Laser hair removal is one of the most popular medical laser applications worldwide and is projected to reach 1.35 billion dollars annually by the year 2022 according to Transparency Market Research. As this market started to explode in the early 2000s, it became popular so quickly that by 2005 Alexandrite (which was the laser of choice at the time) was the second most popular laser crystal grown worldwide, even though there were no other mainstream applications for the laser technology at the time. Over the past fifteen years diode technology especially high power diode stacks have advanced to the point where they are now far less expensive, far more efficient, and have longer lifetimes than flashlamp pumped Alexandrite and Nd:YAG lasers. This has enabled a dramatic decrease in both size and the total cost for ownership of a hair removal laser system and has impart fueled the growth projected in the current market. In this blog post, we will briefly review the basic principles of laser hair removal and why high-power diode bars have become the most popular solution. After which we will discuss some of the critical features of the diode stacks used in modern hair removal systems.
To understand how laser hair removal works first it is essential to understand the growth cycle of hair follicles. As shown in the image to the right there are three different stages in the hair growth cycle: anagen (growth), catagen (atrophy), and telogen (dormancy). Of these three stages, laser hair removal is only effective during the anagen stage of the growth due to the relatively large size of the bulb at the bottom of the follicle and the fact that overlaps with the dermal papilla. At this stage it possible for the laser light to transmit through the epidermis/dermis and be absorbed by the hair burning out and killing the dermal papilla rendering it permanently inactive. Therefore, it is critical to select a laser wavelength which is capable of simultaneously being absorbed by the melanin in the hair follicle, and transmitted through the soft tissue of the dermis. As a side note, this is also why laser hair removal must be done in three separate treatments spaced out over several weeks since at any given time your multipe hair follicles are in one of these three stages.
To understand, which type of laser is ideal for this application we must look at the absorption properties, shown in the figure to the right. From this image, we can see that in the 700 nm to 1000 nm region there is a dip in both the hemoglobin and water absorption, which nicely correlates to not only to Alexandrite but also GaAs. When laser hair removal first started, it was initially far more efficient to generate the high laser flounces needed (20 J/cm2 or greater) via Alexandrite laser technology, which can easily produce 60 J pulses at 755 nm. But these lasers are extremely inefficient often taking upwards of 2kW of power across the flashlamps, to be swung over micro- or millisecond pulse durations. Therefore, requiring high power pulse forming networks (PFNs) consisting of large inductors and mercury relays, which are not only large and costly but are also extremely noisy and off-putting to many patients. But, with the recent developments in diode laser technology companies like Jenoptik have been able to produce high efficiency and reliability 760m and 808nm diode stacks with high output powers into the kilowatt range.
Because of their compact and robust design, Jenoptik diode stacks are incredibly durable and easy to integrate, therefore, requiring minimal maintenance significantly reducing the overall cost of ownership. The compact nature of these diodes also allows for integration directly into the handpiece of the laser hair removal system, reduce the complexity, fragility, and inefficacy of fiber optic delivery systems. A perfect example of this is the series of actively cooled, vertical diode laser stacks. This unit is capable of producing an output power of up to 1.6kW and is available in either 1 or 2 stacks. This corresponds to 110J per pulse at 100ms pulse width (typical pulse width for laser hair removal are between 0.5 and 300ms), which is capable of producing a 26mm diameter spot with a fluence of 20J/cm2 in comparison to the maximum spot size of 18mm produced by most high-end Alexandrite laser systems.
Here at RPMC lasers, we are proud to offer a wide range of high-power laser diode bars and stacks from Jenoptik, which are ideal for laser hair removal as well as other asthenic/dermatological applications such as treatment of vascular lesions, wrinkles, acne, fat cells or pigments, and tattoo removal.
For detailed technical specifications on the diode lasers offered by Jenoptik click here or talk to one of our laser experts today by calling 1-636-272-7227.