"High peak power + narrow pulse width" trend

In recent years, the mainstream power of semiconductor lasers used for laser hair removal has experienced an increase from 300W to 600W, and is rapidly changing to a power above 1200W, which is one of the recognized trends in the industry. Why is there such a shift? The root cause is still reflected in the end user's demand for a more effective and comfortable treatment experience.

Energy density = peak power * pulse width / spot area

According to the above energy density formula, on the premise that the energy density (effect) and the spot area (efficiency) remain unchanged, the higher the peak power, the narrower the pulse width can be compressed. On the other hand, the narrow pulse and broad band bring better clinical effects and a more comfortable clinical experience.

In the entire treatment process of laser hair removal, the laser will first pass through the epidermis, dermis, etc., and finally reach the hair follicle, and destroy the hair follicle. In this process, we want the hair follicles to be destroyed more efficiently, but at the same time, we need to avoid skin damage. Here the pulse width is particularly important.

Generally speaking, 10~30ms is considered as the optimal pulse width for hair removal. This is because the thermal relaxation time of human skin tissue is generally <10ms, while the thermal relaxation time of melanin-rich hair follicles generally ranges from 30ms to 100ms.

When laser hair removal is performed, the laser needs to pass through the human skin tissue before reaching the hair follicle. In order to prevent the skin from being scalded, the corresponding pulse width must be greater than the thermal relaxation time of the skin tissue, so that the skin has sufficient time to come. Dissipate heat to avoid heat build-up and burns. At the same time, in order to destroy the hair follicle and do not want to give it sufficient time to dissipate heat, the pulse width should be smaller than the thermal relaxation time of the hair follicle, so 10~30ms is finally defined as the optimal pulse width. In order to complete the hair removal treatment with such a narrow pulse width, the traditional 300~600W peak power laser has been unable to achieve the desired therapeutic effect. Therefore, "high peak power + narrow pulse width" has become the future development trend. At the same time, during the narrow pulse width treatment, the skin has sufficient time to dissipate heat, the energy will not accumulate excessively, and the treatment process will be more comfortable.

The laser power required by new laser hair removal equipment is usually 1200W and above. Because within this power range, no matter whether the spot output is 10*10mm or 10*20mm, within the optimal pulse width range of 10~30ms, the device can easily achieve the energy density output necessary for hair removal above 10J/cm²

For laser hair removal applications, whether enough effective energy is injected into the skin and reaches the hair follicles during the treatment process, thereby raising the temperature of the hair follicles and damaging the hair follicles, is the core. As hair removal treatments have evolved, so too has the definition of effective hair removal.

Before 2010, laser hair removal used a stamped hair removal method. The effectiveness of this treatment completely depends on the energy value of a single pulse under the premise that the area of ​​the light outlet of the handpiece is determined; the higher the energy value, the corresponding stamped area. The higher the hair follicle temperature will be raised, the better the corresponding treatment effect will be.

After 2010, under the leadership of Feidun, a leader in medical beauty equipment, the treatment method of laser hair removal has changed. In order to make the treatment process more efficient and comfortable, Fiton has innovatively introduced a sliding treatment method, and the treatment frequency is often set at 10Hz. With this sliding type of therapy, it is not enough to consider only the energy of a single pulse. In order to ensure that the area scanned by the laser is not missed, the number of pulses per unit time needs to be taken into account. The more energy injected into the skin per unit time, the more energy will reach the hair follicles, and the better the treatment effect will be.

Therefore, with the change of laser hair removal treatment methods, effective energy has become a new standard for measuring whether laser hair removal is effective, and high effective energy has also become a new industry trend.

 Effective energy = peak power × pulse width × frequency