Abstract: An acne treatment system, device and method includes optical visualization means for identifying areas of skin colonized by the P. acnes bacteria, and further comprises methods, techniques and apparatus for the reduction or elimination of such colonies through the use of light of a power density and wavelength configured to be absorbed by porphyrins produced by the bacteria, resulting in a quenching. Various alternative embodiments are disclosed, including eye safe embodiments, embodiments in which a treatment regimen is provided on a disposable cartridge, embodiments in which the authenticity of the cartridge is verified to ensure proper operation, as well as others.