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ArcticMyst Security by Avery

574nm 36 mW Yellow Laser






paul1598419

paul1598419

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Oh, I've seen that four laser guide star for the telescope before, Singlemode. Yeah, those were quite expensive to obtain and setup. Sure wish OPT Laser would get their problems solved and have these awesome yellow lasers at "wholesale" prices. I was working with mine yesterday trying to see how much current to the pump diode affects the brightness of the output beam. I found that once you get to a Vf over 1.6 volts the driver gets so hot it is difficult to keep it cool even with active air currents over the heat sinks and under the board. I left mine just under 1.6 volts. I need to do more experimenting with it.
 
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steve001

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Singlemode Laser

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steve001 said:
From what I've read recently the beam diameter is 1 foot. Wonder what the divergence is?
Click to expand...

If it is a pure Gaussian (It is very close to it since the light is freq.doubled in a resonant cavity that is a superb mode cleaner) than this would result in
0.001 mrad !

Singlemode
 
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steve001

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Singlemode Laser said:
If it is a pure Gaussian (It is very close to it since the light is freq.doubled in a resonant cavity that is a superb mode cleaner) than this would result in
0.001 mrad !

Singlemode
Click to expand...

At that divergence and output I wonder what the maximum distance would be to illuminate a white surface? Assuming low particulate, low humidity air and 20/20 vision. With my 500mW 532nm I can illuminate a whitish surface at 15000 feet.
 
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Singlemode Laser

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steve001 said:
At that divergence and output I wonder what the maximum distance would be to illuminate a white surface? Assuming low particulate, low humidity air and 20/20 vision. With my 500mW 532nm I can illuminate a whitish surface at 15000 feet.
Click to expand...

These lasers reach at 90km bevor they are getting absorbed by sodium atoms in the upper atmosphere.

Singlemode
 
Cyparagon

Cyparagon

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Singlemode Laser said:
These lasers reach at 90km bevor they are getting absorbed by sodium atoms in the upper atmosphere.
Click to expand...

UecOF.jpg


Sodium absorption is 589nm (588.9950 and 589.5924 if you want to be pedantic). Sodium vapor is transparent to basically every other wavelength.
 
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Singlemode Laser

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Cyparagon said:
UecOF.jpg


Sodium absorption is 589nm (588.9950 and 589.5924 if you want to be pedantic). Sodium vapor is transparent to basically every other wavelength.
Click to expand...

I guess you have misunderstood here something.
These laser has exactly the wavelength of sodium atoms to excite them.

Singlemode
 
paul1598419

paul1598419

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This is about the opening in April 26 of 2016 of the four 22 watt guide star lasers at the Paranal Observatory in Chile which uses these lasers to light up the Na+ ions in the upper atmosphere to compensate for atmospheric aberrations. These guide stars help the adaptive optics of the telescopic to compensate for these aberrations in order to get a clearer view of the celestial bodies they want to observe.
 
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steve001

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Singlemode Laser said:
These lasers reach at 90km bevor they are getting absorbed by sodium atoms in the upper atmosphere.

Singlemode
Click to expand...

That's a long distance up but I still wonder if projected horizontally what the maximum distance would be to illuminate a white surface? Incidentally using a 5mW 532nm laser I was able to see naked eye multiple specular reflections at a distance of 6 miles. Even at that distance the reflection was bright. On a white surface the visible distance at that output is a great deal less.
 
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Singlemode Laser

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steve001 said:
That's a long distance up but I still wonder if projected horizontally what the maximum distance would be to illuminate a white surface? Incidentally using a 5mW 532nm laser I was able to see naked eye multiple specular reflections at a distance of 6 miles. Even at that distance the reflection was bright. On a white surface the visible distance at that output is a great deal less.
Click to expand...

I have no idea how to convert a visible illuminated white surface into something else like power or whatever. It will definitely depends on a lot of parameters, especially the material of the surface. If you could formulate your question in terms of beam intensity or power...

With the information about a range of at least 90km I wanted to show that this beam travels 90km and is still strong enough to excite the sodium layer in the upper atmosphere so that you can see the emission of this layer back on earth with your nacked eye. Based on this I would bet that this beam will be able to illuminate a white surface at least 90km away in the horizontal, so you could see it. How much more than 90km, that is something I can't say.

Singlemode
 
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Singlemode Laser

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Cyparagon said:
You are correct, and I apologize. This is a thread for 574nm and I missed the sudden topic jump to 589.

However, the atmospheric opacity is not 100% at the sodium D line either. Much (perhaps even most) of the light will still pass through.
Click to expand...

Apologies accepted Cyparagon :beer:

I agree with you that a huge part of the beam power is lost on the way up. Also due to scatter on dust particles, water and everything else. On the pictures you can see the beam very clear on the first miles. This means that it is scattered a lot! That is why they use such huge power beams. To have enough power left up there to still be able to excite the atoms!

Singlemode
 
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steve001

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Singlemode Laser said:
I have no idea how to convert a visible illuminated white surface into something else like power or whatever. It will definitely depends on a lot of parameters, especially the material of the surface. If you could formulate your question in terms of beam intensity or power...

With the information about a range of at least 90km I wanted to show that this beam travels 90km and is still strong enough to excite the sodium layer in the upper atmosphere so that you can see the emission of this layer back on earth with your nacked eye. Based on this I would bet that this beam will be able to illuminate a white surface at least 90km away in the horizontal, so you could see it. How much more than 90km, that is something I can't say.

Singlemode
Click to expand...
I will start a new thread so not to hijack this one further. https://laserpointerforums.com/f70/can-you-see-laser-pointer-space-station-103156.html#post1540161
 
hakzaw1

hakzaw1

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kecked said:
Any news on the original laser orders from freeman?
Click to expand...

Grn05gt said:
Adding to Hakz' response, I messaged my contact yesterday about the status and this was the reponse:

The last development failed, we need more time to do it, i will tell u when we have any update,thx

Best regards
Hiyal
Click to expand...

******** cant wrap my head around this.. they were able to fill most if the forum orders then-- no new deliveries-- should I ask for a refund (no fun)?? hak:scowl:
 
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