What should I do? Pen or lab laser?

[MojoLA]

So i'm interested in getting a 5-10mw laser in both the 589nm (yellow/amber) and 437nm (light blue) varieties.

They would both be used to run my little lumia wheel show at home, which I am currently running with ~7mw green. Since the yellow and blue lasers have a similar brightness to the green, I'm sure they would behave similarly with the same mw range.

Since I need the laser to have a 100% duty cycle, that points to getting a lab laser - but at the same time, that seems way overkill if I'm looking for less than 10mw (the green I have is a labbie, but in green it's cheap).

So I could get 5mw pens in those colors (and cross my fingers they are a bit overspec) and "tape down" the on switch, but then pens aren't supposed to be run at 100% duty cycle and I don't want to fry a couple of expensive pens!

I'm also on the fence as it's nice to be able to plug in the labbie and not worry about always changing batteries... but again, lab lasers in these colors will be expensive... and big. Dealing with the circuit board is a pain and there is no easy way to "aim" that big hunk of metal - the pen can be placed inside a cheap, adjustable holder or tripod.

As you can see, there are pros and cons to both with and I see no clear answer. Any suggestions?

 

[00Giorge]

If it's for your lumina wheel get a lab it will last longer and you don't have to change the batteries!
The colors you want aren't that cheap in a pointer either!

 

[MojoLA]

Last night I was using a lab laser for the green and a pen laser for the red, and there is no doubt that the pen laser is easier to adjust for the lumia show. Also it's a focusing pointer, and I learned that changing focus ALSO changes the look of the show, in a very cool way.

I don't think lab lasers can be focused... (?)

Is there a way to convert a battery powered pen into something that can be plugged in? I can always run a fan on the pointers to avoid overheating...

 

[Tech_Junkie]

You're looking at hundreds of dollars for either one. You might want to do a little research first, before deciding what to use.

 

[MojoLA]

Yes, i am doing the research now... part of that is asking here for advice, maybe I've missed a few things i'm not considering.

And a lab laser in those colors is a LOT more than a pen! I may simply have no choice but to do with a pen and keep a fan on it at all times.

And keep changing batteries.

 

[Tech_Junkie]

Clip a + wire on the body, and solder a - wire on the spring. Use a 3v source for the power.

 

[RA_pierce]

You are best with a lab laser.
The yellow and blue pens use a 1.2W diode driven at capacity.
Your pen will be trying to dissipate ~1.5W of heat from the diode plus losses in the driver.
Your show will need a short duty cycle. Not good IMO.

Either way, its going to cost a few hundreds.

 

[MojoLA]

The thing is I managed to run my show with a 5mw green pen, constantly on, kept cool with a fan aimed at it. 5 or 6 hours a night for several weeks, never had a problem.

Did I get lucky, or could I expect the same from other pens, especially ones of CNI's quality?

Or am I inevitably heading towards frying an expensive pen?

What, technically speaking, is the problem with "taping down" the on switch of a pen and keeping it going?

When I first started doing this with my 5mw green, after an hour or so I noticed brightness fluctuations and found the pen quite warm to the touch; I assumed it was an overheating issue, so I kept a small fan trained on it at all times and from that point forward everything was fine.

Of course, that was a $20 pen so I didn't mind taking risks. But if I do the same with a $200 yellow, I'd like to know if there is a good reason why I shoukdnt expect a similar situation as I had with the green...

 

[JaiNobeZ]

589 and 473nm lasers are highly inefficient. The pump diode is forcing out a huge amount of IR into the crystals to produce only a very small amount of the light. This is not the case with 532, as this process has been manufactured to be as efficient as possible.

IMO you've chosen the worst colours to use. But take pics when you're done, it'll look awsome!

 

[RA_pierce]

Like I said above, and as JaiNobez touched on, the DPSS green process is MUCH more efficient than 589nm or 473nm.
In the case of your cheap greenie, the pump is producing only ~200mW of 808nm for 5mW of 532nm compared to ~1200mW pump power for the 5mW blue and yellow.

Yes, the quality is good, but the physics is just really inefficient and you are left with a lot of waste heat. The only solution is active cooling or a large heatsink. Neither are practical in a pointer.

 

[MojoLA]

Ah ok thanks for explaining guys, I understand better now.

So, in real world use, 589 and 437nm devices use a lot more power than 532nm to produce the same amount of light.

So I assume this means battery life is shorter and the amount of heat generated is stronger? Which is more likely to lead to failure if I force a long duty cycle...

CNI is going to send me the price of their cheapest lab lasers in these colors... they told me "it's not so expensive," but even at 10mw I have a feeling it's going to be well over $500.

These WILL make great colors for a lumia show, but at that cost... we'll see. I'd kick myself if it's half the price in a year.

 

[JaiNobeZ]

Why not use RGB\RGV? For the price of a 473 and a 589 you could get a pretty good set-up. But actually that probably wouldn't work so well with a lumia in case it splits up the beam. But then again, it might result in red & green mixing at some points, green & blue\violet mixing at some points, red & blue\violet mixing at other points and all 3 mixing in the middle to produce white light...

Interesting stuff. Like i said, post pics!

And my feeling is that it won't halve in price within the year. Although i'm not greatly experienced in these things, 589 has no known use other than to amuse us and 473 is being phased out to make room for 445.

150th post!!

 

[RA_pierce]

Why not use RGB\RGV?

And my feeling is that it won't halve in price within the year. Although i'm not greatly experienced in these things, 589 has no known use other than to amuse us and 473 is being phased out to make room for 445.

An RGB/RGV setup with lasers at 5mW each would actually make for a neat little project.
It would obviously take more work than just plugging in a labby, but it would definitely be cool and probably cost a bit less... and you get more colors.

However, I would disagree with that second part.
Remember that hobbyists account for a very small percentage of the laser retail market.
In the hobbyist community, DPSS blue still has it's niche (and a special place in my heart ).

 

[MojoLA]

That's a great point, I hadn't considered RGB/RGV. I have very little understanding of what's involved to do this, but that's what homework is for!

And yes, I can see that, through the wheel, most of the time the lasers would be diffracted in multiple directions and you'd rarely get white - but the random, multitude of colors you WOULD get would be very cool.

Great idea!

I'm still looking into amber and blue since I do want to create a show with those specific colors (amber and blue is a classic combo).

 

[JaiNobeZ]

Remember that hobbyists account for a very small percentage of the laser retail market.
In the hobbyist community, DPSS blue still has it's niche (and a special place in my heart ).

I know that hobbyists account for a very small percentage of the laser retail market. It's hardly ever what the diodes\modules are even manufactured for. But for that reason 589 modules are unlikely to go down in price because there are no industrial uses to push them cheaper, and 473 will be used less in industry now that there are 445s.

What are 473 modules used for anyway?

And, to OP, If you put your red and green in the lumia at the same time, do the colours combine at some points to form yellow, or in the spaces where they combine does one overpower the other? If the former, then RGB sounds like the way to go.

 

[MojoLA]

Hi Jai

I've been running red and green lasers in my lumia show for the last few days and no, when they overlap/combine they have not created any new colors. Now that you mention it, that is curious - you'd think they WOULD create new colors in an additive effect. I'll see if I can post a video tonight.

And that's a good point about industrial VS hobbyist - what "real world" use is there for yellow and light blue?? For a moment I was going to say laser shows (which isn't really a huge market anyway) but as has been pointed out, any serious laser show operators are going to be using an RGB setup to create new colors anyway.

So, aside from people like you and me wanting a yellow or "lightsaber blue" laser for fun, there probably isn't much else of a market to drive the price down...