• [Issue] Understanding picosecond laser I

    Interview: Dr. Hoon Hur of Choice Dermatology Clinic in Pyeong-chon


    It has been three and a half years since the picosecond laser was introduced to Korea. In that time, this innovative new laser has won over many aesthetic clinicians but at the same time, many others are still contemplating whether its benefits merit the high price. The trend favors cost-effective laser devices and potential buyers primarily consider whether the picosecond laser performs at the level that merits its cost.

    We have consulted Dr. Hoon Hur of Pyeong-chon Choice Dermatology Clinic who is one of the earliest aesthetic clinicians in Korea to add several picosecond lasers to his practice. He shared his honest opinions on this new device.


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    Picosecond Laser? Picosecond- Domain Laser!

    The more accurate name for the picosecond laser is “picosecond-domain laser.” This is because even the shortest pulse duration of the currently released picosecond lasers are not short enough to qualify as a true picosecond laser.

    Many aesthetic clinicians with a small private practice ask if they would need to purchase a picosecond laser. They are particularly curious about cost-effectiveness of this new device which costs anywhere from KRW 200- to 300 million (USD 180,000 to 270,000). I participated in the trial when the picosecond laser was first released in Korea. I purchased a few devices and have been using them for three years now. However, I think all currently available picosecond laser devices are not truly picosecond lasers, but rather sub-picosecond lasers.

    Let me explain. Irradiating laser on the skin induces the photothermal effect and photoacoustic effect. The nanosecond laser mainly induces the photothermal effect where the TRT concept (thermal relaxation time) is applied. On the other hand, the picosecond laser mainly induces photoacoustic effect where the SRT (stress relaxation time) is more relevant. In short, the picosecond laser causes photoacoustic effect, rather than photothermal effect to minimize side effects (thermal damage) by limiting the thermal energy to the target tissue.

    In a true picosecond laser, the pulse duration should be shorter than the SRT, which should be below 200ps. Looking at the specifications of currently available picosecond lasers, the pulse duration of Picoway 1064nm is 450ps, and that of 532nm is 375ps. Enlighten 1064nm is 750ps and 532nm is 2ns. Therefore, the current picosecond lasers are not in the true picosecond range.  

    For these reasons, it cannot be said that photoacoustic effect is the main action of the currently available picosecond lasers. However, it should be. In photothermal effect, photos emitted by laser destroy the target tissue by boiling, however, heat can dissipate in this process and surrounding healthy tissues can also be damaged, causing various side effects. However, in photoacoustic effect, physical force is used to destroy cells, thereby drastically lowering the risk of unwanted thermal damage.  


    -To be continued-

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