Analysis of Picosecond Q-switched Lasers for Tattoo Removal

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Comparison of Picosecond Tattoo Removal LasersLeading aesthetic practitioners are faced with an important technology decision when buying the latest in tattoo removal systems: how much does science – as opposed to marketing – fit into their evaluation?

“Picosecond lasers” – Q-switched lasers with pulse widths in the picosecond range – have garnered attention over the past couple of years and have been marketed heavily with claims of removing tattoos in fewer treatments.

While picosecond Q-switched lasers have shorter pulse durations, this metric is only one of many that affect the quality of tattoo removal treatments.

The marketing claims that suggest otherwise are now under scrunity in a class-action lawsuit against one of the picosecond laser manufacturers.


Picosecond Q-switched lasers are touted for removing tattoos faster than nanosecond lasers – insisting that pulse duration is the determining factor for fast tattoo removal. However, not only do picosecond systems with their shortened pulse durations not provide any significant peak power benefit over high-end nanosecond lasers, both types of systems shatter ink in qualitatively the same way.

Picosecond systems are vastly underpowered compared to nanosecond systems, forcing practitioners to use small spot sizes when fluence levels need to be increased. And, most importantly, no picosecond system gives practitioners the flexibility to effectively treat the full spectrum of tattoo colors and patient skin types.

While shortened pulse durations theoretically have a benefit for peak power, the benefit only exists if all other specifications (particularly pulse energy) are kept constant – and producing picosecond lasers with high pulse energy have proven to be both difficult and prohibitively expensive.1 Because of these difficulties, the picosecond systems that have made it to market have not delivered on their marketing promises and are plagued with reliability issues.



  1. Wavelengths for Treating Colors

  2. Pulse Duration and Pulse Energy

  3. Photoacoustic and Photothermal Action

  4. Spot Size, Fluence, and Ablation Threshold

  5. Practitioner Experience

  6. Patient Results

  7. Choosing the Right Laser



Wavelengths for Treating Colors

Twenty years ago, when most tattoos treated for removal only contained black ink, it was common for early adopters of laser technology to have only one Q-switched laser wavelength in their office. Tattoo trends have changed over the years toward more colorful designs, and high-end skin specialists are adapting to demand with more versatile technology.

Because different colors of tattoo ink have differences in light absorption and light absorption is the critical factor in ink shattering, multiple laser wavelengths are typically needed to treat a colorful tattoo. In addition, even some “stubborn” black tattoos may require multiple wavelengths to be treated effectively, as inks can become resistant if treated repeatedly with just one wavelength.2

The most commonly used wavelengths of light for tattoo removal are as follows:

  • 1064 nm for treating black and some dark colors – from an Nd:YAG laser
  • 532 nm for treating red, orange, and some yellows or greens – from an Nd:YAG laser
  • 694 nm for treating green, blue, violet, and black – from a ruby laser
  • 755 nm for treating green, blue, violet, and black – from an alexandrite laser
  • 650 nm for treating green – from a dye filter handpiece attached to an Nd:YAG laser
  • 585 nm for treating blue – from a dye filter handpiece attached to an Nd:YAG laser

The most important factor that practitioners should consider when choosing which wavelengths to provide is the overall ability of each wavelength to deliver the desired results on ink colors. For example, the 1064 nm wavelength has proven consistently to be the best solution for treating black ink tattoos on skin types IV – VI, as it has a much lower risk for causing pigmentation changes.Alexandrite and ruby lasers, while both highly effective at treating black ink, often cause temporary pigmentation changes due to a higher absorption by melanin and are not recommended for treating darker skin. In a Fitzpatrick and Goldman study, 50% of patients had temporary hypopigmentation and 12% of patients had transient skin texture changes when treated with an alexandrite (755 nm) Q-switched laser.3

The 650 nm and 585 nm wavelengths are theoretically good options for treating blue and green inks. However, they are currently only produced by dye handpieces, which are grossly underpowered (1/10th the power of a full-powered laser) and only available in small spot sizes – making them highly ineffective.

The leading picosecond Q-switched system on the market is an alexandrite laser; it produces the 755 nm wavelength that is not a desirable solution for treating skin types IV-VI. In a recent study of a picosecond Q-switched alexandrite laser, a red tattoo showed no clearance after four treatment sessions.The system has since added on a 532 handpiece which is still not cleared for use on darker skin tones, can only reach a maximum fluence of 1.1 J/cm2, and has a maximum spot size of 2 mm (which causes lengthier treatment times and shallower penetration).

There are now picosecond Nd:YAG lasers available as well, however they have the same weaknesses as any Q-switched Nd:YAG laser – difficulty removing some bright blue and green inks that are unresponsive to 1064 nm and 532 nm.

Picosecond Lasers for Colorful Tattoos

If a practitioner wants to have the capacity to treat the widest range of tattoos effectively, a minimum of three laser wavelengths are needed: 532 nm for treating warm-toned ink colors, 694 nm or 755 nm for treating cool-toned and resistant black ink colors, and 1064 nm for treating black and dark inks on all skin types safely. No picosecond system provides three wavelengths, so there is no picosecond option that has the capacity to treat both colorful tattoos and tattoos on darker skin tones.



Pulse Duration and Pulse Energy: Equally Important to Peak Power

Picosecond lasers are variants of Q-switched lasers based on just one specification: pulse duration. Pulse duration, the amount of time the laser’s light energy is emitted, only affects ink shattering with regard to its effect on peak power. Peak power (measured in MW) is a laser’s pulse energy (mJ) divided by its pulse duration (ns or ps).

Pulse Energy (mJ) ÷ Pulse Duration (ns) = Peak Power (MW)

The concept behind picosecond lasers is that by decreasing the pulse duration to the sub-nanosecond range, peak power is increased for better ink shattering with each pulse. However, there are two key features of the leading picosecond system that are problematic for it to make this claim.

First of all, the leading picosecond system has a standard pulse duration of 750 picoseconds – which is closer to 1 nanosecond than to 1 picosecond. The difference in the pulse durations of the picosecond system and single-digit nanosecond systems is only a factor of 6-times to 8-times – not the 100-times difference implied in its product marketing. 

The other critical detail is that the pulse energy of picosecond systems is significantly lower than that of high-end single-digit nanosecond systems. The leading picosecond laser only produces 200 mJ per pulse, while competitive Q-switched nanosecond lasers commonly produce at least 1000 mJ. The nanosecond lasers have a pulse energy 5 or 6-times that of the picosecond system.

Pulse Duration Peak Power Picosecond Laser

Peak power is greatest when the pulse energy is high and the pulse duration is low. The leading picosecond laser may have a slightly lower pulse duration than that of the nanosecond lasers, but its pulse energy is also lower – making its peak power very comparable to that of single-digit nanosecond lasers.

When introduced, the leading picosecond system’s pulse duration was originally at 900 ps. Today, it currently has two pulse duration settings, 750 ps and 550 ps, and it may lower even further in the future. It’s important to notice that its pulse energy drops in correlation whenever the pulse duration is shortened. It produces the 750 ps pulse with 200 mJ of energy; with the 550 ps pulse, the energy drops to 165 mJ (miniscule in comparison to that of other Q-switched systems).

High peak power is undoubtedly essential for efficient, quality tattoo removal treatments – that’s why Q-switched lasers are used instead of long-pulsed systems. Since two laser specifications (pulse duration and pulse energy) directly affect peak power, they both should be considered when comparing laser systems.



Photoacoustic and Photothermal Action: Independent of Pulse Duration 

Researchers are still studying the mechanisms that allow lasers to work effectively for removing tattoos. The predominant theory is that tattoo ink is shattered by two mechanisms – photoacoustic (also called photomechanical) and photothermal action.5 Photoacoustic action is mechanical fragmentation of particles due to rapid changes in temperature, and photothermal action is the chemical alteration of particles due to high temperature.

The leading picosecond system claims it “goes beyond photothermal action,” touting its photoacoustic impact as the primary driver of ink shattering and implying that it shatters ink particles differently than nanosecond lasers due to its pulse duration. However, a study comparing tattoo response from picosecond and nanosecond lasers found that the qualitative nature of the ink changes were no different between that of tattoos treated with the two types of lasers.1 In the study, the picosecond laser used had a pulse duration of 35 ps – over 20-times shorter than that of the leading picosecond system on the market.

Best Picosecond Laser for Tattoo Removal

While the mechanisms of photothermal and photoacoustic action are still being studied, it’s clear there is no difference in the way ink particles are broken down by high-end nanosecond and picosecond lasers. Both high-quality nanosecond and picosecond lasers are more efficient at destroying ink compared to older-generation lasers with much lower peak power.



Spot Size, Fluence, and Ablation Threshold

Spot size refers to the dimensions of the laser beam as it enters the skin; fluence is the density of energy within the laser’s beam. The two specifications are directly related – by decreasing the spot size, the energy is focused into a smaller area, increasing the fluence.

Low-powered Q-switched systems are notorious for only providing adequate fluence for ink shattering at small spot sizes. When using a small spot size (2 mm or smaller), there is an increased scattering of energy as it enters the skin, which is undesirable. Scattering deposits more of the energy in the epidermis and superficial dermis – not reaching the targeted tattoo ink particles and increasing the risk for scarring.2 Also, smaller spot sizes make treatments more time-consuming for the practitioner, as more pulses are needed to cover the area of the tattoo.

Picosecond Laser System Comparison

Larger spot sizes are preferred for treating tattoos, but only if the laser produces sufficient fluence for ink shattering at those sizes. While the leading picosecond systems provides a range of spot sizes – all the way up to a 10 mm spot – practitioners will find themselves only using the smallest spot sizes due to extremely low fluence at larger sizes. At the 2 mm spot size, the system reaches its maximum fluence of 6.4 J/cm2. At the 3 mm spot size, it reaches its limit at 2.8 J/cm2.5 For comparison, high-end Q-switched lasers in the nanosecond range often exceed 10 J/cm2 at a 3 mm spot size.

Compensating for its low fluence settings, the leading picosecond system claims that it needs less fluence to react with tattoo ink due to its shorter pulse duration. This claim was put to the test by two separate studies analyzing the ablation threshold fluence of ultra-short duration lasers. The ablation threshold, the minimum laser energy required to induce a reaction with the targeted molecules, was found to be independent of pulse duration for highly absorbing tissues (such as tattooed skin), even when the pulse duration was reduced to the femtosecond (sub-picosecond) range.6 Pulse duration only affects ablation thresholds when the treated tissue is virtually transparent. The studies indicated that the minimum fluence required to elicit the desired whitening response in the skin is consistent across both picosecond and nanosecond systems.

Another issue for the current picosecond system is that it only produces a circle-shaped laser spot. Circle-shaped beams require the most overlapping of pulses during treatment of a tattoo to get full coverage. When pulses need to be overlapped, treatments take longer and there is an increased risk of over-treating the skin and causing unwanted side effects.

Despite offering large spot sizes, the leading picosecond system only produces adequate fluence for removing tattoos at small spot sizes and only with a circle-shaped beam – making treatments less efficacious due to energy scattering and more time-consuming for practitioners.



Practitioner Experience

Laser systems are major investments for medical practices, so it is important to practitioners that devices meet both their clinical and functional needs. A laser needs to be easy to operate, reliable, and cost-effective for the practice.

Warm-up time (from turning a system on until it is ready for use) is a laser specification that few practitioners consider before making a laser purchase, but is important for efficiency. The most popular picosecond system typically takes about 45 minutes to warm up before treatments – which is hugely inconvenient compared to the less-than-a-minute warm up time of many high-end nanosecond lasers.

Also, the picosecond systems have reputations for frequent reliability issues. It costs precious practice time to reschedule patients and have a laser engineer visit the office if a system needs repair. Plus, once the system is out of warranty, those service visits will need to be covered by the practice or an expensive service contract (which is more than twice the rate of most in the industry).

Between the bulkiness of their size, the sensitivity of their components, less-efficient warm-up times, and reliability issues, the picosecond systems are significantly more cumbersome for practitioners than other high-end tattoo removal systems with no added benefits.



Patient Results: Same Minimum Number of Treatments 

The first publicly available picosecond system has been sold since early 2013, and its marketing claims have been put to the test by its users. The consensus from many physician users is that picosecond laser performance (in terms of number of treatments to remove a tattoo) is not any faster than that of other newest-generation nanosecond lasers – and that hypopigmentation is common for skin types IV – VI treated with its 755 nm wavelength.

RealSelf® is a great tool to see actual results from patients treated with picosecond lasers. While many patients write glowing reviews after having just one treatment, those that are further along in the process are generally disappointed. Patients that were told that their tattoos would likely be removed in three or four sessions often needed at least twice as many sessions than they were originally promised.

As both practitioners and patients are seeing through experience, most tattoos treated with picosecond lasers still need a minimum of five or six treatments – which is identical to that of high-end nanosecond systems – but also risk more complications and side effects.

On a related note, a dermatologist in Illinois is starting a class action lawsuit suing one of the prominent picosecond laser manufacturers for false advertising:

Had Plaintiff and the Class known of the [picosecond laser] product’s inability to remove or eliminate tattoos, they would not have purchased the [picosecond laser], would have returned their [picosecond laser] for a refund, would have paid substantially less for it, or would have purchased a similarly functioning product for substantially less.

For comparison, here are some examples of tattoo removal results achieved with the Astanza Trinity, an industry-leading multi-wavelength nanosecond system:

Tattoo Removal Laser Before and After


Choosing the Right Tattoo Removal Laser

The demand for tattoo removal is constantly increasing, despite the fact that science has not yet delivered a laser that can perfectly remove tattoos in one treatment. Practitioners that want to provide the best results possible for their patients have to wade through marketing claims and figure out which laser specifications matter most for providing quality treatments.

Astanza Trinity vs Picosecond LaserThe reality is that laser tattoo removal is a nuanced procedure that requires a variety of settings to accommodate a range of tattoo and skin types effectively.2 

A laser shouldn’t sacrifice one specification (like pulse energy) for another (like pulse duration or wavelength), when both have equally important impact on ink shattering.

Astanza, a company focused on laser tattoo removal, combines a Q-switched Nd:YAG and Q-switched ruby laser in its flagship system, the Trinity. The Trinity provides three full-powered (not dye filtered) wavelengths with the highest peak power of any multi-wavelength system in the world. Its features give practitioners the tools to remove the widest range of ink colors quickly from all skin types with minimized side effects. The Trinity is an excellent solution for practices focused on patient results.



  1. Ross EV, Naseef G, Lin C, Kelly M, Michaud N, Flotte TJ, Raythen J, Andersen R, Comparison of responses of tattoos to picosecond and nanosecond Q-switched Neodymium:YAG Lasers. Arch Dermatol. 1998; 134: 167-171.
  2. Bernstein EF, Laser Tattoo Removal. Semin Plast Surg. 2007; 21: 175-192.
  3. Fitzpatrick RE, Goldman MP. Tattoo removal using the alexandrite laser. Arch Dermatol. 1994; 130: 1508-1514.
  4. Robinson DM, Saedi N, Petrell K, Arndt KA, Dover JS, Confirmatory study of picosecond 755 nm alexandrite laser. Lasers in Surg Med. 2013; 45.
  5. Cenic B, Z. Vizintin, and M. Lukac, Will Sub-Nanosecond Lasers Replace Nanosecond Lasers for Tattoo Removal? J Laser and Health Academy. 2013; 1: S9-S10.
  6. Oraevsky AA, Da Silva LB, Rubenchik AM, Feit MD, Glinsky ME, Perry MD, Mammini BM, Small W, Stuart BC, Plasma mediated ablation of biological tissues with nanosecond-to-femtosecond laser pulses: relative role of linear and nonlinear absorption, IEEE J Select Top Q Electr. 1996; 2: 801-809.

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