Comparison of Alexandrite and Diode Lasers for Hair Removal in Dark and Medium Skin: Which is Better?

 Given the potential use of lasers in various medical applications, including laser hair removal (LHR) and orthopedic treatments, the mechanism of laser-tissue interaction has been widely studied. LHR is currently the most commonly requested cosmetic procedure in the world, particularly for female clients. Thirty years ago, the ability of lasers to damage hair follicles was noted 1 . Physicians involved in simulation investigations need to assure that the fluence rates of the alexandrite and diode lasers for hair removal in deep parts of the skin have an effect on situations leading to skin darkening. Managing human skin in a cosmetic center for investigational purposes on the laser fluence rate is difficult, so different types of phantoms are used to simulate the properties of tissue. Skin-simulating phantoms have been developed to analyze bio-optical instrumentation and techniques for several purposes. Data reported in previous papers 2-4 indicated that the computer model can be used to accurately calculate the light fluence rate even at the deepest parts of the skin layer. Kareten reported that the epidermal contents affect the fluence rate entering the skin depth 3 .

Various simulations and modalities of light-based technology are currently used in the field of laser skin interaction. These simulations include MCL5, Monte Carlo, and Advanced Systems Analysis Program (ASAP®) software.


LHR system is the most effective for people who have light skin and dark hair. A recent study reported that both the skin color and hair color influence the success of LHR 5,6 . As of this writing, few studies have evaluated patient satisfaction and complications after LHR among people of color 7-11 . The penetration of laser beam through human skin for hair removal is extremely dependent on the optical properties of skin 12 . The absorption coefficient of the epidermis varies with the volume fraction of melanosomes and amount of eumelanin concentration in the epidermis 3 . The absorption and scattering of the light in the skin layers determine the fluence rate of the light reaching the intended treatment site. To effectively destroy the target, losses caused by reflection, scattering and absorption must be considered 4 . However, the idea of laser fluence rate for hair removal, including the appropriate approaches for dark skin types and laser sources, has not yet been optimized with the simulation method.

Different types of lasers mainly vary in terms of wavelength 13 ; different laser wavelengths target different skin issues. Therefore, various lasers are needed to treat a variety of skin concerns 5,14,15 . An investigation of different laser wavelengths for hair removal should be conducted to address all the problems that these procedures may have. An explanation of the differences between these different laser types may be very lengthy, technical, and rather confusing, so we focused on the diode and alexandrite lasers as optimal options for LHR of candidates with dark skin types. The fluence rates of the alexandrite and diode lasers in dark skin were compared using computational simulated skin from the Realistic Skin Model (RSM) part of the ASAP® software from Breault Research.


 In this study, the alexandrite laser (755 nm) and diode laser (810 nm) beam–skin tissue interactions were simulated. The simulation results for both lasers differed. The transmission ratio of the diode laser to the dark skin dermis was approximately 4% more than that of the alexandrite laser for the same skin type. For the diode laser at skin depth z = 0.67 mm, the average transmission ratios of both samples were 36% and 27.5%, but those for the alexandrite laser at the same skin depth were 32% and 25%.
سیستم لیزر Nd-YAG با طول موج 1064 نانومتر.
IPL چیست؟
آی پی ال intense pulse light یعنی سیستم های نور شدید پالسی. در اصل لیزر نیست بلکه فلش لامپهای زنون هستند که نور چند طول موجی و non coherent ایجاد می کنند که قادر است اثرات گوناگون بر روی ساختارهای مختلف پوست داشته باشد و می توان با گزینش فیلترهای مناسب اثر دلخواه برای اهداف مشخص را بدست آورد. دستگاه  IPLروش محبوبی جهت برداشتن موهای زائد و جوان سازی پوست و روشن نمودن لکهای صورت وهم چنین آثار سطحی جوش های صورت (آکنه ) می باشد. دستگاه IPL لیزر نیست اما کارایی و عملکرد مشابه دارد. ارزانتر است.
سیستم نوری IPL نیز با روش کار کردی مشابه لیزر ها در درمان موهای زائد به کار می رود. انواع جدید IPL همان E-LIGHT است که علاوه بر نور از رادیوفرکانس نیز به طور همزمان استفاده می کند و به همین دلیل روی موهای کم رنگ (طلایی ، سفید) اثر بهتری دارد. با توجه به پهن باند بودن طیف خروجی از این وسیله، اشعه آن شامل تعداد زیادی طول موج به اضافه طول موج های یاد شده می باشد. در نتیجه این فناوری برای تایپ پوست های 4، 5 و 6 دردناک خواهد بود و توصیه نمی شود.