need some help shopping ;) about focusing down a laser diode

thinking about buying these (link here)
and I already bought this: AixiZ module.
Now those laser diodes (i'd be using one the other would be a spare) create a line shaped dot which I will want to focus down to like a very small dot (round if possible) if I can get it down to 0.1mm diameter or less I would be really happy . and it would be fine if this dot is created at a distance of anywhere from 5mm to 50 mm distance if it was 30mm to 50mm it would be more optimal to prevent the lens from getting to dirty.
Yes this is not for a laser pointer this is for a plan I have to make a "laser etcher" well the only thing I want this to etch is flat black paint (the etch resist) and then the chemicals will be doing the actual etching.
Anyways I looked into it while it might be slow one 1W should be sufficent if it's focused enough, remember the laser height from the object will be constant and fixed once the optimal focus has been determined. cost is really a factor here so the cheapest way to do this reliably would be great.
would be greatful for any advice and major contributors will be mentioned (get credit) if they want to be when I publish this as an open source project.
:thanks: in advance for any advice
terramir

DON'T FORGET PROPER EYE PROTECTION !!!!! rob

phoenix77 said:

DON'T FORGET PROPER EYE PROTECTION !!!!! rob

Click to expand...

Rob already posted in the safety forum about these I bought yesterday
ebay link
still need help on the actual topic though
Rob any advice?
terramir

This picture is so wrong it hurts.


I hope this is not how he tests all his diodes. Running without a heatsink the diode may last 2 whole seconds. Plus burning something so close to the diodes face will deposit residue on the window which can also damage the diode.


Anyway first thought is that I am pretty sure is a multimode diode with a wide line style output. You may have a hard time trying to correct that down to the spot size you want.

If you do go with it you will want a heatsink that is either direct press for the diode or a module like a 12mm Aixiz mount for 9mm diodes that goes in a 12mm drilled heatsink. You will also need a properly coated lens and a laser driver to drive the diode to the current you want. Looks like he is suggesting staying under 1.3A.

I'll be using a heatsink and a friggin overkill fan to make sure the diode stays cool.
I doubt he tests them like that I think that diode was used for a quick demo since he seems to sell quite a bit of these.
But I do need help on the optics if I need to use more than one lens as long as there not too expensive that is fine if I have to drill my own alu tube that would be fine too. I just need to know if it doable economically
terramir

I could not agree more with the advice given so far.
Even once pressed (you need to know how to do this properly BTW) into the AixiZ blank module you should NOT power up for more than a few seconds.
I have two suggestions- PM Dan (Things) with your questions AND join the CNC forum( the one claiming to be the worlds largest) those are the real experts for you.

You may find it hard to focus into a dot as the output is nearly invisible- Trying to do this w/0 proper eyeware is NOT suggested. The diode in the pic is positioned that close AFAIK because the divergence of your typical IR diode is very poor.
Also once you get anything onto the window of the die cleaning it is extremely difficult IIRC.

If you do not understand ESD prercautions or the damage one can do by overheating with your soldering iron you will fail.-- good luck-- hope this has been helpful.

hak

Hi terramir, regarding eye protection, the goggles that I use (& please keep in mind that I bought these several years ago, so prices &/or availability may be different now) are from OEM LASER SYSTEMS, Model # ML-7 for KTP,YAG, RED/IR Diode protection. The protection drops off a bit for the deeper BLUE & MOST YELLOW wavelengths, so I have different goggles for BLUE & YELLOW Lasers, but the ML-7's cover the rest of the WL's quite well. They cost me $156.00 back then but I've no idea what the cost is now. I wear glasses so I bought Frame Style #38 so they would fit OVER my eyeglasses. Hope this info. helps you out some. Good luck with whatever you buy, just make sure that they are QUALITY. You only have 2 eyes, so take good care of them. My eye-sight is bad enough as it is & I don't want any other damage done to them so I went all out for protection & to hell with the cost. I'm sure you can find less expensive goggles now, but I don't like takin' chances with my precious eye-sight (screwed up as it is). IMHO, just buy the BEST you can afford & make SURE they cover the WL's you need covered. I'm sure that any other Members that see this will give their opinions as well & will probably be more up to date than the info. I provided for you. Just be careful & listen to what more experienced members have to say & you should be OK !!! Happy Lasering----------- rob

hakzaw1 said:

I could not agree more with the advice given so far.
Even once pressed (you need to know how to do this properly BTW) into the AixiZ blank module you should NOT power up for more than a few seconds.
I have two suggestions- PM Dan (Things) with your questions AND join the CNC forum( the one claiming to be the worlds largest) those are the real experts for you.

You may find it hard to focus into a dot as the output is nearly invisible- Trying to do this w/0 proper eyeware is NOT suggested. The diode in the pic is positioned that close AFAIK because the divergence of your typical IR diode is very poor.
Also once you get anything onto the window of the die cleaning it is extremely difficult IIRC.

If you do not understand ESD prercautions or the damage one can do by overheating with your soldering iron you will fail.-- good luck-- hope this has been helpful.

hak

Click to expand...

Yeah I know focusing the dot is gonna be a royal pita I understand that on the curve an 808nm diode sits wavelength output wise only a mere 1-10% or less is actually visable light so that will be a royal pita.
As for soldering I usually use a big set of pliers to hold a leg of something like this above the solder point towards the casing this way you heatsink the heat away from the actual component, motto there is get it get out and bring a big sink.
so I do understand this I've been soldering since I was 12 hmmm 29 yeas now. Was miserable as a kid better now LOL.
and btw I'm part of the cnc forum, but I was here to ask about focusing etc.

as for the safety glasses I wanted to ask something anyone know of a good shield I could use while I test my glasses to ensure they are proper?
proposed test aim laser while wearing safety glasses at a thermistor check heat rise for lets say 1 second or two
then put safety glasses in the path of laser beam check if the heat rise ceases or is significantly less. But I would need some sort of shield to put in front of my eyes for this test anyone got any ideas?
terramir

That pic is wrong they are not 1w at all i bought some they want cut 2mm foam all the way with a good drive i know a 200mw will cut 2mm foam all the has any one bought them what do you thank like to here somebody elas

so your saying that these diodes are not even 200mW even though they are advertised as 1000mW i.e. 1W lasers?
Or could it be that your driving circuit is incorrect, what I understand from the theory on lasers (honestly my theory classes were in the 1980 physics classes so hopelessly outdated) it's an all or virtually none situation so if you don't have enough power depending on rating the laser won't lase properly.
It could be the guy from this auction is full of crap, but are you supplying more than 400mA of current. I would like to really know I'll look for another source if this one is not powerful enough.
Also if your using an LM317 Driver circuit it will not work with this diode unless you got a bunch of cooling and the supply voltage is no more than 3V. The way an lm317 works is actually nothing close to efficient and it does have a thermal and current limits. i.e. an lm317T in a to-220 package cannot handle more than it can the higher the temp of the case the lower the current will be and it is almost instantanous that this occurs without one huge frakin heatisink.
also the voltage differential counts for a 250mw laser for example (something I read alot of people play around with) you need 2.2V and about 300mA- 350mA of current.this equals to 660 to 770mW of power. at lets say a supply voltage of 5 volts you would be burning off an additional 700mW to 1 W of power at 12V you'd be burning off about 5 watts of power
With one of these lasers unless the supply voltage is really close to the actual voltage you'd be taking an lm317 out of spec in a real quickness unless you have some monster cooling.
thanks for your warning I will have to investigate further, but I could use some data on your setup. While I don't know much about optics yet I have more than a basic understanding of electronics themselves including power supply design. LM317's are great for low power applications if properly sinked however they fail miserably in high power applications. There very wasteful and they have the efficiency of a sherman tank. (i.e. no gas milage at all)
terramir

i am putting 2.2v at 1.3a its cut dark paper and burns wood but 1w should do better then that i tryed 2 drivers 1 i order and 1 lm317 i put together it works the best

you should complain to the dude on ebay then because he may not know that this is the case. 1.3A 2.2V should be 1watt in real life lasering according to what I saw on his spec sheet (parts) hmmm I may need to get some other led.
terramir

Can anyone tell me if successive lenses may solve my problem I mean Let's say I take my laser output from the laser which will be mounted inside either the axisiZ module or not depending on the advice I get and then put another lens infront of it to do the final focusing or should I forget about the axisiz module I bought all together ( I mean it was what five bucks) I find something else that could do the job with an ir diode/ and if so what would you recommend.
terramir