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kecked

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Laser Pointer Safety - A comprehensive resource, for safe and responsible laser use go to the caclulators
I like the following summary. There are plenty more. https://researchsafety.uchicago.edu...es/uploads/Laser MPE and NHZ Calculations.pdf
I agree it seems extreme. I'm just stating what is the accepted result that professional certified laser safety officers are taught.
Here is the calculations the website uses. Laser Pointer Safety - Laser safety calculations
This is what is used to calculate safety in laser shows in the USA. Is it the same in other countries I do not know.
Like the blue wil kill your eyes article. Goes against my sensibilities but the research seems there. Un like that this is not a single paper.
Anyway paul not fighting. just sharing. You know me by now I don't engage in flame wars.

PS that post last night REALLY REALLY made me angry. Dude hit every post. Before I realized that I thought he was aimed at me.
Going out for a day. Catch me off line if you want more guideance. The website is maintained and created by Patrick Murphy at ILDA.
 

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I don't want to prolong this discustion whether or not a certain laser could cause harm to anyone at any distance. I cannot imagine that anybody can hold a laser steady enough to cause prolonged exposure to a flying plane. Even without doing the math, a beam sweeping across a plane 10 miles away can't be much more than a millisecond flash. Disturbing, but probably not causing permanent (or even temporal) damage.

Governmental regulations are not always backed up by physics, but they occasionally respect their peoples opinion. Better safe than sorry. A laser beam shone into the window is at least very annoying and highly unnecessary. There are laws which explicitely forbid this. You are facing problems if you don't obey.

So the easy answer is: We just don't do it. Whether or not there is a chance it may be completely harmless.

Planes are easily seen in the dark and it should be fairly easy to avoid pointing at them.

As is to avoid pointing onto or into other peoples houses or barns, shooting the beam across a road onto a reflecting sign or any other cool targets. Chances are good that this will upset someone.

But you already have known this before my appearance, so we safely can assume that the people gathering here are responsible by nature. When I look at the impressive list of lasers and their power in some message footer, I bet you are as careful as someone who is juggling with chainsaws.

:friend:
 

RedCowboy

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I was looking at Ears and Eggs pic when I realized something.

Maybe that's why she has her hand back like that, maybe she's saying... Knock it off, you don't even have a torso.

 

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paul1598419

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Laser Pointer Safety - A comprehensive resource, for safe and responsible laser use go to the caclulators
I like the following summary. There are plenty more. https://researchsafety.uchicago.edu...es/uploads/Laser MPE and NHZ Calculations.pdf
I agree it seems extreme. I'm just stating what is the accepted result that professional certified laser safety officers are taught.
Here is the calculations the website uses. Laser Pointer Safety - Laser safety calculations
This is what is used to calculate safety in laser shows in the USA. Is it the same in other countries I do not know.
Like the blue wil kill your eyes article. Goes against my sensibilities but the research seems there. Un like that this is not a single paper.
Anyway paul not fighting. just sharing. You know me by now I don't engage in flame wars.

PS that post last night REALLY REALLY made me angry. Dude hit every post. Before I realized that I thought he was aimed at me.
Going out for a day. Catch me off line if you want more guideance. The website is maintained and created by Patrick Murphy at ILDA.

I see now that you have the extremely conservative examples given to laser show operators for having laser exposures to large crowds of people. These do not translate into use of pointers when used by astronomers to point out stars or constellations. I have seen these figures before and believe me, they are conservative in the extreme. The ILDA is trying to make people who have never used or been exposed to laser radiation to take this responsibility very seriously. I have never taken the test as I have never needed to. I can imagine that they want you to regurgitate these figures which are far beyond safe for every living thing on the planet, but are not what should never be exceeded in star pointing. If you are putting on a laser show for a large crowd, you have legal and civil obligations that could cause you to lose your freedom or all of your money if you happen to cause damage to someone's vision by your negligence. It is an apples and oranges comparison.
 

Benm

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Planes are easily seen in the dark and it should be fairly easy to avoid pointing at them.
Which was my entire point: You can see an airplane in all cases where you could interrupt flight operations. They -must- make themselves visible using the strobes below 10.000 feet, and if they omit to do so and then get hit with a laser, that's partially the pilot's fault as well.

Surely you could fly lower without any lights on (even the red/green wing markers and front stern lights -can- be turned off) and be invisible from the ground at night. This would be deliberately flying in stealth mode, and you may as well turn off the transponders as well at that point. You could get struck by a laser, other aircraft, or risk to be shot down by the airforce since a commercial jetliner still has a huge radar signature so people on the ground will definitely know you're there.

But for astronomy none of this is a problem, and you'll probably even see most airplanes at cruise altitude as they keep the navigation lights on, and most also keep the lights aimed at the tail livery during the entire flight.

So as long as you look first and then turn on the laser you'd be fine.
 

Pelagius

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Thanks all- I am motivated-again-to look at a tracker!

Oh, really?




G'day Pelagius,
This was taken only with a Canon DSLR camera and 16mm lens on a tripod, no tracking.
I kept the sub frames short to minimise trailing, lens set to f/4, ISO 1600, (8) x 30 sec light frames, 4 min total.
I used a program called Registar to register, align and stack the images.

Also as Ears & Eggs said there's a telescope thread, and as Jeff (BowtieGuy) said, it's not considered necroposting if you have a comment and new info to add.

I'm at work atm but I might post some more LPF astro related links for you later.

Cheers
RB

:beer:
https://laserpointerforums.com/f57/p...pe-102999.html

^Some are not so old. :D Awesome to see what telescope everyone has.
Hi Pelagius, some of those threads aren't that old, and besides, if you are posting with new information to add, it's generally not considered necroposting. :yh:
If you want a lot of posts try cloudynights.com. All about Astro

Welcome. Is that mars I see in that image?
Amazon sells three points for 5.00. Rgv. Poorly made but they work.
Please checkout Laser Pointer Safety - A comprehensive resource, for safe and responsible laser use in regards to pointing at the sky.
He is USA it’s a big deal. Maybe not where you are.

A green laser 5mw 1mRad div is a distraction to pilots 2 miles away.
20mw is 5miles
100mw 10 miles and then you are into flash blindness at 1mile
If you can do 5mw it makes sense.

Here is the eye hazard data for same. This means you only have a 50%chance something bad will happen if the beam sweeps over your eye for 0.25s. This does not mean stating into the beam and it is only for the visible not Ir.

5mw 52’
20mw 104’
100mw 234’

End point be safe have fun. Used responsibly it’s all good. Never ever point at airplane.

https://www.amazon.com/pieces-Laser...qid=1534434802&sr=8-10&keywords=laser+pointer
 

Benm

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Good, now go find a nice direct diode pointer for your endeavors.

In the current market it'd be looking for something direct diode, single mode, in the range of 520-510 nm with a power of 20-50 mW to replace your old green DPSS.

These will appear more blue than green compared to what you used before, but the brightness will be comparable and there is zero risk of IR light leaking out etc.

It'll probably best not to go for the cheapest options though, you can order something well made at a reasonable price point, and set to this power point could have a diode that will last for decades even with daily use.
 

hakzaw1

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yeah what you read at ebay etc -

is what the seller hopes Ebay reads/believes ALL of the $3 (two aaa batts) greens are way over 5 mW-a true 5mW can run $140 even today- as far as 'colors' go-- its best to not think of all wavelenghts in regards to 'power'
of the 'three for $9usd and free shipping-penpointers -- combined mW can often be more than 200 mW-- but all 'sold' as 5 mW..
our eyes 'see' lower powers of green many times lower in power--

thus even just a true 5mW has an easy to see beam and bright spot whereas 405-- the 'B' in ebay listings-- not really Blue at all- quite hard to see ..more like a blacklight on crack. ( for most humans 555nm is easiest to see)

The 405 ts the most dangerous IMHO of ALL the lasers most of us collect- of the three the BR (blueray) 405 is most often the one w/ the highest mW and can often light a match even w/o adding a mag glass. 405s have a thin beam-- making it more powerful.
and while it makes day-glo and GITD stuff glow like crazy - anywhere else you shine it will be hard to see unless you are close..
even between the various 'reds' there can be HUGE diff in perceived brightness-= its takes 4000mW of red 655 to be equal to our eyes the same as 2000mW of 635 -638- or 640. (Pics showing this have been posted at PEELEE by 'Norty' )


about 'turning it down or aiming beam thru a tiny hole..' Only very spendy laser would have a way to do that(adjust power).affordable tho if your build it.
. but a pin hole can work' I imagine.. some sky watchers prefer red laser due to less efx on your night vision.. easy to see when 'looking up the beam' but hard to see from the side.. (or someone far away)

btw your English tells me you have majored (or minored) in English.. & I am betting you know several more--I have been self-teaching myself Spanish (I am in Texas so..) but only some success--I know not to order the 'pulpo' soup.... its 'marado' in color so you can guess what its made from.... (pardon my spelling)

have you been to Laserfreaks meet in Berlin? heard lots about that-- wild times..
its on my bucket list..

hak

glad you have joined us -- cheerz!!
 
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even between the various 'reds' there can be HUGE diff in perceived brightness-= its takes 4000mW of red 655 to be equal to our eyes the same as 2000mW of 635 -638- or 640. (Pics showing this have been posted at PEELEE by 'Norty' )
Posted pictures of laser color is as useless as an online Ishihara-test. Visible color of monochromatic light cannot successfully be captured by a digital camera with unknown spectral sensitivity, unknown color processing and unknown color reproduction at the user end by another tricolor device of unknown spectral source. You will get something similar, but clearly nothing near the true color. So even the different brightness is only what the camera had seen.

some sky watchers prefer red laser due to less efx on your night vision.. easy to see when 'looking up the beam' but hard to see from the side.. (or someone far away)
I thought of that too, but to get a reasonable visible beam I have to use considerably more power with a red pointer than with a green one. It seems that the red lasers have better collimation too. This in combination would make a red device not necessarily safer than a green one, even if the energy of the red photons is lower.

btw your English tells me you have majored (or minored) in English.. & I am betting you know several more--I have been self-teaching myself Spanish (I am in Texas so..) but only some success--I know not to order the 'pulpo' soup.... its 'marado' in color so you can guess what its made from....
Thanks for the compliments. Learning English is an important part of our education in Austria. Western Europe has been orientating towards the USA since WW2, so seemed natural. When you have a different language any few miles like in Europe, you need a common language that you can use as a reliable fall back. This even works in France (sometimes, when they want to be polite and when you can express that you are Austrian and not German).

Indeed I have made a minor degree in technical English as part of my scholar education. The school type "HTL" has no direct correspondence to the American education. It's some kind of technical college. The degree entitles you to apply to any university.

But I had a lot of opportunities to read technical articles in English in the last 30+ years. Reading English is almost like reading German to me. Talking is quite another matter. It takes considerably longer to write the post than to read it. I could probably successfully attend an all English meeting without prior notice, but if I had to take a business interview in English, I'd like to be well prepared.

Generally I'm not good at all in languages. I had a little Latin, which is still helpful on any roman language to pick up a few common words. My Spanish is essentially limited to "¿Este el asiento libro?" and "Una cerveza por vavor!". I'm pretty sure at least one of them is badly wrong, but at least I always did get the beer. :yh:

have you been to Laserfreaks meet in Berlin? heard lots about that-- wild times..
No, I have not. Until now Laser was not on my short list for the next hobby. I still struggle trying to play the Saxophone, which keeps me busy. Unfortunately I did not think about learning it 30 years ago, so it takes a little longer. My SO keeps an eye on it, so that I don't develop GAS and rather try to improve by practicing.

I think she would remind me in time that "one usable laser pointer is sufficient", in case I start to develop some symptoms.
 
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Benm

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The argument for using red would be mostly that it doesn't degrade night vision / adaptation that much compared to green or blue light.

This effect is certainly real, but i doubt what role it plays in pointing out stars - i doubt you'd crank up power level to a point where the laser beam in the sky is brighter than most stars in any case, so the effect should be limited.

The optical quality of red diodes can be -very- good, especially from the ones intended for DVD writers since they are single mode diodes and can be collimated very well. The downside is that you do need a lot of power. Presuming you're doing this in the dark under scotopic vision conditions, a 650 nm light source would be about 1000x times less visible for equal power compared to 532 nm green.

It's important to consider the difference between scotopic and photopic vision here: under daylight conditions the visibility of 532 versus 650 is still there, but more like 8 times than 1000.

Practically you rarely have fully scotopic conditions though, even when far removed from cities. If you do you get really odd effects - i remember camping in the egyptian desert in a very remote location, and my eyes got dark-adapted so well that the starlight actually annoyed me when trying to sleep in a tent ;)
 

kecked

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I just came back from cherry hill dark sky site in PA. They used green and red. The red is not worth the trouble. The green worked very well. They used about 30mw of green. The red was barely visible at all. It didn’t affect my night vision in the least but there was a half full moon as well.
 

RB astro

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Hey smallfreak,
I've used both green and red but I prefer green for astro work.
As you say, red works but you need more power.

I'll tell you what would be nice, is a beautiful 490-495nm pointer at around 55mW.
I made one up and took some shots with it in this thread below.

>>>> 495nm Aspire <<<<

Here's a beam shot from that thread.



But make sure you only use one at a time because more than one is a waste..... LOL :crackup:

 
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I'll tell you what would be nice, is a beautiful 490-495nm pointer at around 55mW.
I made one up and took some shots with it in this thread below.
:drool:

Thats quite a distinct color. Could be an argument when some official mocks about using "green laser pointers". :p

Those pure colors do have a certain attraction.
 

paul1598419

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I call my 493nm laser a cyan color. It looks like the margin between green and blue. Mine is well over 100 mW though. It is still single mode so the divergence is great. I think it would make a great star pointer as Andrew has stated here. Mine has a very visible beam in the night sky. :yh:
 

kecked

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I saw one of those in person and the color is assume! I'd agree that is a great astro pointer.
 




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