combining multiple laser diode beams and driving

[m3vuv]

hi all,ive just got a projector ,it has 24x m-140 diodes,,any ideas how to drive say 5 of them and combine the beams,im sure the pic is a knife edge mirror assembly,you will have to excuse me as new to this,cheers in advance m3vuv.

 

[Immo1282]

Can you attach a picture of the projector?

 

[m3vuv]

i tried but it was too big,its not relevant to the question anyway!

 

[Immo1282]

I'd use the search box to look for threads before asking questions outright, as there's a fairly definitive guide thread on combining beams here;

https://laserpointerforums.com/threads/reference-guide-how-to-combine-lasers.77449/

Edit: It seems as if you may not have read the sticky threads or posted an introduction; Read them through and then make your moves on an introduction thread - better late than never, but I'm surprised you haven't been asked to already

 

[paul1598419]

If you ant to combine 5 of these diodes into a single beam you will have to knife edge them as there isn't another way to combine that many beams into a single one. As far as driving them goes, you have two options. Either run them in series and use a driver that can supply about 22 volts of forward voltage at 1.8 amps or parallel them and add limiting resistors to each diode. I would go with the first option.

Of course you could also drive them all separately too.

 

[m3vuv]

ive gone with a row of 8,ive built 317 drivers for each of then at 4.27 volts each,there is a knife edge assy that bolts to the ld assy,im gonna try that then see if i can colminate the output,will post pics when im done,just a last questionif the diodes output 2w each does it mean the beam will be 16w optical power give or take?,cheers m3vuv.

 

[Immo1282]

ive gone with a row of 8,ive built 317 drivers for each of then at 4.27 volts each

Are you configuring the LM317's for constant current not constant voltage? You should be setting the current on each driver, not the voltage. Constant-voltage drivers and laser diode's dont mix so well as LDs have a negative temperature coefficient (as their temperature rises, their resistance decreases) meaning that you can get a thermal runaway, as well as inconsistent output power. by setting the current, you eliminate this as the voltage will fluctuate - but this is fine and safe provided you choose a reasonable value.

You'll probably also need a significant heatsink attached to your LM317s in any case though - as they'll likely get very hot.

 

[m3vuv]

as far as i can see the max current from a 317 is 1.5 amp so should be ok,i think.

 

[paul1598419]

Yes. You cannot get 2+ watts with an LM317 driver. Also, you are going to lose power with a knife edge assy. How much depends on how well you can get the knife edging done.

 

[hakzaw1]

WE still suggest doing more study on your own AND making a respectable 'Intro' (that shows respect for the members here)

Put you location into yr profile and its best if your location in also in the TITLE of your intro--go there and READ!


We only ask that you 'meet us halfway'--

Your ideas about the KASIO diodes wont work .

 

[m3vuv]

i thought i had written an intro!,the knife edge assy is the one that was in the projector,im fully aware of the lm317 current limit of 1.5amp,i may use lm338 regs as i have some handy,i got it working tonight with 8 diodes but cant sus out how to focus the beam!,anyway im 52 live in the uk,electronics and amature radio are my hobbies ,73 m3vuv

 

[diachi]

i thought i had written an intro!,the knife edge assy is the one that was in the projector,im fully aware of the lm317 current limit of 1.5amp,i may use lm338 regs as i have some handy,i got it working tonight with 8 diodes but cant sus out how to focus the beam!,anyway im 52 live in the uk,electronics and amature radio are my hobbies ,73 m3vuv

Figured you were in the UK when you said "cant sus out"!

Welcome!

73 VE8VX

 

[Light superglue]

Hi m3vuv,

I once tried to make this but quickly realised that the position of KE-mirrors and LDs orientation in the A140 light engine was far from ideal to make a collimated and easy to focus beam. Now I am trying to do this with NIchla blocks - need less mirrors for same power.

Sorry if you find this negative input.

 

[hakzaw1]

i thought i had written an intro!,the knife edge assy is the one that was in the projector,im fully aware of the lm317 current limit of 1.5amp,i may use lm338 regs as i have some handy,i got it working tonight with 8 diodes but cant sus out how to focus the beam!,anyway im 52 live in the uk,electronics and amature radio are my hobbies ,73 m3vuv

You mean this:??

hi all,im paul m3vuv a radio ham from the uk,into electronics and just started messing with...
An intro must be placed in the WELCOME/Newcomers section- AND as written- you really need to use UK in the intro title AND place it in your PROFILE--please.

How we help is sometimes dependent upon where you live-- not many will read or remember anything from a profile post-- the old forum covered that with our location under our usernames EVERY TIME WE POSTED-- This new forum sux IMHO for that alone-- we are no longer 'connecting' like we were before.
We appreciate you following up on this...hak

 

[Immo1282]

Hak - it shows it when you hover the mouse over someones username - it's not perfect, but it's not bad either. Obviously it still is prerequisite that the user's filled their location out on their profile...

 

[hakzaw1]

Yeah I knew that BUT with so many NOT putting location into their profile --it still sux.
I have seen forums where there is no choice-- make a proper intro or you wont get to use the forum until that gets posted.
I understand that some are not crazy about giving up their location BUT at least the country is REALLY needed .