An effective and common way to avoid radiation damage to the eyes is to wear protective glasses. The so-called protective glasses are a kind of filter that can change the intensity of transmitted light. and spectrum. This kind of glasses can be divided into two categories, one is absorption type, the other is reflection type, and the former is used more.
Protective glasses can absorb some wavelengths of light and let other wavelengths of light pass through, so they all show a certain color, showing The color of is the color of the transmitted light. When manufacturing lenses, 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 formula. These metal oxides can make the glass selectively absorb electromagnetic waves of a certain wavelength of light. For example, oxides of cerium and iron can absorb a lot of ultraviolet light. Using this glass lens can reduce the amount of certain wavelengths passing through the lens, reducing or preventing damage to the eyes. Protective glasses of different colors can absorb different colors of light. The following is a brief introduction to various types of protective glasses.
Absorbing filter protective glasses: 1. Sunshade glasses are also called sunglasses, and the visible light transmittance is about 20%. , can absorb ultraviolet and infrared rays well. There are many colors, such as light green, light gray, light tea, etc., which are used to make protective glasses for sunshade and snow operations. Among them, the light gray lens has little effect on color recognition; the light brown glass makes the blue sky look darker and reduces the transmission of green light; the light green lens reduces the transmission of red light. 2. Goggles for gas welding. The colorants used in these lenses are mainly iron oxide, cobalt oxide, etc. It is yellow-green and can completely absorb light waves below 500 m. The transmittance of visible light is below 1%, and only a small amount of infrared light can pass through. This kind of glasses is specially used for gas welding. 3. Goggles for electric welding. Short-term exposure to the eyeball by ultraviolet rays generated by electric welding will damage the cornea and conjunctival tissue, and the intense infrared rays generated will easily cause the lens of the eye to become cloudy. Welding goggles can well block the above-mentioned infrared rays and ultraviolet rays. This lens is based on optical glass, uses iron oxide, cobalt oxide, chromium oxide and other colorants, and adds a certain amount of cerium oxide to increase the absorption of ultraviolet rays. The appearance is green or yellow-green, which can completely block ultraviolet rays and transmit infrared rays. The pass rate is less than 5%, and the visible light transmittance is about 0.1%.
Reflective filter protective glasses: Absorbing filters use lenses to absorb light of a certain wavelength, thereby reducing the amount of light entering the eyes light intensity. But some of the rays absorbed by the lenses turn into heat, especially infrared and other longer-wavelength rays, which can be uncomfortable for the eyes due to the build-up of heat generated. If you use a reflective filter, this problem can be solved very well. Coated glasses have been introduced before, if a material film with a higher refractive index than the lens itself is coated on the surface of the lens, it will increase the reflection of light and reduce the intensity of transmitted light, thereby protecting the eyes from strong light and harmful rays. In real life, absorption and reflection are used together in many cases, that is, a layer of high reflection film is coated on the colored lens to make the filtering effect stronger. For example, protective glasses worn by operators such as electric welding, chlorine arc welding, and plasma cutting can be solved by this method.