Famous optical scientists before Newton, Mozi, Bacon and Leonardo da Vinci all studied optical phenomena. The law of reflection is one of the optical laws that people have long known. When modern science rose, Galileo discovered a "new universe" through a telescope, which shocked the world. Dutch mathematician Hans sneer first discovered the law of refraction of light; Descartes proposed the particle of light. ...
Newton and his contemporaries, such as Hooke and Huygens, studied optics with great interest and enthusiasm, just like Galileo and Descartes. 1666, when Newton was on vacation at home, he got a prism, and he made a famous dispersion experiment with this prism. After a beam of sunlight passes through a prism, it is decomposed into several color spectral bands. Newton blocked the light of other colors with a slit baffle, and only let the light of one color pass through the second prism, resulting in only the light of the same color. In this way, he found that white light is composed of different colors of light, which is the first major contribution.
In order to verify this discovery, Newton tried to combine several different monochromatic lights into white light, and calculated the refractive index of different colors of light, which accurately explained the dispersion phenomenon. The mystery of the color of matter has been solved. It turns out that the color of matter is caused by the different reflectivity and refractive index of different colors of light on the object. In A.D. 1672, Newton published his research results in the Journal of Philosophy of the Royal Society, which was his first paper.
Many people study optics in order to improve refractive telescopes. Newton discovered the composition of white light and thought that the dispersion phenomenon of refractive telescope lenses could not be eliminated (later, some people eliminated the dispersion phenomenon with lenses made of glass with different refractive indexes), so he designed and manufactured reflective telescopes.
Newton was not only good at mathematical calculation, but also able to make all kinds of experimental equipment and do fine experiments by himself. In order to make a telescope, he designed a grinding and polishing machine and tested various grinding materials. 1668, he made the first prototype of reflective telescope, which is the second largest contribution. 167 1 year, Newton presented the improved reflecting telescope to the Royal Society. Newton became famous and was elected a member of the Royal Society. Reflecting telescope's invention laid the foundation of modern large-scale optical astronomical telescope.
At the same time, Newton also carried out a lot of observation experiments and mathematical calculations, such as studying the abnormal refraction phenomenon of glacial stones discovered by Huygens, the color phenomenon of soap bubbles discovered by Hooke, and the optical phenomenon of Newton's ring.
Newton also put forward the "particle theory" of light, thinking that light is formed by particles and takes the fastest straight-line motion path. His "particle theory" and Huygens' "wave theory" later formed two basic theories about light. In addition, he also made Newton color wheel and other optical instruments. Learning point
Triangular column
Prism is an optical instrument made of transparent material, and its cross section is triangular, also called "prism". Optically speaking, a transparent body with a triangular cross section is called a prism. The prism of an optically dense medium is placed in an optically hydrophobic medium (usually air), and the light incident on the side of the prism is refracted by the prism and deflected to the bottom of the prism.
Light enters from one side of the prism and exits from the other side, and the outgoing light will be biased to the bottom (the third side). The deflection angle is related to the refractive index of the prism, the vertex angle of the prism and the incident angle.
White light is polychromatic light composed of various monochromatic lights; The refractive index of the same medium for different colors of light is different; Different colors of light travel at different speeds in the same medium.
Therefore, because the refractive index of the same medium for various monochromatic lights is different, the deflection angle of each monochromatic light passing through the prism is also different. Therefore, white light will separate monochromatic light through the prism to form seven colors, namely red, orange, yellow, green, blue, indigo and purple, that is, dispersion. Galileo, the pioneer of the telescope
Galileo galilei (1564 ~ 1642), 1564, was born in a humble aristocratic family in Pisa, Italy. He is a great Italian physicist and astronomer, and also a pioneer of the scientific revolution.
During Galileo's work in Padua University, an accidental event made Galileo change his research direction. He turned from the study of mechanics and physics to the boundless space.
It was1June 609. Galileo heard a news that Lipski, a Dutch optician, saw something invisible to the naked eye in the distance with a kind of lens in an accidental discovery. "Isn't this just what I need?" Galileo was very happy. Soon, one of Galileo's students wrote from Paris, further confirming the accuracy of the news. The letter said that although I don't know how Lipski made it, the optician must have made a lens barrel, which can magnify the object many times.
"lens barrel!" Galileo read the letter several times, and then hurried into his laboratory. He found paper and a gooseneck pen and began to draw a schematic diagram of lens imaging one by one. Galileo was inspired by the hint of the lens barrel. It seems that the secret of lens barrel magnifying objects lies in the choice of lenses, especially how to match convex lenses and concave lenses. He found the information about the lens and kept calculating, forgetting that he climbed the window at dusk and how dawn entered the room.
After a whole night, Galileo finally understood that if the convex lens and concave lens are placed at a proper distance, as the Dutch saw, distant objects invisible to the naked eye can be seen clearly after magnification.
Galileo was very happy. He forgot to rest and immediately began to grind his glasses, which was a time-consuming and meticulous job. He worked for several days, grinding out a pair of convex lenses and concave lenses, and then made an exquisite sliding double-layer metal tube.
Galileo carefully placed a large convex lens at one end of the tube and a smaller concave lens at the other end, and then pointed the tube out of the window. When he looked at one end of the concave lens, a miracle appeared. The church in the distance seems to be close at hand. He can clearly see the cross on the bell tower, and even a pigeon resting on the cross is very realistic.
The news that Galileo had built a telescope spread at once. "The news that I made a telescope spread to Venice." In a letter to my brother-in-law, Galileo wrote: "A week later, I was asked to show this telescope to the Speaker and Members of Parliament. They were very surprised. Gentlemen and members of parliament, although very old, all boarded the tallest bell tower in Venice in order and looked at the ships in the distance of the port, all of them could see clearly; Without my telescope, I can't see for two hours. The utility of this instrument can make objects 50 miles away look like they are within 5 miles. "
Later, in 1609, Galileo built an astronomical telescope and used it to observe celestial bodies. He discovered the unevenness of the lunar surface and drew the first map of the lunar surface himself. 161065438+17 October, Galileo discovered four moons of Jupiter, which provided conclusive evidence for Copernicus' theory and marked the beginning of its victory. With the help of a telescope, Galileo also discovered Saturn's rings, sunspots, the rotation of the sun, the ups and downs of Venus and Mercury, the Sunday and Zhou Yue of the moon and the fact that the Milky Way is composed of countless stars. These discoveries ushered in a new era of astronomy. This is an epoch-making revolution in astronomical research. For thousands of years, the era when astronomers only observed the sun, the moon and the stars with the naked eye ended and was replaced by optical telescopes. With this powerful weapon, the door of modern astronomy was opened.