A new method for measuring the range of a laser

Generally a range given for a laser can be very misleading for a number of reasons. One being that light has an infinite range.

If coherent length was used instead, any range given would be much clearer and reliable. Just one catch

First a definition of coherent length

"is the propogation distance from a coherent source to a point where an electromagnetic wave maintains a specified degree of coherence."


The catch being the "specified degree of coherence". An agreed apon industry standard? Can't see that happening.

But pure "range" is a better sounding word that helps sell lasers. A person new to lasers would not know what the output power in mW means, or what the divergence in mrad means. However, they will see "20 mile range!" and be drawn into that, despite being the most inaccurate and misleading advertised quality of the laser.

If it helps sell lasers, sellers will keep using it. Same with overrating the lasers and not telling the buyer if it has an IR filter or not. It's simply to capitalize on the fact that most people don't know jack about these products.

I know you have been in the business a while now, FNinjaP90 - but there is a clown over on LPF that is trying to sell off some shoddy ebaysers, and said that the 150mw he is selling ..."""will pop balloons, but if you want a laser that will burn matches, then you are looking at serious money"""


Uhm...yeah, so anyways -I think it would be GREAT if there was a laser industry standard for range - but I do not think we will see that in my lifetime - not as long as we have nutjobs like the above individual running around.

There won't be a standard for range because there is no measurement of range! The only thing resembling range would be something like intensity, a power/area at a distance, which can be calculated by dividing the laser power by the dot size at a given distance, say 100m. The higher the power and the lower the divergence, the higher the intensity.

Of course, this still won't work perfectly well in the real world since moisture and pollutants in the atmosphere will absorb a good deal of the light at a long distance.