Why lens need coatings

Jan 10 10:05 2012 David Yvon Print This Article

Why the need for the lens need coating? Because any object has a reflection on the light, even colorless transparent glass has no exception.

The difference is whether the angle of light will form a reflection effect. For the lens in the ideal state,Guest Posting the light through the lens can be completely and correctly in the film or CCD is completely focused. However, the fact is that each lenses titanium dioxide are subject to physical constraints, resulting in the generation of aberration, so the combination of a large number of lenses by the lens is theoretically impossible to complete all the various angles of light pass through. Lanthanum oxide optical glass as an example, the transmission rate can reach 90%, and the remaining 10% will be reflected off the formation of glare. To compensate for this loss, the researchers developed a subsequent lens surface coated with a layer of the lens membrane to increase the light effect In 1950s, people know that coating can reduce the incidence of glare, enhance the image contrast and reduce the photo-blooming. But because of no appropriate processing technology, therefore, the optical lens coating zinc oxide has always been only the highest level of the camera lens was entitled to the honor. Until 1968, a new generation of coating technology was developed to allow cheap coating process and the implementation of standards can only make the increasingly popular with the lens coating. Before1970s, the coating method is based on chemical reactions. This method must strictly control the concentration of chemical solution, a combination of cross-linking agent, reaction time and conditions. Because, only batch production, quality and yield obtained, the Senate defect missing. Commonly used processing method: a method for the dip, and the other was spraying method. For dipping method is based on the configuration properties of the membrane preparation containing components of the solution, and then the glass heated to a certain temperature, good chemical solution into the configuration, the out, drying, dip coating method can only produce two-mask the method. But then some of the lens design does not require double mask. Therefore, the other side must be washed, increased costs and environmental burden. Another deposition method, the solution is to configure a good film mounted on the gun, spray the surface of the glass, drying, and stereotypes. Glass carrier can be moved or rotated in order to increase film uniformity. Can be plated double-sided or single-sided. Extension of this method of students there is a rejection gel method. Drops of the solution to the lens center, high-speed rotation of the lens using centrifugal force, the solution is cast on the surface evenly. To the present point of view, the benefits of chemical coating, in its investment in equipment is low, so it is still a common organic film coating and low-cost method. In order to meet the requirements of photography, it is necessary for modern lens magnesiato multi-layer coat on the film. Different functions of these membranes can be broadly divided into seven categories: antireflective film, reflective film, filter membrane, polarized film, protective film and the electric membrane. In general the lens surface of the coating layer itself is colorless and transparent. Not only through the lens of the light will be reflected back, forming a human eye can see the reflection. The more light through the lens, reflector is weaker. Uncoated lens has relatively low transmittance, the lens surface of the more serious reflection on the spectrum have a strong reflection of light, so the overall color is white reflective; SC single-layer coating lens, the lens of the reflective surface is weak, greatly increasing the spectral transmittance of the central yellow green, only red and blue ends of the spectrum was only reflection, so general was light blue reflective purple; SMC multi-coated lens, The high transmittance of the lens, the lens surface of the direct reflection is very weak, need to cover the end of the lens cover, backlit glass lens opposite view, observed from the side of the lens can see the color of the reflective, this reflection by the different factory coating characteristics can be divided into dark red (AR Blu-ray), blue (AR red), dark yellow (by transparent blue-green) and dark green and so on. Dark green coating which can increase the spectrum of blue and red ends of the transmission, only the central part of the spectrum was only yellow-green light reflected back, so the antireflective film of the transmittance curve of a red and blue an increase in the peak and effective along the wide color gamut. Consider that if all the lenses are antireflection coated with the same membrane, bound to occur if the lens color cast. Therefore, each different camera lenses, the lens must be based on the materials used and the extent of absorption of different shade, were coated with antireflection coatings with different characteristics, each with up to make the lens to increase the total light transmittance, and The transmittance of the lens shade can reach equilibrium. In general, the outermost layer of the coated lens is usually the dura mater, it will not do harm to lens when general's hand touch or cleaning happens. This point, whether it is a traditional SLR camera or digital camera lens consumer alike. Although, this layer of film has a protective effect, but in fact its thickness may be only 0.1 nm, the friction is too strong, or will damage this layer of film formation, thereby affecting the shooting. Therefore, multilayer lens cleaning method, there are several points to note: Cleaning fluid selection: general use of anhydrous alcohol or ether (or a mixture of both) - (Note: ether as toxic chemicals). If you must clean up with water, you need to find ionized water or water, or leave the water classes. Choices for clean cloth: You can use cotton, the most simple and cheapest one. If the fiber left off, with the balloon can be blown off. Generally have a special camera lens shop selling paper, the deerskin, non-woven like cleaning supplies. Leather or cloth products should be used as frequently as possible. Because these reusable things will scratch the coatings when there is very small or hard sand deposition on it. Source:http://www.mhcocm.com

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David Yvon
David Yvon

MHC INDUSTRIAL (CHINA) CO, LTD,specializing in integrating development research and production of the optics coating material, the metal material, the rare earth material and so on, is a comprehensive enterprise.

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