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Lens service life and optical glass lens forming method
If the lens is not scratched, can it be used forever? The answer is no. The resin lens is processed by high temperature or ultraviolet curing of liquefied monomers. As the life cycle becomes longer, the environment and temperature change, the film on the surface of the lens and the material of the lens itself will undergo physical changes. The film will change when viewed under a microscope. It becomes uneven, the local luminosity of the material itself has been different from the time of fitting, resulting in light scattering, reduced comfort, and symptoms of dry and swollen eyes after long use. At this time, you need to replace the lens. The time is about 2 to 3 years.
spherical lens and aspherical lens
The traditional spherical lens is not only thicker, but also seen through the periphery of the lens Distortion and deformation of things occur, which is called aberration. Observing the wearer through the spherical lens sightseeing lens can also clearly find the deformation of the facial contour.
Aspherical lens not only reduces the center thickness and edge thickness of the lens, but also makes the lens thinner, eliminates peripheral aberrations, and gives the wearer natural vision. For high vision For consumers, it may be more appropriate to choose aspheric lenses.
Compared with aspherical surfaces of the same material and same degree, aspherical lenses are flatter, thinner, more realistic, natural and comfortable. If you look at the shape of the coating of the lens against the lamp tube, the lamp tube reflected by the aspheric lens is generally straight (except for high-diopter lenses); while the spherical lens has a larger curvature due to the different curvature of the surface of the lens.
With the continuous development of optical processing technology, optical processing has been continuously introduced into various industries. For example, the processing of optical glass translucent lens mirrors is the use of optical processing technology to process the glass.
The molding technology of optical glass lens is a high-precision optical element processing technology, which is to put the softened glass into a high-precision mold, and heat and press Under oxygen-free conditions, optical parts meeting the requirements of use can be directly molded at one time. The reason why glass can be precisely molded is mainly due to the development of mold materials that do not adhere to softened glass.
The original glass lens molding method is to pour the molten optical glass blank into a low temperature mold that is 50°C higher than the glass transition point and press to shape it. This method is not only easy to cause glass adhesion on the mold surface of the mold, but also easy to produce pores and cold mold marks (wrinkles) in the product, and it is not easy to obtain the ideal shape and the accuracy of the surface focusing lens.
Later, the pressing mold was precision-processed with special materials. In a non-oxidizing atmosphere, the glass and the mold were heated to near the softening point of the glass. The glass and the mold are approximately at the same temperature, and the mold is used to press the glass.
Next, while maintaining the applied pressure, while cooling the mold, the temperature drops below the glass transition point (the glass viscosity at the softening point of glass is about It is 107.6 poise, and the glass viscosity at the glass transition point is about 1013. 4 poise).
This method of isothermally pressing the glass and the mold together is called the isothermal pressing method, which is relatively easy to obtain high precision, that is, it is easy to precisely place the surface of the mold Copy down method.
The disadvantage of the square aspheric mirror method for manufacturing glass optical parts is that it takes a long time to heat up and cool down, so the production speed is very slow. In order to solve this problem, this method has been effectively improved, that is, several molds are used in a molding device to improve production efficiency. However, the cost of aspheric molds is very high, and the use of multiple molds will inevitably lead to excessive costs.
In response to this situation, we have further researched and developed a non-isothermal pressing method that is a little closer to the original lens blank molding conditions, so as to increase the production speed of each mold and the mold Service life. In addition, some people are researching and developing methods for directly forming precision glass flowing out of the melting furnace.
With the continuous development of technology, optical processing technology will continue to be applied to more industries and will be better developed.