For many practitioners in the laser industry, they are absolutely familiar with laser protective glasses, but for many people, their understanding of laser protective glasses is not deep, and most of them are limited to using whichever one is required for any occasion according to the company’s regulations.
Then this article will talk about why we should use laser protective glasses of different colors in different occasions.
Characteristics of laser
First of all, laser protective glasses, the object of protection is laser. Sun Tzu’s art of war says: “know yourself and know your enemy, you can be invincible in a hundred battles”. We need to understand the “opponent” of laser first, so as to know why laser protective glasses are made and used in this way, so as to achieve the purpose of protection.
“Laser” gets its name from the light emitted by atoms. After absorbing energy, electrons in atoms transition from low-energy level to high-energy level, and then fall back from high-energy level to low-energy level. The released energy is released in the form of photons. The photon beam (laser) is induced (excited). The photon optical characteristics are highly consistent, making the laser have the advantages of monochromaticity, good directivity and higher brightness compared with ordinary light sources.
In a more understandable way, according to the physics knowledge of middle school, visible light is an electromagnetic wave with a wavelength of about 400nm-700nm. What we usually call infrared, ultraviolet, microwave, long wave radio, X-ray, gamma ray, etc. are electromagnetic waves with a certain wavelength range.
Different from the above-mentioned electromagnetic waves with a certain wavelength range, laser is an artificial electromagnetic wave with a specific wavelength due to its own generation principle, which is characterized by:
1.Good monochromaticity, that is, the same wavelength makes the laser color more pure, such as all kinds of lasers on the scene of various laser shows;
2.Good directivity, that is, the divergence angle is small after laser emission, and the optical path is more straight. For example, when measuring the distance between the earth and the moon, the laser can be used to aim at the lunar laser reflector hundreds of thousands of kilometers away;
3.Higher brightness, that is, the high concentration of laser energy makes the brightness higher than ordinary light.
It is precisely because of the above characteristics of laser, the “opponent”, that it is extremely harmful to the human eye.
When the laser enters the human eye, due to the aggregation characteristics of the eye, its laser sensitivity is 100000 times that of the skin. The laser focuses on the retina through the refractive medium of the eye, which instantly increases the energy density on the retina by more than 10000 times compared with the energy density incident on the cornea. Therefore, extremely low laser energy irradiation can cause permanent damage to the cornea or retina.
When laser injures the eyes, most people will feel a sudden flash in front of them, and then a light spot or shadow of different colors and sizes will appear, and even the eyes will have an impact. At the same time, vision will decline to varying degrees. In severe cases, they can’t distinguish the objects in front of them in a short time, and their eyes will be dazzled and photophobia.
One thing that needs special attention is not to be confused by the word “light” in the laser. Not all lasers can be observed by the human eye, such as UV laser, infrared laser, 808 semiconductor laser, erbium laser, CO2 laser, etc., are invisible lasers. Ultraviolet light (100nm-400nm) will cause damage to the cornea, and the laser wavelength of 400nm-1400nm will penetrate the lens and damage the retina, causing irreversible damage to human eyes. Laser wavelengths above 1400 mm are relatively safe, but we work in high-power laser environments. For example, in most high-power fiber lasers and CO2 laser working environments, these invisible lasers will still cause serious damage to unprotected human eyes.
Characteristics of laser application scenarios
After we understand the characteristics and hazards of the “opponent” laser, we also need to know the “attack strategy” of the “opponent”, so that we can formulate corresponding protection strategies to achieve effective protection of the laser.
In practical work, we need to use different lasers to produce lasers with different wavelengths according to different application scenarios. Combined with the monochromatic characteristics of laser itself, there will be only one specific wavelength or a few wavelengths of laser in most of a working scene, that is, for a working scene, the laser environment is relatively simple, and only specific wavelengths need to be protected. Therefore, when designing and making protective tools, we can focus on specific wavelengths to achieve more effective protection.
At the same time, due to the high-energy characteristics of the laser itself, especially the working environment of some high-power lasers in practice, the laser environment is more “extreme” than the ordinary natural light environment in a specific working environment. It is like a tall building rising from the ground, and there is no smooth transition. This extreme nature puts forward higher requirements for the protective ability of protective tools.
Laser protective glasses
To sum up, facing the relatively less complex application environment (single and fixed laser wavelength) and the extremes of a single application scenario (high laser intensity), it is necessary to face the efficient protection under different application scenarios through refined protection product classification.
At this time, laser protective glasses are needed.
The basic principle of laser protective glasses is to reflect and absorb artificial lasers that do not exist in nature through different lens coating and special lens materials, so as to avoid damage to human eyes. At present, it is mainly divided into absorption type, reflection type and composite laser protective glasses combining the two.
According to the above requirements for protective glasses, in order to achieve “efficient protection under different application scenarios”, a diversified product line of laser protective glasses has been produced.
The reason why the lens will show different colors is mainly because in order to achieve the most effective protection against single wavelength laser, the use of different nano laser absorbing materials in the lens shows different colors. On the other hand, the different colors of the lens also enable users to intuitively judge the applicable scenes of different glasses, reducing the user’s hands-on cost.
Therefore, we can now answer the first question. The different colors of laser protective glasses represent the application scenarios suitable for different glasses. It is a safety color for each user.