???????After a lot of practice, the greater the laser power density (or energy density) used when irradiating the skin, the greater the damage to the skin, and there is a positive correlation between the two. After the skin absorbs laser energy that exceeds the safety threshold, the skin on the exposed area will appear thermally induced erythema, blisters, coagulation and thermally induced carbonization, boiling, combustion and thermally induced vaporization with increasing dose. Therefore, the mechanism of laser damage to the skin is mainly caused by the thermal effect of the laser. After the skin absorbs laser energy, the local skin temperature rises within a short period of time, and the degree of temperature rise is different, causing different damage. In particular, infrared lasers are prominent, such as CO2 lasers (vapor lasers). The skin has a high absorption rate of 10.6 μm wavelength infrared lasers and low transmittance. The skin absorbs CO2 lasers strongly, causing the local temperature of the skin to rise rapidly. High, very easy to cause damage. The severity of laser damage to the skin is determined by the skin's laser absorption rate, which is determined by the laser's wavelength. The higher the skin's absorption rate of a certain wavelength of laser, the more serious the damage will be. For example, when the skin's absorption rate of ultraviolet laser and infrared laser is very high, these two types of lasers are the main band lasers that damage the skin.
???????The main effect of infrared laser on the skin is thermal burns. This kind of laser irradiates the skin, and the power is relatively small, causing the capillaries to dilate, and the skin is red and fever. As the laser power density increases, the degree of thermal damage also increases. On the contrary, the effect of ultraviolet laser on the skin is mainly light. When irradiated with ultraviolet laser light on the skin, it can cause skin erythema and aging, and can cause severe carcinogenesis when overdose. Ultraviolet light waves that are most harmful to the skin are between 270 and 290 nm, and wavelengths larger or smaller than 270 to 290 nm are relatively less harmful.
The YAG infrared laser with a wavelength of 1.064um is less harmful to the skin.