green lasers

[truhan]

hi 

i am looking at getting a green laser for pointing out objects in the night sky

what mW and wavelength should i look for 

are there anything else to look for ???

 

 

 

 

 

[michael8554]

In the UK lasers are frowned upon because of the danger to air traffic, which we have a lot of, so more than1mW is illegal to sell.

Check out the  rules for SA.

Michael

[PeterW]

<5mW max, avoid generic low cost online retailers as I got one that was dangerously over powered once. Find a company who can assure you of the power you’re getting.

ideally you want a 520nm direct green (not a dpss 532nm), the reason being that the latter will die when cold, the former are new and cold proof (allegedly. I plan to make my own multipurpose pointer when I   Do some CAD design).

power it with lithium batteries as they are cold resistant too.

As always, be careful who uses it (ideally only you), where you point it. Avoid it shining on things that could reflect back to you or planes/animals etc. Be safe.

I used mine to help a friend find objects in their dob from a light polluted location, worked a treat:
 

Peter

[Mr Spock]

From SA: "Although there is no law prohibiting the use of powerful green lasers in South Africa, they must always be used responsibly"

Skywatcher 50mW http://www.skywatcher.co.za/index.php?main_page=product_info&products_id=940

As with the above posts, do not point these at people, animals, cars or planes. In SA pointing a laser at a plane has a maximum sentence up to 30 years in jail... 

[michael8554]

50mW sounds excessive.

Michael

[PeterW]

Yes, 1mW is intrinsically safe, 5mW is generally safe unless you try to damage yourself and any more is additionally risky. I am sure you could use a 1W laser as a pointer, but I wouldn’t want to be within at least a few miles of it. Don’t risk yourself or others, <5mW is plenty.

 

Peter

[Guest]

I would recommend Z Bolt cold weather astronmy lasers.  They are very bright and good down to 14 degrees.  I dont know about shipping to SA.  

[allworlds]

You don't actually need a lot of power. 5 milliwatts is plenty.

If you're pointing out a target, circle it rather than pointing the laser directly at it. That way if it is actually an aircraft you won't lase the pilot. Sometimes an aeroplane looks like a planet or the ISS.

I wouldn't use one at all if I was close to an airport.

[Louis D]

I've found little kids at outreach events get annoying trying to jump up and grab your laser pointer to play with like a light saber (parents need to reign in their kids, but don't), so I just don't bother with them anymore due to the risks involved.  If it's just responsible adults (no inebriated folks present), then laser pointers are fine.

[truhan]

according to this website  https://www.saao.ac.za/~wpk/laser/2006MNASSA..65..80.pdf   15mW lasers are ideal for astronomy 

but that anything in between 7 and 30 mW will work  

 

Truhan

[tooth_dr]

I bought a decent 1mW green laser from a reputable site.  It just isnt quite bright enough as a sky pointer.  Unless it's hazy you cant see it and even then you have to look for it.  You reckon 5mw would be enough?  I only use it myself and no one else is allowed to handle it.

[Louis D]

No idea how powerful my cheap, direct from China, ebay laser sights are, but they're plenty bright to see from multiple feet away in clear skies when aiming my scope.  I'm pretty sure they're not IR filtered, so I'm insanely careful using mine.  I recommend getting the laser sights with the bigger, 18650 battery instead of the smaller, 16340 battery.  I've had much better luck with them in all temperature conditions.

[Pompey Monkey]

On 02/01/2023 at 14:13, Louis D said:

No idea how powerful my cheap, direct from China, ebay laser sights are, but they're plenty bright to see from multiple feet away in clear skies when aiming my scope.  I'm pretty sure they're not IR filtered, so I'm insanely careful using mine.  I recommend getting the laser sights with the bigger, 18650 battery instead of the smaller, 16340 battery.  I've had much better luck with them in all temperature conditions.

From the Ebay blurb:

"Power less than 1MW"

I should hope so!!! ☠️

[Louis D]

2 hours ago, Pompey Monkey said:

From the Ebay blurb:

"Power less than 1MW"

I should hope so!!! ☠️

That's definitely a case of saying it's so doesn't make it so.  They're just covering themselves legally.  I can assure you they're blinding bright indoors.  Looking at the laser spot's reflection on a nearby wall (to check battery and switch function) will leave you with spots in your eyes for a while, so definitely not recommended if you want to critically observe in the near term.

[Pompey Monkey]

5 hours ago, Louis D said:

That's definitely a case of saying it's so doesn't make it so.  They're just covering themselves legally.  I can assure you they're blinding bright indoors.  Looking at the laser spot's reflection on a nearby wall (to check battery and switch function) will leave you with spots in your eyes for a while, so definitely not recommended if you want to critically observe in the near term.

The capital M denotes "mega".

Lower case m denotes "mili".

But why let a factor of 10^9 spoil our fun! Lol

[Clarkey]

At least they are being honest. Definitely less than 1 MW.

Takes me back to the 'Star Wars' days of Mr Reagan.......

[Mandy D]

1 hour ago, Clarkey said:

At least they are being honest. Definitely less than 1 MW.

Takes me back to the 'Star Wars' days of Mr Reagan.......

I find incorrect use and case of SI units really annoying! Another favorite is kelvin-watts (KW), although I have yet to figure out what property this would specify!

Ahh, Mr Raygun ... Why did it never become popular to spell his name like that? I never once saw it, but thought it many times.

[PeterW]

For SI prefix geeks, there are a few new ones just been internationally agreed - UK proposed. https://www.npl.co.uk/si-prefix

I would certainly hope that none of the new ones are needed for laser specification.

Peter

[Clarkey]

1 hour ago, Mandy D said:

Another favorite is kelvin-watts (KW), although I have yet to figure out what property this would specify!

Temperature change across a resistor?

[Mandy D]

36 minutes ago, Clarkey said:

Temperature change across a resistor?

Wouldn't that be K/W, as for thermal resistance?

[Mandy D]

51 minutes ago, PeterW said:

For SI prefix geeks, there are a few new ones just been internationally agreed - UK proposed. https://www.npl.co.uk/si-prefix

I would certainly hope that none of the new ones are needed for laser specification.

Peter

If we simply stuck to scientific notation, instead of having an obsession with naming things, it would certainly help with understanding. Scientific (or even engineering) notation removes the need for excessive thinking and reduces the possibility of making a mistake in calculations. 30,000 mAh springs to mind as part of the latest craze for unnecessarily large numbers; why not simply state the correct, obvious and intuitive 30 Ah? Yes, I know it is a sales ploy! I've always thought that popular science authors should start their books with a preface that introduces scientific notation to the uninformed reader and then proceed with using correct scientific notation throughout the remainder of the text. We can dream!

<RANT_MODE=OFF> 🤣

[Mandy D]

On 01/01/2023 at 09:51, Mr Spock said:

From SA: "Although there is no law prohibiting the use of powerful green lasers in South Africa, they must always be used responsibly"

Skywatcher 50mW http://www.skywatcher.co.za/index.php?main_page=product_info&products_id=940

As with the above posts, do not point these at people, animals, cars or planes. In SA pointing a laser at a plane has a maximum sentence up to 30 years in jail... 

Avast tells me that the site your link points to is infected with JS:Agent-EHS trojan.

[tooth_dr]

Can anyone recommend a decent green laser that will project a beam, UK based.  My 1mw laser pointer doesnt quite cut it.

[Mandy D]

On 02/01/2023 at 14:13, Louis D said:

No idea how powerful my cheap, direct from China, ebay laser sights are, but they're plenty bright to see from multiple feet away in clear skies when aiming my scope.  I'm pretty sure they're not IR filtered, so I'm insanely careful using mine.  I recommend getting the laser sights with the bigger, 18650 battery instead of the smaller, 16340 battery.  I've had much better luck with them in all temperature conditions.

Surely a visible light laser, which produces monochromatic, coherent light by definition would not require an IR filter? My HeNe laser is specified as having a wavelength of 632.816 nm.

[PeterW]

Diode pumped solid state lasers, most of the existing green ones are actually 880nm(ish) IR diode pumped… this causes an and containing crystal to lase at 1064bm, which is then doubled to 532nm. So you’ve got IR in there you don’t want/need that should be filtered out so that the end user only gets the green that want. Without a spectrometer you won’t know the balance of visible to invisible power. The “cold proof” ones that are emerging (seem to be 515-520nm) are direct diode ones that only emit the exact colour you want… no IR, no doubling etc. 

Peter