Chosing cheap a laser diode module

Hello everyone!
I'm looking at laser diodes for engraving wood/cutting vinyl sheets.
i'm aimed at 445/450 nm laser diodes because it is what i can source for relatively cheap, and we've determined in this thread that it's good enough for what i want to do.

So the question now is how to chose such lasers, are there specific things that i should be looking for?
most of the ones i see comes with a TTL driver board (as an example this one is 2.5W with TTL only), some comes with PWM (example 2 : this one is "true" 2.3W, with TTL AND PWM) on top of that.

On one product page, i saw that TTL was to turn on and off, and PWM was to select the power. I thought that TTL was just a signal type, that could also be pulsed with PWM to select the duty cycle?

I also find products like this one : 1000-1500 mW laser diode in 405nm, which is dirt cheap, but doesn't seem to come with any control board. I supose that those diodes need a very specific tension and current to work. Am i wrong here?

Do you think that it would be better to source such a raw module, and search for a driver board separately? or perhaps go even more DiY, and buy a raw laser diode module such as this one, find a suitable heatsink, add the driver board and go on?
(i think that in all cases, if i can find higher powered laser diodes for cheap i'll consider this route on top of buying a pre-made module, and perhaps design a better heatsink, using watercooling)

All in all, i tend to find 3 types of modules :

• raw diodes, or diodes with only heatsink;
• complete modules with a rectangular driver board that goes on the side of the laser module;
• complete modules with a smaller square driver board that goes on the top of the heatsink fan.

Since most of the times, chinese manufacturers mass produce a few of the same circuits, i suspect that most if not all of the modules in this price range are
those options, or a slight variant. Meaning that i could get some returns for people using those (or knwowing them) : so what do you think of those models, if you have something ressmebling?

And if you don't have any of those, but know the field, what would you recommend? what to look for? any insight at all?

My goal is not to have THE laser, but have something correct enough to get started, learn about it. I feel like that it will be the same as for my aquariums, 3D printers, or electronics stuff :
i'll start with one, and will want multiple ones later on to adapt to more use cases

PS : i hope the links are not considered spam, i link those to illustrate what i mean; also those are not necessarily the best ones i can find on chinese provides, but are representative of what i find.

Edited 3 time(s). Last edit at 01/30/2018 10:15AM by sky99.

... some years ago I've collected some information for DIY lasercutting and -engraving - [reprap.org]

And this 10 years old thread could be interesting too - [forums.reprap.org]

- or a more actual one - [forums.reprap.org]

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I seem to be in the same position that you are. Although I have purchased one laser it was not a very good choice.
This is the type of laser that I purchased [www.ebay.com]

So for the last week or so I have been looking into building my own. From what I can tell so far if you build it yourself
you will most likely end up with a better unit for the money that you spend. I have been looking at this web page
[sites.google.com]
for parts research. There are several different diodes, power levels, driver boars and two different types of lenses to look at.

I don't know much about choosing lasers, and I'm in the same boat, wanting to buy one.

I have learnt a bit about buying stuff from AliExpress:

• There is no *guarantee* of quality, no matter what is written in the product description
• Avoid shops that sell a huge range (electronics, shoes, clothes, gadgets, USB cables) of stuff. They're usually just drop-shippers with no idea what they're selling.
• Some AliExpress shops buy items that failed a test, repair them, then on-sell. I think some sell brand-new untested items on the basis that they'll just refund the few that the customer complains about.
• There are many fly-by-night shops that pop up, sell junk briefly, then close down. Look for shops with a long history (years) and lots of orders, and good feedback (> 90%).
• Don't just sort by lowest price. Many shops put some other item as an option in a selection list (e.g. an ammeter in a list of lasers) to appear to be much cheaper. On principle, I don't buy stuff from these sellers.
• Read very carefully what's being sold. I've been caught a couple of times where what's in the detailed description is quite different from what's in the title.
• Do ask the vendor for clarification. If they can't clarify, they probably don't know what they're selling. That might be OK for shoes, but not for lasers.
• If it's not completely clear in the description, ask for written instructions in your own language *before* buying.
• Shipping times vary a lot. Where it's "Free Shipping", it will be a lot slower than paid-for shipping, even if the shipping cost is only a few cents.
• If you're dealing with a reputable store, the description will probably be true. But some corner-cutting may not be obvious (e.g. a 10W laser shipped with a 5W power supply).
• It's probably better to buy a whole item rather than buying parts to build it yourself. Make sure all the parts are up to spec (e.g. a 10W laser shipped with a 5W power supply).
• I'd say that buying off eBay or whatever is probably worse than direct from AliExpress, because you don't know what rules the middleman is following. OTOH, you may get some kind of legal protection about merchantability and quality.
• Check that the plug they're supplying matches your mains type. Any mains adapter included will probably be low quality.
• Things containing batteries are difficult and slow to ship. Buy batteries in your own country.
• Sale prices and discounts and so on are meaningless; just look at the final price.

Edited 1 time(s). Last edit at 03/26/2018 06:33PM by frankvdh.