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Jarndyce

Sensible green laser question?

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Firstly, just a request that this doesn't turn into one of those "green lasers are the devil's work" threads. I think that's been pretty well covered in other threads on the forum. They can be useful, can also be irritating (if not down-right dangerous) if used irresponsibly and should be kept away from starparties.

But, I find them occasionally useful as a pointer, but also as a finder when attached to a non-goto scope. I know other people use them on this forum as finders, so I know I'm not a complete pariah.

So, after much rambling, my question:

I bought a laser pointer to use as a finder from a well known supplier. Green. 5mW. Cost around £25.

Since I got it, it's not been terribly reliable. It doesn't work well in the cold - but this is a well documented issue, and I was prepared for it. Keep it warm, etc.

However, even when it's really warm, sometimes it doesn't work at all. Then occasionally, it displays a very dim red dot and then nothing.

Disturbingly, I came across this thread which mentions this issue:

Some FAQs about green DPSS lasers - Laser Pointer Forums - Discuss Lasers & Laser Pointers

Q: Why, after my DPSS laser suddenly stopped working, do I see just a dim red light coming from the aperture?

A: DO NOT LOOK INTO THE APERTURE!!!!!!! This dim red light is actually being produced by an extremely powerful infrared laser. Since IR light is invisible, all we can see is the dim red light. Don't be fooled by the dimness, even in a 5mW DPSS laser the IR output is guaranteed to be at least 200mW, which is more than enough to fry your eyes. The reason that you can see this is because some of the internal parts of the laser have gone out of alignment..

I don't know how reliable this information is, but the implication is that a misaligned green astronomical laser appears to be not working, but has actually shifted into the infra red and is both invisible, considerably more powerful and consequently highly dangerous.

I tested this by viewing the spot of the "non functioning" laser with the infra red night vision on my camcorder. Sure enough, the laser IS working and is very intense.

Has anyone encountered this before?

If the posting on the laserpointer forum is correct, this is a real hazard. (They are the devil's work after all...)

I'm going to return my pointer and ask for a refund.

However, I wonder if anyone has any experience of these:

Finders - Celestron Green Laser Finderscope

They're more expensive (are they therefore better, more stable etc.?)

How do they perform in cold temperatures?

Anyone recommend them?

Thanks for your patience in sticking with such a long ramble.

I got there in the end. :cool:

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You can get this "effect" when you heat a GLP...

Thanks. How hot does it need to be, Peter?

I haven't heated mine. Shaking it produces/reduces this effect.

Any recommendations for reliable lasers, Peter?

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I had a couple of ebay ones but really these are af very varaible quality... I'd go fro a branded one bought through a dealer as if you have any issues then they will be easier to sort out...

I wrapped mine in a metre of insulated resistance wire.. slide it through heatshrink tubing and conenct it to a 12v supply shrinks it down nicely :cool: i then used to run it on one of the channels of the dew heater...

In very cold weather it would start of very dim... as it warmed up would start to lase green then get brighter and brighter before diiming again and going "red" .. woudl go through the reverse as it cooled...

Taken mine off the scope now seeing as the scopes on the pier .. i used to find it very useful for setting the scope up on the field tripod and wedge.

Peter...

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Thanks Peter.

What do you think to the laserforum post re infra red?

Mine certainly switches to IR. This has to be bad. How long until someone does the old hosepipe trick and looks into the end to see if it's working..?

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I'll do some experiments...

IR lasers are nasty... Used to work with a 600W CW one for materials processing.. remeber one operator at and R&D facility "slicing" the top of their finger with one... well it was cutting through material moving at 5 m/s at the time and they put their finger in to remove the "swarf" which hadn't been picked up by the extraction system... never mind the falshing light the kalxxons etc... Very good seeing as they were supposed to be the LSO for the customer...at least it made the paper work easier seeing as it happened to the LSO ...

Peter...

Edited by Psychobilly

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Is it ticking.

Tick tock tick tock........

Just get rid and buy a proper finder...

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My preferred finder is the Rigel Quikfinder - which works really well. Described to me as a "poor man's Telrad" and I prefer to call "cheaper, smaller and lighter than a Telrad.."

Just don't get on with my optical finders. I'm just not enough of a contortionist.

Perhaps some yoga lessons?

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On my Celestron SCT 6" I use two finders. A William Optics red dot finder which is similar to your Rigel and an Orion 9x50 right angled correct image finder. I use the red dot to find a suitable star for hopping then use the Orion finder to locate the object that I want. This Orion finder is really good and last night I found a number of DSOs in constellations low on the southern horizon including M83, M19 and M62 - thats low!!

I do use my green laser mainly for polar alignment and occasionally place it on the goto if I want to find an object quick in another scope.

However, if I was experiencing your concerns I don't think I would use it.

Hope that helps

Regards

Mark

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Thanks Mark.

I've not used a right angle finder, but the trouble I have with optical finders is when I use it with my equatorial mount, I always seem to end up with the finder in the worst possible position to look through.

The rigel is more convenient.

(Incidentally, I got myself a Hyperion zoom and a Panaview 38mm EP. Very pleased! Thanks for your advice with these.)

Back to the thread, my real concern with these green lasers, is that it would appear that if they malfunction, they can change from being something that is merely a nuisance to a device that is potentially very dangerous and could cause blindness from a high powered invisible IR beam.

I think this is a real problem.

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I use a Hotech green laser.

Never does anything except lase green.

Glad to hear it!

Does the Hotech work well in cold conditions?

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Glad you bought the Hyperion zoom and I would imagine that the 38 degree Panaview would give an excellent FOV. I am tempted to buy one for my 6" SCT.

However, your concern at the laser tells me that you should stop using it and return it for a refund. Its not worth the risk.

Mark

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I fancy a green laser because having one seems to be the high tech and easy way to point to your object and then find.

However...

In my only 2 observing sessions to date, I've pretty much found everything I wanted (except the blinking nebula - more later) within a few seconds.Also, I'm getting quicker at this now, so, I'm torn on how to make the decision

Are they:- contraptions of the devil and should be cast off the face of the earth ? or, something that can quickly help you find those objects instead of cranking your back into some contorted position ?

Opinions are divided, but I haven't ordered one yet and this post seems to qualify why it might not always be a good idea. Interesting post.

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Glad you bought the Hyperion zoom and I would imagine that the 38 degree Panaview would give an excellent FOV. I am tempted to buy one for my 6" SCT.

However, your concern at the laser tells me that you should stop using it and return it for a refund. Its not worth the risk.

Cheers Mark. I intend to return it.

The Panaview works really well with my SCT, although with the WO 2" diagonal, it adds a lot of weight at the rear. It's a big EP!

I intend to get a refund. As I rely mainly on my Rigel, I'm not too worried. If I want a better laser, I'll probably get the Celestron model from FLO.

Unfortunately, if it can happen to mine, it can happen to someone else's. I think there should be an additional warning with these things.

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Opinions are divided, but I haven't ordered one yet and this post seems to qualify why it might not always be a good idea. Interesting post.

Thank you.

Everything negative I'd read about them to date was along the lines of, "don't shine them at planes", "they're a pain at starparties", "why do you need one anyway?", "they should be banned".... sort of thing.

I'd never come across anything that indicated that they can be highly dangerous when faulty.

Beware.

(I still find them useful, though) :cool:

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Well, it depends on what you call "cold". It's worked down to about -2C without any problems.

I use it mainly for educational purposes, as I tend to have a lot of beginners out on sessions, and it's a big help.

Having a three stage red LED and white LED combined with it is a big plus.

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Cheap ebay GLP's are renown for not even having an IR filter. Those are lethal. You can never be sure what you are getting. While I find the astronomical 5mw GLP's too dim and went for a 10mw version, this was purely to guarantee I got about 7 or 8mw at least. Bought from a reputable company and cost about 90 euros. Mine is being permanently mounted in a scopestuf GLP mount, with the batteries replaces with a 3v feed from my Dewbuster and heated with a .925" Dewnot dew strip that sits underneath the GLP in the scopestuff mount.

Will I use it all the time? No. but they are handy to have.

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I've tried to contact Scopes'n'skies, but they don't seem to be answering the phone at the moment.

The GLP I bought is supposed to be a good one. Maybe I got a duffer?

Sounds like the Hotech is a good one, epk.

Anyone recommend any others?

How about the Celestron laser finder. That should be a good one, shouldn't it?

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I have a Revelation 5mw green laser. It does what is says on the tin. Never had a problem with it but I only use it at public outreach events to point things out. I don't use it with my scopes as I live near the flight path of Glasgow Airport. Not a good plan!

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My faulty GLP was also a 5mW Revelation.

I've now returned it to Scopes'n'skies.

They can't replace it, because, apparently "They're now being outlawed" and S'n'S are not selling them anymore.

Outlawed? News to me.

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Have a look here....

HPA - Laser Pointers

I have quite a few contacts in what was the NRPB now the HPA having been involved as an "industrial" repesenatative on a working group on optical safety of other non-laser devices...

Peter....

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Cheap ebay GLP's are renown for not even having an IR filter. Those are lethal. You can never be sure what you are getting. While I find the astronomical 5mw GLP's too dim and went for a 10mw version, this was purely to guarantee I got about 7 or 8mw at least. Bought from a reputable company and cost about 90 euros. Mine is being permanently mounted in a scopestuf GLP mount, with the batteries replaces with a 3v feed from my Dewbuster and heated with a .925" Dewnot dew strip that sits underneath the GLP in the scopestuff mount.

Will I use it all the time? No. but they are handy to have.

Okay, I see your 'point'. In my experience (I own two cheap ebay pointers) they seem to work just fine. At the same time, I would like to gather some information without exaggeration (wouldn't we all?).

When you say "lethal" this is obviously not a literal use of the word. I'm guessing these inferior pointers you speak of emit I-red light more than just forward in the actual beam? I suppose one could say they "leak" the radiation? This would mean over a long period of time with repeated exposure (not direct blasts in the eye, but reminiscent of second hand smoke) it could adversely affect your vision, right?

Second, how would one find out if and how much infrared light is being emitted?

Third, (this one's for you, Jarndyce) if you're interested in them, the model I bought was from ebay seller 'hottestdealever'. He's got some currently available - item # 390055321678rtCurve.gif the description is "Guaranteed Brightest True 5mw Green Laser Pointer J05". As I said previously, I've got two of them and they've performed without flaw (other than some aversion to the cold you're familiar with). As for infrared radiation I am unaware, but it's worth finding out. I will take solace in the fact there is no biohazard symbol printed on the box (yeah, I'm prodding you a bit calibos -in good fun, I hope).

Conclusion? I love the bonus the pointers give for pointing things out to rookies (myself included), and they're indispensable for lining up your dob- just shine it through the finderscope and it'll tell you within a few degrees where you're pointed. Sure beats laying on the ground trying to sight down the tube! Ebay makes it affordable ($20 versus $80) and astronomy can be an adventure rather than a guided tour (my two bits on goto).

Jamie.

P.S. Calibos, do get back to me on the second thing, I am interested in ruling out the possibility of I-red radiation. I'll even quit bugging you and plugging for ebay if the result is positive.

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