Laser Focus World ~ www.optoelectronics-world.com November 1999 63

Medicalwatch  -  Kathy Klncade, Contributing Editor

Alexandrite: the unsung hero of hair removal

Despite concerns that the hair-removal market is overcrowded and the customer base nearly saturated, sales of ruby, alexandrite, Nd:YAG, and diode lasers for this application continue to rise. Laser hair removal is expected to account for 65% of the total US aesthetic-laser market this year, up from 59% ($7137 million) in 1998 and 30% in 1997, according to a report issued earlier this year by Frost & Sullivan (Mountain View, CA). That report concludes that hair removal will continue to dominate the aesthetic-laser market for the next several years, peaking at 76.5% of total revenues in 2004.

Another report released by BlueStone Capital (New York, NY) at about the same time estimates that revenues from the sale of hair-removal lasers will reach $235 million next year, up from $45 million in 1997. This is a drastic change from just three years ago, when skin-resurfacing lasers accounted for 55% of revenues and vascular- and pigmented-lesion-removal lasers accounted for 45% of the market. Hair-removal lasers first entered the market in 1997, quickly garnering nearly 30% of overall sales that year—the same year that skin-resurfacing laser sales fell to only 37% of revenues. Skin-resurfacing laser sales accounted for only l60/o of market revenues last year; by 2005, these lasers will make up only 6.3% of revenues, according to Frost & Sullivan. However, as sales of hair-removal lasers increase, the price is likely to go down; thus, overall revenues will not reflect actual market penetration.

Despite the early success of the ruby laser, the alexandrite laser currently accounts for the bulk of laser hair-removal-system sales. There are several reasons for this. The outputs from alexandrite and ruby lasers are both highly absorbed in melanin, which is critical to effective hair removal because the laser energy is attracted to and absorbed by the melanin in the hair follicles (see photo). Alexandrite has an inherent advantage over ruby, however, in that the laser output is naturally longer pulsed. And the longer the pulse, the safer and more effective laser hair removal is. Alexandrite emits typically between 710 and 810 rim and generates longer pulses (up to 250 ps per pulse) than tunable dye lasers or solid-state crystals such as ruby or Nd:YAG. In addition, alexandrite is tunable, which gives the user more flexibility in treating different hair and skin types.

Another reason for the strong sales of alexandrite hair-removal lasers over the past year is probably the attractive price point of the GentleLase, manufactured and marketed by Candela Corp. (Way-land, MA). The GentleLase currently sells for $69,000, some $30,000—$40,000 less than most other hair-removal lasers and also is designed to treat leg veins.

GentleLase was used to remove hair from a man's back (left). There is no hair regrowth after two months (right).

Candela recently enhanced its position in this market with the introduction of the GentleLase Plus, which features a larger spot size (18 mm). "The larger the spot, the more forward the penetration of light—that is, more laser light actually reaches the hair follicle," says Jeffrey Dover, MD (Harvard Medical School; Cambridge, MA). "In addition, the bigger spot gives us the ability to accelerate treatment times, which can be particularly important when treating large areas such as the back or legs."

As with most manufacturers of alexandrite lasers and systems—including Cynosure (Bedford, MA), Light Age (Somerset, NJ), and Laser Energetics (Princeton, NJ)—Candela gets its laser crystals from Litton Airtron (Charlotte, NC). Litton is the leading supplier of solid-state laser crystals in the USA.

Next generation?

The market for alexandrite lasers could get even more interesting in the near future, following Laser Energetics' acquisition of a significant portfolio of alexandrite patents and related assets from AlliedSignal Corp. (Morristown, NJ) last June. The Laser Energetics purchase, which includes 33 patents, bills of materials for more than 30 lasers and systems, laser laboratories, and hundreds of alexandrite laser rods and boules, represents $100 million in development costs by AlliedSignal over the last several years, according to Bob Baths, president and CEO of Laser Energetics.

More significant is the type of alexandrite laser developed by AlliedSignal. Because much of this development work was done under contract with the US Department of Defense and involved technology geared to mobile laser weapons, the emphasis was on creating an alexandrite laser that could operate in the most extreme conditions, including sub-zero temperatures. Thus, Allied developed an air-cooled laser that Battis believes is superior in many ways to the current generation of water-cooled alexandrite lasers. Removing the water and using passive air cooling on the outside of the pump chamber eliminates much of the reliability problems found in water-cooled lasers—including their tendency toward corrosion.

"Allied invested a lot of money to make an air-cooled laser rifle that was backpack portable and weighed 20—25 lb," Battis says. "It was compact, lightweight, and very energy efficient. The voltage-in-to-laser-energy-out ratio had to be very high and very efficient. So what we have is an air-cooled alexandrite laser with a 110-V power supply to fire a laser pulse at up to 3 J/pulse."

This could be an important advantage in the medical field, he adds. The same conductive-cooling technology, on which Laser Energetics now holds five patents, can also be applied to other solid-state lasers used in medical and industrial applications.

"Unlike the Nd:YAG laser, the alexandrite laser likes to run hot, and water cooling has a limitation there," says Jerry Cooper, chief scientist for Laser Energetics. "Once you reach the boiling point, you have problems with system integrity. So we believe air cooling is going to become the next generation in alexandrite lasers."

Not everyone in the medical-laser field agrees that air-cooled alexandrite offers significant advantages over water-cooled systems, however. One drawback is that the air-cooled design does not allow as high output powers as the water-cooled design. In addition, some vendors maintain that water corrosion is not an issue, especially for medical applications that have long used solid-state lasers.

Laser Energetics, which plans to market its alexandrite lasers only to OEMs, is currently working with several medical-device vendors to develop three specific medical applications: hair removal, tattoo removal, and dual-wavelength lithotripsy. The company is also interested in developing this technology for refractive-surgery applications and is in negotiations with several ophthalmics companies.

"Our experience in the industrial arena will benefit the medical OEMs,' and the end result will be that our lasers will have a much greater mean tine between failure," Baths says. "We have to make them more robust than what the medical community has so far seen from alexandrite."

Diodes on the horizon

It is not clear at this point which type of laser will emerge as the hair-removal laser. The general consensus is that, despite advances in ruby and diode lasers for this application, the alexandrite laser will continue to sell strongly in this market niche for at least another two to three years, as will the long-pulse ruby laser.

However, new diode and even Nd:YAG lasers continue to enter the hair-removal foray; for example, Altus Medical (Burlingame, CA), which is headed by former Coherent Medical president Kevin Connors, introduced a high-power, 1064-nm hair-removal laser at the summer meeting of the American Academy of Dermatology, and Mehl/ Biophile (Gainesville, FL), the first company with a ruby-laser device for hair removal, has returned to this market after a Chapter 11 reorganization.

There is a general trend toward more-compact and reliable systems that are less expensive and easier to use. This should translate into increased sales of hair-removal devices over the next few years; at the same time, however, lower prices and product dumping could result in reduced margins. But overall, the market for hair-removal lasers appears to be in a growth mode for at least a few more years.