Laser General Information

information on medical grade lasers in our clinic

What is laser?

Laser stands for Light Amplification by Stimulated Emission of Radiation. Laser light is composed of particles called photons and have the same colour and phase. Essentially, this means that a laser will emit a pure wavelength of light. Medical lasers use this property to induce a certain effect on a particular target on the skin.

This page covers the principles of laser treatment, the difference between laser and intense pulsed light or IPL machines, and the range of lasers available at Victorian Cosmetic Institute.

If you are more interested in what lasers can do for your skin instead, then click on this link to our laser skin treatment page.

What are the effects of medical lasers on skin?

 

There are a large variety of medical lasers, each emitting a certain wavelength that have a different effect on skin. Each laser wavelength is attracted selectively to a particular substance on the skin. A particular laser wavelength can therefore target a particular problem on the skin, depending on what it is attracted to. Some wavelengths will be attracted to melanin (pigment), others to haemoglobin (blood), and others are attracted to the water in the skin. Each laser wavelength will also penetrate a different depth. Lasers that are attracted to melanin are used for the removal or reduction of excessive pigment such as freckles, sunspots, and brown birthmarks. Also because melanin is found in hair, these lasers are also used for laser hair removal.

What is selective photothermolysis?

One of the benefits of laser treatment over other modalities of treatment (such as IPL) is the specificity of laser treatment. For example, to remove a brown spot in the skin, it may be possible to use liquid nitrogen to burn it off, however, by doing so, this will non-specifically affect the normal skin as well as the brown spot. Lasers are able to selectively treat the brown spot with minimal or no disruption to the normal skin. Lasers are able to specifically target a particular problem when the principles of selective photothermolysis are used.

Selective photothermolysis is the principle that allows lasers to be used to target a specific area/problem in the skin with minimal or no disruption to the surrounding normal skin. For selective photothermolysis to be successful, the following must occur (we will use the example of removing an unwanted blood vessel with laser to illustrate each point);

  • The laser wavelength must be highly attracted to the target e.g 532nm laser wavelength (as found on the Gemini laser) is targeted to haemoglobin which is present in blood vessels
  • The target must dissipate heat slower than the surrounding skin, and therefore accumulate heat from the laser e.g the blood vessel targeted by the 532nm wavelength will dissipate heat energy slower than the surround skin, therefore it accumulates heat and this causes it to shut down. The laser energy also must be applied to the target quickly enough for the target to heat up to a critical temperature.
  • The laser wavelength must reach the target e.g the 532nm wavelength needs to be able to penetrate down to the level of the capillary it is targeting.

If the above criteria are satisfied, it is then possible for laser to specifically target a particular problem in the skin, whether it be a freckle, capillary, or excess hair, without damage to the normal skin.

What is the difference between laser and Intense Pulsed Light (IPL)?

 

Lasers have specific wavelengths to target a specific problem. The KTP laser, for example has a wavelength at 532 nanometres (nm) that targets melanin and haemoglobin. This makes it very specific to problems such as broken capillaries, rosacea, freckles, sunspots and pigmentation.

IPL is a broad spectrum of light that has a large band of wavelengths. Hence, it tends to target a number of problems simultaneously and not as selectively as laser. If for example, you are trying to selectively target capillaries, the broad band of light wavelengths emitted by IPL will target capillaries as well as other parts of the skin. The amount of energy delivered to the intended target will also be delivered to the unintended targets, and at times, cause unnecessary skin damage.

Although versatile, IPL devices are as a rule less effective at a given task than a laser dedicated to the purpose.

What does each laser and laser wavelength do?

This graph is an illustration of the relative attraction of each laser wavelength to a particular target in the skin. It also illustrates the band of wavelengths which IPL machines cover. Again, as lasers only emit a single wavelength of light, they are much more specific than IPL at targeting a particular problem. The diagram below depicts the various laser wavelengths and the relative attraction of each wavelength to the particular targets in the skin.

medical grade laser wavelengths
What is the difference between ablative and non-ablative lasers?

Ablative lasers such as Erbium and CO2 lasers are attracted to the water in skin and as a result remove the top layers of the skin. These are usually used to reduce wrinkle and improve skin texture/tightness.

Non-ablative lasers such as the Gemini laser, Ruby laser, Pulsed dye laser, and Medlite lasers (see below) are attracted to melanin (skin pigment/hair pigment) or oxyhaemoglobin (in blood) and only selectively remove skin problems such as excess pigmentation or capillaries, leaving the rest of the skin intact.

A summary of the various lasers

(Wavelength / name of wavelength / name of laser)

532nm / KTP laser / Gemini laser The Gemini laser emits two wavelengths, one of which is 532nm. The Gemini laser emits this wavelength in millisecond pulses (which is considered to be a ‘long-pulse’ in the laser world). As seen on the graph, this wavelength is highly attracted to a peak in the haemoglobin (the iron in blood cells) curve, and is also highly attracted to melanin (the pigment in skin). It is therefore suited to treating broken capillaries, port wine stains (red birthmarks), sunspots/pigmentation, freckles, and certain skin lesions like skin tags and seborrhoiec keratosis.

532nm /  KTP laser / Medlite laser –  Like the Gemini laser, the Medlite laser also emits two wavelengths, one of which is 532nm. The Medlite laser is a q-switched laser and emits much shorter pulses than the Gemini laser. Each pulse only lasts a few nanoseconds or a few billionths of a second (one milllion times shorter than the Gemini laser’s pulses). These high energy, short pulses are particularly suited to the removal of pigmentation. As can be seen on the above graph, the 532nm is attracted to both haemoglobin and melanin. However, the Medlite laser is not suited to the treatment of broken capillaries, as its short high energy pulses cannot heat the capilllaries adequately. For pigmentation problems such as sunspots and freckles, it is prefered in most cases over the Gemini laser as these short and high energy pulses tend to shatter the melanin particles to help clear them from the skin.

The other primary use of the 532nm wavelength in this q-switched mode is for tattoo pigment. The 532nm wavelength is highly attracted to red inks in particular

694nm / Ruby laser / Sinon laser – The 694nm wavelength of the Ruby laser is attracted to melanin in the skin, but unlike the 532nm wavelength, is not attracted to haemoglobin. This makes it an ideal laser for the treatment of pigmentation problems. It also penetrates deeper than the 532nm/595nm wavelengths. The Ruby laser is also attracted to the melanin in hair follicles, which makes it a good laser for laser hair removal. Its high attraction to melanin however, makes it unsuitable for laser hair removal in olive or darker skins. Finally, the Ruby laser is used for removing green tattoo pigment, a colour which the other laser wavelengths do not treat very well.

755nm / Alexandrite laser / Apogee elite  – The 755nm penetrates deeper into the skin than the above wavelengths, and has slightly less attraction to melanin in the skin the the above wavelengths. These properties make it an ideal laser wavelength for laser hair removal as it penetrates deeply to the hair follicle. Also, because it has less attraction to melanin than the 694nm wavelength, it is more suited to laser hair removal in the more olive/darker skin types than the Ruby laser.

1064nm / Nd:YAG laser / Gemini laser – The 1064nm is a wavelength that is emitted by the Gemini laser for treatment of leg veins, deeper facial veins, and for laser hair removal on darker skin types. The 1064nm wavelength has only a small attraction to melanin, but a high affinity for haemoglobin. This makes it an ideal laser for the treatment of veins/hair on all skin types from fair to dark. It is best suited to vein removal over hair reduction.

1064nm / Nd:YAG laser / Apogee elite  This laser emits the same 1064nm wavelength as the Gemini laser, but it emits pulses that are more suited to laser hair removal. It is usually used for laser hair removal in those with olive or darker skins due to its minimal attraction to melanin.

1064nm / Nd:YAG laser / Medlite laser –  This is actually the primary laser wavelength of the Medlite laser. The 532nm wavelength is generated from the 1064nm wavelength by passing it through a KTP crystal in the laser which halves the wavelength. The 1064nm is a very deeply penetrating laser that is suited to treating deep dermal pigmentation, stimulating new collagen production to smooth skin, as well as for tattoo removal of most ink colours (except for red and green). Again, this laser is q-switched which means it produces very short pulses high energy pulses, which tend to have a mechanical effect on its target rather than a thermal effect. Therefore, pulses from this laser are not particularly suited to removal of hair or capillaries, as these targets require a laser with a more thermal effect.

Fraxel re:store 1550nm and 1927nm This laser has two wavelengths and is fractional in nature. The At 1550nm, this laser penetrates deeply into the skin to help treat skin concerns such as acne scarring. The 1927nm penetrates less deeply into the skin, but covers a greater percentage of the skin, to help treat concerns such as pigmentation, freckles and sun damage.

2950nm Erbium-  This laser is an ablative laser which removes a very fine layer of skin with each pulse. It can be used in skin resurfacing to remove wrinkles, or it can also be used to remove lumps and bumps on the skin.

10600nm Carbon dioxide laser  – Like the erbium laser , this is also an ablative laser. It is primarily used for skin resurfacing, and is considered the gold standard for this treatment. The carbon dioxide laser can be used in fractional mode or non-fractional mode for more aggressive resurfacing. The carbon dioxide also generates some thermal heating of the skin which helps to tighten skin.

 

Dr. Gavin Chan
Dr. Gavin Chan

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