The procedure:
Depending on the size and colour of your tattoo, the number of treatments will vary on how much it will take to remove the tattoo.
· Protective eye shields are placed on the patient.
· The skin's reaction to the laser is tested to determine the most effective energy for treatment.
· The treatment itself consists of placing a hand piece against the surface of the skin and activating the laser light.
· In either case, the tattoo requires several treatments and multiple visits. At each treatment, the tattoo should become noticeably lighter.
· Immediately following treatment, an ice pack is applied to soothe the treated area. The patient will then be asked to apply an antibiotic cream or ointment. A bandage or patch will be used to protect the area and it should be covered with a sun cream when out in the sun.
· Most patients do not need any anaesthesia. Although, depending on the location of the tattoo and the pain for the patient, the physician may say to use some anaesthesia.
http://www.jimonlight.com/2012/06/11/laser-tattoo-removal-its-like-a-skin-eraser/
This is basically how the laser works: