Violet Ray is like a laser comb on steroids, it was recommended by edgar cayce, he successfully predicted many things including day of his own death and date Dead Sea scrolls would be found as well as revealed information only contained in the Dead Sea scrolls. He said most baldness is caused by lack of circulation due to spinal problems or thyroid problems.
He may not be liked here since he gave a cure for baldness which was scalp massages with crude oil and Vaseline but said youe wouldn't notice results for 6 months, not sure if anyone ever tried it though people are so impatient when it comes to hair.
http://www.edgarcayce.org/are/holistic_health/data/prbald3.html
Violet ray, dermarolling all increase circulation, as well as scalp massages. They would all help, I think violet ray and scalp massages are good for maintenance and getting thicker hair and can grow more hair on people with decent blood vessels that have not died. Some people don't bleed with 1.5 probably because their scalps blood vessels start dying and they cannot carry nutrients to follicles. These people have severe baldness and may need to go deeper and then work their way back to a 1.5 after blood vessels start growing.
dermarolling is like the electric shocks doctors use to revive people, it's needed in the beginning but eventually I think people should be able to maintain their hair easy when it grows back by stimulating scalp and proper diet.