Principle of operation and history of development of optical microscopes
Optical Microscope (OM) is an optical instrument that uses optical principles to magnify and image small objects that cannot be distinguished by the human eye, in order to extract microstructural information.
As early as the first century BC, it was discovered that observing small objects through spherical transparent objects can magnify and image them. Later, I gradually gained an understanding of the law that spherical glass surfaces can magnify and image objects. In 1590, eyewear manufacturers in the Netherlands and Italy had already created magnifying instruments similar to microscopes. Around 1610, Galileo of Italy and Kepler of Germany, while studying telescopes, changed the distance between the objective and eyepiece to obtain a reasonable microscope optical path structure. At that time, optical craftsmen were engaged in the manufacturing, promotion, and improvement of microscopes.
In the mid-17th century, Robert Hooke from England and Lewandowski from the Netherlands made outstanding contributions to the development of microscopes. Around 1665, Hooke added coarse and micro focusing mechanisms, lighting systems, and workbenches to carry specimen slides in the microscope. These components have been continuously improved and become the basic components of modern microscopes.
Between 1673 and 1677, Levin Hooke created a single component magnifying glass type high-power microscope, of which nine have been preserved to this day. Hooke and Levin Hooke achieved outstanding achievements in the study of the microstructure of animal and plant organisms using their self-made microscopes. In the 19th century, the emergence of high-quality achromatic immersion lenses greatly improved the ability of microscopes to observe fine structures. In 1827, Archie was the first to use immersion lenses. In the 1870s, German Albert laid the classical theoretical foundation for microscopic imaging. All of these promoted the rapid development of microscope manufacturing and microscopic observation technology, and provided powerful tools for biologists and medical professionals, including Koch and Pasteur, to discover bacteria and microorganisms in the second half of the 19th century.
Along with the development of the structure of the microscope itself, microscopic observation technology is also constantly innovating: polarized microscopy emerged in 1850; In 1893, interference microscopy emerged; In 1935, Dutch physicist Zelnik created phase contrast microscopy, for which he was awarded the Nobel Prize in Physics in 1953.
Classical optical microscopes are simply a combination of optical and precision mechanical components, using the human eye as a receiver to observe magnified images. Later, a photography device was added to the microscope, using photosensitive film as a receiver for recording and storage. In modern times, photoelectric components, television cameras, and charge couplers are commonly used as receivers for microscopes, combined with microcomputers to form a complete image information acquisition and processing system.
Optical lenses made of glass or other transparent materials with curved surfaces can magnify and image objects, and optical microscopes use this principle to magnify small objects to a size that can be observed by the human eye. Modern optical microscopes typically use two stages of magnification, each completed by an objective lens and an eyepiece. The observed object is located in front of the objective lens, and after being magnified by the objective lens in the first stage, it forms an inverted real image. Then, this real image is magnified by the eyepiece in the second stage, forming a virtual image. What the human eye sees is the virtual image. The total magnification of a microscope is the product of the objective magnification and the eyepiece magnification. Magnification ratio refers to the magnification ratio of linear dimensions, not the area ratio.
