In the present work two CO² laser systems have been used. The first one is a surgical CO² laser imported for medical applications, and the second system is an industrial pulsed CO² laser with two optical systems especially designed for the purpose of this research. The two optical systems implemented to make the industrial system suitable-for medical application. Although the area of the exposure laser beam produced from the two optical designs are the same but it has been found that the second one with the compound lens was more suitable for medical treatments, because the distance between the laser focused beam and the skin sample was smaller than of the first system with the single lens (i.e. high accuracy which is very important in medical treatment). Values of vaporization parameters such as the etch hole depth per pulse, the etch hole diameter per pulse, the ablation threshold and the absorption coefficient are obtained from the experimental findings for both CO² laser systems and for normal reference tissue and a diseased tissue with psoriases are included. In this work, a practical comparison is made between the results of each C0² laser system to prove that the optical systems succeeded to make the characteristics of the industrial system applicable for medical treatment.