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Astronomy Red Laser Pointer

Pedsam2

Pedsam2

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Does anyone have any idea of which Astronomy red laser pointer has a limited distance of infinity?
 





Sigurthr

Sigurthr

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Assuming the OP is not trolling and just is misinformed...

I think the OP is trying to say "which (red) laser has a beam, that when focused to infinity, stops at a certain distance in the sky".

To which the answer is that no laser's beam actually stops suddenly, it is just that the light is no longer reflecting back to your eyes beyond that angle, so you don't see it anymore.

Also, red lasers, at least the common 658nm ones, are terrible for star pointing because if the air is clear enough for good astronomical viewing, you won't see any of the beam at all, even from something powerful like 300mW.
 
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S

Stix62

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Sigurthr said:
Assuming you're not trolling and just are misinformed...

I think the OP is trying to say "which (red) laser has a beam, that when focused to infinity, stops at a certain distance in the sky".

To which the answer is that no laser's beam actually stops suddenly, it is just that the light is no longer reflecting back to your eyes beyond that angle, so you don't see it anymore.

Also, red lasers, at least the common 658nm ones, are terrible for star pointing because if the air is clear enough for good astronomical viewing, you won't see any of the beam at all, even from something powerful like 300mW.
Click to expand...

Me trolling?...no, I was being serious :D (mis-informed I guess)

Actually, I'd been wondering why the beam seemed to suddenly stop myself until this thread popped up and you answered. I googled also (clear air huh?:D)
Haha, I only said to someone here earlier you learn something new every day - how ironic :D
 
Pedsam2

Pedsam2

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Actually I was asking if there is a laser that has no limit!

But if the 658nm red laser is terrible for star gazing which one is best?
 
Sigurthr

Sigurthr

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I didn't mean you, Stix, I meant the OP! =P

Edit: replying to OP:

All lasers have no limit, but we can only see their beams so far, which is determined by the density of particulate matter in the air. As you increase in altitude the density of the air, and particultes, drop. Eventually the air/dust is so thin that it no longer reflects back the laser's light with sufficient intensity to be seen.

What lasers are good for stargazing? Well, the best are high powered yellows, but those are serious money. That's what observatories use though, beautiful 589nm. :drool:

Anything between 445nm and 600nm will work very well, but light lower than 580mn will have a negative effect on your dark adaptation. Usually it isn't too bad if you are careful to not shine the laser on anything close though.
 
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AnthoT

AnthoT

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Pedsam2 said:
Actually I was asking if there is a laser that has no limit!

But if the 658nm red laser is terrible for star gazing which one is best?
Click to expand...

Go with a 635nm laser those would be bright enough probably :beer:
-Anthony
 
AnthoT

AnthoT

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A 635nm laser if you want red or if you want it super visible get any green over 15mw
-Anthony
 
Pedsam2

Pedsam2

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Sigurthr said:
I didn't mean you, Stix, I meant the OP! =P

Edit: replying to OP:

All lasers have no limit, but we can only see their beams so far, which is determined by the density of particulate matter in the air. As you increase in altitude the density of the air, and particultes, drop. Eventually the air/dust is so thin that it no longer reflects back the laser's light with sufficient intensity to be seen.

What lasers are good for stargazing? Well, the best are high powered yellows, but those are serious money. That's what observatories use though, beautiful 589nm. :drool:

Anything between 445nm and 600nm will work very well, but light lower than 580mn will have a negative effect on your dark adaptation. Usually it isn't too bad if you are careful to not shine the laser on anything close though.
Click to expand...



Thank you!
 
Sigurthr

Sigurthr

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I will partially redact my earlier statement and say that if the atmosphere is still visibly clear but there is enough moisture or suspended particulates that 200mW of 658nm CAN be used for star pointing rather well. But only on nights when conditions are just right. I had such a night tonight.

For a reliable star pointer, go with a low power green as stated above, though.
 
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