why the aperture is imaged as an inverted real image are:

The light from the upper part of the candle flame passes through the small hole in a straight line and shines on the lower part of the white paper; The light emitted from the lower part of the candle flame shines on the upper part of the white paper through a small hole, so that an inverted image is formed on the white paper. This just shows that light travels in a straight line.

Reasons why the size of the hole affects the sharpness of the image:

When the hole is small, the light emitted by different parts of the object will reach different parts of the screen without overlapping each other on the screen, so the image on the screen will be clearer.

When the hole is relatively large, the light emitted by different parts of the object will overlap on the screen, and the image on the screen will naturally not be clear. If the hole is quite large, the light will overlap, the light information will be confused, and the image will not be possible.