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Optometry Phoropter With Toughness While Improving The Hardness
Jun 14, 2017

First, wear-resistant film (dura mater)

Optometry Phoropter Whether it is inorganic materials or organic materials made of glasses, in the daily use, due to dust or gravel (silica) friction will cause lens wear, scratches on the surface of the lens. Compared with the glass, organic materials made of relatively low hardness, more prone to scratches. Through the microscope, we can observe the lens surface scratches are divided into two kinds;

First, due to gravel produced scratches, shallow and small, wearing glasses are not easy to detect; the other is produced by the larger gravel scratches, deep and rough surrounding, in the central area will affect the vision.

(1) technical characteristics

1, the first generation of anti-wear film technology

Anti-wear film began in the early 1970s, when the glass lens is not easy to wear because of its high hardness, and organic lenses are too soft so easy to wear. So the quartz material in the vacuum conditions plated on the surface of organic lenses to form a layer of very hard anti-wear film, but because of its thermal expansion coefficient and the matrix material does not match, it is easy to stripping and film fragmentation,Optometry Phoropter so anti- Wear effect is not ideal.

2, the second generation of anti-wear film technology

After the 1980s, the researchers found that the mechanism of wear is not only related to hardness, but also has the hardness of "hardness / deformation", that is, some materials have higher hardness but smaller deformation, and some Material hardness is low, but the deformation is large. The second generation of anti-wear film technology is through the soaking process in the organic lens surface coated with a high hardness and not easy to crack the material.

3, the third generation of anti-wear film technology

The third generation of anti-wear film technology is developed after the 20th century, 90 years, mainly to solve the organic lens coated with anti-reflective film after the wear resistance problem. Because of the hardness of the organic lens base and the hardness of the antireflective film, the new theory suggests that there is a need for an abrasion resistant film between the two,Optometry Phoropter allowing the lens to cushion when subjected to gravel friction And not easy to produce scratches. The hardness of the third generation of anti-wear film material between the anti-reflective film and the hardness of the film between the film, the friction coefficient is low and not easy to crack.

4, the fourth generation of anti-wear film technology

The fourth generation of anti-film technology is the use of silicon atoms, such as France Essilor's TITUS (TITUS) plus hard liquid contains both organic matrix, but also contains silicon-containing inorganic ultrafine particles, so that wear-resistant film With toughness while improving the hardness. Modern anti-wear film technology is the most important way to use immersion, that is, after a multi-channel cleaning lens,Optometry Phoropter immersed in the hard liquid, after a certain period of time to a certain speed. This speed is related to the viscosity of the hardened solution and is critical to the thickness of the wear resistant film. After the addition of 100 ° C in the oven about 4-5 hours, the coating thickness of about 3-5 microns.

(2) test method

The most fundamental way to judge and test the abrasion resistance of abrasion resistant membranes is to use it so that the wearer wears for a while and then observes and wears with the lens. Of course, this is usually in this new technology before the formal promotion of the method used,Optometry Phoropter we often used more rapid and intuitive test method is:

 1, frosted test

The lens placed in the gravel containing promotional materials (the provisions of the gravel of the particle size and hardness), under certain control for back and forth friction. After the end of the lens with a haze meter to measure the amount of light diffuse before and after friction, and compared with the standard lens.

 2, steel velvet test

With a specified steel velvet, at a certain pressure and speed, the number of times the friction on the surface of the lens, and then use a haze meter to test the lens before and after the light diffuse reflection, and with the standard lens for comparison. Of course, we can also manually manipulate the same number of times the same pressure on the two lenses, and then use the naked eye to observe and compare.

The results of the two test methods and wearing glasses who wear long-term clinical results are relatively close.

(3) the relationship between the anti-reflective film and the anti-wear film

The anti-reflective film on the surface of the lens is a very thin inorganic metal oxide material (thickness less than 1 micron), hard and brittle. When coated on the glass lens,Optometry Phoropter the base is relatively hard, gravel over it, the film is relatively easy to produce scratches; but the anti-reflective film is coated on the organic lens, the base is softer, gravel in the film Layers across the film is prone to scratches. Therefore, organic lenses must be plated with anti-wear film before plating, and the hardness of the two layers must match.

Second, the anti-reflective film

(1) Why do you need to reduce the reflective film?

1, mirror reflection

Light through the front and back of the lens surface, not only will produce refraction, but also produce reflection. This reflected in the front of the lens produced by the light will make others see the eyes of the glasses, see the lens is a white surface. When taking pictures,Optometry Phoropter this reflection will seriously affect the appearance of wearing glasses.

2, "ghost"

Optical glasses optical theory that the lens of the refractive power will make the object in the wearer's point of view to form a clear image, can also be interpreted as the light of the object through the lens deflection and gathered in the retina, the formation of image points. However, since the curvature of the front and back surfaces of the refractive lens is different, and there is a certain amount of reflected light,Optometry Phoropter an internal reflection light is generated therebetween. The reflected light produces a virtual image near the far point sphere, that is, a virtual image point near the image point of the retina. These virtual image points will affect the visual clarity and comfort.

3, glare

Like all optical systems, the eye is not perfect, as in the retina is not a point, but a fuzzy circle. Thus, the sensation of two adjacent points is generated by two juxtaposed or more overlapping fuzzy circles. As long as the distance between the two points is large enough,Optometry Phoropter the imaging on the retina will produce a two-point feeling, but if the two points are too close, then the two fuzzy circles will tend to coincide with, is mistaken for a point.

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