Laser question to lasers gurus

What is your thoughts about the penetration of the lasers, to reach the scalp.
An old question, with lots of Theories....remember the red laser light color through the finger ( and nail ) etc...

and the marketing acts THE TEETH : http://www.hairmax.com/Introduction/MechanismsofActionHypothesis.aspx

So compared to a laser messiah 2 helmet for ex. I'm not talking about the power and time exposure...

I'm talking here about the absorption, how the laser can reach the scalp/follicules...considering a head with a bit hair left....

FWIW, that video was stating not that light can't penetrate his finger but that once the laser light enters his thumb, it is no longer coherent light but becomes non - coherent light such as an LED, sunlight, household bulbs. Of course this was wrong and a quick google search at the time would have shown otherwise.

Even if that wasn't true he was still getting caught up in another companies marketing ploy that only coherent light (e.g. LLLT) gives biostimulation and thus results for hair loss and that non - coherent (i.e. LED light) will not. Of course this marketing ploy was wrong in that non - coherent light does provide biostimulation ... just to a lesser degree.

Here's a quote

Q: Does the coherence of the laser light disappear when entering the tissue?
A: No.

Q: Does the coherence of the laser light disappear when entering the tissue?
A: No. The length of coherence, though, is shortened. Through interference between laser rays in the tissue, very small "islands" of more intense light, called speckles occur. These speckles will be created as deep as the light reaches in the tissue and within a speckle volume, the light is partially polarized. It is easy to show that speckles are formed rather deep down in tissue and the existence of real speckles prove that the light is coherent.


a HeNe laser [632 nm] with a power output of 3.5 mW has a greatest active depth of 6-8 mm depending on the type of tissue involved. A HeNe laser with an output of 7 mW has a greatest active depth of 8-10 mm.


So to answer your question, yes, 650 nm lasers will penetrate to your hair follicle as shown in bold.