multiple color laser pointers for multiple presenters

Hello,

I work at a university where we frequently have talks (arguments) from multiple presenters. Sometimes it gets pretty confusing when 3-4 people are all pointing with red lasers, so I hit on the idea to get some other colors.

We just need to point at things across a large, well lit hall. no burning etc. I was thinking 3 colors - red, green, blue - since they're all simple, inoffensive colors that appear to be available. But I get confused when it comes to options and brightness, so I'm looking for help.

red and green seem fairly easy to find, but blue seems tricky. I found a few violet-ish (405nm) for not too much money, but it looks like 473nm would work better. Thoughts?

What's probably key is that we need all the lasers to be about the same brightness - egos and all. oh, and we're trying not to spend too much money. Say $100ish for all three. less would be better.

so, in a nutshell - a set of primary color laser pointers of similar brightness for $100. possible?

Hello. Sorry but your goal of obtaining these lasers for $100 or less is no where near possible. Blue 473nm lasers start between $300-400, new, for even low power 2-5mW pointers.

In terms of brightness, green is always going to appear brighter than any other conventional color laser of the same power (mW) because the human eye is more sensitive to the wavelengths of light in and around 532nm. Your desire to find lasers of different colors with perceivable equivalent brightness will not be safely attainable. For a red or violet laser pointer to appear as bright as a 5mW green laser, you'd be looking at levels of power that could cause eye damage.

Maybe try taking turns talking with the pointer? ;-D

Hope that helped.

Hey, thanks.

I was assuming all the expensive blue lasers I found were just high powered versions. Bummer. What about the blue-violet ones? are any bright enough to use as a pointer? maybe we'll just get some low power green ones and be done with it.

Other questions just because I'm curious:

one the perceived brightness thing - how much of difference is there? 5mw green = ? red. blue?

also curious about how this all relates to things like lcd displays and camera sensors - would a 5mw green laser and a 5mw red laser look equivalently bright if you took a photo of them side by side?

Just as suggestion ..... if you are a DIY maniac ..... building an assembly something like the white fuson kit, you can easily obtain a single unit capable to give you red, yellow, green, cyan, blue, magenta and white .....

http://laserpointerforums.com/f64/fs-white-fusion-laser-mixing-kit-42013.html


Also, probably you need for like, 50mW of green, to use 150mW of red and probably around 200mW of blue, for compare apparent intensities and balance the white .....

You can get red, green, and violet for less than $100 combined, but not true blue.

Violet, green and red can all be used as presentation pointers as well. Violet doesn't work AS well, but it does work, especially in smaller settings. It actually works VERY well is your projector screen fluoresces blue, but the projector screens often don't fluoresce as well as, say, regular paper. But it's still very doable. Often old people in the back of the room have trouble with the violet, but it still often works well enough.

From my experience, 5mW red, 2mW green, and 15mW violet all look pretty decent together in a room that will hold about 50 people. Those powers of red and green work well in larger rooms as well, but you might have to play around with the power of the violet in a larger room, since you want people in the back to see it while not being uncomfortable to people in the front.

And if you projector screens fluoresces under the violet light, you won't need nearly that much power either, but none of the projector screens I've used fluoresce to any reasonable degree. Also be careful of the cheap greens like on DX or o-like, they're often over-spec and end up too bright, especially for use in dark or small rooms


I personally have 6 colors of pointer in presentation-level powers (including the very expensive blue and yellow), but in discussion meetings I've had up to 5 all in use by different people at the same time, for the exact reason you mention.

You can always get in on a GB & get a CNI PGL that puts out RED, GREEN, then combines the two colors to make YELLOW, all in one unit. Talk to scopeguy20 (Glenn)
He's a hell of a nice guy. Tell him I sent you. rob

manamana said:

Hey, thanks.

I was assuming all the expensive blue lasers I found were just high powered versions. Bummer. What about the blue-violet ones? are any bright enough to use as a pointer? maybe we'll just get some low power green ones and be done with it.

Other questions just because I'm curious:

one the perceived brightness thing - how much of difference is there? 5mw green = ? red. blue?

also curious about how this all relates to things like lcd displays and camera sensors - would a 5mw green laser and a 5mw red laser look equivalently bright if you took a photo of them side by side?

Click to expand...

Super great questions my friend.

The blue-violet lasers you're referring to are also known as "blu-ray" lasers. Blu-ray lasers have wavelengths that reside extremely close to the edge of our visual spectrum, in that they, as you mentioned before, are 405nm lasers. The UV spectrum which the human eye isnt lucky enough to see into without the help of our technology starts at <400nm. For this reason, it appears exponentially less bright than a green 532nm laser of the same power. Also, because it is so close to the UV spectrum, Blu-ray lasers will become extremely bright, even at low power, when shown on florescent materials. Just based on personal experience, I would say something around the range of 40-60mW of blu-ray laser light would be equivalent to a 5mW greenie in terms of brightness. However, once you've entered into the range of power over 5mW, the implementation of such equipment becomes questionable for indoor pointing. Direct exposure to the laser "dot" on the wall, or in the worst case scenario, the beam entering someone’s eye through direct exposure or reflection off of any number of surfaces, could both cause irreversible eye damage.

I am completely unsure about compensations made for reds and blues in LCD TVs. That is a great question and maybe something worth looking into. However, without a scientific background in the dealing of camera sensors, I can tell you that every camera I have ever taken laser beam or dot shots with has yielded a different outcome. Some cameras pick up Blu-ray's "violet" color as pure blue, often extremely bright. Others capture it closer to what the human eye perceives. Same goes for reds.

Here are two examples of the same 405nm light, taken with different cameras.

Here, use this for reference:

thx kingdave that's a nice distribution map... i now know why my 405nm from dinodirect looks like crap

Get a 10mW red, a 5mW green, and a 10mW bluray. All for less than $50.
Or a red-and-green in one: DealExtreme: $31.07 2-in-1 Hybrid 5mW Red + 5mW Green Laser (Supports Dual Laser Mode)
For about $32

You could also try to give JAYROB'S TRI-COLOR laser build a shot. Buy the red & green combo laser from DX, & the kit to create yellow by mixing the red & green from JAYROB
rob

I don't think that would work, because I'm assuming he need three seperate lasers that will all be pointed at different things at the same time. I suggest the same thing as above, buying a low powered green (1-2 mW), a 5-10 mW red and a 10-15 mW bluray.

Try to buy all of those from members here with LPMs who can measure the true power, because lower powered lasers tend to be much stronger than advertised (sometimes an increase of up to 35, 40 mW... not eye safe!)

I see, he needs 3 SEPARATE lasers of different colors. Gotcha. Then I'd go with the ideas already presented. rob

here you go

red: 2.12$
New 5mW Ultra Powerful Red Laser Pen Pointer Beam Light on eBay (end time 21-May-10 06:49:46 BST)

green: 5.40$
Newest 5mW 5 mW 532nm Green Beam Laser Pointer Pen on eBay (end time 12-May-10 17:05:44 BST)

violet: 8.60$
Newest 5mW 5 mW 532nm Green Beam Laser Pointer Pen on eBay (end time 12-May-10 17:05:44 BST)


all for 16.12$ and free shipping (2-3weeks)

stuart

AndyR said:

I don't think that would work, because I'm assuming he need three seperate lasers that will all be pointed at different things at the same time. I suggest the same thing as above, buying a low powered green (1-2 mW), a 5-10 mW red and a 10-15 mW bluray.

Try to buy all of those from members here with LPMs who can measure the true power, because lower powered lasers tend to be much stronger than advertised (sometimes an increase of up to 35, 40 mW... not eye safe!)

Click to expand...

Looking around for these now. Dealextreme looks like the cheapest, but I haven't heard good things about them in the past. can someone point me to a storefront that would have the above, that would not be too powerful? prefer to stay in the US as well.

also, on true blue - are they getting cheaper or is that something that will always be expensive?

manamana said:

also, on true blue - are they getting cheaper or is that something that will always be expensive?

Click to expand...

in time they will get cheaper as people will have done more research about them and figured a way to build them cheaper and cheaper. im sure red and blu-ray lasers were very expensive when started out.

stuart