The difference and knowledge of aspheric and spherical optical lenses

by:Crylight     2021-05-11

Most people probably know about optical lenses. Lenses are divided into spherical lenses and aspheric lenses. So what is an aspherical lens, and what is the difference between a spherical lens and an aspherical lens?

The surface curvature of aspherical lens is different from that of ordinary spherical lens, in order to pursue thinner lens It is necessary to change the curved surface of the lens. In the past, the spherical design was used to increase the aberration and distortion. As a result, there were obvious unclear images, distortion of the field of view, and narrow field of view. The current aspheric design corrects the image and solves the problem of distortion of the horizon. At the same time, it makes the lens lighter, thinner, and flatter. Moreover, it still maintains excellent impact resistance, allowing the wearer to use it safely.

  From the appearance of the lens, generally aspherical lens is more beautiful. This is because aspherical lens, under the same material and power, aspherical lens The lens is flatter and thinner than the spherical lens, so people with higher power usually wear aspherical lenses. This kind of aspherical lens feels very comfortable to wear.

   Generally, if you look at things from the periphery of a traditional spherical lens, distortion will appear. Instead of a spherical design, the edge difference of the lens is reduced to a minimum. The surface curvature of the aspheric lens is aspherical design, which makes it more natural to see things, with less distortion and more lifelike viewing.

   For patients with mild myopia, spherical lenses and aspheric lenses are similar, so you can choose spherical lenses. But if it is more than -2.00DS and people with astigmatism, it is better to choose aspherical lens, which can reduce the deformation of things very well and is very comfortable to wear.

The higher the degree of    spherical lens, the worse the appearance will be. The spherical lens cannot eliminate the difference. The aspheric lens has a beautiful appearance, reduces the phase difference of the optical lens, and can obtain a clearer vision. And after the lens is coated, the lens of the aspheric laser protection mirror has a more perfect visual performance, a clearer vision and more comfortable.

   Optical glass refers to glass that can change the direction of light propagation and can change the relative spectral distribution of ultraviolet, visible or infrared light. The difference between optical glass and other glasses is that as an integral part of the optical system, it must meet the requirements of optical imaging. Therefore, the judgment of the quality of optical glass also includes some special and stricter indicators. Components made of optical glass are key elements in optical instruments.

  The optical glass lens is an indispensable part of the machine vision system, which directly affects the quality of the image and the realization and effect of the algorithm. The choice of optical glass materials is very important, because different glass types have different characteristics. The basic properties of optical glass: Specify the ratio of the speed in the material-this laser collimator is a description of how the speed of light slows down as it passes through the optical material. The refractive index of the optical glass, nd, has a specified wavelength of 587.6nm (helium D line). The material with low refractive index is usually called'crown glass', and the material with high refractive index is called'flint glass'. The typical refractive index tolerance of the components in our catalog is ±0.0005.

  chromatic dispersion

  chromatic dispersion refers to the phenomenon that the refractive index changes with wavelength. Using the Abbe value, expressed by vd, is defined as (nd-1)/(nF-nC); nF and nC are the refractive indices at 486.1nm (hydrogen F line) and 656.3nm (hydrogen C line), respectively. A low Abbe value indicates high dispersion. Crown glass usually has a lower dispersion than flint glass. The typical Abbe tolerance of the components in our catalog is ±0.8%.

  Transmission

  Standard optical glass provides high performance for the entire optical lens visual spectrum and the near ultraviolet and near infrared range. transmission. The transmission of crown glass in NUV is usually stronger than flint glass. Due to the high transmittance of flint glass, which results in high Fresnel reflection loss, it should always be specified to be used in conjunction with an antireflection coating.

  Optical glass is mainly used in various specifications of cameras, high-performance mobile phone displays, and optical lenses and glass parts of mobile phones with camera functions. At present, the mainstream resolution of camera and video phone is 5 million pixels, and it is gradually increasing to 8 million pixels, 10 million pixels and other higher resolutions. Higher resolution requires more complex optical systems and more precise optical glass parts. The introduction of features such as autofocus and zoom functions in mobile phones will increase the number of lenses required. The general 2, 3 and 4x zoom lenses require 4 to 6, 6 to 8 and 7 to 9 lenses respectively. Therefore, it is necessary for optical glass components The demand is also growing.

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