You want to do laser light scattering. One of the core components of any light scattering system is a laser. And for this design laser power plays a role. So, is higher laser power always better? And what about laser safety? Is this still an easy and safe-to-use class 1 product? In this post, we look at the laser radiation safety factors for light scattering experiments, especially for Zetasizer laser safety.

photo of laser light show - how important is zetasizer laser safety - what do we need to consider
Laser beams, Photo by Jovydas Pinkevicius, Pexels

What are laser safety classes ?

Laser safety is part of the standard Environmental Health and Safety [EHS] concerns at workplaces with optical measurement equipment. As such, a risk assessment by a local safety officer may involve your instrument, if it contains a laser. Fortunately, there are some standard laser safety classes (or regulations) where there are different categories of risk. Let’s zoom into two specific laser classes of relevance to the Zetasizer in this post.

  • Class I lasers = inherently safe, no possibility of eye damage
  • Class IIIb lasers = hazardous for direct exposure, >5mW

The laser in a Zetasizer

What laser is part of the Zetasizer Advance series? Well, this depends. The Zetasizer Lab Red, Pro Red, and Ultra Red instruments use a class 3B laser. The Lab Blue, Pro Blue, and Ultra Blue instruments, on the other hand, use a class 3R laser. It is always a Helium-Neon laser, and the laser output power is slightly different. However, in the normal operation of the system, no laser radiation is leaving the instrument to expose an operator. Therefore this means that the system is safe to operate under all conditions of normal use. As a result, the Zetasizer Advance series is a Class 1 since it fully contains the laser beam such that no light can escape.

Class 1 – safe to use!

The Zetasizer system (and any of its variants Lab, Pro, Ultra) is a class 1 laser product. This is the lowest laser hazard category. Since the laser is completely embedded inside the instrument, it cannot be accessed by a user. Nobody in your lab will be accessing the laser beam in normal operations. In addition to the enclosure, there are several fail-safe design features in the system

  • by default the laser is blocked. This block only opens, when a measurement starts via the software.
  • a mechanical laser shutter is connected to the sample holder lid. To clarify, this extra shutter only opens when the sample holder lid is closed and secured.
  • the laser beam passes through the lowest part of the sample holder. Consequently. a sample cell with cell lid would block visual access to a laser beam.

In summary, there should really be no problems with Zetasizer laser safety. So if your internal health and safety group asks, we can help address their questions.


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