Laser Hair Removal Theory
Laser hair removal is everywhere yet, surprisingly, there is little scientific research into the theory and practice of it. Consumers spend thousands of dollars without understanding the science behind the technology. Unsurprisingly a significant number of them end up disappointed and disillusioned when they don’t achieve their hair removal goals. This is because laser hair removal isn’t always permanent, it’s actually a long term reduction.
How Does Laser Work To Kill Hair?
A basic understanding of physics is all you need to understand the theory of laser hair removal. There are 3 simple things to know about lasers: A laser beam is a beam of light. Light is a form of energy. Light energy has the ability to create heat.
It’s common sense that you don’t wear black in the summer sun. Dark colours absorb more of the sun’s energy and, thus, you get hotter. This is essentially the principle behind laser hair removal. The dark root of the hair attracts the light of the laser. The light generates heat upon contact with the hair. This heat necrotizes the cells and tissue responsible for hair growth.
Clients must shave prior to their laser treatments to ensure as much of the energy as possible reaches the root of the hair. Dark hair above the surface blocks the light energy from reaching the target area.
More information on laser hair removal found on wikipedia.
Drawbacks Of Laser Hair Removal
What many people don’t realize is that the vast majority of hair in certain areas do not have a dark root most of the time. This is because the majority of body hair is in the telogen, or resting, stage of hair growth. Its root has shortened and lightened because it’s getting ready to shed. Hairs can stay in the telogen phase for months before they begin the cycle anew and grow a thick, dark root. (The diagram above is NOT accurate in saying that the anagen phase lasts for 2 to 6 years, I’ve included this illustration only because it gives a visual of how laser works)
Laser treatment does not affect blonde, red or white hair because unpigmented hair does not attract and absorb the light energy. The same can be said for dark hairs in the telogen phase. You have to repeat treatments to ensure all hairs are in the active growth phase.
To summarize, laser hair removal relies on the contrast between dark hair and light skin. The light energy is drawn to the dark pigment and heats up the follicle to kill the hair growing cells. Laser is an effective way to reduce hair on the lower arms, legs, bikini and underarm.
Indian Women More Susceptible To Paradoxical Laser Induced Hair Growth