Picosecond vs Nanosecond Laser Tattoo Removal: which is better?

I recently read an excellent article entitled “Effects of picosecond laser on the multi-colored tattoo removal using Hartley guinea pig: A preliminary study” by some researchers in South Korea.

You can obtain a copy here.

In it, they compare the use of two picosecond lasers and a nanosecond Nd:YAG laser. In all, they use three wavelengths – 532, 755 and 1064 nm, with a range of spot diameters and fluences (see table 1).

They tattooed some guinea pigs and then treated them only once with these lasers, and compared the results.

Table 1: The laser parameters used in this study

They show a series of photos of various coloured inks before and after treatment. They then calculated a percentage loss in ink after a three week period and present them in a table.

I have taken this data and drawn up another table showing the order of effectiveness of each wavelength/pulsewidth combination on the coloured inks – see table 2:

Table 2: Order of effectiveness of lasers on coloured inks

I have colour-coded the results to make them easier to interpret.

Clearly, for all colours, the picosecond lasers work more efficiently than their nanosecond counterparts (top row). However, interestingly, the 532 nanosecond output appears to be very useful in treating red, orange, yellow, green and blue inks (row 2) – although, not so good at black!

The picosecond lasers then come in strongly in row 3 for all colours.

But, perhaps most interesting, is that the alexandrite laser (755 nm) appears to be poor for all colours, except green and blue, when compared with the other systems (including the nanosecond laser).

Conclusion

These are very interesting results. I think they show that picosecond lasers are ‘generally’ better at inducing ink removal than nanosecond lasers. But, the 532 nanosecond output appears to do very well for most colours – except black!

I have two comments on this study:

  1. The range of fluences is quite large, from 0.8 to 3.4 J/cm^2. It would have been better if they had used the same fluence across the study;
  2. I think they should have left a longer period following the treatment. Anecdotal evidence indicates that there is more clearance around six to eight weeks post-treatment.

My thoughts…

Given the extortionate cost of picosecond lasers, the above study might suggest that a good, reliable nanosecond laser might be ‘nearly as good’ as a very expensive picosecond laser…

What do you think?

Ciao,

Mike.

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8 thoughts on “Picosecond vs Nanosecond Laser Tattoo Removal: which is better?

  1. Hi Mile,
    Thanks for your excellent work. One comment I would have is 3.4 joules is at the low end of what we would use except on skin-types above III. We would generally start at 4.5-5.5. 1064nm @5ns.
    Once you do that there is isn’t much difference. Partly because using the equivalent fluence in Pico causes too much skin damage. We think that’s a result from plasma releasing at the surface.
    As always, your input would be appreciated.

    1. Hi Chris,
      Yeah, I would also say that 3.4 J/cm2 is a bit low for a nanosecond 1064nm output. I’m trying to work out why pico lasers need less energy than nano lasers, yet can produce similar results. I think I know, but I need to do a bit more work…

      1. Nanoseconds use photothermal effects, while picoseconds are photoacoustic effects. Their principle of eliminating ink is different.

      2. That’s not true. Both nano and picoseconds induce a photoacoustic effect in tattoo inks. The nanosecond pulsewidth is far too short to result in a photothermal effect!!

  2. Thanks Mike. Interesting reading and kind of backs up my thoughts that pico technology is probably not worth the expense over a well maintained ns laser. Interesting results on the ns KTP for blue/green… especially as the laser light is green…

    1. Hi Mark,

      There is a general misunderstanding out there about laser wavelengths and ink colours. Most people think that the green 532nm cannot treat green inks.

      This is not quite right. The reality is more to do with the absorption coefficient of the ink. While our eyes might “see” a green colour, its absorption coefficient is not so obvious to us. When you fire a laser at that colour, the absorption coefficient determines how much energy is absorbed, and hence the temperatures achieved.

      The appearance of the ink is irrelevant!

  3. Hi Mike,
    I found this video on YouTube, I think it explains well why and when nanosecond and picosecond lasers are better than the other:

    I have no qualifications of any kind in this subject but I want to have. I’m investigating and learning now because I want to enter the tattoo removal world.
    I want to attend some courses, from the basics to the advanced ones until I feel I’m comfortable with the subject. Then, select and buy a tattoo removal machine and start with myself, I have plenty of ink that I want to remove.

    In case you can advice on any courses and where to attend them I’d be much appreciated too.

    1. Hi Paulo,

      Thanks for getting in touch and the video link. Very interesting.

      I offer training based on my 30 year experience in the field. You can find out more here – https://www.dermalase-training.com. Thanks to Covid-19 I now offer my courses on Zoom. It has proved quite popular!!

      Where are you based? I also sell devices, but it depends on your location!

      I look forward to hearing back from you,
      Best regards,
      Mike.

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