PPE

Specifications of goggles

The most effective and commonly used method to avoid damage to eyes caused by radiation is to wear protective glasses. The so-called protective glasses is a kind of filter, which can change the transmitted light intensity and spectrum. This kind of glasses is divided into two categories, one is the absorption type, the other is the reflection type, the former is the most used.

This kind of glasses can absorb light of certain wavelengths and let other wavelengths of light pass through, so they all present a certain color, and the color presented is the color of transmitted light. When this kind of lens is manufactured, a part of metal oxides, such as iron, diamond, chromium, strontium, nickel, manganese, and some rare earth metal oxides such as neodymium, are added to the general optical glass formulation. These metal oxides enable the glass to selectively absorb electromagnetic waves in a certain band of light. For example, iron oxides can absorb a large amount of ultraviolet rays. The use of this glass lens can reduce the amount of certain wavelengths passing through the lens, reducing or preventing damage to the eyes. Different colors of protective lenses can absorb light of different colors. The following is a brief introduction of various types of protective glasses.
1. Absorption filter
1. Sunglasses
The visible light transmittance is about 20%, and the absorption of ultraviolet and infrared is good. There are light green, light gray, light tea and other colors, used to make sun-shading and snow work protective glasses. Among them, light gray lenses have the least effect on color recognition; light tea glasses make the blue sky look darker and reduce the transmission of green light; light green lenses reduce the transmission of red light.
2. Goggles for gas welding
The colorants used in this kind of lens are mainly iron oxide, cobalt oxide, etc., which are yellow-green and can absorb all light waves with wavelengths below 500 urn, and the transmittance of visible light is below 1% , Only a small amount of infrared rays can pass through. This kind of glasses is specially designed for gas welding operation.
3. Goggles for electric welding
Ultraviolet rays generated by electric welding can cause damage to the cornea and conjunctiva tissue (28nm light is the most serious). The strong infrared rays produced can easily cause opacity of the eye lens. Welding goggles can block the above infrared and ultraviolet rays well. This kind of lens is based on optical glass and uses colorants such as iron oxide, cobalt oxide and chromium oxide, and a certain amount of cerium oxide is added to increase the absorption of ultraviolet rays. The appearance is green or yellow-green. It can block all ultraviolet rays, the infrared transmittance is less than 5%, and the visible light transmittance is about 0.1%.
4. There are two kinds of blue goggles, one is colored iron oxide and cobalt oxide, and the filament is purple red with it, and the other is colored copper oxide and manganese oxide. The filament is white. They can all absorb the dazzling glare in the 500-600nm (visible light sensitive area of ??the human eye). The light transmittance at 400nm is below 12%. It also has a certain absorption effect on ultraviolet rays. It is suitable for various industrial high-temperature furnaces. Personnel wear.
5. Crimson glass glasses
This kind of spectacle lens is a kind of dark red glass colored with cadmium sulfide and cadmium sulphur selenide, which can absorb all light with a wavelength below 600nM. It can be used as goggles for medical or industrial personnel operating X-ray fluoroscopy equipment.
6. Laser protective glasses
This kind of glasses has two forms, namely reflective and absorptive. The surface of the former is coated with a metal film by vacuum coating method. It is suitable for laser wavelengths of 532nm, 694nm and 1060nm. The reflectivity is greater than 99.5%; the latter lens can fully absorb the 1060nm laser waveband. The lens must be equipped with a closed or semi-closed frame to prevent the laser from bypassing the lens and entering the eye. It can be used as protective glasses for laser operators.
7. Microwave protective glasses
Microwave is an electromagnetic wave with a wavelength of about 1nm-1M, which can also cause harm to people, especially eyes. Under the action of strong microwaves, it can cause eye fatigue, dry eyes and dizziness, and can even cause lens opacity, cataracts and retinal damage. It is protected by spraying tin tetrachloride on the surface of the lens and a metal compound that can increase conductivity, forming a multilayer conductive film on the surface of the lens, which plays a role in shielding microwaves. Because the microwave can bypass the lens and enter the eye, the frame of the lens should also be shielded to prevent the damage to the eye caused by the microwave.
2. Reflective filter
Absorption filter, which uses the lens to absorb certain wavelengths of light to reduce the intensity of light entering the eye, but because the lens absorbs some light, it changes Heat is emitted, especially infrared rays and other light with longer waves. The accumulation of heat generated makes the eyes feel very uncomfortable. If a reflective filter is used, this problem can be solved well. As mentioned in the previous coated glasses, if the surface of the lens is coated with a layer of material with a higher refractive index than the lens itself, it will increase the reflection of light and reduce the intensity of light transmission, so that it can protect The eyes are not harmed by strong light and harmful rays. In actual work and life, in many cases, the absorption type and the reflection type are used in combination, that is, a layer of high reflection film is plated on the colored lens to make the filtering effect stronger, such as electric welding, chlorine arc welding, plasma cutting and other operators. Wearing glasses can be solved by this method.

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