Detail the telescope's working principle and related products

The purpose of a telescope is to magnify the Angle of distant objects so that the human eye can see smaller details. Another function of the telescope is to send the beam of light collected by the objective lens, which is much larger than the diameter of the pupil (about 8mm at most), like the human eye, so that the observer can see faint objects that were previously invisible. Here is a typical pair of binoculars. A telescope in which the objective lens is a convergent lens and the eyepiece is a divergent lens. The real image refracted by the light through the objective lens is at the rear of the eyepiece (close to the rear of the human purpose) focus, which is a virtual image to the eyepiece, so after it is refracted into a magnified upright virtual image. The magnification of a Galilean telescope is equal to the ratio of the focal length of the objective lens to the focal length of the eyepiece. Its advantage is that the tube is short and can be positive, but its field of view is relatively small. The device that puts two Galilean telescopes with low magnification side by side and adjusts their clarity at the same time with a bolt knob in the middle is called the "opera mirror"; Because it is convenient to carry, it is often used to watch performances. You can build a Galilean telescope at very low cost. Buy a lens with a larger diameter and focal length as an objective lens and a lens with a smaller focal length and diameter as an eyepiece from a cultural supplier. By placing two lenses in a cardboard tube with glue and a small slot, and making a simple pedestal, a telescope was made that could see the mountains on the moon, the stars in the Milky Way, and the moons of Jupiter. Come to think of it, Galileo discovered it with this guy. But remember, don't look directly at the sun through a telescope, lest the heat burn your eyes! Galileo's refractor telescope had the annoying drawback of producing "false colors" around bright objects. The problem with "false colors" is that what is commonly called "white light" is not white light at all, but a mixture of all the colors from red to purple that make up the rainbow. When the beam enters the objective and is refracted, the degree of refraction of the various colors of light is different, so the focus of the imaging is also different, and the blur is produced. In 1611, another astronomer Kepler used two convex lenses as the objective lens and the eyepiece, which significantly improved the magnification, and later people called this optical system Kepler-type telescope. These two types of refracting telescopes are still used today. But the "false color" problem remains unsolved. Lippert, who was not an astronomer, never thought of pointing his new device at the sky. But it wasn't long before news of his discovery spread. Fortunately, Galileo Galilei, a professor at the University of Padua in Italy, found out about it. Galileo soon built a refracting telescope. He uses a plano-convex lens as the objective lens and a concave lens as the eyepiece. Light from the object under study strikes a glass lens of the telescope's objective. The objective refracts the light and focuses it on a point called a focal point, where the image of the luminous body is formed. This image is amplified by the lens of the eyepiece and enters the human eye.