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i tried google, some say forever... many different opinions..
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[solved]how far will 5mw green laser beam travel at night?
- Thread starter Newb2Lasers
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Re: how far will 5mw green laser beam travel at night?
Why at night...:thinking:
It will travel the same distance in daylight as
as night if the atmospheric conditions are the
same..
The distance will depend on the impurities in
the air...
Jerry
Why at night...:thinking:
It will travel the same distance in daylight as
as night if the atmospheric conditions are the
same..
The distance will depend on the impurities in
the air...
Jerry
Re: how far will 5mw green laser beam travel at night?
As long a the photons are not scattered and or absorbed these photons of green light will travel on forever.
Most distant object seen to date Most distant object ever seen… maybe | Bad Astronomy | Discover Magazine
As long a the photons are not scattered and or absorbed these photons of green light will travel on forever.
Most distant object seen to date Most distant object ever seen… maybe | Bad Astronomy | Discover Magazine
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Re: how far will 5mw green laser beam travel at night?
wow i didnt know this, thanks guys
wow i didnt know this, thanks guys
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I think all he wants to know is how far out will the beam itself be visible. Like Laserbee said, it is heavily dependent on atmospheric conditions as particles in the air scatter the light in the beam which makes it more visible but reduces the overall distance that the beam will be visible. Example: crisp night with low humidity I can see the beam from my green laser as a nice thin line hitting low clouds and hitting a tower several miles away. However, on a foggy night the beam appears as a fat glowing "light saber" sort of thing and only travels a few hundred meters at best. While you shouldn't point your laser at any inhabited structure as to cause annoyance, you could just check it seeing if you can hit objects of know distance from you such as mountains (if possible), cell phone/radio towers etc. You can used google maps to determine how for they are from your location. My 0.02, - Matt
JBTexas
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I have two "targets" that I use to help focus to infinity outside at night.
They are other buildings in my apartment complex. One is ~60 meters away, the other is ~260 meters away. I determined this from satellite images from Google Maps.
Of course my 200mw green and ~370-380 mw red are visible at night for the ~260 meter target.
For my 5mw green; the green spot at ~260 meters is FAIRLY visible. For a ~3mw red, I CAN find it at ~60 meters, but for the ~260 meter target, the ~3mw red is VERY DIFFICULT to even find... it becomes VERY DIM.
-----
There is also a radio tower (at first I thought it was a cellphone tower, but that is not the case, my guess it is a radio tower for local city utilities); I can light it up with my 200mw green from a spot nearby to my front door. I've just determined from a satellite map that it is *almost a mile away*. I have not tried it with my 5mw green yet.
* I will try this this evening, and report whether I can see the spot from my 5mw green on that tower.
If I take a short walk, I can see a large white watertower from a certain spot... apparantly is is about ~ 1.3 miles away. I intend to try all of my lasers on that object soon (probably at about 3 or 4 A.M. to avoid interfering with automobile traffic).
They are other buildings in my apartment complex. One is ~60 meters away, the other is ~260 meters away. I determined this from satellite images from Google Maps.
Of course my 200mw green and ~370-380 mw red are visible at night for the ~260 meter target.
For my 5mw green; the green spot at ~260 meters is FAIRLY visible. For a ~3mw red, I CAN find it at ~60 meters, but for the ~260 meter target, the ~3mw red is VERY DIFFICULT to even find... it becomes VERY DIM.
-----
There is also a radio tower (at first I thought it was a cellphone tower, but that is not the case, my guess it is a radio tower for local city utilities); I can light it up with my 200mw green from a spot nearby to my front door. I've just determined from a satellite map that it is *almost a mile away*. I have not tried it with my 5mw green yet.
* I will try this this evening, and report whether I can see the spot from my 5mw green on that tower.
If I take a short walk, I can see a large white watertower from a certain spot... apparantly is is about ~ 1.3 miles away. I intend to try all of my lasers on that object soon (probably at about 3 or 4 A.M. to avoid interfering with automobile traffic).
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JBTexas
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I've already used binoculars with the 200mw green @ ~260 meters (and the ~380mw red), to help "focus to infinity" better (the focused green spot @ ~ 260 meters appeared to be a little over 30 cm, BTW, from comparing it to the size of automobile license plates). (VISUALLY, the red spot appears smaller and tighter than the green, but I didn't bother to try to estimate the red's size).
I'm not going to bother with binoculars for the ~3mw red at ~260 meters (What for? It is a non-focusable cheap red laserpointer; not really interested ... and visually, a green 5mw is *fairly* visible at ~260 meters).
I'm not using binoculars any more because by now I am used to focusing my 200mw green and ~380mw red... I have a "feel" for it now.
Anyway; here is a depiction of my "Laser Testing Range":
(EDIT) For the radio tower, "see shadow to N.E."; you can see a little dark diagonal line to the N.E. of the marker. The Radio tower is actually quite tall.
I have not figured out how to use Google Maps (from WITHIN Google Maps) to depict streight-line distances... I don't think it can do that (but if anybody knows, please post the procedure).
You can see the scale in the lower left. Using that scale, then it is basically a visual estimation for distances. Previously from more-zoomed-in maps, I'm guessing from my apartment to building #1 is ~60 meters, building #2 is ~260 meters; but make your own guesses. I'm just simply going to guess that distances to the radio tower (from my apartment) and from the observation point to the water tower is "1+ mile".
(EDIT AGAIN)
BTW,
From about the area of that water tower observation point; one night I walked to a convenience store near that point, and carried my 200mw green. I noticed a lit church steeple-like structure, and could light it up real well. I didn't know exactly what it was at the time. I've since determined that is "St. Johns Episcopal School" on the map.
I'm not going to bother with binoculars for the ~3mw red at ~260 meters (What for? It is a non-focusable cheap red laserpointer; not really interested ... and visually, a green 5mw is *fairly* visible at ~260 meters).
I'm not using binoculars any more because by now I am used to focusing my 200mw green and ~380mw red... I have a "feel" for it now.
Anyway; here is a depiction of my "Laser Testing Range":
(EDIT) For the radio tower, "see shadow to N.E."; you can see a little dark diagonal line to the N.E. of the marker. The Radio tower is actually quite tall.
I have not figured out how to use Google Maps (from WITHIN Google Maps) to depict streight-line distances... I don't think it can do that (but if anybody knows, please post the procedure).
You can see the scale in the lower left. Using that scale, then it is basically a visual estimation for distances. Previously from more-zoomed-in maps, I'm guessing from my apartment to building #1 is ~60 meters, building #2 is ~260 meters; but make your own guesses. I'm just simply going to guess that distances to the radio tower (from my apartment) and from the observation point to the water tower is "1+ mile".
(EDIT AGAIN)
BTW,
From about the area of that water tower observation point; one night I walked to a convenience store near that point, and carried my 200mw green. I noticed a lit church steeple-like structure, and could light it up real well. I didn't know exactly what it was at the time. I've since determined that is "St. Johns Episcopal School" on the map.
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JBTexas
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Actually; I just checked my mail, and while I was at it, took a short stroll to another part of my apartment complex to check. There IS a closer place, in my apartment complex, where I can see BOTH the radio tower (which is fairly tall) and the water tower (which is very big).
After dark I will try my 5mw green, my 200mw green, and my ~380mw red on these objects. The Original Poster's interest seems to be what a 5mw can do... so I will check.
I used the Google Map scale and some precision rulers to make a streight edged scale on paper from my computer monitor; it should be fairly accurate. The radio tower is about 675 meters from the observation point and the near surface of the water tower is about 1025 meters.
After dark I will try my 5mw green, my 200mw green, and my ~380mw red on these objects. The Original Poster's interest seems to be what a 5mw can do... so I will check.
I used the Google Map scale and some precision rulers to make a streight edged scale on paper from my computer monitor; it should be fairly accurate. The radio tower is about 675 meters from the observation point and the near surface of the water tower is about 1025 meters.
Last edited:
mfo
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I've already used binoculars with the 200mw green @ ~260 meters (and the ~380mw red), to help "focus to infinity" better (the focused green spot @ ~ 260 meters appeared to be a little over 30 cm, BTW, from comparing it to the size of automobile license plates). (VISUALLY, the red spot appears smaller and tighter than the green, but I didn't bother to try to estimate the red's size).
I'm not going to bother with binoculars for the ~3mw red at ~260 meters (What for? It is a non-focusable cheap red laserpointer; not really interested ... and visually, a green 5mw is *fairly* visible at ~260 meters).
I'm not using binoculars any more because by now I am used to focusing my 200mw green and ~380mw red... I have a "feel" for it now.
Anyway; here is a depiction of my "Laser Testing Range":
(EDIT) For the radio tower, "see shadow to N.E."; you can see a little dark diagonal line to the N.E. of the marker. The Radio tower is actually quite tall.
I have not figured out how to use Google Maps (from WITHIN Google Maps) to depict streight-line distances... I don't think it can do that (but if anybody knows, please post the procedure).
You can see the scale in the lower left. Using that scale, then it is basically a visual estimation for distances. Previously from more-zoomed-in maps, I'm guessing from my apartment to building #1 is ~60 meters, building #2 is ~260 meters; but make your own guesses. I'm just simply going to guess that distances to the radio tower (from my apartment) and from the observation point to the water tower is "1+ mile".
(EDIT AGAIN)
BTW,
From about the area of that water tower observation point; one night I walked to a convenience store near that point, and carried my 200mw green. I noticed a lit church steeple-like structure, and could light it up real well. I didn't know exactly what it was at the time. I've since determined that is "St. Johns Episcopal School" on the map.
You can do that with google Earth.
JBTexas
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Okay; re: My previous few posts, maps, pictures.
Note that the radio tower (that top triangular part) is painted a *very dark* gray / dark gray-blue. It is NOT optimal for diffuse reflections. For some reason, it does NOT have any aircraft warning lights on it (?). I had to let my eyes get dark-adapted a bit to see it reliably from my observation point. Again, that radio tower is ~675 meters away from my observation point.
That watertower is white / off-white with a light peach tint. It has one constant-on non-flashing red-orange aircraft warning light on top; a typical round red-orange glimmer that you would see on a tall object. The tower itself was "fairly" visible by ambient light at night. The tower itself is NOT illuminated with any floodlights or anything. Again, that watertower is ~1025 meters away from my observation point.
I DID NOT bother to carry binoculars with me. It's kind of an "iffy" neighborhood; whenever I go out at night I am "armed"; I did not want to lug around TOO much stuff. I was carrying 3 lasers in a small camera case (SMALL case), one of my stun guns, and "something else".
-----
5mw green (LaserGlow Lyra, fixed focus);
"Fairly fresh" alkaline batteries were used.
I CAN see a dim green spot on the watertower. Not "barely visible" dim, just "dim but readily seen". It "appears to be" slightly larger than the aircraft warning light in size, and the spot is "soft around the edges".
I could see the spot from the 5mw green better off of the radio tower, despite the radio tower's dark color. That tells me that between 675 meters and 1025 meters, the "distance limit" for 5mw green is "starting to show".
SO; What can a 5mw green do? If it is fairly well built, with good divergance, etc., you can expect a diffuse reflection from a 5mw green from a kilometer or more; BUT a kilometer is starting to reach a limit.
-----
660nm ~380mw red (Survival Laser R 660nm 300mw with a 650-G-1 Lens);
532nm 200mw green "Gatlin";
Batteries for both were fully charged this afternoon.
I endeavoured to focus both of these into as small a spot as possible on the water tower ("focused to infinity").
For both of these, the spot on the watertower was BRIGHTER than the spot from the radio tower (opposite from the 5mw green). On BOTH the radio tower and the water tower, for BOTH lasers, I would call the sight "dramatic". Fairly bright to very bright.
The red spot from the ~380mw red laser on the water tower was fairly small, compact, tight. A deep ruby red contrasting to the red-orange aircraft warning light. Visually, the red spot SEEMS about the same size as the aircraft warning light. Visually, the red spot is "about 50% to 75%" compared to the brightness of the aircraft warning light.
The green spot from the 200mw green laser was nothing short of "very dramatic".
First of all, there is that bright green beam. For these experiments, I lightly but firmly held the lasers against my right temple to hold them fairly steady; with a bright green beam shooting out towards the target.
The green spot was VERY visible on both the radio tower and the water tower.
The green spot on the water tower, "visually", is EASILY brighter than the aircraft warning light. Seems to be "moderately larger" than the aircraft warning light in size. A VERY bright green spot, but with noticibly "soft edges".
It was an interesting "experiment". Learned something about the limit of a 5mw green.
Note that the radio tower (that top triangular part) is painted a *very dark* gray / dark gray-blue. It is NOT optimal for diffuse reflections. For some reason, it does NOT have any aircraft warning lights on it (?). I had to let my eyes get dark-adapted a bit to see it reliably from my observation point. Again, that radio tower is ~675 meters away from my observation point.
That watertower is white / off-white with a light peach tint. It has one constant-on non-flashing red-orange aircraft warning light on top; a typical round red-orange glimmer that you would see on a tall object. The tower itself was "fairly" visible by ambient light at night. The tower itself is NOT illuminated with any floodlights or anything. Again, that watertower is ~1025 meters away from my observation point.
I DID NOT bother to carry binoculars with me. It's kind of an "iffy" neighborhood; whenever I go out at night I am "armed"; I did not want to lug around TOO much stuff. I was carrying 3 lasers in a small camera case (SMALL case), one of my stun guns, and "something else".
-----
5mw green (LaserGlow Lyra, fixed focus);
"Fairly fresh" alkaline batteries were used.
I CAN see a dim green spot on the watertower. Not "barely visible" dim, just "dim but readily seen". It "appears to be" slightly larger than the aircraft warning light in size, and the spot is "soft around the edges".
I could see the spot from the 5mw green better off of the radio tower, despite the radio tower's dark color. That tells me that between 675 meters and 1025 meters, the "distance limit" for 5mw green is "starting to show".
SO; What can a 5mw green do? If it is fairly well built, with good divergance, etc., you can expect a diffuse reflection from a 5mw green from a kilometer or more; BUT a kilometer is starting to reach a limit.
-----
660nm ~380mw red (Survival Laser R 660nm 300mw with a 650-G-1 Lens);
532nm 200mw green "Gatlin";
Batteries for both were fully charged this afternoon.
I endeavoured to focus both of these into as small a spot as possible on the water tower ("focused to infinity").
For both of these, the spot on the watertower was BRIGHTER than the spot from the radio tower (opposite from the 5mw green). On BOTH the radio tower and the water tower, for BOTH lasers, I would call the sight "dramatic". Fairly bright to very bright.
The red spot from the ~380mw red laser on the water tower was fairly small, compact, tight. A deep ruby red contrasting to the red-orange aircraft warning light. Visually, the red spot SEEMS about the same size as the aircraft warning light. Visually, the red spot is "about 50% to 75%" compared to the brightness of the aircraft warning light.
The green spot from the 200mw green laser was nothing short of "very dramatic".
First of all, there is that bright green beam. For these experiments, I lightly but firmly held the lasers against my right temple to hold them fairly steady; with a bright green beam shooting out towards the target.
The green spot was VERY visible on both the radio tower and the water tower.
The green spot on the water tower, "visually", is EASILY brighter than the aircraft warning light. Seems to be "moderately larger" than the aircraft warning light in size. A VERY bright green spot, but with noticibly "soft edges".
It was an interesting "experiment". Learned something about the limit of a 5mw green.
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Just be careful not to cut any of the supports on that water tower with the Laser- it looks like it's already leaning now............................
Thanks very much for this experiment- I'm thinking of getting a 5 tp 20 MW green to play around with-as a first Laser- and the 5mw sounds like it might be best so I could play around in the house without worrying about reflections.
Yes- I will have to get a measured one and preferably with a IR filter so I don't have to worry about reflections inside, off walls etc. won't point at mirrors but above 20 to 30 mw can be dangerous to look at the dot on white walls- right- so 5 to 10 mw should be max ..........
I want to see the beam and a more powerful one sounds like fun but nowhere to play with it in the City without alarming people , I'm afraid- so 5 to 10 mw green sounds best and a 1 km range is good, more controllable for outdoor use and also a more subtle beam if I play around outdoors.
Thanks very much for this experiment- I'm thinking of getting a 5 tp 20 MW green to play around with-as a first Laser- and the 5mw sounds like it might be best so I could play around in the house without worrying about reflections.
Yes- I will have to get a measured one and preferably with a IR filter so I don't have to worry about reflections inside, off walls etc. won't point at mirrors but above 20 to 30 mw can be dangerous to look at the dot on white walls- right- so 5 to 10 mw should be max ..........
I want to see the beam and a more powerful one sounds like fun but nowhere to play with it in the City without alarming people , I'm afraid- so 5 to 10 mw green sounds best and a 1 km range is good, more controllable for outdoor use and also a more subtle beam if I play around outdoors.
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