Laser pointer alternative?

[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...item460631270a

[Stardrifter_WA]

Originally Posted by 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.

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 (Ken)]

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 (Stu)]

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 (Ken)]

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 (Ken)]

Originally Posted by 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?

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 (Ken)]

Originally Posted by 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????????

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 (Stu)]

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 (Andrew)]

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 (Ken)]

IR? Sorry Ken. Got that one wrong.

????

[Osirisra (Ken)]

Originally Posted by 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

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

[Merlin66 (Ken)]

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 (Stu)]

Originally Posted by Osirisra

????

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 (Ken)]

Originally Posted by 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.

We Ken's rule!

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 (Stu)]

Originally Posted by Osirisra

We Ken's rule!

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.

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.

[Osirisra (Ken)]

Originally Posted by 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.

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 (Ken)]

Here is the paper on the 'home test'

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

[Shark Bait (Stu)]

Originally Posted by Osirisra

Here is the paper on the 'home test'

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

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 (Simon)]

Originally Posted by 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.......

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

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.