Buyers Guide |  How do I choose laser safety glasses?

Buyers Guide | How do I choose laser safety glasses?

Published by The Laser Safety Experts | Laser Safety Industries on Jun 7th 2020

Typically, to determine what type of laser safety glasses or goggles to buy, the following is needed:

1) Wavelength of the laser

2) Find out what protection level is needed premised on your laser's output.  Do this by looking for the recommended Optical Density (OD), asking your Laser Safety Officer, or feel free to give us a call at 1-888-752-7370 and we can assist.  The needed OD is ultimately a function of both the laser being used, and what the laser needs to be reduced to or what is known as the Maximum Permissible Exposure ("MPE") based on several parameters mentioned here.

Below we've illustrated what the laser safety lens fundamentally needs to accomplish for proper laser safety:

Maximum Permissible Exposure ("MPE") Laser Safety

 Before we continue with optical density, our primary categories of laser safety PPE is directly below:  

Laser Safety Glasses
Laser Safety Windows  Laser Safety Curtains
Laser Safety Barriers

Laser Safety Glasses

Laser Safety Window

Laser Safety Curtain

Laser Safety Barrier

For a "Green Laser" safety glasses guide, click here.

Optical Density: Refers to the amount of light attenuated[i] by a lens and ultimately let through to hit the eye.  Different lasers (and corresponding wavelengths) have different impact on the human eye (the ANSI has created standards and published them based on research).  If you are having trouble knowing the appropriate optical density needed for your glasses or laser safety protection, please give us all call at 1-888-752-7370 or 952-405-6947.  We have included a diagram to aide a buyer in common industry notation.  Please note, some assumptions have been made (the photons depicted are not drawn to scale, and finally please be sure to reach out if there is any uncertainty).

Optical Density Notation

Often, a laser has two wavelengths:

1) An aiming beam wavelength - The aiming beam is typically "eye safe" | depicted in the image below as red

2) An operating beam wavelength - The operating beam is typically what your purchasing laser safety protection for | depicted in the image below as green

Operating Beam Laser vs Aiming Beam Laser (Typically Eye-Safe)

What is an alignment laser beam?

The aiming beam is to aid the user in positioning the operating laser beam. Generally, the aiming beam will be low powered and typically red. A common use case for an aiming beam is a laser pointer.

If you are in doubt whether or not your aiming beam is eye-safe for diffused viewing, please check with your laser safety officer or call us before making any assumptions. Recently our team has come across wavelengths utilized for aiming beams that are inappropriate without proper laser safety protection. Never look at any laser directly - including the aiming beam (stand behind the beam while viewing it), and do not bring your eyes near the axis during alignment or any other operation with lasers. All laser safety protection is for diffused viewing only. Proper laser safety is to never look directly at a laser beam; if you are hit with any laser in the eye, look away immediately.

If the alignment beam exceeds the MPE, of course utilize proper alignment eyewear (where the MPE threshold is not exceeded factoring appropriate exposure duration). The aiming beam needs to be able to be seen to align the laser correctly (that is the point of an aiming beam), and therefore attenuating the laser to a point it cannot be seen is an issue.  Laser safety alignment eyewear should be used if possible and may be needed.  Always be safe when dealing with lasers. 

Appropriate  laser safety glasses and other PPE are only one component of proper laser safety.  Engineering controls and administrative controls are also needed.  For more information surrounding these key components of laser safety, click here.

Visibility Light Transmission (“VLT”):  Color and visibility of specific color ranges often are significantly affected by laser glasses and goggles. Think distortion when wearing sunglasses to block the sun, (often less expensive) sun glasses do an effective job of blocking the sun, however everything is much more difficult to see because not a lot of light generally is coming through. Other times with (typically more expensive) sunglasses, the sun is blocked and everything else looks very similar to how it would without the glasses.  The image below is a relative comparison of visual light transmission. 

Higher VLT Lower VLT

Visible Light Transmission (VLT) Explained

Frame Styles - Our most popular frame for our polycarbonate filters is the 10-frame fit-over.  It fits over almost all prescription glasses and many labs find it easiest to use for a universal style instead of ordering individual pair designated for particular people.  Our other most common frame for glass and coated glasses is the 35-frame Spectacle. The frame fits over large faces and heads and over most prescription eyewear.

Fit-over 10-Frame            

For videos and more information on all of our primary frames, please see our  frames article here.

Comfort and Price – weight, shape of the frames, and size of the glasses may affect your decision. These parameters are in large dependent on the type of material used.  Click here to view our  Laser Safety Glasses.

Below is a table to display generalize trade-offs of different laser safety glasses and goggles:

Polycarbonate Glass Dielectric Coating
polycarbonate laser safety glasses

glass laser safety glasses Dielectric coated laser safety glasses
Weight Lighter Heavier Heavier
Price Lower Medium Higher
Wavelength/laser category Ultra-Violet, Visible Light, Near and Far Infrared (IR) Infrared Depends (All over the electromagnetic spectrum)

[i] Outside of the context of laser safety, optical density more commonly refers to the refractive index, and the term absorbance is used in lieu of what we are referring to here as "optical density".