How can you block laser light?
Thursday, February 03, 2022
Do you need to momentarily shield a target from a low-powered laser? Are you looking for a safe way to halt a high-power beam’s propagation? Or is it eye protection you seek? Different needs, different solutions.
Everyday objects as laser beam blockers
Depending on the wavelength and power, blocking a laser beam could be as simple as placing an object in its path. For instance, certain barcode scanners, laser pointers and LIDAR technology literally depend on everyday objects blocking laser light.
LIDAR is basically the laser equivalent of a bat using echo localization to map out its surroundings. Short bursts of laser light are emitted in all directions, and by measuring the time it took for the light to bounce off of objects and back, the distance can be calculated.
Historically, LIDAR was used mainly for industrial and scientific purposes, but as prices have gone down, the use-cases have diversified. Self-driving cars and even some smartphones have incorporated lasers to better account for the 3D nature of our world.
All this to say that some lasers can be blocked rather easily. If your setup only uses low‑power lasers, simple beam shutters may be all you need.
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Beam dumps: How to stop a moving train (of photons)
Not all lasers are so benign. Class IV lasers can damage the eyes even if you are just looking at their diffuse reflection (the laser “dot”). Some lasers are used for welding and cutting steel. Others are even used to shoot down missiles.
Blocking these lasers with everyday objects is… well, not recommended.
To block lasers like these, you will need a beam dump – a device designed to safely absorb and dissipate laser energy. In many cases, an energy or power detector can act as a beam dump, as long as it is used within its specified safety rating.
Beam dumps must have a heavy-duty absorption surface with low reflectivity. They must also have appropriate heat dissipation. As the incident light power increases, active cooling becomes a necessity. Gentec-EO’s water-cooled beam dumps and high power laser beam measurement solutions have the highest capacity on the market, with custom solutions able to withstand up to 100 kW of continuous power.
Last line of defense
No matter the laser, it is always recommended to follow safety guidelines. Usually top of that list, is appropriate protective equipment. Laser safety eyewear is designed to block only certain selected wavelengths. Because other wavelengths are transmitted, you can still see and function normally, but are afforded some protection.
They always come with specific safety ratings that indicate which wavelengths they are designed to block, how well they block them (optical density) and which power levels they can withstand. They are a useful safety precaution, but are of course not designed to withstand the brunt of high-power lasers for long durations.
When in doubt, ask for help!
Keep in mind that lasers can be devastatingly powerful. This is meant as an informational article only. If you’re looking for an expert opinion on how to block laser light in your specific setup, contact one of our laser beam measurement specialists.
