Are Picosecond Lasers Really Better than Nanosecond Lasers?

08 Apr

If you’ve been researching the laser tattoo removal process you’ve almost certainly read about picosecond and nanosecond lasers. There is quite a debate at the moment about which is better for tattoo removal, and if you’re not up-to-date with technical advances in Q-switched laser technology (ie. most people) then it probably all seems quite confusing.

There is large amount of information about picosecond and nanosecond lasers on the Internet if you do a search for it, but much of it is from sources that are biased in their presentation of the facts. That’s why it can be quite a confusing subject – because what you read is often framed by vested interests

The purpose of this blog is to attempt to explain the general theory of Q-switched laser technology and how it is used in tattoo removal, the latest developments in this field, and the claims and counterclaims made by both sides in the discussion.

First of all, let’s remind ourselves about the science behind Q-switched lasers and how they work.

A Q-switched laser produces a huge amount of power – enough energy to light up a whole city in fact – but delivers it in a fraction of a second. This is what makes a Q-switched laser different from continuous lasers and longer pulsed lasers such as IPL – the type used in some other aesthetic applications like hair removal.

When used in tattoo removal treatment, these brief pulses of highly concentrated laser energy are targeted at the tattoo pigment in the skin’s dermis. The energy is selectively absorbed by the ink particles; this means that the laser pulse is so precise it doesn’t affect the surrounding tissue. The ink particles are shattered into smaller fragments, which are then small enough to be engulfed and expelled by the white blood cells of the body’s immune system in a process called phagocytosis.

But how does the laser energy break up the ink particles? Actually, the mechanism is not fully understood (or agreed on) by scientists. However, it is generally accepted that there are two main forces acting on the ink: the photothermal effect and the photomechanical effect:-

  • The absorption of the highly intense light energy by the tattoo pigments leads to rapid heating – temperatures can reach 900C. The Q-switched laser pulse is so short (tiny fractions of a second), that the target ink particles undergo a rapid expansion in volume, or ‘micro-vaporisation’ and causes structural damage. This heating caused by selective light absorption is the photothermal effect. The expansion is so violent it generates shockwaves which can be heard as a popping sound with each laser pulse.
  • Acoustic shockwaves are created by this rapid heating and this is known as the photoacoustic effect. These acoustic waves create such forces that they fracture the tattoo pigment, leading to fragmentation into smaller particles. The photoacoustic effect is also known as the photomechanical effect. The high temperature also causes rapid vaporisation of water which forms gas bubbles. The rapidly forming gas bubbles then create ‘cavitation’ – a force created when the bubbles implode – and create intense shockwaves which further rupture the pigment particles.

So that’s the concept behind Q-switched lasers and how they remove tattoo pigment in the skin. This process is what all tattoo removal machines have in common. Now let’s look at the difference between nanosecond lasers and picosecond lasers.

For years Q-switched nanosecond lasers have been the ‘gold standard’ (a very clichéd term used by tattoo removal laser manufacturers) for tattoo removal. However, from 2012 there have been several new Q-switched lasers introduced to the market which the manufacturers have claimed are superior. These are the picosecond machines. The first commercially available laser, the PicoSure, was introduced in 2012 by Cynosure. Since then other picosecond machines have been brought out, such as the Picoway from Syneron Candela and the Enlighten from Cutera.

So what’s the difference between the picosecond lasers and the nanosecond lasers? It’s all to do with the pulse duration. The ‘fraction of a second’ that the machine delivers the pulse of laser energy is what makes picosecond lasers differ from nanosecond lasers:

  • 1 nanosecond is a billionth of a second, or 1/1,000,000,000 or 10-9s
    Typical pulse durations of nanosecond lasers are between 5 nanoseconds to 30 nanoseconds.

Picosecond devices have a shorter pulse duration:

  • 1 picosecond is a trillionth of a second, or 1/1,000,000,000,000 or 10-12s
    Typical pulse durations of picosecond lasers are between 375 picoseconds to 750 picoseconds.

Therefore a typical picosecond laser’s pulse duration is 100 x shorter than that of a nanosecond machine.

Proponents of picosecond lasers claim that the shorter pulse duration creates more of the photoacoustic effect than the photothermal effect and that this breaks down the ink pigments down more efficiently into smaller fragments. These smaller particles are easier for the body to remove and consequently fewer treatments are needed for total removal of the tattoo.

So are these claims of superior performance made by the picosecond Q-switched lasers justified? Well yes and no. If you do a search on Google you can find dozens of scientific studies about picosecond lasers vs nanosecond machines. And yes, there are quite a few articles that do conclude that picosecond lasers do remove tattoo pigment at a faster rate than nanosecond machines. However, there are also several studies that come to the opposite conclusion – that picosecond lasers don’t give noticeably better results.

In fact, some of the scientific studies comparing picosecond lasers and nanosecond lasers have their critics. There are three main criticisms of the way these studies have been carried out:-

  • Firstly, that the picosecond machines have been compared with older nanosecond lasers, so it isn’t really a fair comparison.
  • Secondly, many of the studies that have endorsed picosecond lasers have been sponsored by the manufacturers of those machines or have employees of those companies on the research team.
  • Third, because picosecond lasers are so new, there aren’t enough studies, and where studies do exist, the sample sizes are too small to be statistically meaningful.

Laser tattoo removal Sydney

But arguments about scientific studies are only half the story. There are other factors to consider when deciding on a clinic with a picosecond laser or a nanosecond laser.

Laser Wavelengths

First of all is the other parameters that lasers use: wavelength and fluence. Some Q-switched lasers have different wavelengths which are used to treat different ink colours: tattoo removal relies on the ability of a particular ink pigment to strongly absorb the appropriate laser wavelength. The two main wavelengths found in the most common Q-switched machines are the 1064nm and 532nm Nd:YAG laser (By the way, Nd:YAG is the name of the artificial crystal through which the high intensity beam of light is pumped that then creates the laser beam. Its full name is neodymium-doped, yttrium-aluminum-garnet). The 1064nm wavelength is absorbed by black and dark coloured pigments, while the 532nm wavelength is absorbed by red, orange and pink pigments. That means that ND:YAG lasers can treat 90 – 95% of all tattoos since red and black are the most popular tattoo ink colours.

The next two other most commonly found wavelengths in tattoo removal lasers are the 694nm ruby laser and the 755nm alexandrite laser. The 694nm is used to treat light blue and green pigments; the 755nm alexandrite is used on black, blue and green inks.

The PicoSure has the single ‘all purpose’ 755nm Alexandrite laser. Because the 755nm wavelength is not too far on the spectrum from the 694nm ruby laser, it is good for black, blue and green inks. However, the 755nm is a red beam and unfortunately cannot remove red and orange inks. The manufacturer of the PicoSure, Cynosure, responded to this by offering an additional handpiece which simulates the 532nm wavelength. However, as with all such dye handpieces for medical lasers it severely reduces the energy of the laser which results in insufficient power to get deep into the dermis and shatter the pigment. Therefore, the Picosure is generally not useful for red inks, which is the second most common tattoo colour.

Later picosecond lasers have the ‘standard’ 1064nm and 532nm wavelengths and although they may be better than the Picosure, their results have not appeared to be any better or quicker than the nanosecond lasers they aim to improve on.

Length of the Entire Course of Treatments

Another thing to think about when considering the difference between picosecond and nanosecond Q-switched lasers is how long it will take to achieve full clearance of the tattoo ink. According to the proponents of picosecond machines, the shorter pulse length breaks down the ink into smaller fragments that can be removed more quickly by the body. Laser clinics that use picosecond machines sometimes advertise that only 2 to 4 week intervals are needed between treatments. This is misleading, because it suggests that the whole process can be shortened. Laser tattoo removal is unfortunately a lengthy undertaking. It relies on the body’s immune system to clear the ink particles after the laser treatment. It’s therefore a natural process and one that just can’t be rushed. If you are undergoing laser treatment for tattoo removal you should wait at least 6 to 8 weeks between sessions to allow the body to carry out its autoimmune and ink excretion processes. A standard black tattoo will need between 8 to 10 treatments on average for full removal, so at 8 week intervals that means that the whole process will take at least a year. There’s no getting around that, and there’s really very little point in getting treatments done more frequently. It would be a waste of money shortening this to 4 weeks. If you are paying two or three times as much for picosecond laser treatments you should at least follow standard protocol and wait for the correct amount of time between sessions. Don’t be talked into spending more money unnecessarily.

Price

While we’re on the subject of money, the prices of individual treatments from a picosecond machine is generally double or triple of that of the cost of that of nanosecond lasers. This isn’t because the treatment is twice as effective, but more because a picosecond laser costs generally two or three times the price of a nanosecond machine. The clinic has to charge premium prices to recoup the cost of the initial investment in the equipment. The laser clinic then justifies the higher prices by implying that the total cost of full tattoo removal is less because fewer treatments are needed. This is of course a perfectly reasonable strategy if it is true. If you are choosing a tattoo removal clinic, you need to decide whether you accept this claim or not.

Guarantees

Closely related to the number of treatments required is the concept of guaranteed results. Some laser clinics offer a guarantee to remove your tattoo in x number of sessions. This is misleading because it suggests that all tattoos are similar and need an equal number of treatments to remove. Of course they are not. Each tattoo and client is different, and even for most experienced laser clinic is not going to be able to provide an accurate prediction of the total number of sessions required at the start. The number of treatments needed depends on many factors, such as the age of the tattoo, the density of the ink used, the location on the body and lifestyle factors. You can read more about this subject here. Giving a blanket guarantee of x number of sessions doesn’t take into account your individual factors, and will likely lead to disappointment.

One particular tattoo removal clinic in the CBD operating a picosecond laser is offering a 10 treatment guarantee for black tattoos. That is, they’ll keep treating you for free if your tattoo hasn’t fully cleared after 10 sessions. In fact most black tattoos should be fully cleared after an average of between 8 and 10 sessions at any decent laser clinic operating a Q-switched nanosecond laser so guarantees like this are not that special. If picosecond lasers really can remove tattoos in just a few treatments, then those clinics should put their money where their mouth is and guarantee this!

A good tattoo removal clinic should give you as realistic a prediction as far as they can, and manage your expectations both before and over the course of the treatments.

Our view

Ok, so here’s the part of this article where we give you our opinion on the nanosecond vs picosecond debate.

At Fade to Blank we think that the manufacturers of picosecond lasers and the clinics that use them have made a lot of overblown claims about their performance. However, this seems to be mostly marketing hype with very little substance to it. Generally, there doesn’t seem to be a large amount of real-world evidence that picosecond lasers are really any better than nanosecond machines. Maybe that’s because they are new and haven’t had a chance to prove themselves yet, but more likely it’s because they haven’t lived up to expectations. In fact, we’ve had clients who have had picosecond treatments at other clinics and the results have been no better than with Q-switched nanosecond lasers. Clients are disappointed that they’ve paid over the odds for treatments that haven’t fully removed their ink..

If you’re in a rush and are prepared to pay twice or three times the price per treatment for tattoo removal, then by all means go to a laser clinic with a picosecond machine and see if it lives up to the marketing spiel. However, if you want honest advice, reasonable pricing, and results that you’ll be amazed by, then contact us today.

At Fade to Blank we’re proud of our Quanta Q-Plus C and the results it’s achieved. We sincerely believe it’s the best Q-switched laser in the industry. With its three wavelengths it can remove even multi-coloured tattoos safely and effectively, as well as the black ones.

Either fill in the contact form or call the number at the top of the page. We hope to see you soon!

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