Some high-grade lasers can damage the eye and burn the skin. Most lasers that are capable of inflicting such injuries are categorized under Class 2, Class 3 and Class 4. For example, UV lasers that emit wavelengths between 180-400nm can cause corneal damage; while some near-IR lasers, ranging between 780-1,800nm, may burn one’s retina. On the extreme end of injuries related to high-intensity lasers, exposure to specific Class 3 and Class 4 units may lead to electrical shock and burns to the skin.
Because of this, individuals who work around laser machines must wear protective gear. At the very least, operators should have goggles or eyewear that matches the wavelength and strength of the laser he or she is working with.
Read on to understand the different types of eyewear protection for hazardous lasers.
Laser Protection Mechanisms
Glasses that are designed to protect people from laser damage consists of a special lens that blocks specific wavelengths, allowing other beams outside of the blocked range to pass through. Protective eyewear for lasers usually come in various grades, also known as optical density. The grade of the lens determines the strength of the filter, by a multiplying factor of 10. For instance, if the optical density grade of the glasses is 3, it can decrease the power of the laser by 1/1,000.
Protective eyewear for dangerous lasers increases in complexity when the beam fired is comprised of multiple wavelength ranges. This is an issue for lasers that also emit infrared wavelengths with the beam, that are not filtered by the machine or unit. Unfortunately, commercial lasers do not frequently specify such properties on labels.
Outside of eyewear protection, some laser machines come with automatic shutdown mechanisms that cuts power to the laser in the event a “door” is opened that causes the laser to become exposed. This is common in machines with Class 1 lasers, such as CD and DVD players. In laboratories, the protective mechanism can also be applied to actual doors to a room or enclosure where the laser is being used.
Glass versus Polycarbonate Filters
The two main types of materials used for protection against harmful lasers are glass and polycarbonate. Both are effective in mitigating the negative effects of powerful lasers; however, their applications vary depending on the strength of the beam and visual requirements of the user. Polycarbonate is suitable for low to mid-range lasers. It is known for being cost effective, lightweight and sturdy. As a result, the material is ideal for mass laser beam protection over long periods of use.
For high-strength lasers, glass filters perform noticeably better than polycarbonate (at higher price points). The material also provides better visible light transmission and offers more accurate color balance. With these factors in mind, glass lenses are recommended for workers who need to be able to distinguish colors quickly and accurately, such as a person using a laser-cutting machine on products with colored outlines. For higher levels of protection (higher optical density levels, as described above) without altering the blocked wavelength range, glass lenses may be manufactured with thicker properties.