Classification of Lasers

1. Lasers are classified by their working medium into solid-state, gas, liquid, and semiconductor lasers.

- Solid-state lasers and gas lasers were developed early. They offer high and stable output power, are convenient to use, have high efficiency, and require few consumables.

- Liquid lasers have numerous working media and provide high output power with good optical properties. Their drawbacks include the need for frequent dye replacement, higher consumable usage, complex maintenance, and relatively lower efficiency (frequency).

- Semiconductor lasers are compact, low-cost, highly efficient, and have a long lifespan.

2. Classification by excitation method includes optically pumped lasers, electrically excited lasers, chemical lasers, and nuclear-pumped lasers.

3. Classification by operation mode includes continuous-wave (CW) lasers, single-pulse lasers, repetitive-pulse lasers, Q-switched lasers, mode-locked lasers, single-mode and frequency-stabilized lasers, and tunable lasers.

4. Classification by output wavelength range includes far-infrared lasers, mid-infrared lasers, near-infrared lasers, visible lasers, near-ultraviolet lasers, vacuum ultraviolet lasers, and X-ray lasers.

Lasers and their applications related to plastic and aesthetic surgery：

Non-Surgical Aesthetic Lasers

Various lasers are suitable for non-surgical, non-invasive cosmetic procedures, including continuous-wave Nd: YAG, Q-switched Nd: YAG, frequency-doubled Nd: YAG, KTP, argon ion lasers, flashlamp-pumped dye lasers, alexandrite lasers, and ruby lasers.

These lasers can be used to treat skin conditions such as vascular and pigmented lesions, tattoos, acne, early scars, and warts. 

Vascular lesions can be treated with KTP, argon ion, copper vapor, and flashlamp-pumped dye lasers.

Each laser type has its own advantages. Nd: YAG lasers have deep penetration capabilities and have been used successfully to treat deep hemangiomas.

Pigmented skin lesions can be treated with Q-switched Nd:YAG, alexandrite, ruby, or KTP lasers, with the wavelength selected based on the specific condition.

Nd: YAG is suitable for black, blue, and gray-brown tattoos; ruby lasers are suitable for green and blue-violet tattoos; while alexandrite lasers are suitable for black, green, and blue tattoos.

Frequency-doubled Nd: YAG lasers are suitable for red and orange tattoos.

1. Intense Pulsed Light (IPL)

IPL, OPT, AOPT, DPL, BBL, APL, etc.

IPL aesthetic systems utilize patented intense pulsed light technology, with an output spectrum ranging from 500 to 1200 nm. The energy density is typically 20–48 J/cm², the pulse width is mostly 2–7 ms, and the spot size is usually 8 mm × 34 mm. They can safely and non-invasively remove various facial pigmented and vascular spots while stimulating collagen production to restore skin elasticity.

2. Combination of Laser and High-Frequency Electromagnetic Waves

This approach combines the advantages of light energy and high-frequency electromagnetic waves. It leverages the difference in impedance between target tissues and normal skin caused by the skin's selective absorption of light energy. By enhancing the target tissue's absorption of high-frequency electromagnetic waves at lower light energy intensities, it significantly reduces potential adverse reactions and discomfort caused by the thermal effects of the light energy process.

3. Excimer Laser Technology

308nm is the optimal wavelength for UV light treatment of vitiligo and psoriasis. Excimer lasers can induce T-cell apoptosis and promote pigment synthesis. With a pulse width of 30 ns, a single pulse energy density of 2–3 mJ/cm², and a local irradiation dose of 25–2100 mJ/cm², excimer laser treatment is superior to traditional UVA and UVB therapies for treating vitiligo.

The scope of treatment for laser cosmetic therapy

Pigmented Skin Disorders:

Nevus of Ota, café-au-lait spots, coffee-colored patches, age spots, Becker's nevus, melasma, freckles, vitiligo

Exogenous Pigmented Skin Lesions:

Explosive tattoos, traumatic tattoos, cosmetic tattoos, poor eyeliner tattoos, poor eyebrow tattoos, poor lip tattoos

Vascular Skin Disorders:

Port-wine stains, hemangiomas, vascular nevi, telangiectasias, angiokeratomas, angioma serpiginosum, etc., hypertrichosis

Benign Skin Growths:

Skin tags, calluses, corns

Disorders of Skin Appendages:

Axillary osmidrosis, porokeratosis, keratosis pilaris, syringoma, seborrheic keratosis, rosacea, sebaceous adenoma 

Metabolic Skin Disorders:

Xanthelasma, melasma, amyloidosis, psoriasis

Skin Aging:

Photoaging, skin laxity, wrinkles

Poor Skin Healing

Microbially Invasive Skin Disorders:

Flat warts, common warts, condylomata, papillomas, plantar warts