We get asked this question a lot at NOVAlasers so we thought that a small article on the subject would be useful.

When a website or retailer states the “range” of a laser pointer, or makes claims that the light from a given laser pointer can go a certain distance (ex. 500 yards) this is usually stated for the purposes of a marketing gimmick.

The range of a laser pointer is not really a useful description of the function or power of that particular laser pointer. This is because range depends highly upon atmospheric conditions. Theoretically, laser light will travel infinitely and will have an infinite range. Much more useful criteria by which to judge the power of a laser are output power and divergence.

Output power: the actual output power of the laser is the best way to judge how powerful the laser is and how far away you will be able to see the light impacting a surface. The higher the output power, the more visible the laser light will be. Output power is measured in milliwatts (mW).

Divergence: the divergence of the beam is how fast the light is increasing in diameter as it travels away from the aperture. The lower the beam divergence, the smaller will be the diameter of the beam. The smaller the diameter of the beam, the smaller (and brighter) will be the spot of laser light projected onto a surface.

Wavelength: the wavelength of the laser directly corresponds to what we perceive as color. The human eye is most sensitive to wavelengths in the middle of the human visible spectrum, corresponding to green laser light. For this reason a green laser of 5mW power will appear several times brighter than a red laser of the same power level. As a result the distance at which the laser is visible is much greater for a green laser than for a red laser of the same output power level and divergence.

When purchasing a laser it is much more useful to inquire about the output power and beam divergence of the unit, rather than its range. 

NOVAlasers wishes you fun exploring!

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