What are the optical instruments developed in ancient China?

Any device that uses optical principles to observe or measure is called "optical instrument". According to the strange phenomena of plane mirror, spherical mirror and lens, the working people in ancient China made a large number of optical instruments.

China made the earliest optical instruments in the world in ancient times-bronze mirror and periscope. With the understanding of convex mirror and concave mirror, optical instruments such as glasses, binoculars, microscopes and searchlights were later developed.

On a Mid-Autumn Festival night in the Kaiyuan period of Tang Dynasty, the emperor of Tang Dynasty invited Shen and Fang Shiluo to enjoy the moon together. While the three men were enjoying the moon, drinking and laughing, Tang was full of joy and wanted to visit the Moon Palace.

Therefore, Shen's practice, alchemist Luo threw a crutch in the sky of the moon and turned it into a silver bridge. On the other side of the bridge, there is a city gate with a horizontal plaque that reads: Cold and empty house.

Luo said to Tang, "This is the Moon Palace!"

Emperor Tang Ming set foot on the silver bridge and boarded the moon palace. He saw the fairy graceful and dancing on the broad court, and the emperor was fascinated. He used to study music. After hearing the beauty of Yue Xian, he memorized the music and decided to play it in his own palace.

After Emperor Ming of the Tang Dynasty returned to earth, he ordered the officials in charge of the court music and dance to sort out a beautiful tune, which seemed to be the sound of nature, and with the dance of the court dancers, it was the famous colorful feather.

The legend of the Tang King's visit to the Moon Palace has become a legendary story, so the Moon Palace is also called "Guanghan Palace". In Liao Dynasty, there was a "Tang King visited the Moon Palace Mirror" to commemorate this event. The mirror has a diameter of 2 1.8cm, a thickness of 0.75cm and a weight of 1460g. The decorative pattern is a combination of high relief and line carving.

The bronze mirror is like a full moon, and the undulating ornamentation seems to reflect the cold palace in the middle of the month; Pavilions and pavilions in the Moon Palace are hidden from time to time, and swaying osmanthus trees shake their branches in the shadow of the moon; Jade Rabbit, who was tinkering with medicine, was very happy, and Jin Chan, who welcomed the guests, stretched himself. Clouds in the wind, crescent bridge and dragons in the pool under the bridge are eager to try; The king of the Tang Dynasty came by cloud. What a fairyland paradise, the scenery on earth, people can't help but sigh the wisdom and unique casting technology of the ancients.

In fact, China made and used bronze mirrors 3000 years ago, and he had a deep understanding of light reflection very early.

In ancient China, the technology of making mirrors was very developed, and the imaging principles of various mirrors were deeply studied. As early as the pre-Qin period, China had already used bronze mirrors, which are still regarded as treasures in the history of world civilization.

In addition to bronze mirrors, the ancients also made the earliest periscope in the world by using the reflection principle of flat mirrors. Liu An, the king of Huainan in the Western Han Dynasty, wrote in "The Wall Book of Huainan Bay" that "take a big mirror, put a pot down, and you will see your neighbors". Although this device is rough, it has far-reaching significance, and the periscope used in modern times is made according to this principle.

While using plane mirror, people found the strange phenomenon of spherical mirror. There are two kinds of spherical mirrors: concave mirror and convex.

It has a long history in China to understand concave mirror's focusing characteristics and use concave mirror to ignite Japan. Concave mirror was called "Yangsui" in ancient China, which means using sunlight to make a fire. This is the original use of solar energy.

As early as the Spring and Autumn Period and the Warring States Period, Mo Zhai and his students made an in-depth study of concave mirror and recorded their research results in the book Mo Jing.

Through experiments, they found that when an object is placed in the center of the ball, it will get an upright image. The image near the center of the ball is large, and the image far from the center of the ball is small. At that time, Mohism had clearly distinguished the focus from the center of the ball, calling the focus "Zhong Xiang".

Mohism also studied the convex mirror and realized that no matter where the object is on the convex mirror, there is only one upright image.

Shen Kuo, a scientist in the Song Dynasty, summed up the ancient mirror casting technology in Meng Qian's Bi Tan and said: If the mirror is big, make it flat; If the mirror is small, make it slightly convex, so that the mirror can shine on the whole face even though it is small.

Shen Kuo also correctly stated the principle of concave mirror imaging on the basis of previous studies. He pointed out: When you put your finger in front of concave mirror for imaging, the image changes as the distance between your finger and the mirror moves.

Shen Kuo used this example to illustrate the relationship between concave mirror imaging and focus. When the finger approaches the mirror, it gets an upright image; When you are far away, you can't see the image because your fingers are not in focus; Out of focus, the image becomes an inverted image. He pointed out that the four mirrors "converge into one point", which he called "the obstruction", which is the so-called "focus" in modern optics.

Because there was no application of glass in ancient China, the knowledge of lenses was poor. In ancient China, wise people realized the focusing phenomenon of convex lens through special methods.

Zhang Hua, a scientist in the Jin Dynasty, wrote a book called Natural History, in which he said, "If you cut the ice, your life will be round. If you lift it to the sun, you will get angry with it." This can be said to be an ingenious invention.

Ice will melt when heated, but the ancients made it into a convex lens and used focusing to make a fire. It seems incredible, but it is actually possible.

It can be seen from here that the focusing of convex lens was completely understood at that time.

The ancients not only realized the characteristics of concave mirror and convex mirror, but also used this principle to manufacture optical instruments such as telescopes.

Telescopes were called "telescope", "telescope", "telescope" and "telescope" in Ming and Qing Dynasties. 163 1 year, the scientist Bojue creatively installed the telescope on the homemade copper gun. This pioneering work is of great significance. Later, telescopes were also deployed on astronomical observation and geodetic instruments. The Calendar Bureau led by Li Tianjing, a historian in the Ming Dynasty, also made telescopes.

In the late Ming Dynasty, Sun, a manufacturer of optical instruments, first invented the telescope. He once climbed Huqiu Mountain on the outskirts of Suzhou with a nearsighted friend Wen Kang, and saw the towers and pagodas in the city clearly with a self-made "storage eyepiece", even the distant mountains such as scales, lingyan and vaults were vivid.

Sun's "eyepiece" is said to be "a hundred times brighter and nuanced", which is probably a magnifying glass. He also invented an "inspection micromirror".

Zheng, a scientist in the Qing Dynasty, introduced the types, structure, principle, use and maintenance of telescopes in the book "Mirror Insanity", which is highly practical and highly praised by future generations. The book introduces a kind of "light-passing microscope", which is basically a magnifying glass, but equipped with a flat mirror, which can reduce the burden of vision.

Zheng's Mirror Idiot specially introduces the viewfinder, which is not only old but also improved. It also illustrates its principle, structure, advantages and disadvantages with device diagrams. This viewfinder is to spread white paper on frosted glass or transparent glass to shoot the real image of the scene.

From about 1844 to 1867, the scientist Zou introduced the viewfinder into the mirror, removed the reflective plane mirror, and added photographic film, shutter and aperture to make a camera. This was a very novel technology at that time.

Zou also explored the preparation method of photosensitive materials and achieved good results. He took many photos with the complete set of equipment and materials he developed, and these photos have become one of the earliest photographic works seen in China at present.

One of them is now in Guangzhou Museum. Although it lasted more than 100 years, there are still clear images, which shows that the full set of photographic equipment and materials developed by Zou are of high quality.

According to historical records, at the end of the Ming Dynasty in China, searchlights placed candles near concave mirror. The light from the candle flame is reflected by concave mirror and shines on the wall, just like the moonlight shines on the wall.

Huang Lvzhuang, a young inventor in the late Ming Dynasty, also made a "Ruiguang Mirror" with a maximum diameter of five or six feet. It is said that "the light shoots for miles" and "in winter, people sit in the light and feel hot all over, as if in the sun". Its range and radiant heat are somewhat exaggerated.

At that time, there were only candles and other light sources, so concave mirror had a large caliber, so it could accommodate a large number of light sources, which made people increase the intensity of light sources. After reflecting to form parallel light, they would feel "warm all over" and the brightness would be greatly increased.

During the Ming and Qing Dynasties, people in China invented many optical instruments, such as kaleidoscope, projector, West Lake scenery and so on. The development of these things was also inspired by western knowledge.

As can be seen from the above introduction, the manufacture of optical instruments is one of the remarkable achievements of ancient physics in China, which shows the contribution of our ancestors to human science.