Since the invention of the wheel, women and men have contrived ways to eliminate the appearance of unwanted hair. Until the late 19th century none of the earlier methods of hair removal produced any permanent eradication of hair growth. This changed with the first method of permanent hair destruction which was called "electrolysis". It entailed a slow process involving inserting a metal wire into the hair follicle and energizing it with a small amount of DC electrical current. This process caused a chemical transformation to occur which creates sodium hydroxide within the hair's follicle causing destruction of the hair's regenerative properties through chemical decomposition of the papilla which allows blood to nourish and stimulate the matrix cells that give birth to a new hair. Permanent cessation of hair regeneration was now an achievable reality. Thus an industry was born! With the advancements in electrical engineering in the 20th century came high frequency alternating current. While still having to insert a metal wire inside the follicle, high frequency current introduced into the hair follicle destroyed hair growth by generating heat through its oscillating electron affect upon the moisture within the follicle walls. This process is called "electrical coagulation" and causes hair destruction in a split second as opposed to the old direct current electrolysis method which took up to three minutes to destroy one hair.
In the mid 1990s a new approach to permanent hair destruction was applied which revolutionized the industry, making it possible to disable thousands of hair follicles in a few minutes. This is laser hair removal. Laser is an acronym that stands for Light Amplification by Stimulated Emission of Radiation. It is the most popular permanent hair reduction method in use today. Hair elimination by laser, unlike any other permanent hair destruction method is completely noninvasive. It operates on the principals of selective photothermolysis whereby the electromagnetic energy emitted by the laser is absorbed into the target chromophore which is the hair's melanin. This process creates heat within the hair shaft that travels down to the papilla and denatures its regenerative capability.
Lasers are by far the most efficient weapon we have today in our fight against unwanted hair. However, different lasers produce electromagnetic energy {light} of different wavelengths. The wavelength emitted by the laser is indicative of its target chromophore. Therefore different wavelengths of energy will have more or less impact regarding melanin absorption whereby being more or less affective in causing reduction in hair growth. This being said, let's take a look at the lasers that are used for hair destruction and the pros and cons of their particular emitted wavelengths. The ruby laser emits light at a 694nm wavelength. It achieves the highest melanin absorption of any other laser used for hair removal. However, with this extreme absorption potential comes a high risk of hyperpigmentation and hypopigmentation on anyone other than the lightest skin tones. Also because of its shorter wavelength, maximum depth penetration is limited to about 2mm. This is often too shallow to send enough heat to disable the blood supply which promotes new hair growth especially in coarser, more developed hairs. The ruby laser was used in the mid 1990s but soon took a back seat to safer and more effective laser systems, such as are used by hair removal professionals today.
The Nd:YAG laser emits an invisible ray of light at a 1064nm wavelength. It is weaker pertaining to melanin absorption in comparison to other laser systems used for hair reduction. While it may lack in melanin absorption, which makes it the laser of choice for tanned and darker toned individuals, it has the highest depth penetration of all laser systems designed for hair destruction {almost 6mm} due to its longer emitted wavelength. This makes it possible to reach the hair producing papilla of even to deepest rooted hairs. However, because of the weaker melanin absorption capability of the Nd:YAG laser the hair will require more treatments than with other laser systems to achieve permanent elimination of hair growth; due to its lower heat producing ratio within the structure of the hair shaft. Diode lasers produce a few different wavelengths of light depending on their internal circuitry.
Regarding hair eradication we are concerned with the 800nm wavelength of visible electromagnetic energy {light} emitting diode laser. It has higher melanin absorption potential than the Nd:YAG laser. Therefore it is more likely to cause adverse skin reactions on clients with darker skin types. It can penetrate up to 4mm below the skin surface which is more than necessary to sufficiently denature even the coarsest and deepest hairs. The alexandrite laser emits a ray of visible light at a 755nm wavelength. The alexandrite is the prodigy of the old ruby laser, whereas it has excellent melanin absorption while still being safe and effective in causing permanent hair reduction even up to olive skin tones. Like the 800nm diode laser it can penetrate up to 4mm below the skin surface instilling sufficient heat to disable the regenerative properties of hair follicles on a massive scale. For client comfort, efficient permanent hair destruction, speed, and ease of use, the alexandrite laser far surpasses all other laser systems in use today. Expected results are of paramount concern to anyone contemplating laser hair removal treatment. This can be assessed through careful observation of the four intrinsic factors which determine if a client is a candidate for this procedure.
These factors are:
1. Skin tone. This determines the percentage of the laser energy that will be absorbed by the skin. Darker skin tones dictate a lessening of the laser's intensity output in order to prevent unfavorable tissue reaction. Therefore in darker skinned clients more treatments will be needed to achieve comparable results to clients of lighter skin tones.
2. Hair color. This is a relevant factor in evaluating the potential outcome of a laser hair destruction treatment. Melanin concentration within the hair shaft is indicative of the amount of heat generated and released into the germinative matrix cells and papilla, which are responsible for producing new hair growth. This is evaluated by the laser technician so that the proper energy perimeters are applied in order to achieve maximum denaturing effect within the follicle.
3. Hair density. When many hairs are treated in close proximity to each other some cumulative heat is produced which is absorbed by the surrounding tissue. This is not an adverse situation as a competent laser hair removal technician will set the laser's energy perimeters to compensate for this effect while still achieving optimum results.
4. Hair diameter. The thickness of a hair is a relevant consideration regarding its thermal relaxation time. A thicker hair will take longer to absorb sufficient heat than a thinner hair. Also a thicker hair will hold its heat for a longer time, instilling its heat into the surrounding tissue. This need not be a problem as a competent laser hair removal technician will adjust the timing and intensity levels to safely achieve optimum hair destruction.
Through an understanding of these laws of photodynamic behavior it becomes obvious that many different scenarios can exist. However, some rules of thumb do apply and from these a probable outcome can be estimated of the efficacy of the treatments. This can best be ascertained through observation by your laser hair removal technician during your initial consultation. In general a 30% elimination of hair regrowth per treatment session is an average result.
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