The spot size of a laser determines how much skin area can be covered per laser pulse. Additionally, only the largest spot sizes can address hair follicles at deeper levels. Lasers with larger spot sizes (18 mm)can cover more area much more quickly. For example, a laser hair removal treatment of the back or full legs could take as long as 2 hours with older lasers. Today, these areas can be completely treated in less than 20 minutes.
There is no single laser that can effectively treat all skin types. Light skinned people need s short pulse for efficient hair removal,while dark skinned people require a longer pulse to ensure safety and to protect the skin. Be sure to find a medical practice with a minimum of 2 lasers.more info here
Each laser has a different way of cooling the skin. Some lasers use a topical cooling gel, others use a chilled tip. The most consistent, comfortable and safest way to cool the skin is with a Dynamic Cooling Device or DCD. Lasers equipped with a DCD cooling system are so effective in providing cooling to the skin that no topical numbing creams are necessary.
Intense Pulsed Light (IPL) Systems are not lasers. They can remove hair, but recent peer reviewed medical studies show that IPL systems are not the current standard for laser hair removal.
Many laser hair removal centers today operate without a physician. It is important to be certain that a board certified physician is on the premises or available in case of a concern.
Laser Hair Removal works on hair while it is in the growth phase only. At any given time, between 20% to 40% of the hair on any face or body area may be in a growth phase. Multiple treatments are required for complete clearance of the hair. However, each person may respond slightly differently. Laser hair removal centers should charge for just one treatment at a time. A reputable medical office or medical spa offering laser hair removal will offer individual treatments and not insist on payment of multiple treatments up front.