Beam Diameter of a Laser

The beam diameter of a laser is the thickness of the laser beam at aperture (where the beam exits the laser device). Beam diameter is usually measured in mm or millimeters.

Why is beam diameter important? While the concept of beam diameter is a simple one, a laser with a small beam diameter can be beneficial in many ways. First, a narrow beam diameter increases visibility. Let's take two 125mW green lasers for example, one has a beam diameter of 1mm, the other with 2mm. Given these two lasers have the same power, the one with a 1mm beam is brighter. This is because all of the laser's energy is concentrated into an 1mm beam.

For the same reason, lasers with low beam diameters are better at burning. In fact, you can focus the beam of a laser by using a basic magnifying glass. Have you ever played with a magnifying glass when you were a little kid? If you can concentrate the sun's energy in a small dot, you can burn paper and other fun things in your garden. The same theory applies high power lasers. If you can focus the laser beam diameter into a pin-point dot (using a magnifying glass or convex lens), you will intensify its already amazing burning powers! You can learn more about this and find tips on improving burning in our section dedicated to burning laser pointers.

You can find the laser beam diameter of each of our laser products in the "additional information" section of each product page. Please note that the laser beam diameter of our portable lasers is adjustable! You do not need to purchase additional lenses or lens caps to focus our portable lasers.