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Why a laser beam suddenly stops. (revisited)

Rodomontade

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I'm new here and far from an expert. That said, here is my observation.
A buddy and I happen to have performance boats.
We were on Seneca lake that is approximately 37 miles long and has very good line of sight.
My buddy stayed in mostly one place at the Watkins Glen end and fired an Arctic laser parallel to the water surface (very low to the waterline to virtually eliminate the possibility of lasing an innocent boater/person). We could both very clearly see the point where the laser abruptly stopped. (this was completely within the planet boundary layer so that eliminated that variable).
I took off in my boat and headed for the point where the laser disappeared from vision right up to where I could inspect the vanishing point. I was able to boat the the exact spot it vanished. The beam, while wider, at that point went to a very faint full scatter of light that was not visible from the starting point almost as though it was going through a type of wide angle lens.
As far as I am concerned the the viewing angle has zero to do with the phenomenon mentioned many times before. Also the theory of the PBL is eliminated as a possibility.
Now I went (carefully) the best I could and looked back (with laser safety glasses) toward the laser origination point and can say it was clearly visible from far past the point it appeared to vanish. It was hard to say just how powerful it was because my safety glasses blocked most of the blue light. The beam was impossible to hold steady at that distance due to the originating boat bobbing around.
So to summarize:
1) Planet Boundary Layer theory proven wrong
2) The trigonometry theory of viewing angle proven wrong

I'm still trying to find why this beam termination actually happens.
If anyone can elaborate constructively in addition to this unscientific test I would greatly appreciate it.

Sorry for the long read and my lack of signature. I'll work on that next.

EDIT Reason: SP
 
Last edited:



Cyparagon

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I'm sorry, are you some sort of flat-earther? Someone that flunked trig in high school? A conspiracy theorists? What exactly do you think you've disproven and how?

Here's a thought experiment that might help you understand this rather simple concept. Imagine for a moment that the earth was flat, and that the earth was infinite in its surface area. Would it still have a horizon?

(hint, the answer starts with a "y" and ends with "es")
 

hakzaw1

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agree with all who posted.....
Your first thread should have been an intro with your location in the title and placed in the welcome/newcomers section...
then do some searches as there are many posts here on that topic (if I understand what you mean) .
Some of your assumptions are wrong. Not enough knowledge of lasers can be very dangerous.
 

steve001

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I'm new here and far from an expert. That said, here is my observation.
A buddy and I happen to have performance boats.
We were on Seneca lake that is approximately 37 miles long and has very good line of sight.
My buddy stayed in mostly one place at the Watkins Glen end and fired an Arctic laser parallel to the water surface (very low to the waterline to virtually eliminate the possibility of lasing an innocent boater/person). We could both very clearly see the point where the laser abruptly stopped. (this was completely within the planet boundary layer so that eliminated that variable).
I took off in my boat and headed for the point where the laser disappeared from vision right up to where I could inspect the vanishing point. I was able to boat the the exact spot it vanished. The beam, while wider, at that point went to a very faint full scatter of light that was not visible from the starting point almost as though it was going through a type of wide angle lens.
As far as I am concerned the the viewing angle has zero to do with the phenomenon mentioned many times before. Also the theory of the PBL is eliminated as a possibility.
Now I went (carefully) the best I could and looked back (with laser safety glasses) toward the laser origination point and can say it was clearly visible from far past the point it appeared to vanish. It was hard to say just how powerful it was because my safety glasses blocked most of the blue light. The beam was impossible to hold steady at that distance due to the originating boat bobbing around.
So to summarize:
1) Planet Boundary Layer theory proven wrong
2) The trigonometry theory of viewing angle proven wrong

I'm still trying to find why this beam termination actually happens.
If anyone can elaborate constructively in addition to this unscientific test I would greatly appreciate it.

Sorry for the long read and my lack of signature. I'll work on that next.

EDIT Reason: SP
I believe the answer is simply there was not back scattering light to the point on origin. It you were to illuminate a white or light colored surface at the same distance that illusion would disappear.
 

paul1598419

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The OP sounded like he was describing the beam just terminating at some point in space. If that is correct, it doesn't make sense to me. Lasers do diverge, but not all at once at some indeterminant distance.
 

steve001

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The OP sounded like he was describing the beam just terminating at some point in space. If that is correct, it doesn't make sense to me. Lasers do diverge, but not all at once at some indeterminant distance.
What he's describing is the apparent termination whether it's pointed skyward or at some distance as he did were the beam is not stopped by an object as stated in his post. In either the apparent termination is caused by not enough light reflected back to the point of origin.
 
Last edited:

Rodomontade

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The point I was trying to make:

I wanted to eliminate the argument that the Planet Boundary Layer PBL is the reason the beam abruptly appears to terminate due to a rapid decrease in aerosols to reflect light back to the observer at the point of origin. That was the purpose of keeping the beam as horizontal as possible with no obstacles. (thus, the relatively flat surface of the lake) No other location comes to mind with that much clear flat area to perform the experiment. The lake also allowed me to travel to the exact spot the beam stopped in thin air.

I have seen the theory floated that the vantage point determines the point the beam stops. I don’t see how this is possible when I can travel to the exact spot the beam appears to end. It made no difference whether the angle was 20* or 90* or anything in between. The beam still appears to stop at the same point regardless of how close or at what angle it was viewed.

I fully agree the amount of aerosols play a direct role in visibility however the aerosols were reasonably consistent other than the possibility of some minor surface fog above the water. There certainly is no PBL at 1 to 2 feet above the water.

I am not looking for an argument, quite the opposite. I’m just curious what causes this phenomenon. I am fully aware the beam continues on after the reflected light vanishes.
 

Rodomontade

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I'm sorry, are you some sort of flat-earther? Someone that flunked trig in high school? A conspiracy theorists? What exactly do you think you've disproven and how?

Here's a thought experiment that might help you understand this rather simple concept. Imagine for a moment that the earth was flat, and that the earth was infinite in its surface area. Would it still have a horizon?

(hint, the answer starts with a "y" and ends with "es")
I am a pilot so I would say I'm pretty familiar with the horizon.

As far as being some sort of flat-earther... Mmmmmm no. Riddle me this: The borough of Manhattan is approximately 13 miles long. Almost all of it is covered with skyscrapers. Does this mean every skyscraper is closer together at the base as opposed to the top? (hint: the answer starts with a "y' and ends with "es") less than 1/8 of an inch or 1.357 mm but still closer at the bottom than the top. Point I'm trying to make is the resolution we humans can observe at ground level is simply insignificant.

There remains the possibility that I could be a conspiracy theorist, I'd suggest, but hey... 2 out of 3 ain't bad.

Thanks for your input none the less
 

Rodomontade

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Nov 2, 2019
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agree with all who posted.....
Your first thread should have been an intro with your location in the title and placed in the welcome/newcomers section...
then do some searches as there are many posts here on that topic (if I understand what you mean) .
Some of your assumptions are wrong. Not enough knowledge of lasers can be very dangerous.
Agreed.
 

Rodomontade

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Messages
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What he's describing is the apparent termination whether it's pointed skyward or at some distance as he did were the beam is not stopped by an object as stated in his post. In either the apparent termination is caused by not enough light reflected back to the point of origin.
Thank you for the constructive input and understanding my curiosity.
 

hakzaw1

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Pilot??
awesome
we have a few but not enough.

Many here would like to get your opinion on laser incidents reported by pilots.
Its no secret that many pilots are NO FANS of lasers (I assume mostly pointers).

So it is only human nature to exaggerate things depending on ones feelings about lasers in general.... That is bad as we need to know as many facts as possible . (ie unbiased) IMHO anyone intentionally lasing a pilot should go to Federal prison (no early release ever).

BUT just seeing beams (not aimed at the pilot) and reporting that..only makes things seem worse than they really are. And surely takes time away from those who deal with this-- time that might be better spent on something that is not partially imaginary.

Thankfully there seems to be less reports from pilots of late-- best place to confirm that would be at laserpointersafety.org
Mr Murphy misses very little about these incidents.. sorry for going so off-topic.
hak
 
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