Laser pointer alternative?

[gb_astro]

Given the controversy around the use of laser pointers
I was wondering if any one has found a usable alternative.
I was thinking of some of these narrow beam, high lumen LED flash lights that are appearing in the hardware shops.
With a red filter over the end....?

gb.

[nandopg]

GB,
Please, what controversies are those ? I have a serious problem on my back that every once in a while takes me to the wheel chair. You can imagine that for me it is totally impossible to be in certain postions to point the telescope using an optical finder, then the laser pointer came in my life to end this suffering. But I am not aware about any controversy regarding its use. Could you please to enlighten me.

Thank you,

Fernando

[jjjnettie]

Laser pointers are all but illegal here in Australia.

[dannat]

Yes gb the newer bright focusable beam led torches, my ASV guide put me Onto them,I've got a LED lenser, jaycar do sell them also, the big advantage of them is they still Visible in th city with heavy light pollution, obviously not as narrow a laser beam though- what Did you wnt it for?
It's ok for night sky tour stuff, don't know how accurate it'd be for aligning

[5ash]

Was getting interested in this post but am obviously too long in the tooth to understand Daniels abbreviations in the last reply. Can anyone translate for me ?
Philip:shrug:

[OICURMT]

Fat fingers on a mobile, dim lighting and too much to drink? :question:

:rofl:

[Merlin66]

I've just spent the last three month between Vic police and Australian customs trying to get approval to "import" three laser pointers I used in Belgium...I've now applied for a Chief Commissioner of Police permit ($170 for three years) to hold and use a laser pointer in Victoria...
I then have to re-apply to Australia Customs to release the pointers they current have confiscated...
onwards and upwards

[AndrewJ]

Gday Ken

If they do approve them, just make sure you dont get any speeding and parking tickets in your haste to go pick them up.
New numberplate logo
"Victoria, kept in the black by licenses and fines".

Andrew

[dannat]

iPad overcorrection is my problem, I've tidied the post up a it:thumbsup:

[DavidTrap]

20+ years ago, my high school teacher used a 2 cell torch on which you could focus the beam into a reasonable "pencil of light". You could see the beam and work out to which star he was pointing. Sure the laser is more defined, but it did the trick. Certainly helped if there was moisture or dust in the atmosphere so there was something for the light to reflect off. A dolphin torch is better, but more likely to blind those around you when you forget to turn it off as you point it downwards.

DT

[gb_astro]

Thanks guys.
I wanted it just for hand held sky tour pointing but able to be used at star parties. So I guess the question should have been is there one bright enough that it still gives a usable beam with a red (or green) filter over it?

gb.

[mithrandir]

gb, NSW does not ban laser pointers but does restrict the power level and who is allowed to have them without an explicit permit. Read the NSW Police entry (http://www.police.nsw.gov.au/services/firearms/prohibited_weapon_permits#Prohibite dWeaponsLaserPointerPermit).

[gb_astro]

Thanks for the info Andrew but I just don't want to use a laser.
We might know the rules but I doubt any of my neighbours do.
At star parties I think they are just light pollution (sorry).
The advantage of a flash light is that beam is usually only visible to someone
standing within a few metres of it, assuming the bulb end is shielded from direct observation and the air is not to polluted.

gb.

[Peteren]

Laser pointers! take your pick

http://www.telescopes-astronomy.com.au/green-laser-pointers-international-supplier.htm

Kick myself for not keeping the one I had at work, it would burn through 2m of steam to acquire it's target

[sil]

You can also add a tube to a high powered LED torch with a washer in either end. The small holes in the washers will allow a more narrow parallel beam to be emitted. Basically baffles over a few cm will help to get a nice beam. Just don't use easily flammable materials, the high power torches I've got get very hot.

[Peter Ward]

:question: Incendiary rounds work well.

That said, the hysteria (mostly from the media ) over the "dangers" of laser pointers is a sad indictment of the even more miserable understanding, our bureaucrats and legislators, have about coherent light.

[dannat]

GB I tried red film but it dimmed too much, green could work though if it's thin enough to let the light thru

[Jarrod]

g'day,

This talk of an alternative is interesting but really unnecessary.

Handheld green lasers under 1mW are legal Australia wide, which is more then bright enough for what we use them for.

With regards to being "noticed" using a green laser, the beam itself is invisible to anyone more than 5 to 10 metres away, so only the person holding the pointer and anyone standing next to him will see the green line. Neighbours won't see a thing unless you point it toward them.

If the green colour is a concern, red laser pointers do the trick, but have to be much brighter for the beam to be visible... but the law is with regard to "handheld laser pointers", ie the type that go on keyrings and fit in your front pocket. You can legally buy the laser modules (just a laser with out a casing) up to any power you like, so you can quite happily purchase a 150mW red module and mount it to your telescope.

There are some nice 1mW green pointers on ebay for around the $8 mark, again perfectly legal and ideal for astronomy. Just keep in mind that customs doesnt like individuals importing them due to the amount of people trying to import the overpowered ones, so try to go for an aussie seller.

anyway that's my 2c,

j

[gb_astro]

Daniel thanks for testing that out.
I guess there is just not much red in LED light.

gb.

[gb_astro]

Jarrod thanks for the green 1mW info.
The only low wattage laser I have tried was in my laser collimator.
That was a red one quoted at 5 mW.
That did not work at all.
I just assumed anything else around 1 mW would be the same.

gb.

[Jarrod]

No worries gb, but yeah it's a colour thing. Our eyes are just much more sensitive to green light. You need about 100mW before a red laser beam is clearly visible and even then a 1mW green laser will still appear much brighter.

They can get a bit distracting when you're dark adapted though so a bit of a dark bin bag plastic or something wrapped on the end dims them down nicely. The beam is visible in the eyepiece aswell so if the laser is well mounted you can bypass the finder all together and aim with the laser beam alone as Fernando pointed out.

j

[Suzy]

Wow thanks Jarrod for all that info- I have now ordered the 1mw on ebay- brand new from Sydney for only $10 incl. postage!
I had no idea they were so cheap on e-bay until I read your post. :)

http://www.ebay.com.au/itm/Laser-Pen-Pointer-Light-Stylish-Disco-Party-Green-Effect-Stage-Lights-/300751595274?pt=AU_LaserPointers&hash=item460631270a

[Stardrifter_WA]

Similar situation in WA. Lasers are not banned, per se, but are classed as a controlled weapon, that is, you must have a legitimate use for it; and there are only a few legitimates uses now, one being Astronomy.

I recently verified this, as there appears to be conflicting views. The major change is that, according to the police, is that GLL are now limited to <5 mW. You can no longer import anything greater than 5mW into WA. A gun shop in Midland (suburb of Perth) still sells <5 mW GL lasers rifle sight kits over the counter. The onus is on you as to whether you have a legitimate use or not.

Cheers Peter

[Osirisra]

I did some research on this and...

Laser diodes of sizes larger than 1mw are very cheap and not a prohibited item so you can import them in from any where with out any problems.

Laser pointers are classed as items that are 'built and ready to go' but the diodes are not and thus they don't class as a laser pointer which is crazy law if you ask me as it takes 5 min with a diode to make a laser pointer and you can get some crazy spec diodes therefore very dangerous for very cheap.

I have imported quite a few in along with other members of our group, only $20-$40 for a 30-40mw.

Wire up a battery, switch and something to mount/hold it in and you are all good to go. I put a toggle switch and a push button on mine for added protection in the case of dropping, bumping etc. Bit of pvc pipe with couple end caps from Bunnings or the like makes a good housing and hand holder.

I've made a couple scope mountable ones with power adapters to run of 12volt as well. A old 6x30 finder makes a great housing and mounting all ready to go!

Here is a pic of my MK1 hand laser.

I wouldn't dream of not having my pointer for public viewings, such a great tool.

[Shark Bait]

Food for thought Ken. I have been looking into this myself and it is fine to buy green laser modules and diodes from Jaycar but they are not selling any assembled laser pointers above 1mW. At least the law in QLD still allows us to use green laser pointers without a permit if we belong to an astronomical society.

I have been constructing some electronics recently and it isn't that hard to put one together when you have all the parts. My only concern is the IR filter.

Are the diodes and modules fitted with the IR filters?

[Merlin66]

Stu,
Why the concern with IR filters?
The laser beam is effectively a narrow wavelength beam either in the green or red...there's no IR involved????????

[Osirisra]

It all depends on the module or diode, I don't think it actually matters when you are pointing the laser in the open straight up. As long as it never hits another persons eyeballs directly or by a reflection it all good.
Most of the large mw chinese el cheapo type ones don't have IR filters.

[Osirisra]

Green lasers actually produce quite a bit of IR and without a filter can cause major damage and most laser eye damage is caused by IR. The IR beam is quite large without a filter and most of the real cheap and nasty Chinese style ones don't have them installed in production or even removed to reduce cost. Alot of these el cheapo lasers have ridiculous output claims but the actual out put is dim due to the fact they are counting the IR as well. Eg; a 100mW output is more like 20mW visible and 80mW IR.

[Shark Bait]

I have digging around the net trying to find information. I know that this is often inaccurate, but I have read that some cheap imports do not have a filter to protect your vision.

IR? Going with what I have been reading.

Obviously we are not going to be pointing these lasers in peoples faces but some sites seem to imply that there is a problem even without this happening.

Either way it is quite legal to import the parts and build your own. As long as it is done well and handled properly the risk should be eliminated.

[vaztr]

Hi guys

I work for a govt agency that handles air traffic and I can tell you that anyone who points a laser into the sky that is 'noticed' by a pilot will be in trouble no matter what the wattage. Just thought you guys might want to turn any laser off if you notice a plane overhead

VAZ

A worker for the fun police :(

[Osirisra]

????

[Osirisra]

Very true! I make sure that I use mine with the utmost care :)

[Merlin66]

Hmmmm,
Sounds like I'll have to get the spectroscope on these lasers...I honestly thought they were single wavelength beams. I use them to generate diffraction patterns for the measurement of slit gaps.......

[Shark Bait]

There is two Ken's here. I prepared my reply to Merlin66 and you posted before I hit send.

I am just trying to get the correct information before I dive in. Your reply is in line with multiple internet sources that reference the IR issue when filters are absent or removed. The truth is that I just don't know enough about lasers yet and will have to do some more research.

The cost of the Jaycar 10mW module is $99. That sounds pretty dear compared to the imported items.

Vaz,

At this stage, QLD law still allows us to own and use a green laser pointer without a permit if we belong to an astronomical society. That said, if anyone uses them in an illegal manner they deserve a visit from the police.

[Osirisra]

We Ken's rule! :P:D

Yeah I remember looking at the jaycar one and 99 is way to much for a 10mW.

There is a home test ya can do to check the IR on a laser using a CD to make the spectrum and then a IR sensitive Cam or camera.

[Shark Bait]

That's a brilliant way to detect IR. Thanks for the tip.

Jeez. This thread has drifted way off topic. It's gone from laser alternatives to how can we build our own. :doh:

[Osirisra]

But that is an alternative :), a lot of people know that you cant get laser pointers into the country so that is why they are looking for alternatives, but they don't know you can get the modules/diodes and build pointers.

[Osirisra]

Here is the paper on the 'home test'

http://www.nist.gov/customcf/get_pdf.cfm?pub_id=906138

[Shark Bait]

Thanks Ken,

It is good to get hold of a paper that I can have some confidence in. Time for a little light reading.

[MrB]

The green laser pointers do indeed output IR if there is no IR blocking filter fitted.
They are actually DPSS or Diode Pumped Solid State lasers.
Basically, an IR laser diode(at 808nm) pumps a crystal (Nd:YAG or more commonly now Nd:YVO) which re-emits a beam at 1064nm (Neodymium line) which then passes through a frequency doubling crystal(KTP) which emits at the 532nm green we all see.

I have an 8W pump diode (yes that is 8000mW) which is also used in a DPSS laser that emits at ~473nm (Blue) but the DPSS is so very inefficient that the Blue output is 'only' approx. 20mW.

Anyone interested in learning indepth about how these lasers work is recommended to visit Sam's Laser FAQ (http://www.repairfaq.org/sam/laserssl.htm)

Edit:
In the graphic below, AR, HT, HR etc are the coatings... Anti/High and Reflectance/Transmittance
Also, my 473 Blue DPSS uses an identical configuration as that at the bottom of the graphic labeled "Medium Power" with the corrective optics.
The only difference is it works on 808nm > 946nm(instead of 1064nm) > 473nm
The TEC (Peltier cooler) keeps the crystals working at their peak efficiency.
Blue DPSS do not work at room temperature without the TEC.

[Osirisra]

Darn 8W, imagine that sucker at full efficiency!!!

[MrB]

It does output 8000mW of laser light, just at 808nm.
It's the rest of the process that is inefficient so that only ~20mW of 473nm blue is emitted.

In all honesty the sucker scares the crap out of me whenever I use it.
It can burn thru plastics and will ignite paper and cardboard in a fraction of a second.
8W of IR will send you blind in hundredths or even thousandths of a second.
Thats not even looking at the beam, the scattered IR could do it.

I only ever operate the Blue DPSS with it's covers on or open while wearing laser goggles.

Edit: I just worked out that the power in the beam(8W) is approx. equivalent to using a 100mm/4" magnifying glass in the Sun at ~1kW/m^2.
Actually, the spot size from the laser is probably much much smaller than the average magnifying glass would make, so maybe the power density from a 200mm/8" short focus lens would be more realistic.

[Osirisra]

I'm not suppressed, I'd be terrified of the thing turned off!

[Merlin66]

Simon,
Thanks for the additional input!
I didn't realise that some lasers as so complex.....

[gb_astro]

Well I ended up buying one of those < 1mW green lasers off an eBay Australian site and although it might not impress Luke Skywalker it works perfectly as a hand held pointer and I would assume mounted to a scope. In fact I find it a little too bright. I needed a two stop ND filter to get it dim enough for discrete backyard use in suburbia. For $8 posted and no $127 license fee in NSW it seems a no-brainer.

gb.

[doppler]

We checked laser visibility from a distance and found that from a side veiw the beam was invisible from the house next door. It was only visable for a long distance if aimed directly at something. The lowest power green laser that I have ever found o/s is <5mw so I am curious, I did not think green lasers would work at that low wattage.

[doppler]

If anyone wants to import laser components try this site. http://odicforce.com Customs will let modules and housings through but only in separate packages. Hand held Laser pointers are a restricted import. A laser module (of any power) fitted to a telescope is not hand held and is therefor legal in all of Australia.

[Shark Bait]

Thanks for the information Rick. I intend to construct my own and I did not want to risk using a dodgy Chinese supplier.

[gb_astro]

Hi Rick.
It will only take $8 to find out.
You won't be disappointed.
gb.

[Suzy]

Exactly. :thumbsup:
For $10 (mine cost) I figured that I didn't have much to lose.:D

Russ & I couldn't get over how bright the 1mw was here in suburbia with street lights around! We thought it'd be really dim, but it does the job very nicely! Russ said they have a 5 metre range (re neighbous) but I guess it's up for debate.:question:

He's been using it more to play with the cats who go crazy for it. And then I rouse at him for using up my 5,000 laser life and he keeps coming back with "who cares for $10" :rolleyes:. Buying another one for the cats! :screwy::lol:

[Shano592]

Wow, I build my own 110mW red ones, from broken DVD-RW drives.

Apart from the heatsink/housing, and narrow breadboard, everything else is available at Jaycar.

I know their visible range is at least 500m at noon, on a sunny day.

Haven't tried it at night, as I have several flight paths crossing close to my home, and I'm not that bold.

I know that the red can burst balloons at 20m, easily.

Just about to build a purple (445nm) one, with the diode from an XBox 360. That should look perty!

[Shark Bait]

Can we have some photos of your finished product?

Maybe a photo of the beam at night time?

Roughly how much does it end up costing you when you have the finished product?

[MrB]

Do you mean 405nm? This is the wavelength used for Blu-ray drives.

445nm is Blue and used in Casio projectors.
These are quite dangerous as they are readily available up to 2000mW output.

A pretty, but outdated(not many Diode lasers shown), chart showing various laser wavelengths can be viewed here: http://www.blackgto.com/laser/spectrumchartv10.jpg

[Shano592]

You are completely correct ... 405nm it is. It is a very distinct purple. Definitely beyond blue.

It is still in component pieces atm, but I will get some pics in the next couple of days. I guess I'll need a smoke machine (or some fog) to show the beam properly. We'll see how we go.

I think it would come in around $15-20 all up per laser, after importing the housing for the diode ($4), buying the small breadboard off of eBay ($12 for 5 pcs), and getting the rest of the bits from Jaycar ($10 all up ... but makes 3 or 4 lasers).

I like the idea of housing it in Electrical conduit pipe. I never considered it. Great idea.