So I ended up buying the famous 405nm "BDR-209" laser module with the G2 lens from "DTR" at eBay. Seems like Mr. "DTR" is a serious laser guy, with over 7K 5-stars at eBay, I gotta say thanks to Mr. "Giannis_TDM" and "Alien Laser" for providing such reputable laser source, I always seeks for the most professional, reliable and honest sources when it comes to buying electronic components.
I got in contact with two professional "f-theta" lens company, one from "Egimos" and another from "Geomatec".
"Egimos" can produce f-theta lens like the ones found in laser printers and can customize tailored to my needs.
"Geomatec" has precision based f-theta lens like the ones fiber lasers use with galvo scanners.
Hopefully I'll find a solution which can make the scanning laser beam down to 0.01mm at the surface accurately and reliably all day without breaking the bank...