The microscope is an optical instrument consisting of a lens or a combination of several lenses. It is a symbol of mankind's entry into the atomic age. Instruments used to magnify tiny objects become visible to the human eye. Microscope is divided into optical microscope and electron microscope. Optical microscope is in 1590 by the Dutch Janssen father and son of the first. Nowadays, optical microscopes can magnify an object 1600 times, and the minimum limit of resolution is 0.1 micrometers. There are many types of optical microscopes, in addition to the general, there are: ① dark-field microscope, a dark-field spotting mirror, so that the illumination of the beam does not come from the central part of the specimen, but from the four sides of the microscope to the specimen. ② fluorescence microscope, ultraviolet light as a light source, so that the irradiated object emits fluorescence microscope. The electron microscope was first assembled in 1931 in Berlin, Germany, by Knorr and Haroska. This microscope uses a high-speed electron beam instead of a light beam. Because the wavelength of the electron stream is much shorter than the light wave, so the magnification of the electron microscope can be up to 800,000 times, the resolution of the minimum limit of 0.2 nanometers. 1963 began to use the scanning electron microscope can be seen on the surface of the object's tiny structure. Microscopes are used to magnify images of tiny objects. They are generally used in biological, medical, and microscopic particle observation. Telescope is a visual optical instrument for observing long-distance objects, can be a very small angle of the far object according to a certain magnification, so that in the image of the space has a larger angle, so that the original can not be seen with the naked eye or distinguish the object into a clear and discernible. Therefore, the telescope is an indispensable tool in astronomy and ground observation. It is a kind of optical system through the objective lens and the eyepiece to make the incident parallel beam of light still maintain the parallel emission. According to the principle of telescope is generally divided into three kinds. An instrument that observes distant objects by collecting electromagnetic waves. In everyday life, telescope mainly refers to optical telescope. In modern astronomy, however, astronomical telescopes include radio telescopes, infrared telescopes, X-ray and gamma-ray telescopes. In recent years the concept of astronomical telescopes has been further extended to include gravitational waves, cosmic rays and dark matter. In everyday life, an optical telescope is usually an optical instrument in the form of a cylinder, which is used to focus light through refraction by a lens, reflection by a concave mirror to produce a direct image, or through a magnifying eyepiece for observation. Optical telescopes in everyday life are also known as "binoculars". It mainly includes amateur astronomical telescopes, theater telescopes and military binoculars.
The telescope is an eyepiece is a magnifying glass. Objective lens is the principle of the camera. Microscope is the eyepiece is a magnifying glass. But the objective lens is the principle of the projector.