Microscopic imaging principle

Microscope uses the magnifying imaging principle of convex lens to enlarge tiny objects that can't be distinguished by human eyes to the size that can be distinguished by human eyes. Its main purpose is to increase the opening angle of nearby tiny objects to the eyes (objects with large viewing angle image on the retina), and its magnification is expressed by angular magnification m.

Because the opening angle of the same object to the eye is related to the distance between the object and the eye, the magnification of the image at a distance of 25 cm (apparent distance) from the eye is generally specified as the magnification of the instrument. When observing an object with a microscope, the viewing angle is usually very small, so the ratio of viewing angles can be replaced by the ratio of tangents.

The microscope is one of the greatest inventions of the 20th century. Before it was invented, human's concept of the world around him was limited to what the naked eye could see, or through holding a lens.

Microscope shows a brand-new world in human vision. For the first time, people saw hundreds of "new" tiny animals and plants, and all the internal structures from human body to plant fibers. Microscopes also help scientists discover new species and help doctors treat diseases.

The earliest microscope was made in Holland at the end of16th century. The inventor is the Dutch optician Yas Zhan Sen, or another Dutch scientist Hans Lipper. They made a simple microscope with two lenses, but they didn't make any important observations with these instruments.

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Microscopic classification

According to the number of eyepieces used, optical microscopes can be divided into three-eye, binocular and monocular microscopes. According to whether the image has stereoscopic effect, it can be divided into stereoscopic microscope and non-stereoscopic microscope; According to observation, objects can be divided into biological microscope and metallographic microscope; According to the optical principle, it can be divided into polarization microscope, phase contrast microscope and differential interference contrast microscope.

According to the type of light source, it can be divided into ordinary light, fluorescence, infrared light and laser microscope. According to the type of receiver, it can be divided into visual microscope, photographic microscope and television microscope. Commonly used microscopes include binocular continuous zoom stereo microscope, metallographic microscope, polarizing microscope and ultraviolet fluorescence microscope.

Binocular stereoscopic microscope provides stereoscopic images for left and right eyes by using dual-channel optical path. Essentially, two single-lens-tube microscopes are placed side by side, and the optical axes of the two lenses are equivalent to the visual angle formed when people observe an object with their eyes.

So as to form a stereoscopic vision image in a three-dimensional space. Binocular stereomicroscope is widely used in biology and medicine, for slicing and microsurgery. It is used for the observation, assembly and inspection of micro parts and integrated circuits in industry.

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