Sodium laser visibility vs distance.

To catch up the 574 nm yellow laser took a tangent here.
https://laserpointerforums.com/f40/574nm-36-mw-yellow-laser-102893-35.html#post1539994


I've rephrase the question. Assuming naked eye 20/20 vision clear air with minimal particulates and dry desert air at what distance would this sulfur laser if projected horizontally at a matte white surface have an apparent spot brightness of a 6 magnitude star? This video I think covers (sorta) the question.
https://www.youtube.com/watch?v=DCQ2CbfGs6g

"Green laser pointers are amazingly useful tools for teaching the general public about the night sky, it's easy to point out specific targets and have everyone know what you mean. Sometimes people will point out satellites and even the ISS, so I wanted to figure out whether an astronaut on the ISS would be able to see lasers from people on the ground.

Here's the original video of the ISS Flash project: "
https://www.youtube.com/watch?v=2UoY1...

Re: Can You See A Laser Pointer From The Space Station?

My best guess is without a beam expander on a multi mode direct diode laser, it would diverge too much to be seen from the international space station when fired from earth. It would also take into account the power of the laser as a 1 watt would be less likely to be seen than a three watt of the same divergence. I see that Alaskan has more information on this.

Re: Can You See A Laser Pointer From The Space Station?

Alaskan said:

Yes, someone with a Wicked Lasers did a test some time ago with one of their high power (blue?) lasers, a photo taken from the ISS was floating around the net from it some time ago, there is also a youtube video showing the activity where a group of astronomers were using high power flood lights pointed at the ISS, a laser flashed on and off each time they blocked the light from theirs. I am not completely convinced the blue light in the photo was the laser, but WL reported that was it. I don't know if the wicked laser had a beam expander on it, but if it didn't, no way... my bet is they wouldn't see it, even if DPSS.

Click to expand...

All three lights were visible

paul1598419 said:

My best guess is without a beam expander on a multi mode direct diode laser, it would diverge too much to be seen from the international space station when fired from earth. It would also take into account the power of the laser as a 1 watt would be less likely to be seen than a three watt of the same divergence. I see that Alaskan has more information on this.

Click to expand...

Let's not go off topic to soon. Paul, I only used this video because the person in the vid explained some of the math which could be applicable to this topic. Singlemode and me were talking about the 22 W sodium laser. See first link.

This link shows a photo of one of the launch telescopes. https://wikivividly.com/wiki/Laser_guide_star

Re: Can You See A Laser Pointer From The Space Station?

Way ahead of you Steve. I already was looking on in real time as you were discussing the four 589nm lasers. In fact, I did post there yesterday. If no beam expander was used to flash the ISS, what power was the laser? I could accept that a digital camera might pick up the faint light involved in that experiment, but I do wonder how visible it would be at the ISS as planes at cruising altitude can't see a laser on the ground much of the time. That is only 35,000 feet or so.

Re: Can You See A Laser Pointer From The Space Station?

paul1598419 said:

Way ahead of you Steve. I already was looking on in real time as you were discussing the four 589nm lasers. In fact, I did post there yesterday. If no beam expander was used to flash the ISS, what power was the laser? I could accept that a digital camera might pick up the faint light involved in that experiment, but I do wonder how visible it would be at the ISS as planes at cruising altitude can't see a laser on the ground much of the time. That is only 35,000 feet or so.

Click to expand...

I've changed the title as I think it is confusing.

A 1W blue laser. It does not mention a beam expander. But using a beam expander would make this blue laser more visible at distance as it does with the sodium laser.

Singlemode asked me to ask my question specifically. I asked in this post, see first post. I'd Like to have that answered first before going off on related tangents.