This question is asked very often by people working on lasers but who have glasses with marking associated with the American standard. In the field of laser safety, two main standards are followed: the American National Standards Institute (ANSI) and the European Standards (EN) adopted by the member countries of the European Union. We will focus on those relating to laser protection glasses, namely ANSI Z136 and EN207.
Where do these standards apply?
ANSI Z136: The ANSI standard is applicable here in the United States and North America, as well as in most other locations outside the EU. It is created by volunteers and diverse viewpoints to build consensus on laser safety issues.
The European standard (EN 207) is created in a similar way, but with an important difference: it is harmonized, so it indirectly becomes law. In addition, an independent body must issue certification attesting that a level of protection is achieved by the glasses.
Main differences between these two standards
The biggest difference is in the testing and certification process for CE marking. The EN standard took a very conservative (and expensive) approach, requiring testing of each mount as well as the filters. Laser glasses are designed for diffuse observation and accidental direct impacts.
Using laser glasses for direct observation is not permitted and we never recommend looking directly at a laser, even though EN207 performs direct shot impact testing. In any case, for questions on this subject, contact your laser safety representative or complete laser safety training to master the subject.
In this image you will see the difference between CE marked specifications (left bezel) and OD specifications (right bezel) which are common industrial ratings here in the United States and North America.
In the image above, the scope on the left would have the specification of an LB6, as this would be the minimum of the mount and filter: Min(LB6,LB7). The OD optical density marking on products that do not carry the CE mark is just a calculation on the filter, and the image on the right will be marked with an OD7.
In summary, ANSI standards are widely used in the United States and North America, while EN standards are adopted in Europe and are indirectly a compliance with the law. In addition, the EN207 standard is intended to be more restrictive than ANSI Z136 because of the test on the frame (and not just the filter).
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