Green Laser Pointers ?

[Totnesdave]

I picked up one of these 5mW green laser pointer pens with a scope-tube mount, thinking 'hey what a great idea to avoid all the gymnastics of getting my refractor tube in rough alignment, pre-finderscope"

I'm used to lab lasers of old but puzzled in that.. i can shine it across the room in the dark, see a spot, can shine it through a bush in the garden and see the beam caught in dew droplets etc, but...can I see a continuous green beam as suggested ?..No. Can I see a dot up in the sky to align by ?... No.

It was lovely clear night tonight and I would sort have instinctively expected a laser beam to only really show up when hitting water vapour, dust, clouds etc

Am I expecting too much or is the thing just faulty ? Anyone have any experience with these things ?

cheers

Dave

[Chris H]

Sounds faulty. I tried a green laser pointer and it was really good, it produced a beam of light that stretched up into the sky and was clearly visible.

[yeti monster]

If the air is so clear that there is nothing to reflect the beam, then you won't see one. But as there are generally some particles, you'll see it on most occasions.

Last night I had the best beam yet, but could barely see the moon through the clouds!

[yeti monster]

Sorry Kris, but if it's showing a point of light on a target, how can that be a fault?

[vince 66]

I've been using one for about a year now one of the best investments I've made for pointing my dob the only problem I have found is that they are effected by the cold weather just a thought have you checked the batterys.

[brantuk]

Yep that was my thought Vince - as the battery wears down or gets cold the beam seems to diminish. Put some fresh duracells in it and it should come back

[nicnac]

i found the 10mW better.

i hear there is a blue laser now that is much better than the green but it is rediculous expensive and im not 100% you might need some kind of licence for it like you do the high power greens.

[Chris H]

Sorry Kris, but if it's showing a point of light on a target, how can that be a fault?

Because as you said the idea of these is to produce a beam of light rather than a point of light on a target. For example if you have a laser collimation tool and you point that into the sky it won't create a beam just a point which you won't see because there is nothing for it to reflect back off. It is possible that it is not faulty at all just the wrong type of laser pointer, for example the type used in lectures for highlighting things on a white board, these don't create a beam.

[G4YVM]

Not sure low power is a fault, but I suppose it might be so construed.

I bought a cheap, ten quid, 5mw off ebay a few weeks ago and it is USUALLY fine, but sometimes the power drops and then there is a dot but no real beam. I assume this (actually, I KNOW this) is due to reducing / reduced power. I know this because I can see it happen on cold nights...turn it on, bright light sabre-like beam, three second later a noticable step-down in reflected beam, then seconds later, a dot but no beam at all. Pop it in the pocket to warm up and repeat till bored.

Its still a great tool though.

D

[Totnesdave]

Tried new duracell batteries in lieu of the ones supplied, no change.

Absolutely no beam visible, and only a dot at close range

I have emailed the supplier for assistance.

Thanks for your help guys

[Brett]

Maybe its the power of the laser, I have a <50mW and get a beam but only once its warmed up. Try keeping the laser in your pocket for 20mins or so and then try it

Brett

[nicnac]

got to agree with chris on this one, you must have gotten the wrong kind of pointer, have alook here -

Green laser pointer , High quality and low prices

[Totnesdave]

yes, I bought it from an astro supplier with a telescope mounting frame though ... so you would think it would be the correct sort of item. You also have to hold down the button to keep it turned on, and I've also noticed that , after about 20 seconds or so it fades out completely, even the close range dot.

Thanks for the link, it looks identiocal to this one: High Power Green Laser pointers - MEGAGREEN though that isn't where I got it from.

Dave

[cathalferris]

I mislaid my 5mw pointer recently, and purchased another 5mw pointer. Of course I then located my original item...

However it appears that the new pointer behaves as if it is about 1mw, and has the faintest beam in clear air at night, even with dark-adapted eyes. The original green laser pointer is almost lightsaber-like in comparison.

It's possible that the faulty one got a shock in transit, and this will affect the bit in the laser that halves the wavelength from the IR diode that all of these pointer actually have as the laser source.

Definitely contact the vendor, as a 5mv green laser should be startlingly bright at night, and you should see the dot in daytime on tarmac up to 100 feet away in the sunshine, and at night well over 1km away. The beam should be obvious even in dust-free air as Rayleigh scattering will allow the beam to be seen even without dust to reflect from.

[johninderby]

Reading some of the posts brings up the common "it's cold so my laser doesn't last very long" type of comments. A decent quality laser will have an output power regulator that keeps the beam bright until the batteries are completely exhausted and so they aren't affected by the cold.

I've seen many lasers that are supposedly for astro use (some of them quite pricey as well !) that are actually just of the cheap unregulated variety. The regulated 5mw green lasers can be had from about £30.00 upwards if you shop around, so it isn't necessary to spend a lot to get a good one.

You'll probably have to go to a laser specialist rather than an astro dealer to find someone who actually knows the technical specs and can tell you if the laser is in fact regulated.

John

[Totnesdave]

Thanks for all the advice on the laser pointer, guys. I learnt some stuff along the way too, as always here

Supplier is replacing it as defective...fingers crossed that the replacement is OK eh

Dave

[LukeSkywatcher]

Mine sends a constant strong beam out into the universe. I see a green dot on any target i point it at. The cold weather does effect the batteries. I usually roll mine between my hands for a minute or so before using it.

[Capricorn]

Bit late if it has gone back but check that it is a 5mW. Most I have seen sold by astro shops in a scope mount are rated at 1mW not 5mW.

I have a 5mW and find it poor. Simply not sufficent power from it.

As said to see the beam there needs to be "stuff" in the air for the beam to reflect/scatter off of. So if very clear, clean air it will not actually be all that prominent. Additionally light pollution will make the beam less visible. This I think is the problem I have in the garden.

The 5mW I have needs to kept warm, if it gets cold then the beam fades. I think it is more to do with the laser producing chip and how it operates. One of the GLP sites has an explanation of how they operate. It's not simple, 2 or 3 stages before it is a green laser.

Sitting in a scope mount means that the laser will be cold almost all the time and I wouldn't expect it to do anything.

Don't use rechargeables, they are 1.2v and too low a voltage, also rechargeables don't like the cold either.

[LukeSkywatcher]

ALSO.................IF you MUST use a green laser pointer as a finder............please turn it off if you see any aircraft passing overhead.

I ONLY use mine to point peoples eyes in the right direction when i am trying to show them things of interest in the night sky.

I have tried to have fun and games with my 2.5 yr old Yorkie but she is too intelligent to even care less about this strange green light flashing about the place.

If you own a cat that is great cuz they love chasing lasers.

Dogs just aint impressed.

[ollypenrice]

I have a seriously excellent sky and can see my beam easily. You don't need a fixed bracket. Just ao

im it through your finder! Works a treat. Mine is Galaxy Products and is several years old and going strong. Couldn't live without it!

Olly