With the rapid development of medical cosmetic technology, laser treatment has become the first choice for many beauty lovers. This article will analyze the key terms of laser: energy (Energy) and energy density (Energy Density) in detail to help you have a more comprehensive understanding of the professional knowledge in the field of medical cosmetics.

Energy and Energy Density

Laser energy refers to the total energy released by the laser during the emission process, usually in Joules (J). Energy density refers to the distribution of laser energy per unit area, and the commonly used unit is Joules per square centimeter (J/cm²).

The energy of a long pulse laser refers to the laser energy carried by a single pulse, which determines the ability of the laser to act on the target tissue. In long pulse laser treatment, energy density reflects the energy distribution of the laser on the surface of the skin or other tissues, which usually affects the treatment effect and tissue response.

In laser treatment, energy and energy density are two important physical quantities that directly affect the treatment effect and safety. In the field of medical cosmetology, the control of laser energy is particularly critical because it directly affects the accuracy and effect of the treatment.

1.Basic principles of laser energy
Laser energy is the total energy released during laser emission, which determines the degree of impact of the laser beam on the target tissue. In medical cosmetic treatment, laser energy usually acts on the skin through heating, cutting, ablation, etc. The energy of the laser not only affects the treatment effect, but also directly determines the safety of the treatment. For example, when laser is used to remove pigmentation, the laser energy is absorbed by the pigment and converted into heat energy, thereby destroying the pigment particles and eventually causing the pigmentation to fade.

Energy density refers to the energy released by the laser per unit area, which is closely related to the total energy of the laser and the size of the area of action. Different treatment methods and target tissues require different energy densities. For example, when performing laser skin resurfacing or laser pigmentation removal, a lower energy density helps reduce damage to the skin; while in cases where deep treatment is required, such as laser tattoo removal or skin tightening, a higher energy density may be necessary.

The other two concepts related to laser energy and energy density are power and power density. The formula relationship between these four concepts is as follows:

Specifically:

The total laser energy refers to the total energy delivered by the laser beam during the pulse duration and the total spot area, and the unit is joule (J).

The laser energy density refers to the total energy delivered by the laser beam during the pulse duration and per unit area, and the unit is joule/square centimeter (J/cm²).

Laser power refers to the energy delivered by the laser beam per unit time and total spot area, representing the energy transfer rate, and is measured in Watts (indicated by capital "W"). 1 Watt = 1 Joule/1 second.

Laser intensity refers to the energy delivered by the laser beam per unit time and per unit area, representing energy intensity, and is related to the power and spot diameter of the laser beam, usually measured in Watts per square centimeter (W/cm²).

Laser power density refers to the energy delivered by the laser beam per unit time and per unit area, and is calculated as "power density = energy density ÷ pulse duration". Since the unit obtained by Joule/time is Watt, the unit of power density is Watt/square centimeter (W/cm²). It can be seen that power density is actually another expression of laser intensity.

The choice of energy density not only affects the effect of treatment, but is also closely related to the recovery time after laser treatment and possible side effects (such as redness, skin burns, pigmentation, etc.). Precise energy density control can optimize treatment effects and minimize side effects.

The amount of laser energy determines the extent to which the laser beam affects the target tissue. In medical aesthetics, laser energy is usually applied to the skin in the following ways:

1. Heating
The laser energy is first absorbed by the pigment or water in the skin and converted into heat energy. This heat energy can be used to heat and coagulate the target tissue to achieve the purpose of treatment. For example, when laser removes spots, the heat generated by the absorption of laser energy by the pigment breaks up the pigment particles and is then eliminated by the body.

2. Cutting
In some treatments that require precise cutting (such as laser repair surgery), laser energy is used to precisely cut the skin or other tissue. This application requires high energy density to ensure the accuracy and effect of the cutting.

3. Ablation
High-energy lasers can also be used for ablation, which is to evaporate or remove the surface of the tissue or certain diseased areas. For example, in laser skin resurfacing treatments, laser energy evaporates the surface cells of the skin, thereby promoting the formation of new skin and overall improvement of the skin.

2.The importance of energy control in medical cosmetology
In medical cosmetology, energy control is crucial because it directly affects the safety and effectiveness of treatment. Here are some specific application scenarios and considerations for energy control:

1. Laser spot removal
In spot removal, laser energy must be precisely controlled to avoid damage to the surrounding normal skin. If the energy is too high, it may cause skin burns or pigmentation; if the energy is too low, the spots may not be effectively removed. Therefore, doctors need to adjust the energy output of the laser according to the depth of the spots and skin type to achieve the best effect.

Laser skin resurfacing removes aging cells and promotes the formation of new skin by ablating the surface layer of the skin. Appropriate laser energy can remove dead skin cells on the surface while avoiding excessive damage to the deeper tissues of the skin. Energy control can determine the recovery time after treatment and the final effect of the skin.