(a) Coagulation and charring treatment 1. CO2 laser: CO2 laser is a far-infrared laser output through the light-guiding fiber arm or fiber. Wavelength of 10600nm, its main biological effect is strong, cutting, can coagulate and vaporize tissues. The ability to cut and vaporize tissue is superior to Er:YAG and Nd:YAG lasers. Since the CO2 laser can be completely absorbed by the water in the tissue, the damage to the deep and surrounding tissues is relatively light. 2, indications: skin exophytic viral diseases such as common warts, flat warts, condyloma acuminata. Benign skin tumors such as sweat duct tumor, strawberry hemangioma, angiokeratoma, angiosarcoma, dermatoglyph, squamous cell carcinoma, basal cell carcinoma and many kinds of spots and moles such as pigmented nevus, sebaceous warty nevus, freckles, seborrheic keratosis (age spots) and superficial scars on the face, sebaceous cysts, pierced ear holes, etc. 3. Treatment method: superficial and small damages can be treated without anesthesia, such as freckles, which can be treated directly with CO2 laser coagulation and charring; those with larger damages and deeper parts need to be treated with local infiltration anesthesia. The laser output power is adjusted to 1-30W according to the skin lesion, and the focused beam is aimed at the skin lesion for coagulation, charring or cutting. The charred material is swabbed out layer by layer with a sterile wet cotton fiber until the lesion disappears. To treat sebaceous cysts, pinch the skin on both sides of the cyst with hands and punch holes with CO2 laser beam aimed at the bulge until the sebum-like powdery material inside the cyst overflows, with appropriate pressure around the hole to empty the internal material, then peel off the whole cyst wall completely with mosquito-type vascular forceps, and finally close the holes with CO2 laser. If the clamped cyst wall is not clean, the CO2 laser is used to aim at the residual wall and vaporize it directly to destroy it completely. The wound after laser treatment on the face should be treated as flat as possible. After surgery, apply antibiotic ointment and expose the trauma, and keep the treatment area dry for three days. 4. Coagulation and charring treatment of infant hemangioma: Infant hemangioma is essentially a benign tumor formed by abnormal proliferation of endothelial cells and capillaries. According to the different levels of distribution of new blood vessels in the skin, those located on the surface of the body are called strawberry hemangioma and those located under the skin are called cavernous hemangioma. According to the latest classification of vascular diseases, it is now called benign venous malformation, and the presence of both in the same place is called mixed hemangioma. Since strawberry blood vessels are located on the surface of the body, most of them can be cured after one treatment by using CO2 laser direct carbonization or Nd:YAG laser coagulation treatment, and larger ones can be treated in several sessions. Spongiform hemangioma and mixed hemangioma are treated with Nd:YAG direct coagulation or insertion, which can often achieve ideal results after 1-3 treatments. (ii) Selective photothermal therapy is the best means of treating various skin pigmented damages by laser through the special absorption of laser, which causes limited tissue damage in the target tissue, called “selective photothermal action”, using simple, selectively absorbed pulsed laser to destroy a large number of structures containing pigments. depends on the wavelength of the laser and the time of the thermochromic valve for a given target. By using selective wavelengths, including appropriate pulse widths, damage can be effectively controlled within the range of tissues treated, and treatment targets on the skin such as endogenous pigments (hemoglobin, melanin) can be eliminated without damaging nearby collagen, thus reducing the possibility of posterior scarring. If the chromophore is irradiated for longer than the thermochromic valve time, or if the wavelength chosen is inappropriate, the heat energy will spread to nearby normal tissues, resulting in scarring or hyperpigmentation. The commonly used lasers are Q-switched ruby at 694nm, Q-switched emerald at 755nm, Q-switched Nd:YAG at 1064nm, multiplied Nd:YAG at 532nm, Q-switched frequency doubled Nd:YAG wavelength 532nm and dye laser wavelengths 585nm, 595nm, etc. As melanin fully absorbs the milli-microscopic pulse width and instantaneous high energy provided by the Q-switched laser, rapid thermal expansion and shattering of pigment particles occurs with minimal damage to the surrounding normal skin tissue. The resulting inky pigment particle fragments are subsequently eliminated through phagocytosis of macrophages, transport of lymphatic vessels and expulsion via epidermis, etc., thus achieving good treatment results. 1. Nevus of Ota is caused by the increase of benign dendritic ink pigment cells in the papillary and upper dermis, mostly distributed in the area innervated by the first and second branches of the trigeminal nerve. Microscopically, dendritic or spindle-shaped melanocytes are scattered in the dermal reticular layer. In some cases, the lesions appear in the first few months of life, while in others they appear in adolescence, and some melanocytes are also found in the conjunctiva, cornea and retina. The incidence in China is about 0.3%. The treatment of nevus of Ota with Q-switched laser can achieve ideal results, and it usually takes 3-7 treatments to completely fade away without recurrence. The treatment interval is about 6 weeks. The interval can be extended appropriately for later treatments in order to distinguish whether it is pigment cell residue or pigmentation, and the latter does not need to be treated again to reduce unnecessary treatment and alleviate the patient’s pain. External skin surface anesthetic or nerve block plus local infiltration anesthesia can be applied before each treatment, and children need to be treated under intravenous anesthesia. The wavelength size is not related to the degree of darkening reaction during treatment, but the threshold size and the depth of penetration into the skin will affect the degree of darkening. The shorter the wavelength the less density needed to destroy skin pigment cells, the longer the wavelength the deeper the penetration, and the number of treatments is most closely related to the characteristics of the lesion. From the visual observation of melanin particles in melanocytes and the pattern of melanocyte microscopic distribution, the cells tend to appear dark brown or brown when they are distributed in the superficial dermis and blue or gray-black when they are distributed in the deep dermis, and the shade of the same color is related to the distribution density of melanocytes. This rule is very useful in judging the prognosis and determining the number of treatments before treatment. These melanocytes only increase in number, and each treatment has a “cumulative” result, so the treatment effect is reliable. Because the melanocytes in nevus of Ota have a deeper distribution, after the first treatment, there is a darkening phenomenon in the treated area, which is suggested by electron microscopy that the melanin particles in the melanocytes are not phagocytosed by macrophages and are dispersed from inside to outside. As the number of treatments increases, the pigment gradually fades. It is generally believed that Q-switched Nd:YAG 1064nm laser has the greatest penetrating power and is the most ideal wavelength for the treatment of nevus of Ota, and the number of treatments can be reduced by using high energy density laser treatment. Recently, Q-switched emerald 755nm laser has received attention in the treatment of nevus of Ota. The advantage is that its skin penetration depth is deep, and the skin’s own melanin absorbs little of it, which can selectively destroy pigment particles without damaging adjacent skin tissues. It is especially effective in treating blue and dark blue nevus of Ota; it is more effective in treating children’s nevus of Ota. No bleeding after treatment, healing fast, pigmentation is less for its characteristics. 2, tattoo The key factors affecting the removal of tattoos in addition to the type of laser, including the type of tattoo (trauma, non-professional, professional carving), size, location and tattoo time. Traumatic tattoos are easier to remove than retouching tattoos. Amateur tattoos are easier to remove than professional tattoos. Domestic tattoos from the 1990s are easier to remove than tattoos from more recent years. It may be that the type and amount of ink contained in the tattoo is different; later tattoos contain a lot of organic metal colors: such as iron ions or iron oxide, while earlier ones had only a smaller amount of carbon ink. Tattoos that have been around for a long time are easier to remove than those that are more recent. This is because the body can diffuse the ink as time passes. The greater the extent of the tattoo, the longer it will take to remove it. Q-switch Nd:YAG1046nm for washing blue ink color, ink color and gray ink color tattoo and eyeliner is best. Energy density is generally selected 2-3J/cm2, 1-2 times will be able to completely cure, the operation of attention to no bleeding is preferred. Q-switched emerald 755nm and multiplier Nd:YAG532nm laser used together can treat green, black, blue and red tattoo pigment, and can successfully remove most professional and retouch tattoo pigments. Red tattoos with a wavelength of 585nm flash lamp pumped pulsed dye laser machine to treat better results. 3, coffee milk spot single coffee milk spot for benign lesions, visible in 5-10% of adults, dark light brown lesions can occur in any part of the body, lesion size 0.5-1.5CM. very small cases of larger lesion area, the lesion can be accompanied by neurofibromas and other neuroectodermal syndrome patients. Histopathological examination showed that the number of melanocytes in the epithelium was not altered, but the amount of melanin was increased in all cases. Since the melanocytes of milk coffee spot are distributed in the epidermis, the melanocytes of the epidermis can be destroyed by using shorter wavelength and smaller energy density, Q-switched laser treatment and photon therapy are better choices. 4. Selective hair removal The more mature hair removal technology has been formed in recent years. Laser hair removal is the use of hair follicles, hair bulbs and other hair structures in the melanin particles can be destroyed by the selective photothermal absorption of laser energy, so as to achieve the purpose of hair removal. Photon hair removal is also an important technology that has emerged in recent years. Its true mechanism is not yet fully understood. It is generally believed that photons are capable of destroying the isthmus and upper hair shaft, thus causing a halt to a long hair growth cycle and allowing successful hair removal. The commonly used laser and photon hair removal are both based on the principle of selective photothermal action and have been shown to be clinically effective in white people. However, in colored people, because their skin is relatively rich in melanocytes, it is easy to affect the metabolism of melanocytes, so people also designed the photon system with corresponding laser pulse width and appropriate wavelength combination and energy combination according to the difference in volume of hair follicles and skin melanocytes as well as the difference in thermodynamic parameters, so that the destruction of hair roots is realized with higher selection, no effect on skin texture and increased treatment safety. In addition to the long-term effect of the treatment itself needs further observation, because the growth of hair is generally divided into active and resting phases, the ratio of active and resting phases varies for each part, and the resting time varies for each part, the effect of hair removal also varies, understanding the ratio of active and resting phases and the resting time for each part has a guiding meaning for hair removal, and at the same time the ratio of active and resting phases and the resting The ratio of active and resting phases and the resting time of each area also indicate that repeated treatments are needed to achieve the purpose of lasting hair removal. The proportion of hair in common hair removal sites: site Active phase proportion Resting phase proportion Resting time Upper lip 65% 35% 6 weeks Axillary 30% 70% 12 weeks Lower limbs 20% 80% 24 weeks Beard 70% 30% 10 weeks Bikini body hair 30% 70% 12 weeks 5, Vivid nevus Although the history of research into the treatment of vivid nevus with laser technology dates back to 1963, the most appropriate laser parameters have not actually been established. laser parameters have not been established. The ideal laser treatment should be: when the hemoglobin in the lesion absorbs the laser energy, the resulting thermal effect causes the blood vessels to contract and photocoagulate, so that the hypoxic lesion will gradually fade and the erythema will disappear, thus achieving the treatment goal. According to the current research, the most suitable wavelength should be satisfied. According to the highest absorption peak of hemoglobin, the most suitable laser wavelength is 577nm, when the treatment laser produces the least damage to the epidermal pigment cells and at the same time can produce destructive effect on the deepest part of the lesioned blood vessels. Since pigment cells have a weaker absorption of longer wavelengths, wavelengths from 577-590nm are theoretically desirable. The duration of light exposure should be so long as to allow heat conduction from the heated red blood cells to the outer layer of the vessel wall. One unexplained problem at this point is the light absorption coefficient of the capillary wall itself and the amount of temperature increase in the vessel wall due to direct laser absorption by the vessel. In addition, from the clinical point of view, the pulse width of laser irradiation should not be too short, otherwise it will produce a bursting effect and cause the rupture of blood vessels, thus not effectively closing the vessels and the phenomenon of purpura, while the pulse width of laser should be optimal at 1-10 milliseconds. If the pulse width is too large then it causes thermal damage to the surrounding tissue. Frequency doubling Nd:YAG532nm is another choice for laser selective photothermal treatment of bright red nevus, its principle is that hemoglobin at 532nm, there is a larger absorption rate of reduced hemoglobin, providing a larger energy density, the ideal pulse width is between 1-40 milliseconds, and the phenomenon of “purpura” does not appear immediately after treatment. “purpura” phenomenon immediately after treatment is its advantage. Current treatment results have a cure rate of about 30% with a high cure rate for light, small areas of erythema. Since the FDA approved the clinical application of dye lasers in 1985, the pulsed dye laser with an output wavelength of 585 nm and pulse widths of 0.5,2,20,40 ms has been increasingly used as a representative of laser photothermal action treatment for superficial vascular diseases, because its wavelength is close to the absorption of hemoglobin at 577 nm, and the energy released by the pulse width it provides is sufficient to cause Because its wavelength is close to the absorption of hemoglobin at 577 nm, the energy released by its pulse width is sufficient to cause coagulation in the target blood vessels and shorter than the thermal relaxation threshold time, the laser of pulsed dye is still one of the more effective means of treating the erythema. Its safety and effectiveness have been recognized worldwide. Current research has found that photon can treat patients with certain purple nevus and hypertrophic nevus, in addition to those who have poor results with laser treatment. Photodynamic treatment Photodynamic treatment for nevus erythematosus has been widely used. Its mechanism: the photodynamic action of photodynamic method on the endothelial cells of microvascular network leads to necrosis of endothelial cells and destruction of vascular wall; the bright red nevus is caused by the capillary tube network aberration in the papillary layer of dermis, and the lesion site will be superficial, which is suitable for photodynamic treatment; after intravenous administration of photosensitizer, the absorption of photosensitizer by vascular endothelial cells is faster than that of epidermal tissue, and the content of photosensitizer in vascular endothelial cells is much higher than that of epidermal tissue. When laser irradiation with appropriate wavelength and energy is given, the vascular network at the lesion site is selectively destroyed, but the normal skin overlying it is not damaged because the photosensitizer content is very small. Large and thick lesions often require fractionated or repeated treatments. The use of excessive doses of light may cause dystrophic damage to the epidermal tissue or photosensitive damage to the skin due to the long treatment time, so great care must be taken during treatment and short-term postoperative light avoidance is required. (iii) Laser cosmetic surgery laser surgery can simultaneously cut and coagulate, reduce intraoperative bleeding, increase visibility of the operative field, ensure better surgical excision accuracy and integrity, and avoid accidental nerve damage. The purpose of using lasers is to reduce post-operative bruising, swelling and pain, thereby shortening the healing time of the wound and resulting in a significant improvement in the outcome of facial cosmetic surgery. In facial wrinkle removal surgery, a laser with high energy pulses and a flexible fiberoptic endoscope can perform fine cutting of tissues, while good thermal coagulation provides effective hemostasis and produces only minimal crusting. The wavelength characteristics of the CO2 laser are well suited for rapid crust cutting, and the advantages of the flexible fiberoptic system are that the facial muscles can be cut and separated under direct endoscopic vision during wrinkle reduction surgery. The surgical peeling process will greatly reduce the unnecessary damage to blood vessels, nerves and unrelated tissues, and stop bleeding more thoroughly. Currently, common laser cosmetic surgery procedures include brow lift, upper faceplasty, lower faceplasty (including transconjunctival lower faceplasty), facial lift and wrinkle removal, and laser hair transplantation. (iv) Laser skin resurfacing is defined as the re-smoothing of the skin. Compared to abrasion or chemical ablation, laser skin resurfacing offers significant advantages in terms of depth of treatment, hemostasis of the treated wound and outcome when treating skin defects of different sizes and shapes. The final result of skin resurfacing depends on two main processes: tissue ablation and reconstruction of residual collagen. Tissue ablation is based on the principle of selective photothermolysis, in which case we want to understand the cause of dermal destruction, and to achieve this, three elements must be met: (1) Sufficient energy must be transmitted to achieve vaporization of the dermis, while lower energies only coagulate the collagen. （The CO2 laser can be absorbed by skin tissue with a water content of more than 60.9%. (3) The energy to the target skin must be able to spread rapidly to ensure minimal thermal damage from laser radiation and the thermal relaxation threshold time of the target tissue. Laser technology has also evolved from continuous wave to ultra-pulsed, ultra-short pulse and scanning delivery systems. The application of the CO2 laser has replaced chemical ablation and dermabrasion for skin resurfacing, resulting in improvements in facial wrinkles, solar aging and acne scarring, as well as superficial scarring from trauma. Because this new high-energy pulsed laser can be operated precisely and with minimal thermal damage, and has fewer postoperative complications such as scarring and hyperpigmentation than other laser techniques, it can also be used to treat other difficult to treat skin lesions with a high cosmetic impact, such as skin wrinkles around the mouth and eyes. During laser resurfacing, some photodamaging lesions are physically removed from the epidermis and various thicknesses of the dermis, while a significant contraction of the skin tissue occurs during the grinding process. This shrinkage will persist during the healing process. Therefore, the postoperative treatment of laser resurfacing is very important. If the postoperative treatment is improper or untimely, more obvious pigmentation will occur, but most of the pigmentation will subside between 3 and 6 months after proper treatment and care, and it is customary to use biosynthetic semi-permeable dressings or routine topical antibiotic creams for postoperative wound treatment. It is worth mentioning that any laser skin resurfacing, including the photorejuvenation mentioned later, should be avoided or shaded by sunlight, which increases the number of melanocytes and the amount of pigment in each cell, and also increases the conversion of melanocytes to keratinocytes. The production of melanin is dependent on the spectral band of ultraviolet light. During the erythematous phase after skin debridement, the UV-A band increases melanogenesis more strongly than the UV-B band. Sun exposure increases hyperpigmentation, which affects the results of peels. The use of effective sunscreen shades (SPF > 30) and an understanding of the basics of peak sun hours are basic principles of all peels. (v) Role of Botox in peels Botox injections and laser resurfacing (including photorejuvenation) eliminate wrinkles in different ways. Botox blocks the release of acetylcholine from the neuromuscular junction of cholinergic innervated muscles, thus causing reversible paralysis of the affected transverse muscle. Histologically, muscle atrophy occurs within two weeks after Botox injection as some muscle fibers are more atrophied than others. This atrophy stabilizes after 4 weeks, and muscle atrophy occurs as the entire muscle fibers are more atrophied. This atrophy stabilizes after 4 weeks, and cholinesterase activity can appear throughout the muscle fiber membrane, and these enzymes return to their original muscle junction sites after 4-5 months. Botulinum toxin acts on cholinergic motor nerve terminals to somehow antagonize the action of calcium ions and interfere with the release of acetylcholine from motor nerve terminals, so that the muscle fibers cannot contract, thus muscle tone is reduced and muscle spasm is relieved, but this muscle relaxation is of limited duration and can be maintained for 3-6 months. Botox removes the innervation of the facial muscles that cause wrinkles, while the high energy laser vaporizes the photochemically aged epidermis and dermis, causing the formation of new epithelial skin protoproteins and elastin. Muscle loss occurs 24-72 hours after Botox injection and its effects last 3-6 months, while the optimal recovery process after laser resurfacing takes 3-6 months. Both methods treat static and dynamic wrinkles, but each has its own focus. Botox works mainly on the facial muscles, so it is used to treat dynamic wrinkles; high-energy laser works mainly to change the skin structure, so it is used to treat static wrinkles. Since the combined effect of the two may be greater than the effect of one method alone, most wrinkles actually have both static and dynamic factors in their formation. It is now believed that the combination of Botulinum toxin injections and laser resurfacing can result in a less wrinkled form of newly synthesized collagen after laser treatment with inactivity of the muscles beneath it. Such a combination treatment produces better near and long-term results for wrinkles in areas such as the eye area. Botulinum toxin therapy is extremely safe, with an estimated semi-lethal dose of 40 units per kilogram of body weight or 2,500-3,000 units for 70 kg of body weight. Our use for cosmetic purposes is generally below 50 units, which is considerably lower than the average level. Contraindications to botulinum toxin injections are women during pregnancy and lactation; severe myasthenia gravis; allergy to raw ingredients such as botulinum toxin, human albumin or gelatin; and those with too high expectations and psychoneurological instability. The reason why botulinum toxin cosmetic wrinkle removal cannot be done once and for all is mainly due to the mechanism of action of botulinum toxin and the changes in ultrastructure after injection. Tests have shown that the leg muscles of mice injected with botulinum toxin showed atrophy of the muscle fibers and germination of the nerve fibers in a complex branching arrangement; the muscle atrophy lasted 6 weeks or longer and then thickened within a few weeks. The amount of motor nerve sprouting can be determined by measuring acetylcholine receptors with I125-labeled chrysotoxin. This type A botulinum toxin denervation effect is temporary, typically lasting 3 months, and essentially coincides with the duration of clinical efficacy. Histological studies have shown that botulinum toxin induces reversible denervation atrophy and allows the formation of new nerve associations, i.e., new motor endplates, by independent germination from unmyelinated terminal axons immediately approaching the endplates and maintaining the original properties of innervated muscles. The above histological changes indicate that after a period of Botox injection, the original symptoms recur or reappear due to the formation of new neurosynaptic sprouts and the reestablishment of neuromuscular conduction. This is the reason why Botox cannot be used once and for all after treatment and wrinkle removal. (vi) The role of non-tissue excisional low-energy lasers in skin aging Skin aging can be divided into two categories: endogenous aging and exogenous aging. Endogenous aging refers to the changes that occur simply with ageing. This change in the skin is relatively mild and is mainly characterized by mild thinning of the epithelium, loss of elasticity and loss of certain substances. Exogenous aging mainly refers to photochemical aging, which is the result of long-term effects of photochemical damage on the skin. Photochemical aging is manifested by wrinkles, capillary dilation, pigmented spots, and seborrheic keratosis. Non-excisional, low-energy lasers can improve wound healing or rejuvenate aging or photochemically damaged skin by inducing changes in dermal composition and structure without damage. He-Ne lasers are representative of these lasers. The low-energy light produced by these lasers has the ability to induce fibroblasts to join with substrates, increase collagen synthesis, and cause fibroblasts to proliferate. It also has the ability to promote vascular regeneration due to the promotion of cellular metabolism and blood circulation, and this vascular regeneration may be partly responsible for the improvement of age-related or photodamaged skin after laser treatment . As a result, the skin becomes smooth and tender, deeper wrinkles become lighter, and lighter ones become flatter. The helium-neon laser wrinkle removal method is simple and painless, and its method is as follows: the first choice is to use electronic instruments to detect the potential difference between the subcutaneous nerve endings – that is, the lost energy – and then the wrinkle remover will determine the nerve endings around each wrinkle, and then the laser will irradiate the wrinkle furrow several times to produce fibrosis and refill this to achieve the effect of removing wrinkles. Newly reported in the United States in the use of a few thousand light-emitting diodes composed of low light beauty instrument for facial rejuvenation irradiation. (vii) Photon therapy The first commercially available photon therapy device was introduced in 1994, and in recent years, a series of new products have emerged and the application of photon therapy has become increasingly widespread. 1. Biological effects The light source of the intense pulsed light system is a xenon lamp that emits a broad spectrum (515-1200 mm) of mixed light. The therapeutic mechanism of intense pulsed light is to use the selective photothermal effect of this light. Due to the different absorption rates of various wavelengths of light by different target tissues, photon absorption is related to the tissue characteristics and the relevant parameters of the light wave, the corresponding wavelengths of light can be used to act on the tissue, causing the temperature of the tissue to rise above 80 degrees, thus eliminating the diseased tissue. The greater the absorption coefficient of skin to light, the deeper the light transmission depth, the greater the local damage The shallower the light transmission depth, the greater the local damage. The choice of wavelength takes into account the light penetration ability in addition to the peak absorption of the tissue. In the visible range, the penetrating ability of light increases with wavelength. By using different wavelengths of light sheets (515-755nm), (535-950nm), (640-1200nm), different wavelengths of light can be selected to treat different depths and different diseases (blood vessels of different depths and thicknesses, hair follicles, pigmented lesions, etc.). Likewise, the appropriate wavelength can be selected according to the patient’s human skin type. The absorption of photons is related to the depth of transmission and tissue color. The more pigment absorption, the more wavelength increase reflection decrease, the deeper the transmission depth, the lower the surface absorption. Because longer wavelength filters filter out light to reduce light absorption by melanin, people with darker skin tones should choose longer wavelengths to reduce light absorption by the epidermis, thus preventing severe erythema, blistering and crusting on patients with darker skin. The pulse width of the intense light can be set between 0.5 and 88.5 milliseconds. The energy of the light is independent of the depth of light transmission, but affects the distribution of the energy; the more the energy is focused within the tissue, the greater the damage. Pulse width is the time that the pulse acts on the tissue, a certain energy with a fixed pulse width, acting on the tissue, if the energy remains the same and the pulse width becomes smaller, the degree of damage to the tissue is increased; conversely, the energy remains the same and the pulse width increases, the lighter the damage to the tissue. In order to avoid damage to the surrounding tissue, the pulse width should be shorter than the heat dissipation time of the target tissue. There are single-pulse intense light systems and intense light systems that combine single-pulse light into multiple pulses. The delay interval between multiple pulses can be set between 1 and 300 ms. In photon therapy for skin pigmentation, vascular lesions and hair removal, the pulse delay gives a cooling time to epidermal cells and small blood vessels to prevent damage to them during the treatment, thus achieving a selective photothermal treatment effect. Different models have different pulse peak power range, energy density and light spot area. 2. Treatment items (1) Simple vasodilatation of the nose and cheek vasodilatation causes serious aesthetic problems for many patients. (2) Non-invasive facial rejuvenation treatment photon whose treatment mechanism is selective thermal action causes dermal collagen denaturation, which further causes collagen reaction synthesis, and has better effect on skin wrinkles, poor skin texture, enlarged pores, laxity, skin pigmentation lesions, oily skin, etc., with less side effects and short treatment process without damaging the epidermis, and plays a role in skin rejuvenation. High-energy pulsed photon therapy is an effective and non-invasive treatment in addition to laser treatment and other conventional treatments. The absence of post-treatment hyperpigmentation is its advantage, especially for Asian skin. It also has a wide range of uses in the field of aesthetic medicine and can earn high patient satisfaction because it is very effective and has few side effects.