What Are Safety Goggles?

Protective glasses are a type of filter that can change the intensity and spectrum of transmitted light. The most effective and common way to avoid eye damage from radiation is to wear protective glasses. These glasses can absorb light of some wavelengths and allow light of other wavelengths to pass through, so they all show a certain color, and the color presented is the color of transmitted light. One is the absorption type and the other is the reflection type. The former is used most often. Goggles are glasses that can change the intensity and spectrum of transmitted light to prevent radiation from causing damage to the eyes. These glasses are divided into two categories, one is the absorption type, and the other is the reflection type. The former is used the most.

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Protective glasses is a

When this lens is manufactured, a part of metal oxides such as iron, diamond, chromium, strontium, nickel, manganese, and some rare earth metal oxides such as and neodymium are added to the general optical glass formula. These metal oxides enable glass to selectively absorb electromagnetic waves in a certain band of light. For example, oxides of cerium and iron can absorb ultraviolet rays in large quantities. The use of such glass lenses can reduce the amount of light passing through the lens at certain wavelengths, reducing or preventing eye damage. Different color protective lenses can absorb different colors of light. These glasses are divided into two categories, one is the absorption type, the other is the reflection type, the former is used the most.

Lens hair is generally round, the specifications are expressed by its diameter, the unit is mm, there are 48, 50, 52, 56, 60, 65, 70 and so on. The most commonly used are 56, 60, and 65. Due to the popularity of large frames, the use of large size lenses such as 70 has increased.

The size and shape of the spectacle lens that conforms to the shape of the frame after the hair piece processing is naturally determined by the curve of the inner edge of the frame. The lens should indicate the horizontal direction and the nasal side, otherwise the asymmetrically shaped lens will become a completely different shape after rotation. The size of the lens is expressed by both the length of the reference line and the height of the reference line (reference line method), that is, AA '× B'B in mm (for example, 46 × 40); or the horizontal and vertical dimensions of the circumscribed rectangle ( Box method).

The lens shape is represented by a shape difference. The so-called sheet shape difference is the difference between the length of the reference line and the height of the reference line (baseline method), or the difference between the horizontal and vertical dimensions of the circumscribed rectangle (box method). What is not specified is the baseline method. For example, a 46 × 40 lens has a sheet shape difference of 6 (ie, 46-40). Different lens shapes of some lens series are represented by the shape difference. The shape difference is 3 or 4, which is a high shape; the shape difference is 10, which is a short shape. Early lenses were symmetrical-round or oval. The circular lens has a difference in shape of 0, a short ellipse of 4, and a long ellipse of 9. The semicircle is connected under the semiellipse to form a "Pantoscopic Round Oval" (PRO). There are a variety of sheet differences. The larger sheet difference is called the "wide field of vision" shape. In addition, there are "outline shapes", "squares", "borderless shapes" and "sport shapes" and so on. The change in lens shape is mainly caused by the continuous refurbishment of modern eyeglass frames. Frames with different baseline lengths (such as 40, 42, 44, 46) can have the same sheet shape difference 4 (such as 40 × 36, 42 × 38, 44 × 40, 46 × 42), but they are not the same as each other Proportion, so the sheet shape also varies.

In the box method, it is the difference from the horizontal size of the circumscribed rectangle. Therefore, LSWF should indicate whether it is a box method. Determine the LSWF, find the geometric center of the frame or the cut lens that conforms to the shape of the frame, which is the M point in the baseline method; measure the maximum distance from the center of the collection to the edge of the frame or lens; twice the distance is the minimum The diameter of the uncut lens; the measured length of the scene or the baseline of the lens; the difference between the minimum uncut lens diameter and the length of the baseline is LSWF. The maximum distance from the geometric center (M) of the lens to the edge of the lens is 29mm, so 58mm is the minimum diameter of the lens. If its reference line length (AA ') is 48mm, the LSWF is 10mm. LSWF, optional

Lens measurement table (spherical instrument):

This table can measure the sag between K and L. The distance from K to L is 2y, the middle moving stylus and the surface pointer are connected by gears, and the surface scale is

The most common goggles are welder goggles with a shading number of 14, which are available on the welding equipment market. The goggles sold by various online shop owners usually cost 5 yuan, 10 yuan and 15 yuan. The price of an ordinary color goggle is generally around 5 yuan. The German Bud film silver lens goggles 10 yuan, black lenses 15 yuan. Most of these shop owners who sell goggles are "halfway homes" and make a fortune while they are in the sky.

According to experts, when using the astronomical telescope or the naked eye to observe the sun, a Bard film or other filtering device must be added in advance, otherwise the fundus and instruments will be burned. Among them, Bard film not only has stronger contrast, but also makes the sun show true colors. The reporter searched on Taobao.com and found that in most online shops selling paper eclipse observation mirrors, they were marked with "Bad film", but most of them did not indicate whether they had been tested by professional departments. In this regard, relevant experts remind that in accordance with international standards, the use of a 5.0 bard film density mirror can be used for total solar eclipse observation, and the reasonable price of such a solar eclipse observation mirror is about 5 yuan. Qualified protective goggles look at the sun, the sun will appear gray and white, and the ground is black, and basically nothing can be seen clearly.