NOOB questions about art laser setup

[tkt]

hey Guys
Im very glad this forum exists!
so I have gone trough the FAQ, and read a lot on this and other forums, but still have some questions,

First what I need to do, Im working on an art performance, I need to mount some lasers [pointers?] on 5 tripods that have mirrors on them that bounce the light beam as to "draw" a 5 pointed star.

I am an electronics engineer but work as software developer, and have a little bit of experience tinkering on hackerspaces .) [so not afraid on getting my hands dirty], the problem is not much time.


My question is
. should I use laser pointers?, or better to buy laser diodes?
. if I want to bounce the beam 4 times + source = 5, what is the maximum distance for a 1mw source? bouncing on mirrors. [as I don't need want the hassle of registering it with the local police (Australia)]
. should I buy laser mirrors? or any mirror would work?
. can I turn on and off the laser pointer like an strobe light? [will this diminish the life of the laser?]
. how to "join" different beams of light on to one?

Thanks!
more questions coming soon!

merry xmas!
.)

[Galvonaut]

Hi tkt - where are you from? Worth filling your profile out so that people local to you can help!

The first thing to bear in mind about lasers is the safety aspects. I think the US legal limit for laser pointers is 5mW. Is it 1mW in Australia? - there is a reason for this - Lasers can cause permanent thermal damage to your retina - and the retina does not have pain receptors - plus the brain is pretty good at filling in the blanks after you knock some of your vision out, so people may not notice the damage, or think that the damage is not permanent.

If this is a public performance you will also have to check what the rules are on operating lasers over a certain class (ie class 2). There are some members in Australia and a thread especially for you guys down under! It would be worth speaking to those guys for some advice.

I would not recommend laser pointers for anything that needs to be on for any length of time. They tend to have terrible thermal management and are designed for intermittent use. A new member recently posted a similar enquiry and found a laser pointer which was both legal and safe(ish) in the USA and designed for longer use.

Please be very aware that laser pointers sold on ebay seem to be advertised as 1mW or 5mW just to get past the selling rules and laws in certain countries. This means that lasers that are many hundreds of times over the MPE (Maximum Permissible Exposure) are being sold as 'safe' - even lasers that burn skin, let alone sensitive eyes!

The low power that you are suggesting may not be suitable for what you want, it really depends the size star you want to create, how dark the room is and how much smoke is in the room.

Diodes modules may not be ideal either. Do you want the beams to be creating the star or for a star to be projected? If you want it projected, a laser projector would be ideal - and a GREAT project if you like a tinker!

Strobing or 'modulating' a laser beam is normal and fun! Most (all?) diode lasers can be modulated. I imagine it lengthens the life of the laser, rather than shortens it, as it will be off or at lower power than otherwise.

If you are using beams, then they would likely need to be terminated, rather than flying off into the audience or cast and crews' eyes.

Mirrors are great and underused - something on my to-get list! For lasers you would want to use front surface mirrors which keep the beam crisper and reduce additional divergence and refraction caused my the glass in normal mirrors.

I hope I haven't put you off! I only got into lasers a few years ago and got my LSO training and am now building my first RGB projector (well, I've got some of the parts)
It is great fun despite the expense and the effects laser can produce are unsurpassed (IMHO)!

Keith

[tkt]

Hey Keith, thanks for the response!
I come from South America, but live now in Sydney [profile filled out now thanks].

in Australia the limit for pointers is 1mw, but no restrictions on modules!
http://www.ozlasers.com/australian-laser-laws
According to federal law in Australia, any hand-held, battery operated laser with a power emission above 1mW is considered a dangerous weapon, and written consent must be obtained prior to possessing/importing such a laser pointer. However, according to an Australian Customs fact sheet, laser diodes, modules and other laser equipment above 1mW is legal to import.

This is for a public performance indoors, no rules or restrictions on what laser class is to be used.
Thanks for the link of the Oz laser enthusiasts I will contact them!.

>I would not recommend laser pointers for anything that needs to be on for any length of time. They tend to have terrible thermal management and are designed for intermittent use. A new member recently posted a similar enquiry and found a laser pointer which was both legal and safe(ish) in the USA and designed for longer use.

> The low power that you are suggesting may not be suitable for what you want, it really depends the size star you want to create, how dark the room is and how much smoke is in the room.

> Diodes modules may not be ideal either. Do you want the beams to be creating the star or for a star to be projected? If you want it projected, a laser projector would be ideal - and a GREAT project if you like a tinker!

The setup will be indoors on the night time, no other lights in the room, i can get some smoke also. But the idea is to have the beams to create the star. Also the beams will be on top of some tripods, above a the people height, so no danger of beams on people faces.

So if the pointers are not the way to go for this [for special permissions and thermal management], should I use a laser module better?

how strong [watts] should i get the module for?
I have some budget to make this happen, i have read of modules on the $150 mark, is this right?
Can you please recommend what intensity should be fine for my need and please where to buy a good quality module?


>Strobing or 'modulating' a laser beam is normal and fun! Most (all?) diode lasers can be modulated. I imagine it lengthens the life of the laser, rather than shortens it, as it will be off or at lower power than otherwise.

Excellent!

> If you are using beams, then they would likely need to be terminated, rather than flying off into the audience or cast and crews' eyes.

Ok, got it, so, if I want to make the star, can I just keep the beam on the star shape loop?

> Mirrors are great and underused - something on my to-get list! For lasers you would want to use front surface mirrors which keep the beam crisper and reduce additional divergence and refraction caused my the glass in normal mirrors.

Thanks for the tips!

Great, im really interested in making the star happen,
so basically what would be the appropriate wattage needed for this?, where to get the module?

Thanks a lot!
Im going to get a projector pretty soon but will ask on other thread .)

[Galvonaut]

Although their may not be rules on importing higher power lasers, there are usually health and safety rules you have to abide by. I know nothing about these relating to Australia.

I'm probably not the best person to advise on power. Lasers look their brightest when the are coming towards the audience, less bright when going away and even less bright when viewed from the side of the beam. As a beginner it is best to start with some lower power stuff and use safety goggles for the wavelength of diode you are using. It is very easy to flash a beam across your eyes in error and until you have done it, and experienced the worry having done so, it's best to do it with something that won't cause damage.
Laser power depends on experience (in my opinion) size of star, distance to audience, brightness of room or other lights, quality of mirrors and what smoke you are going to use. Oh, and wavelength of laser - the eye is far more sensitive to certain wavelengths (like green).

If you experiment with lower power stuff you will get a feel for how bright they are too and what you may need.

I think a loop could be doable using mirrors and the laser mounted behind to avoid a large gap in the loop. Another thing that you could do is to use side-glow laser fiber. These can be as cheap and simple as a length of extruded plastic to glass or plastic doped with elements that create optical gain in the fiber. This method could remove some of the risk of a beam escaping too.

Modules come up on the forums quite a bit, so worth keeping an eye out in the Buy/Sell/Trade section.

Keith