Two hundred years of development history of vacuum coating machine technology and equipment

Two hundred years of development history of vacuum coating machine technology and equipment

Electroless coating was first used to prepare a protective film on the surface of optical components. Subsequently, in 1817, Fraunhofe attacked glass with concentrated sulfuric acid or nitric acid in Germany, and obtained an anti-reflection film for the first time by accident. Before 1835, someone deposited a silver mirror film by a chemical wet selection method. They are the first optical glasses prepared in the world. film. Later, various optical films were plated in chemical solutions and vapors. In the 1950s, except for some applications of antireflection coatings for large windows, chemical solution coating was gradually replaced by vacuum coating.

Vacuum evaporation and sputtering, the two vacuum physical coating processes, are the two most important processes for preparing optical thin films in the industrial field so far. They were applied on a large scale, in fact, after the appearance of oil diffusion pumps in 1930, mechanical pumping systems.

In 1935, someone developed a single-layer anti-reflection film deposited by vacuum evaporation. But its first application was in spectacle lenses after 1945.

In 1938, the United States and Europe developed double-layer anti-reflection coatings, but it was not until 1949 that high-quality products were produced.

In 1965, a broadband three-layer anti-reflection system was developed. In terms of reflective film, General Electric Company of the United States produced the first aluminum-coated lamp in 1937. Germany made the first anti-abrasion hard rhodium film for medical use in the same year. In terms of filters, Germany experimented in 1939 to deposit a metal-dielectric film Fabry-Perot-type interference filter.

In the field of sputtering coating, about 1858, researchers in Britain and Germany successively discovered sputtering in the laboratory. The technology has undergone a slow process of development.

In 1955, after Wehner proposed high-frequency sputtering technology, sputtering coating developed rapidly and became an important optical thin film process. Deposition processes such as bipolar sputtering, tripolar sputtering, reactive sputtering, magnetron sputtering and dual ion sputtering are available.

Since the 1950s, optical thin films have developed rapidly mainly in two aspects: coating process and computer-aided design. In terms of coating, a series of ion-based new technologies have been researched and applied.

In 1953, Auwarter of Germany applied for a patent for optical film coating by reactive evaporation, and proposed a proposal to increase chemical reactivity with ionized gas.

In 1964, Mattox introduced the ion plating system based on previous research work. The ion system at that time worked under a pressure of 10Pa and a discharge voltage of 2KV, and was used for coating wear-resistant and decorative coatings on metals, and was not suitable for coating optical films. Later, high-frequency ion plating was used to deposit optical films on insulating materials such as glass. Since the 1970s, a series of new technologies such as ion-assisted deposition, reactive ion plating and plasma chemical vapor have been studied and applied. They provide sufficient activation energy due to the use of energetic ions, increasing the rate of reaction at the surface. It improves the mobility of adatoms and avoids the formation of columnar microstructures, thereby improving the performance of optical thin films to varying degrees, which is the research and development direction of optical thin film manufacturing technology.

In fact, the development process of vacuum coating is far more complicated. Let's take a look at this two-hundred-year-old technological process:

19th century

Vacuum coating has a history of 200 years. In the 19th century, it can be said that it has always been in the stage of exploration and pre-research. The hardships of the explorers were fully reflected during this period.

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