Judgment requirements for optical glass and optical lens performance requirements

by:Crylight     2021-05-25

There are many types of    glass, of which optical glass is one of them, which can change the direction of light propagation. It is widely used in lenses, prisms, etc. of optical instruments. Optical glass is not better than ordinary glass, and the requirements for the quality of optical glass are also very high. 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 optical glass quality also includes some special and stricter indicators. There are the following requirements for optical glass:

   One, specific optical constants and the consistency of the optical constants of the same batch of glass

Each type of optical glass has a prescribed standard refractive index value for different wavelengths of light, which serves as the basis for optical designers to design optical systems. Therefore, the optical laser focusing lens constants of the optical glass produced by the factory must be within a certain allowable deviation range of these values, otherwise the actual imaging quality will not match the expected result during the design and the quality of the optical instrument will be affected.

   At the same time, because the same batch of instruments are often made of the same batch of optical glass, in order to facilitate the unified calibration of the instruments, the allowable deviation of the refractive index of the same batch of glass should be compared with their deviation from the standard value. More stringent.

  Second, high transparency

  The image brightness of the optical system is proportional to the glass transparency. The transparency of optical glass to light of a certain wavelength is expressed by the light absorption coefficient Kλ. After the light passes through a series of prisms and lenses, part of its energy is lost by the interface reflection of the optical parts and the other part is absorbed by the medium (glass) itself. The former increases with the increase of the refractive index of the glass. For high-refractive-index glass, this value is very large for laser protective mirrors. For example, the reflection loss of one surface of the mirror glass is about 6%.

   Therefore, for an optical system containing multiple thin lenses, the main way to increase the transmittance is to reduce the reflection loss on the lens surface, such as coating a surface antireflection coating. For large-size optical parts such as the objective lens of an astronomical telescope, the transmittance of the optical system is mainly determined by the light absorption coefficient of the glass itself due to its large thickness. By improving the purity of the glass raw materials and preventing any coloring impurities from mixing in the entire process from batching to smelting, the light absorption coefficient of the glass can generally be made less than 0.01 (that is, the light transmittance of the glass with a thickness of 1 cm is greater than 99%) .

  In the past, the optical lens used a spherical design to increase the aberration and distortion, resulting in obvious image blur, distortion of the field of view, and narrow field of view. Phenomenon, the image is corrected, and the distortion of the field of view is solved. At the same time, the optical lens is made lighter, thinner, and flatter. Moreover, the optical lens still maintains excellent impact resistance, so that the wearer can use it safely and see objects around the optical lens. There are distortions that limit the wearer's field of vision. In the era of continuous technological advancement, the aspheric design, an optical miracle, minimizes the edge aberration of the optical lens, making it a wide field of view to meet the needs of customers.

   The base curve of the optical lens is flatter, lighter, and looks more natural and beautiful. In the case of high diopter, it can reduce the distortion of the eye. For consumers with high vision, it may be more appropriate to choose aspherical optical lenses for optical lenses. After wearing aspherical optical lenses, you can hardly feel the existence of optical lenses. It will lose weight for your eyes and enjoy the ease it brings you. At random, the outer surface of the optical lens reflects the image of the fluorescent tube in the form of a wooden barrel with a bulge in the middle and gradually narrowing on both sides; the higher the luminosity of the optical lens, the more obvious the optical lens.

  Measure the diopter change trend of the optical lens from the optical center to the edge. The optical lens places the aspheric optical lens laterally under the transmitted light of the fluorescent light source, and selects the best base curve The optical lens controls the aberration in a small range. The modern eye optical lens has been designed by computer. The computer can make a very accurate optical path tracing, find the best form of the optical lens, and find the surface of the optical lens. The whirlpool effect appears. The higher the luminosity, the more obvious this effect is. This inspection method is also suitable for higher luminosity myopia and presbyopic optical lenses.

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