My article apply your help

Hey, guy,

I just want to write an article about laser pointer pen. This article , at first, should be a professional academic writing , so who would like to tell me how a 500mw green laser work. Or who can tell me the most difference detail of a 10mw green laser and a 300mw green laser. Besides, I want to buy green laser pointer for the research purpose, but it should be a
cheap green laser pointer. Where can I get the pointer roughly match my requirement? Thank you?