Recommendations for a laser for light sculpture

[kingwisp]

Hi everyone, first post!

I'm an art student interested in making some light sculptures using lasers and mirrors, and I'm having trouble finding what kind of laser it is I need- I want a laser which can be left on for long periods of time, ideally all day in a gallery space, so I guess it would need to be mains-powered? (if it's just an ~8hr battery that's also fine) I would prefer to buy a pre-made one but I'm not averse to putting one together if the process is well documented, my electronics skills are limited though. I would like it to be blue or green (blue is preferred if I can afford it) I also don't want to get something which is too powerful for my needs and a safety risk, but equally has enough power. So what kind of power would I need to make something with a beam reflected say 20 or 30 times (on front surface mirrors), in a 3m x 3m darkened space? Could I achieve that with a laser that is safe to walk through the beams? Alternatively I could buy several cheaper lasers which are less powerful and safer. The main stipulation here is leaving them on without overheating.

If you have any recommendations I would be grateful. My budget is £75/~$115 but I don't really know if that's possible. I'm UK based.

Thanks for your help!

 

[DrSid]

Laser with visible beams is practically always not safe to eyes. You can increase visibility drastically by filling the room with smoke, even the safe disco smoke works fine. You can also improve visibility of the beam by using green color, which is most visible at given power (thus safety precautions), and by darkening the room. Total darkness works best.
To allow people walk between the beams, the power would have to be under 5mW. At such power, beams might be just visible at dark with smoke. It won't be anything spectacular though. For spectacular you would need 50mW, or even more .. but that would not be eye-safe, everyone would have to wear goggles, which would prevent them to see the beams.
So only option I see is the statue being isolated from people, ideally by glass, so they can't get close even when drunk or something. Then you could use stronger laser.
At the moment, blue is the cheapest option for high power lasers, above 500mW. That is rather lot for your needs. Greens in lower powers are rather cheap too, and much more visible.
For constant run you will need so called lab builds. They have good cooling, but are a bit more expansive. You will also need special mirrors. Depends on count of reflection you would need, you will loose some power with every reflection, but I don't have much experience with that.
Interesting alternative for lasers would be optical fibers. They can look JUST like lasers, we had some photos here lately with some statues which really confused us. Check this thread:

http://laserpointerforums.com/f48/interesting-effect-reportedly-lyon-france-78891.html

 

[pschlosser]

you'll want to locate a 10-15mW Helium Neon gas laser. They can run all day, even continuously, and have a life rated in 1000s of hours. Red is the most common color. If you want other colors in HeNe, costs go up. If you want diode lasers, costs go up, but for $300 USD you can get something much stronger in a diode lab laser.

If the beam will not move, inside your sculpture, the mirrors fixed, and no one can stick their head in there, or maneuver their eyes into the beam path, the danger is minimal. But if the sculpture is open to touch, and/or placing reflective objects into the beams path, you'll have to keep the power low, down in the 10 mW range.

Bouncing 10mW 20-30 is possible with efficient mirrors. Consider using multiple lasers to achieve the same effect. For example, bounce each 10mW laser 10 items means 3 lasers.

Start with a HeNe. They are common and will get you started. If you like it, you can always get other colors, or types of lasers as your budget allows.

 

[blasterman]

You don't need a gas laser. Constant run diode modules are available for cheap and simply require 12volts. I have many.

The problem....is intensity. Anything over 5mW technically runs you afoul of guidelines in the U.S. if people have direct eye exposure to the beams, and even that has problems. Enforcement is a different arguement. 5mW might seem pretty low end, but let's say somebody walks through your art-work, and decides to stare right at a beam for 30 seconds for no good reason. That's a problem.

You could bounce a 5mW green laser off a dozen front surface mirrors, but the room would have to be dark and the air would have to have an atmospheric like haze or a humidifier to see it. Even then it would be fairly dim.

 

[kingwisp]

Thanks for the replies guys! I've got a smoke machine so I can definitely add that to mix and make everything a bit more visible. The space will be pretty dark anyway. Putting the safety issues aside for a moment (the construction can be isolated from people), could anyone recommend some stockists of premade constant run diode modules? Or is it hard to find them for sale pre-assembled? Some brief research on gas lasers seems to put them firmly out of my price range anyway- I am a student.

Thanks

 

[DrSid]

You would need something like this:

600mW 445nm laser module/focusable/TTL [OL-445-600] - $145.99 : Zen Cart!, The Art of E-commerce

150mW green laser module TTL &Analog modulation /12VDC [OL-532M-12V] - $112.99 : Zen Cart!, The Art of E-commerce

You could build them, or maybe even have them built by forum members, a bit cheaper, and much more reliable. O-like is company with good reputation, but nothing professional grade though.

 

[blasterman]

Prices for fixed lasers really depends on color and wattage. Reds (650nm) are the cheapest and most common because these are used as DVD burners. A 200mW, 12volt module can be had for less than $30 (shipped) off Ebay and the last one I bought not only had a perfectly tight beam but has been impossible to kill. Just plug it into a 12volt adapter and away you go. No duty cycle. I could buy 20 of these for the price of my old 7mW HeNe.

Greens are a bit more expensive, but are far more visible per watt because of the color. They are also notoriously variable in terms of advertised power. I see 50mW 12volt modules going for $50, and 200mW modules going for $200. No guarantee the 200mW one is 4x the out-put.

Blues (445nm) are also available as modules, and have the highest practical power levels, but the problem is this color appears fairly dim to the eye. At ~500mW (the most common power for 12volt modules) they will burn.

Another idea would be to buy a s-load of lower powered, 5mW 12volt capable diodes (green or red). No need for mirrors.

An ultrasonic humidifier makes for a cheap ad-hoc haze machine without the smell and noise of a combustion fogger. Put a tablespoon of Glycerine in the humidifier to give the haze some staying power.

 

[Things]

Yep, just get yourself a 5mW green module off eBay - with a heatsink on it, and you'll be fine. Won't cost you any more than around $20, and it'll run constantly for months. You'll definitely need a fog/smoke/haze machine to make the beams visible, but if you can use good quality first surface mirrors, it should keep the beam pretty clean, thus making it more visible.

What you could also do is use a few lasers. Instead of having 1 laser for 30 mirrors, maybe have 1 laser for each 10 mirrors. Still eye safe, but it'll be brighter overall.

 

[DrSid]

I doubt 5mW will be bright enough. Can anyone with fog generator test it ?

 

[blasterman]

Any laser will be plenty bright enough if you are viewing it close enough on axis, and you have even a small amount of smoke/fog. However, if people are viewing the beams perpendicular you will need something on order of 'The Myst' to be subjectively bright enough with low powered...aka 'cat chasers'. Not really sure how the OP intends to orient the lasers. That's a big consideration in terms of how visible they are.

 

[jakeyboii]

I doubt 5mW will be bright enough. Can anyone with fog generator test it ?

i have a fog machine, but sadly no laser in the 5mW Range

 

[Things]

A true 5mW is plenty visible in a very dark room with fog. Your best bet is to also let the audience go through a series of dark rooms/corridors to allow their eyesight to adjust before getting to the laser. Entering from a bright room will decease apparent brightness badly.

 

[Multimode]

If you can configure the display to ensure the viewers can not come into contact or be hit with the beams, then your power options can be higher.
For example, laser shows in night clubs run multi watt systems, they are set up to ensure a beam can not enter the crowd.
ATB
MM

 

[kingwisp]

Hi, thanks for your help guys! I've since had a cheap laser pen I got for testing arrive in the post- it's advertised as 5mw but it's one of those generic ones so could easily be anywhere between 1 and 5mw I guess, I've no way to tell. I've had a go with that and my smoke machine and the dentists mirrors and at 4 or 5 reflections it seems to be quite effective really. Definitely less visible perpendicular to the axis but still adequate. I've not been able to stand back and view it as i have to be holding the laser on as it's just a pen, but having read some safety stuff I'm concerned that if I get anything much more powerful my uni or any gallery wouldn't let me use it anyway.

Here's a photo of a quick experiment which if memory serves is reasonably accurate in showing the brightness:

I may well have got lucky and got one with the full 5mw thinking about it, because it seems to be of similar brightness to a mate's pen and I think he'd burnt out the limiting circuit on his.

Back to safety.. so if I did have a number of green 5mw laser modules, and put a safety sign up telling people not to stare directly into the laser beams, and had some kind of mission impossible type construction of horizontal lines where people could walk through the beams, for example, would that be adequate or still risky? If the beams were considerately arranged etc- none at head height towards you as you walk through which would be particularly easy to look at and so on. And should I be getting an IR filter for each as well?

Thanks