What are the types of telescopes? What are the types of telescopes?

1. There are three main types of optical telescopes:

1.reflexive, mainly referring to Newtonian;

2.fold trans, mainly Kepler;

3.refractive; Mainly refers to the Galilean style;

2. Radio telescopes.

There are two types: the Galilean telescope, which uses a concave lens as an eyepiece; A convex lens as an eyepiece is called a Kepler telescope. The basic principle of Keplerian telescopes is that the light from a distance first enters the convex lens of the objective lens, and the first time it becomes an inverted, reduced real image, which is equivalent to a camera; Then this real image enters the convex lens of the eyepiece, and for the second time it becomes an upright and magnified virtual image, which is equivalent to a magnifying glass.

Because the chromatic aberration and spherical aberration of single-lens objectives are quite serious, modern refractive telescopes often use two or more lens group lenses. Among them, the bilens objective lens (ordinary achromatic telescope) is the most commonly used. It consists of a convex lens made of crown glass and a concave lens made of flint glass that are very close to each other, and completely eliminates positional chromatic aberration for two specific wavelengths, and can also reduce positional chromatic aberration for the remaining wavelengths.

Galileo telescope.

The objective lens is a converging lens, whereas the eyepiece is a telescope of divergent lenses. The real image formed by the refraction of light through the objective lens is on the focal point behind the eyepiece (near the back of the human eye), which is a virtual image of the eyepiece, so it is refracted into an amplified upright virtual image. The magnification of the Galilean telescope is equal to the ratio of the focal length of the objective lens to the focal length of the eyepiece.

The advantage is that the lens barrel is short and can be orthodox, but it has a relatively small field of view. The device that juxtaposes two Galilean telescopes with low magnification and uses a bolt button in the middle to adjust their clarity at the same time is called a "theater viewing mirror"; Because it is easy to carry, it is often used to perform and so on. The telescope invented by Galileo occupies an important place in the history of human understanding of nature.

It consists of a concave lens (eyepiece) and a convex lens (objective). Its advantage is that it has a simple structure and can be directly formed into a positive image.

<> optical stool astronomical telescopes are further divided into reflective, reflective and catadioptric astronomical telescopes.

As the name suggests, a refracting telescope uses the principle of refraction of light to concentrate light rays. Early telescopes generally used a convex lens, but this introduced a chromatic aberration problem.

The dispersion of light knows that light of different frequencies has different refraction angles after passing through the lens, so when the light passes through the refractive telescope, there will inevitably be chromatic aberration, which is embodied in the purple color at the edge of the object.

In order to solve this problem, people use a variety of lens combinations to reduce chromatic aberration to a certain extent, and now the chromatic aberration of good refracting telescopes has been reduced to a negligible level. But because of the use of a variety of lenses, it is relatively high. The advantage is that the imaging is sharp, which is conducive to astrophotography.

Land Bridge Sail. Reflecting telescopes use the principle of light reflection to concentrate light. Since the reflection principle is used, there is no problem with chromatic aberration. However, compared to refraction, the objective lens of a reflecting telescope has a secondary mirror in addition to the primary mirror, which generally blocks the light path.

In addition, the imaging of reflective telescopes is very sensitive to the optical axis and accuracy, and the lens barrel is open, so it is easy to enter the dust, and the optical axis needs to be adjusted, which can be a bit difficult for novices. But its advantage is that it is cheap, and the caliber can be made very large.