Typical green laser pointer range?

[MJCfromCT]

Hi all,

I have a Nova X25, and I'm wondering if there is any data out there regarding the range of the laser beam? I know that when you point it at the sky, it seems as if you are pointing to infinity because your eye cannot distinguish between infinity and the end of the beam, but is there any data out there regarding a laser such as the Nova X25, and its' beam range (assuming some "standard" value of beam divergence, for example). Thanks!

 

[steve001]

The way you've asked the question is meaningless. You'll have to define the question more concisely. I find it an interesting question none the less.
Are you shining it a someone ?
Are you looking at surface reflection ?
You'll have to define beam parameters, atmospheric conditions and terminating surface reflectivity.

 

[MJCfromCT]

Well, in this hypothetical scenario, you are shining it at a wall which a person is standing next to. They are x meters away from you, and they observe the beam hitting the wall, can see the beam, and can see the dot. You yourself may not be able to see the beam at this x meters distance, or be able to see the dot at x meters, but the person standing next to the wall would be able to observe it. In this situation, what is the maximum distance at which the beam would be visible to this person?

 

[Rhith]

The biggest issue here is that it will diverge so much that it will become something similar to a "green glow" in the general area that "person 2" will see.

 

[Cyparagon]

And even then, that occurs at no definite distance.

 

[MJCfromCT]

so there is no conrete data regarding maximum beam range? I might have to do some tests myself, seeing at what distances the beam is visible, and when the dot becomes more of a green glow. Sure, it wouldn't be completely scientific, but good enough to get a general idea.

 

[Rhith]

Well you can figure out your laser's mRad to see how much it diverges per meter and its initial beam diameter and calculate at what distance the size of the "dot" would be but it would be hard to determine how visible the beam would be considering all the variables for atmospheric conditions and angle you are from the beam. But be sure to let us know what you can find out.

 

[steve001]

so there is no conrete data regarding maximum beam range? I might have to do some tests myself, seeing at what distances the beam is visible, and when the dot becomes more of a green glow. Sure, it wouldn't be completely scientific, but good enough to get a general idea.

The weather's getting cold out that will also affect the output power. So keep the pointer within it designed operating temperature if you don't live where it is still warm. I look forward to see what you find out. Links of interest
http://www.repairfaq.org/sam/lasersaf.htm#saftoc
http://www.lasercomms.org.uk/france.htm

 

[Benm]

The 'range' of a laser is a marketing quantity really. There are at least 3 ways you can define what you are actually looking for:

- dot on remote object visible to the one handling the laser
- dot on remote object visible to observer near the object
- laser visible to remote observer looking directly at the laser

All 3 obviously depend on ambient light a great deal, the first two also on target albedo, and all also on divergence to ascending degree in the list.

Visibility of the dot to the one handling the laser would be the most practical scenario, but also gives the lowest number... but still a few miles for say a 50 mW green in low city lighting at night and an albedo of 0.5 or so.

Visibility to someone remote looking directly at the laser is probably limited by the horizon in most realistic scenarios. A 10 mW green is likely to be the brightest object at night, even miles away.

But bear in mind that the 'dot' will not be much of a dot on longer distances. With 1 mrad divergence, at 2 km out, the 'dot' will be a circle with 2 meter radius.