Hi,
It is quite involved and I think you will have to do it in several steps so to speak, I take it that you are not familiar with building high power lasers?
I just started out doing that after finding some good stuff on eBay so I have very recent experience and I was thinking of documneting my build a bit so I might as well do it here.
I looked into rust cleaning lasers and they seem to use 1064nm diode lasers that are pulsed between 10kHz and 200kHz, the pulsing seems to be hard part.
I also don't know what kind of optics they use or if it is a bar type diode driven directly so to speak.
You can get some diodes and parts on eBay and drivers off the shelf from electronics distributors but the hard part is getting the short pulse lenghts/high frequencies of modulation.
I suggest you start out with someting simple and cheap, I got a 300W Rofin 976nm diode and a 50A driver as my first test. The driver can only do 5khz since it is used for conventional machining processes and you need to get much shorter pulses to do this.
Here is the driver I'm using, it will deliver slightly current (50A) less that the diode needs to do 300W (60A) but it was the cheapest I found at the time and it is nice to be on the safe side and it should do at least 250W.
https://www.distrelec.biz/en/laser-d...=10&track=true
Then I found this driver that is very cheap if you are in the US. It doesnt do that fast modulation though but it is a good thing to start with for beginners since it has the power supply built in.
https://www.ebay.com/itm/Lumina-LDD-...kAAOSwvXReZvkm
For the Meanwell driver you need power supply, for exampl one form the same manufacturer, 24V, 60A should work and is decently priced.
This is the laser diode I found, used so it it a bit of a gamble but mine worked fine. It is meant to be used with a fiber collimator so you need to remove the internal optics to use it.
https://www.ebay.com/itm/Rofin-sinar...AAAOSw-K9ZH3lT
The output is two lines about 4mm apart that will melt steel even at 100W. If you move the fiber optic collimator lens to the outside of the unit you get a very hot focus pointy and the two bar beams can instantly vaporise rust at 100W which is the most I can get until I get a beefier power supply. To protect the lens you will need pressurised oil free air exiting through a small hole along the beam.
Next step would be finding or building another driver capable of 100kHz modulation. I have seen some DIY attempts but the engineering at those power levels are really hard! There is a guy called Viktor on a German laser forum that has made some cool stuff.
Just google translate this post:
https://reprap.org/forum/read.php?414,849307
The step after getting a proper driver would maybe be to try a bar type diode that outputs a line. Some quite powerful ones can be found in paper printing equipment and medical/hair removal units (!) and they sometimes end up on eBay.
Maybe a Coherent diode with the fibers removed?
https://www.ebay.com/itm/Coherent-FA...kAAOSwCppefaDJ
I hope this helps!
I enclose a couple of pictures of my experiments!