diode vs regular collimated light?

[jeff8j]

I am beginning the building of a laser cutting cnc machine. I have been looking for laser diodes with drivers but having a hard time determining a good cheap one that can cut.

I dont know much about how the laser work but was wondering if I could just use regular light through a colimating lens into a fiber cable? Id figure it would be much cheaper easier and simpler. Would that work?

[Exsecratio]

Hi Jeff,

To be honest my friend I'd stop looking at building and start doing some research in depth. *Regular* light won't cut, fibre optics of the kind you mention won't handle laser radiation, diodes don't cut much more than paper and finally laser sources aren't cheap no matter what any supplier promises.
You would also be dealing with very dangerous / potentially fatal voltages 12,000+ volts and the nature of your questions suggest at this point that may well not be a good idea.
High power lasers pump dangerous radiation, unless your fully up to speed with the dangers you stand a good chance of being badly injured.

best wishes

Dave

[jeff8j]

Thanks for the concern thats why im asking because I dont know.

In my current project im not trying to cut more than paper so I dont need that high of voltage infact currently im using a dvd burner laser I know can still do damage im taking every precaution with my eyes a little less with my hands than I should though.

I just dont understand the difference in the light im dumb on the subject so in my opinion light is light what makes the laser diodes have different light? From what I found is its basically a led diode between two mirrors.

[jeff8j]

I keep reading more about lasers but still dont see a difference in laser light vs regular light
Laser Facts
that says that they are the same just laser light is more directed
Cant you use a collimating lens to direct any form of light? Wouldn't that be the same effect?

[Exsecratio]

Yes and no Jeff, Laser light is as close to parallel as you will get, optical light (leds etc) fire off photons in all directions. There is also the wavelength to consider (UV through to IR).Yes you can burn stuff with small DPSS systems but the heat generated will mean cooling becomes a problem very quickly if you don't want to kill the diode. The diode and pump electronics of a good 4Watt IR laser (solid state) is going to cost considerably more than a basic CO2 DC excited tube and power supply. You can burn material with a magnifying glass using the sun but it would be unlikely you could build a budget system to use these kinds of parts (and it wouldn't work at night )
True both LED's and Lasing diodes provide *light* but it would be akin to comparing a ferrari with a childs battery powered car. Both have wheels and will travel along but the battery car isn't going to be winning too many races

Tweakie who posts here is an excellent source of information about home brew machines and has built his own combination router/laser system (and has probably forgotten more about electronics than I'll ever know).

Overall the cost of building a small DPSS based system is going to be very close to that of a 35 watt Chinese tube based system.

I hope in the future that diode pumped solutions become more common but at the minute the technology just isn't quite *there* yet.

best wishes

Dave

[jeff8j]

I think I got it. Its not that you cant do it its just going about things in the least efficient way.

Oh and you said fiber optics of the kind i mention cant handle the laser radiation. I would like to keep the laser stationary is there a kind of fiber optics that I can use for that?

Thanks

[Exsecratio]

If you're going for a diode solution Jeff I'd probably move that and rely on the flex in the wire over trying to use a fibre optic solution. Yes there are fibre laser diodes available but the solution will be complex for a beginner and not easy to achieve good results.

8W Fiber Coupled Laser Diode 915nm 100um Multimode Pump | eBay

You mean this kind of thing?

[jeff8j]

Yea that kind exactly and thats cheaper than the ones I was looking at I like that kind of price I was looking at ones half as powerful for twice as much but anyways I was thinking a fiber optic line would be easier because I could have the laser some where else where I can have some serious fans going to it and I cant do that on the cnc itself because I dont want what im cutting to blow around. I guess watercooling would fix that but that adds more complexity. What would the downsides be using a setup with fiber optic cable?

[Exsecratio]

Cost Jeff, you need the power supply, collimating lens system, very good cooling, then you have to control the pulses via some kind of driver card that likely won't come with a driver suitable for that diode or those like it.

best wishes

Dave

[pontiacg5]

Might I suggest a "1W" blue laser diode? They can be found on e-bay for under $50. They provide around 1.2-2W of 445nm light when paired with a special lens (~$50.) They are super resistant to heat, heir tolerances are magnitudes larger than any red or IR diode you'll find. They're also very friendly with power requirements, they often don't die if you run too much current through them.

I guess what I am trying to say is I would start with a blue laser. They are cheap but still powerful, cheap to drive (I can point you to a PWM/full analog driver for less than $50) but most importantly they are extremely robust. If you buy a $500 IR diode it WILL die the second you give it too much voltage or current.

445nm is also more readily absorbed by more colors than (lower) IR wavelengths.

If any of this sounds interesting I can go into a little more detail or I can point you to a site that has all this info.

Oh, I almost forgot. Since the diode is so small you would have no problem mounting it directly to your flying head. No need for mirrors and mirror mounts or fiber optics.

[jeff8j]

That sounds really good would a 1W blue laser diode be enough to cut through cardboard or maybe some plastics?

[Exsecratio]

I'd agree with Ponti, 445 NM's are cheap and easy to drive, not too important if you kill one either.
Tweakie mounted a red diode on his multi/machine and managed to cut paper and film with it.

Tweakie.CNC - Low Power Lasers

The above is Tweaks site and full of useful stuff for the home laser builder.

best wishes

Dave