At last a definitive answer to this quandary from the experts!
According to Dr Singh "Learning the basics of laser physics plays a vital role in the usage of a laser. Get yourself adequately trained in the laser you are planning to purchase. Read the instruction manual supplied with the laser machine before starting practising laser."
This makes perfect sense and is exactly what we recommend whenever we get asked this question (which is lots). If you understand the principles of how the machines work, how light interacts with skin, safety measures and what skin conditions you can treat with what combinations you can make an informed decision and spend your time and money wisely.
Singh, S, K. (2016). in Textbook of lasers in dermatology. Jaypee Brothers Medical Publishers, New Delhi.
Rafael Nadal has it nailed. Low level laser therapy also known as cold laser is increasingly being used for sports injuries, wound healing, pain management and surgical recovery. So how does it work?