I just looked at mine earlier today under a 10x loop. There's a definite difference between the engraving on my Rouse and Dr. Rocket tubes and the markings on my AeroTech and what I'm 100% positive is laser engraving on aluminum anodizing.
My new AT tubes, purchased this year, all look like the marking is white ink roll printed, there's clearly no break in the surface finish where the white ink is.
Is it possible it's just better (more modern) Laser etching?
Somewhere I had pictures of a tube that my buddy played with his Laser on my old Dr Rocket case. You couldn't feel anything from his etchings. Just red color changed to white.
It's definitely different than how they were done by Dr Rocket. That style you could feel. It's almost like Dr Rocket engraved the cases and wiped white dye (ink?) into the letters. My buddies Laser just changes the surface color to white by Laser magic...