Laser Physics
Aside from understanding the natural hair growth pattern it is very important to understand how our laser technology works to effectively destroy the hair follicle. With a strong understanding of both concepts, we can deliver the best results possible to our clients!
Electromagnetic Spectrum
Any form of light is made up of particles called photons. These photons can travel at different wavelengths which can change the way our eye sees the light.
Think of a wavelength as waves in water. Some may be smaller, closer together, and move more rapidly likely creating these little shock like motions when reaching the shore. Verses larger waves that are likely further apart, move slower, but are very impactful when reaching the shore. Our light travels in the same manor.
A shorter wavelength = less penetration depth
A Longer wavelenth = More penetration depth
Wavelength is measured in nanometers which is the distance between the highest points of each “wave”.
Depending on the individual wavelength, it will appear as a single color int he visible spectrum. Throughout the years, it has been discovered that with the right grade laser or light, we can use specific wavelengths to interact with, and create change within our tissue.
Blue light = Acne treatments
Green light = Vascular treatments
Yellow/ Orange light = Hyperpigmenation treatments
Red Light = Hair removal or collagen induction (depending on type of laser/light source)
Different forms of Light/Energy in our Industry
High Frequency - Formed from argon or neon gases to produce a blue/purple light (argon) , or a pink/red light (neon). We uses this topically during facial treatments with glass probes that we apply to the skin
LED Light Therapy - Formed by LED lights, can come in multiple colors, but often seen in Blue & Red
IPL - Intense Pulsed Light is form of energy that emits a strong powered light at specific wavelengths to target concerns. It is very different than laser but it has the same goal. This form of light is broad spectrum meaning it can move into different wavelengths, and typically has shorter wavelengths. This means it is best for lighter skins, and more superficial skin concerns. The photons are divergent, meaning it can spread within the skin tissue and may not be focused for precise treatment
Laser - A different form of light where the photons are monochromatic (one color) and non- divergent meaning the photons stick together and create a very focused, powerful beam of light. We typically use this technology for deeper skin concerns such as hair removal, deep pigmented lesions, and forms of skin tightening. Lasers are too powerful to be used at shorter wavelenghs, There for we usually see them in the red spectrum.
Radio Frequency - Found in the invisible spectrum, radio waves are delivered into the skin vibrate at high frequencies to create heat within the cells. RF technologies work best for tissue regeneration & tightening
Ultrasound - Ultrasonic waves vibrate rapidly to create vibration within the cells to eventually blast and destroy fat cells. We typically see this with sculpting and contouring treatments.
Different Types of Lasers
Alexandrite
755 nm
used for laser hair removal
Safe for skin types I-III only
best for fine and light hairs
Diode
810 nm
used for laser hair removal
safe for skin types I-IV only
best for med-light colored hairs
ND: Yag
1064 nm
used for laser hair removal, pigmented lesions, and some vascular lesions
safe for all skin types
best for dark and coarse hairs
CO2 & Erbium
Wavelength is deeper but their target is water. Since we have water everywhere in our skin, this laser is used for skin ablation & resurfacing
Selective Photothermolysis
This is a concept developed by a scientist named Rox Anderson in the 80s which suggests that a light at a specific wavelength, can damage the targeted tissue containing the adequate chromophore, by controlling the light through a combination of different parameters. The surrounding tissue will not be affected provided that the thermal relaxation time of the target is not longer than the pulse duration.
Let’s Break It Down:
Selective = Something specific
“Photo” = particles of light are called photons
“Thermo” = Heat
“Lysis” = death or destruction
Selective Photothermolysis = causing destruction with heat, produced by light on a specific target
Target = what we are treating. Ex: laser hair removal we are treating hair, Acne treatment we are killing bacteria that creates acne etc..
Chromophore = The substance the target is made from or contains that directly absorbs the light energy & transfers it to heat. Ex: the melanin in our hair and skin absorbs the light energy. Without melanin, the target is untreatable because there will be no transfer of heat. More melanin means more heat, less melanin means less heat
Thermal Relaxation Time (TRT) = The time that it takes for the target to lose 50% of its heat (measured in nanoseconds, or milliseconds). A larger target (thick hair) will take longer to cool down (longer TRT). A smaller object (fine hair) will cool down faster (shorter TRT)
Treatment Parameters
Fluence: The amount of energy being produced by the laser. Measured in Joules per cm2 (j/cm2). The higher the energy, the higher the absorption rate by the chromophore. A higher fluence is more suitable for light skin and light hair. A lower fluence is more suitable for dark skins and dark hair.
Pulse Duration: The time that it takes for the laser pulse to deliver the total energy into the targeted tissue. Measured in miliseconds(ms), or nanoseconds (ns). The shorter the time means the target has lest time to cool down, which will provide a more intensive treatment. The longer the time means the target has more time to cool down, which will provide a slower heating to the target and a safer treatment. A short pulse is more suitable for fine hair, and a long pulse is more suitable for coarse hair.
Repetition Rate: The time in-between each pulse. This is important when using HR mode in the auto setting. If the hair is more dense we will need a lower(slower) repetition rate. Measured in Hertz (Hz)
Kilojoules (Kj): Total accumulative energy delivered into the target, based on the fluence.
The Soprano
We are using the Soprano by Alma Lasers. It is a diode laser (810nm). It uses multiple treatment modes to effectively and safely deliver the energy for all skin types.
SHR Mode
This is the most common mode used on this device. It utilizes a lower energy, but a very rapid repetition rate (10hz = 10 pulses per second). If we used a higher energy at this repetition rate, we will burn the skin. In order to ensure that we are delivering enough energy to the target, we must now calculate the total accumulative energy (Kj) in very specified areas we call grids. With the correct amount of Kjs delivered in the corresponding grid sizes, and correct fluence for the hair type and skin type, we will get proper heating of the target. Due to all the above, we are now able to treat all 6 skin types safely with the appropriate settings, even though it is a Diode laser.
HR Mode
HR Mode is the traditional method for laser hair removal. We can only treat up to skin type IV in this mode with the appropriate settings. We also now have the option of selecting our pulse duration to have better control over the laser beam.
Sub Stack Mode
Think this: SHR & HR made a baby! Sub stack mode utilizes the technology of SHR Mode, but with a stationary technique. This is great for stray hairs, or for clients with darker skins who need a sightly more precise treatment. The fluence is still chosen based on skin type and hair type, and the number of stacks is determined based on density and texture (similar to pulse duration). More stacks = less cooling & more total energy. Less stacks = more cooling & less total energy. It is not advisable to use this setting for skin type VI.