How Do I Choose Laser Safety Glasses?

NOV 13

How Do I Choose Laser Safety Glasses?

By cosmick

If you are working with and around lasers daily, you will already know and appreciate the importance of protecting your eyes. Whether you are involved in lasers in an industrial, military or even medical setting, there is no denying, one of the most important safety accessories that you need to invest wisely in, therefore, is laser safety eyewear. This article covers how to choose laser safety glasses.

Although all laser safety eyewear is designed with the same purpose in mind, not all are designed for the same applications and in use in the same environments. You need to understand that lasers operate at different levels, emitting very different levels of radiation that are affected by several different factors including the power of the laser, its wavelength, and even its operating system.

When faced with the decision of which laser safety glasses to choose, you may feel a little overwhelmed. That’s where this guide will be useful as we discuss the most important things you need to consider when investing in laser safety eyewear.

The Need to Stay Educated About Laser Developments

Laser technology is always evolving and with all new research, changes and improvements are made to the current laser equipment and machinery used. To cope with these improvements and advancements, the corresponding safety equipment like glasses and eyewear is also updated. Therefore, when you are investing in laser safety eyewear, you must make sure the products you are looking at have been designed and manufactured to the latest and highest industry standards.

Understand the Laser

The first thing you need to think about when choosing safety eye gear that’s suitable for lasers it the laser operating system your organization, company or department uses. Find out as much information, if you don’t already know it, about the laser as possible. That includes everything from the beam delivery system and diameter to the power output and wavelength. You will find that the details of the power and output are marked on the laser, and anything else you need to know will normally be published in the laser’s operator’s manual. This data is important as it will help you to choose the safety glasses that will block and protect you from the operating wavelength with the correct optical density.

The Optical Density and Wavelength of the Laser

You need to know the operational parameters of the laser in question to determine the wavelengths you need to either block or absorb and at what optical density.

Wavelength is used to measure the spatial period of a light wave. In other words, the distance that a wave repeats its shape over. Waves are measured either from the valley to valley or crest to crest and then displayed on what is known as a light spectrum or electromagnetic spectrum starting with the wave that’s the shortest through to the wave that’s the longest. It is measured in meters or nanometers and designated the Greek letter lambda.

Important to note is the fact that some waves are not visible and with regards to lasers, these waves can be especially dangerous for your eyes. Therefore, it is important to understand the output wavelength of the laser you use to understand the wavelengths the protective eyewear you are going to wear needs to block.

OD, also known simply as absorbance, is in some ways more difficult to understand. However, to put it in simple terms, it is the ratio used to measure the amount of light absorbed at specific wavelengths. It is a crucial aspect of safety eyewear as it denotes how effective or ineffective a pair would be absorbing the laser wavelengths you need protection against.

When referring to laser applications, the optical density of filters will be described as ranges, highlighting their optical density for specific ranges of wavelengths.

The higher or bigger the optical density of a pair of glasses, the more light is blocked from that wavelength.

Within a medical environment, the recommended optical density of laser safety glasses is at least 5 or more. There is no harm in opting for a pair with a higher optical density than is suggested in the laser’s operator’s manual, as this simply means you will benefit from even more protection.

Thinking About Visible Light Transmission

You will read a lot about visible light transmission about laser safety glasses. One of the biggest downsides of investing in a pair of safety glasses with an exceptionally high optical density is that you sacrifice visibility. As the lenses used are darker, it makes it much harder to see.

To cope with this issue, there have been many advancements made and you will be able to find safety glasses that have lenses made with a higher level of VLT, while still maintaining an effective and safe optical density.

Many companies and suppliers list the VLT along with the wavelength the glasses protect against and the optical density.

Filter Lenses

The next consideration you need to make when choosing laser safety eyewear is the filter lenses that will be the safest and most effective at offering the required level of protection and the most affordable and within your budget.

Filter lenses are either made from glass or polycarbonate and are chosen to match the nanometer measurement of the wavelength along with the OD level.

Let’s look at these individually, highlighting their key features and benefits. Knowing this will guide in how you choose laser safety glasses.

Glass Filters

Depending on the wavelength and power level of the laser you are using, you may not have a choice over using glass or polycarbonate filter lenses, because for some applications only glass is suitable. Compared to polycarbonate, glass renders a much higher transmission of visual light. It is important to choose a glass filter that is suitable for the widest range of laser applications you are involved in. You can even by tailormade custom glass filters designed to meet your specific specifications.

There is also the option to use combination glass filters for those harder-to-solve laser applications and you may benefit from glass filters that have greater OD levels for the same wavelength. This is done by making the filters thicker.

Key Features of Glass Filters

  • The best option for work involving mid to very high-power density lasers.
  • Exceptional color balance
  • Much greater visible light transmission
  • Premium optical properties

Polycarbonate Filters

Polycarbonate filter lenses, although they are not suited to mid to high power density laser use, offer specific benefits. For one thing, compared to glass filters, they are incredibly affordable. They also offer a greater level of resistance to impact, all the while being far lighter in design. Modern polycarbonate filter lenses offer broadband filtering and a huge variety of wavelength absorption capabilities.

Many improvements have been made to polycarbonate filters over the years and they now offer greater visual light transmission than they have done in the past. When looking for a supplier, it’s wise to consider one that understands the various dyes related to the absorption of specific wavelengths. As well as ensuring, if required, that they can tailor and customize filter lenses to meet your specific preferences and requirements.

Key Features of Polycarbonate Filters

  • Some are available that offer impact resistance and are fully compliant with the ANSI 787 standard
  • Usually available in the widest range of different frame styles
  • They are best used in applications involving low to mid-power density lasers
  • They are made from a more economically sound material
  • Lighter in weight and therefore less likely to cause fatigue or discomfort

Thin-Film-Coated or Nano spec Filter Technology

Thin-film coating or nano spec filter technology is one of the most cutting-edge developments in eyewear for laser safety. These are reflective coatings that can be applied to either glass lenses or polycarbonate lenses to improve their capabilities for protection. As well as offering superior protection they also offer the highest visible light transmission across all laser applications.

Key Features of Thin-Film-Coated or Nano spec Filters

  • Offers protection in applications involving most low to high power density lasers
  • Provides suitable protection against femtosecond and Pico pulse protection
  • Great color balance
  • Premium quality visible light transmission
  • Higher optical density than alternatives

How To Choose Laser Safety Glasses That Are Prescription

There are some scenarios where you may need more specialized laser safety glasses. For instance, if you need to wear glasses either for reading or to correct general sight issues. Fortunately, most laser safety glasses available these days can be fitted with lenses for your specific prescription. It should be pointed out though that, not all laser safety glasses available can be equipped with prescription lenses. Therefore, you should be careful to only choose those pairs marked with RX-Able as it means they can be fitted with the prescription lenses that protect against the lasers you use and work with. 

It makes sense if you can invest in prescription laser glasses as it will be a lot more practical and comfortable wearing just one single pair of glasses rather than prescription ones beneath your protective pair.

You have two options when it comes to choosing prescription laser safety glasses –

Single Vision Prescription Laser Safety Glasses

Single Vision Prescription glasses provide you with the same prescription throughout the entire lens. This is just for correcting sight issues and does not offer additional assistance if you require reading glasses or bifocals.

Lined Bifocal Prescription Laser Safety Glasses

Lined Bifocal Prescription glasses, on the other hand, correct both reading and near-sightedness in the bottom half of the lens and long-sightedness in the top half of the lens. A line is designed to mark these two specific areas. The reading half of the lens has a semicircle shape, while the top half is flat, which is why you will often see the specification describing the lens as FT and a number, FT for flat top and the number is the width in millimeters.

The Frames

The last consideration you need to make when choosing laser safety glasses is the frames. You will find that, depending on which type of lens you are looking to have, the choice of frames will be limited. That’s not to say there are not many options.

While style is not something you should be thinking about when choosing protective eyewear when using lasers, you will still find a few options that hopefully meet your taste and preference.

It can be a bit overwhelming when you first look at the variety of laser safety eyewear available. Given how important having the right protection for your eyes is when working with lasers, it’s vital you are able to overcome it. With the use of our comprehensive and very practical guide, we hope, we have made it a lot easier to understand and that you will find it easy to navigate through the various options and choose the best laser glasses for the industry you work in and the kind of laser you use and how powerful it is.

Hopefully, this article helps you to choose laser safety glasses that are perfect for you. Contact us today if you’re still having trouble.

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