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New to forums, what is the smallest laser currently available?

bambbrose

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Hi all, just found this forum tonight. I just wanted to introduce myself and ask a question.

I work with high power lasers all day from 1.0mJ per pulse Excimer 193nm units to my baby, a 500W Coherent Co2 Diamond 10.6um (can turn a brick into glass:D). I design and calibrate power meters and pyroelectirc heads for Ophir-Spiricon.

Anyway, I'm working on a small side project for an experiment of my own, not work related, and I need to find the absolute smallest diode laser I can.

I want something that doesn't already have a housing, or if it does, I can remove it from the housing and install it into my own machined housing. I'd prefer less than 5mw, and I'd prefer green, but I can do reds if it's significantly smaller than any greens available.

The current diameter of most of the laser pointers is fine, although a bit smaller would be nice, but the length of the pointers is much too long. I need something that is less than an inch if possible. I can have an external power/control unit if necessary, but it must also be lightweight and small.

Any suggestions?

Thanks for your help
 

jayrob

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Welcome to LPF!

Here's one of the smallest greens I've seen:
DealExtreme: $15.90 Chromed Mini 5mW Green Laser Pointer Keychain (1*CR1/3N)

For red or blu-ray, I don't know if you can get much smaller than my 10280 key chain build: (that is, if you want to have a driver in there)
http://laserpointerforums.com/f38/215mw-6x-key-chain-blu-ray-flexdrive-20124.html

Also, I just found out that you can get small green modules for cheap from o-like. (8mm diameter - 1.5 volt input - 30mW) See here: (and read post #3)
http://laserpointerforums.com/f45/30mw-green-laser-single-aaa-battery-45548.html

There are tiny green modules available, but they are very expensive:

http://www.laser66.com/html/scl_over.html
 
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RA_pierce

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That Coherent Co2 sounds impressive! I'd love to see one of those in action.

What exactly do you plan on using this for?

A red or violet laser will have a smaller minimum than a green.
For 5mW of red you can get these:
aixiz.com StoreFront

There are also smaller diode types available. I think there is a 3.8mm (3.6 maybe?) red diode capable of >100mW in the 8X Blu-Ray burners. Member Daguin has tested one. You can just run it at low current for <5mW.
That is probably the smallest diode type you will find other than the crappy flat diodes in cheapo $1 pointers (those are usually around 640-635nm, though).

Violet diodes are all 5.6mm package as far as I know.

The smallest 5mW green at low cost would be:
8mm smallest green laser module£*>5¡«500mW green laser module£*>Laser&lighting products£*>www.0-like.com
If you are using a different power supply, the one on this could be removed easily.

Red will be smaller because they don't use doubling crystals like greens (I'm sure you know this).

If you are making your own housing, then you can always get a tiny red diode (they are cheap as chips) and all you will need is a collimating lens.
Also, if you go with green, you will need at least some heat-sinking for continuous use since the pump diode will produce a small amount of heat.
Since you are only going for 5mW, you don't need to worry about too much heat-sinking mass.
Hope this helps!
And welcome to the forum.
 
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Asherz

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I believe someone recently built a laser in an aixiz housing, using a red diode, no driver and some button cells. It probably won't last long but it burns and will work for a fair while, depending on if it gets a voltage spike :)
 

HIMNL9

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bambbrose

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Thank you for the replies thus far. It's certainly helping out.

I can kind of explain the use without giving away my idea.

I need the unit to be tiny and lightweight as it will be mounted in a small portable tabletop robotics unit. The entire unit is less than 2"x2"x3". In that small area, I have to mount a track wheel system, power pack, and two arms, one of them a laser, the other a multiuse tool, an optical head system (IR camera or maybe a retrofit VIS unit).

As you can tell, space is extremely limited. The smaller the better. The more energy efficient the better.

Now as for the laser, the wavelength doesn't really matter, it just has to do one thing. I need it to have relatively low divergence over the course of approximately 10', which shouldn't be difficult with the proper collimating lens. It needs to be able to shine into a white-body cavity, and light up an electrical switch.

On that note, do any of you know of a photoconductive switch that is cheap as dirt? Something that I can mount inside of a cavity, and then when the laser light is incident upon that cavity it will complete the circuit?

It seems that the small cheapo $1 red diodes would actually suit me just fine. It won't be continuous use, only pulsed use on occasion. I'd actually prefer to build it myself with parts from a source like digikey or similar. If my idea works, I will need to order around 500 of them, and therefore I need something that is cheap, reproducible, and readily available.

I'm building a prototype right now and need to keep my total costs as low as possible.


What exactly do you plan on using this for?

A red or violet laser will have a smaller minimum than a green.
For 5mW of red you can get these:
aixiz.com StoreFront

There are also smaller diode types available. I think there is a 3.8mm (3.6 maybe?) red diode capable of >100mW in the 8X Blu-Ray burners. Member Daguin has tested one. You can just run it at low current for <5mW.
That is probably the smallest diode type you will find other than the crappy flat diodes in cheapo $1 pointers (those are usually around 640-635nm, though).

Violet diodes are all 5.6mm package as far as I know.

The smallest 5mW green at low cost would be:
8mm smallest green laser module£*>5¡«500mW green laser module£*>Laser&lighting products£*>www.0-like.com
If you are using a different power supply, the one on this could be removed easily.

Red will be smaller because they don't use doubling crystals like greens (I'm sure you know this).

If you are making your own housing, then you can always get a tiny red diode (they are cheap as chips) and all you will need is a collimating lens.
Also, if you go with green, you will need at least some heat-sinking for continuous use since the pump diode will produce a small amount of heat.
Since you are only going for 5mW, you don't need to worry about too much heat-sinking mass.
Hope this helps!
And welcome to the forum.
 
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bambbrose

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RA_pierce

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An idea if you want to use green...
I got a $10 greenie from Dealextreme, took it apart, and made a tiny green module similar to the picture Jayrob posted.
All I had to do was put the pump diode in a tiny (7.5x6mm) heatsink for 5.6mm diodes and position the crystals directly above the diode. After a couple minutes of careful alignment and a drop of epoxy, I had a green module that was about 10mm long and 7.5mm wide (not including driver).
It worked. And with the current turned down I got a steady ~5mW green. The divergence wasn't great but could have been corrected with just a small convex lens.
I can take pictures if you'd like.

Edit:
Actually, this has inspired me to re-do this experiment and make it even smaller. When I get home I think I'll give it a shot...
 

bambbrose

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Any chance you can get some pics? Sounds very interesting and I'd love to see your results.


An idea if you want to use green...
I got a $10 greenie from Dealextreme, took it apart, and made a tiny green module similar to the picture Jayrob posted.
All I had to do was put the pump diode in a tiny (7.5x6mm) heatsink for 5.6mm diodes and position the crystals directly above the diode. After a couple minutes of careful alignment and a drop of epoxy, I had a green module that was about 10mm long and 7.5mm wide (not including driver).
It worked. And with the current turned down I got a steady ~5mW green. The divergence wasn't great but could have been corrected with just a small convex lens.
I can take pictures if you'd like.

Edit:
Actually, this has inspired me to re-do this experiment and make it even smaller. When I get home I think I'll give it a shot...
 

bambbrose

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With the APC units like that that have the module/driver in one assembly, they do not need anything additional to run? Just hook them up to the proper power supply and they automatically control the current flow?

If so that is all I really need. You can't ask for a simpler setup.
 

daguin

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With the APC units like that that have the module/driver in one assembly, they do not need anything additional to run? Just hook them up to the proper power supply and they automatically control the current flow?

If so that is all I really need. You can't ask for a simpler setup.
Yep. With the 3.3mm, you just hook up 3V power to it. The "board" limits the voltage and the APC unit controls the output.

Peace,
dave
 




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