The invention of the laser became one of the most important and significant achievements of the twentieth century. Currently laser technologies are used in almost all spheres of life: science, armaments, industry, etc. Lasers are also widely used in medicine, one of the areas of which is cosmetology.

A laser is a device that converts pumping energy (light, electrical, thermal, chemical, etc.) into coherent, monochromatic, polarized and narrowly directed radiation flow energy.

Laser types:

Existing types of lasers can be classified according to several criteria. First of all, by the aggregate state of the active medium.

Therefore, lasers can be divided into the following large groups:

The most common gas lasers used in cosmetology are CO2 lasers. Solid-state lasers include: ruby laser, Nd:YAG, KTP, Er: YAG and alexandrite lasers. The group of liquid lasers most often includes dye lasers. And diode lasers can only be separated by wavelengths. 

Laser types used in cosmetology:

CO₂ lasers

CO₂ lasers or carbon dioxide lasers are one of the first gas lasers invented. It was invented by Kumar Patel (Engl.: C. Kumar N. Patel) in 1964 and is still one of the most popular and powerful lasers. The wavelength is from 9.4 to 10.6 µm in the infrared range.

Carbon dioxide lasers are devices that operate on a combination of the following gases: carbon dioxide, helium, nitrogen, hydrogen and/or xenon. The specific proportions of the gases vary depending on the specific laser, wavelengths, etc. Light amplification in such lasers is achieved by transitions in CO2 carbon dioxide molecules.

Carbon dioxide lasers are divided into two types of radiation modes:

Continuous is a type of laser where the radiation is constant in time, which makes it possible to treat large areas. This laser has a disadvantage: the depth of laser penetration is unpredictable and nearby tissues can be affected.

Pulse or fractional is a type of laser where the radiation is a flash with a strictly dosed energy, which allows it not to affect nearby tissues and makes the procedure more comfortable and safe.

It is worth noting that modern carbon dioxide lasers are most often a combination of continuous and fractional lasers.

Imperfections that can be eliminated with a CO₂ laser:

-skin roughness;

-wrinkles;

-scars and scar tissue;

-dermal neoplasms;

-stretch marks;

-pigment spots.

Diode lasers

The action of diode lasers is based on the following principle: one of the components of the laser is the so-called semiconductor crystal — a wafer, with carefully polished sides and which are a p-area and an n-area with different types of conductivity. When a photon enters the plate, it begins to reflect, creating new photons. As soon as the number of photons that move perpendicular to the sides of the plate exceeds the number of photons that fly out of it, a laser beam will start generating, usually 810 nm and 940 nm in wavelength.

In medicine, this laser is usually used for laser hair removal and the treatment of varicose veins, because the laser beam heats the pigment in the epidermal cells, which leads to its destruction.

Nd: YAG lasers

Nd: A YAG laser or a solid-state neodymium laser with a wavelength of typically 1064 nm, where an yttrium-aluminium garnet (“YAG”) is used as an active medium, which is doped with neodymium ions (Nd).

The physics of the process is as follows: upon transition to an excited state during a flash of a pump lamp, the atoms of the active element begin to emit photons that are generated into the laser beam using a system of mirrors.

The laser effect is based on homogeneous photothermolysis. Thanks to an ultra-long pulse with a strong thermal component, controlled tissue burns are created.

In the area of the action of Nd: A YAG laser causes aseptic inflammation, which creates the conditions for collagen formation and elongation of its fibers, tissue revascularization occurs, and the number of new fibroblasts increases.

Nd: A YAG laser can be used for such procedures:

-depigmentation of tattoos and permanent makeup;

-removal of xanthelasmas, age spots and other pigmentation;

-removal of birthmarks (black, red, purple, brown);

-cutaneous rejuvenation.

KTP lasers

The KTP laser (potassium-titanium-phosphate laser) is based on the same principle of action as the Nd: A YAG laser, but instead of neodymium, it uses a calcium phosphate titanium crystal (KTP). Because of this key feature, the wavelength of 532 nm also changes. Due to its wavelength, the laser beam is well absorbed in haemoglobin and melanin, which makes it suitable for the removal of vascular and pigmented skin lesions.

Er: YAG laser

Erbium laser is “relative” to the KTP laser and Nd: It is a YAG laser because it works on the same principle. An yttrium-aluminium garnet is also used as an active medium, but erbium oxide is used to generate radiation.

Er: The YAG laser is designed to work with the upper part due to its short wavelength of 2.94 microns. Like a CO₂ laser, an erbium laser destroys the epidermal cell structure, which subsequently leads to regeneration.

An erbium laser is especially good for removing age-related skin changes, removing small benign lesions and age spots, as well as for removing scars and post-acne.

Ruby lasers

A ruby laser is a solid-state device where a ruby crystal acts as an active medium, presented in the form of a cylinder, the ends of which are polished. Sometimes, the ends are covered with a layer of silver or a dielectric film. By activating the xenon pulse lamp, photons start to avalanche. At the same time, the resonator, which is a system of mirrors, has feedback from the ends of the ruby rod. This is the generation of a laser beam with a wavelength of 694 nm.

The ruby laser beam has a very strong absorption in melanin and black and blue ink pigments. Therefore, this laser is suitable for tattoo removal, laser hair removal and pigment stain removal.

Alexandrite lasers

Like a ruby, an alexandrite laser consists of a system of mirrors, a light source and an active medium, but alexandrite is used instead of ruby. The principle of operation of alexandrite is similar to the principle of the ruby laser, but this laser emits a beam with a long wavelength in the range of 700-820 nm.

This wavelength allows the laser to be successfully used for vascular removal (mainly blue), laser hair removal and pigmentation removal.

PD-lasers

PD-Lasers (PDL) or, otherwise, dye lasers are liquid lasers with a wavelength of 585 to 595 nm in a yellow band of visible light.

This laser uses a liquid organic dye solution as the active medium. Usually other lasers, such as YAG lasers, are used for pumping (the process of pumping the energy of an external source into the working medium of the laser), but sometimes, though very seldom, there are lasers that use a flash lamp.

The use of this laser is effective against rosacea, wine stains, telangiectasia on the face.

Contraindications:

Like any procedure, the use of lasers has a number of contraindications. The presence of at least one of them must be reported to the cosmetologist:

-chronic renal failure.

-low blood clotting;

-cases of vitiligo in a family history;

-inflammation and skin lesions;

-hypertension;

-systemic lupus erythematosus;

-pregnancy, lactation;

-predisposition to thrombosis;

-diabetes mellitus;

-rheumatoid arthritis;

-the presence of a large number of moles;

-oncology;

-tan;

-early postoperative period;

-ischemia;

-phlebeurysm;

-the existence of mental illness.

-reception of antibiotics, hormonal drugs, sulfonamides, and other medications;

-predisposition to colloidal scarring.

These contraindications can cause a rejection to the procedure.

Articles:

1. Use of Lasers in Dermatology: Laser Hair Removal. Dr. Hanish Babu
2. Zhukov B. N., Lysov N. A., Bakutsky V. N., Anisimov V. I. Lectures on laser medicine: Textbook. – Samara: SMI, 1993. 52 p.
3. Dobro L. F., Bogatov N. M., Suprunov V. V. Lasers in medicine: Textbook — Krasnodar: Kuban State University 2011. 80 p.