Is duetto laser effictive for fine and gray hair? And is there any possibility that they become thicker or ther growth increase?

i am white girle , i have dark hair in some parts of my body and gray or weak hair in the other , i did one setion full body gentle lase , then I realized that i should not do it , so i am scared now , and i want to solve that by using the right machine . i was thinking of using midlight , but is it possible to use midlight to my upper arm cause while it have the compination of dark in some sits and gray or weak in the other, i don't remember my hair how look or where is the gray hair exactly .

No doctor answers yet