In short: RootReach™ is the light-delivery design inside Weave, Reseen's laser comb. Its 36 light-guided teeth part the hair, and 660nm red laser light travels through each tooth to exit at the tip, which rests on the scalp. Hair absorbs and scatters light, so delivering it at skin level, rather than shining it onto hair, is the core idea behind every well-designed laser comb.
The problem: your hair is in the way
On the face, light meets skin. On the scalp, it first meets hair, and hair is very good at intercepting light.
The main reason is melanin, the pigment that gives hair its color. Laser hair removal is built on exactly this property. Wikipedia's laser hair removal entry explains that melanin is the primary target (chromophore) for hair-removal lasers, and sums up the physics simply:
"Light is absorbed by dark objects but reflected by light objects and water" — Wikipedia, Laser hair removal
A hair-removal laser wants the pigment to soak up energy. A scalp-care device wants the opposite: light that reaches the skin and the follicle area rather than being absorbed, reflected or scattered by the strands above it. How much hair gets in the way depends on:
• Density. More strands per square centimeter means more surfaces for light to hit.
• Length. Longer hair lies in overlapping layers over the scalp.
• Color. Darker hair carries more melanin and absorbs more light. Lighter hair reflects and scatters more.
How much light a given head of hair blocks varies widely from person to person. In principle, any light that lands on hair first may never arrive at the scalp. That's the gap RootReach is designed to close.
How laser combs have tackled this
The idea of using comb teeth to get light past hair isn't new. The HairMax LaserComb was among the earliest home-use laser combs studied in published research. A 2021 systematic review by Lueangarun and colleagues in the Journal of Clinical and Aesthetic Dermatology (JCAD) describes these hand-held devices as delivering laser light to the scalp, with comb teeth that help it get through, and notes that these combs beep or vibrate every four seconds to prompt the user to move to a new section.
In a multicenter, sham-controlled trial published in the American Journal of Clinical Dermatology in 2014, Jimenez and colleagues tested HairMax combs with 7, 9 or 12 red laser beams at 635–655nm, used three times a week for 26 weeks. Participants with pattern hair loss using the active devices showed greater increases in terminal hair density than those using sham devices. These findings belong to the devices and people studied; they don't transfer to any other product.
RootReach builds on that idea by putting the light inside the teeth themselves.
How RootReach™ works
1. The teeth part the hair
As you glide Weave through your hair, its 36 teeth separate the strands into narrow channels and open a path down to the scalp.
2. Light travels inside each tooth
Each tooth works as a light guide. The principle is the same one that lets optical fibers carry light: total internal reflection. Light traveling inside a clear material that meets its boundary at a shallow enough angle reflects back in instead of escaping, so it's channeled along the material's length.
In RootReach, 660nm red laser light enters each tooth and is guided down its length, shielded from the surrounding hair, until it exits at the tip.
3. The tip meets the scalp
Because the tooth tip touches the scalp, there's essentially no air gap and no layer of hair between where the light exits and where the skin begins. That matters for two reasons:
• Less spreading. Light spreads as it travels away from its source, so the power per square centimeter, or irradiance, falls with distance. Releasing light at skin level keeps it concentrated where you want it.
• Less loss to hair. Light that never passes through hair can't be absorbed or scattered by it.
These are design principles, not measured Reseen results.
Why 660nm red light
Wavelength decides how light interacts with tissue. Red and near-infrared light are the workhorses of photobiomodulation, the research field studying how low-level light influences cells. In a 2017 review in AIMS Biophysics, Michael Hamblin describes the primary light-absorbing molecule as cytochrome c oxidase in mitochondria. Wikipedia's low-level laser therapy overview notes the effects appear limited to specific wavelengths.
For laser combs, red has been the standard. The devices in the JCAD review and the Jimenez trial used diodes at about 655nm. RootReach uses 660nm, in the same deep-red band. For more on this wavelength, see our red light entry.
Why VCSEL lasers suit a comb
RootReach is powered by VIPE™, Reseen's VCSEL Intelligent Photonic Engine. A VCSEL (vertical-cavity surface-emitting laser) emits a narrow, well-defined beam. VIPE™ keeps the beam angle under 20°, compared with up to 120° for conventional LEDs, according to Reseen.
That narrow beam is a natural fit for light guides. A small tooth can only accept light arriving within a limited range of angles, so a tight beam couples into it far more readily than a wide LED spray. VIPE™ also runs at under 5mW per emitter, a low, non-thermal output, so the comb stays cool against the scalp. For the full story on the chip technology, read VIPE™ laser technology.
Laser comb vs. laser cap
Both formats aim to get light to the scalp. They do it differently.
|
|
Laser comb (Weave) |
Cap liner (Halo) |
|
How it reaches the scalp |
Teeth part hair; light exits at the tooth tips |
Flexible liner holds light points close to the head |
|
Coverage |
Section by section, guided by your hand |
Whole scalp at once |
|
Best for |
Targeted areas like a widening part or crown |
Hands-free, full-scalp routines |
|
Effort |
Active, hands-on |
Put it on and go about your day |
In the JCAD review's subgroup analysis:
"There was no significant difference between the comb- and helmet-type LLLT devices." — Lueangarun et al., JCAD
The honest trade-off is that a comb's scalp coverage is only as even as your technique. A cap covers everything at once but has to rely on fit rather than parting hair. For the cap side of the story, read FlexArray™ technology, the design behind Halo.
How to use a laser comb well
General good practice for any laser comb:
• Start with a clean, dry scalp. Skip heavy oils and styling products that coat hair and scatter light.
• Work in sections. Mentally divide the scalp into front, top, crown and sides, and finish one before moving on.
• Go slowly. Slow, overlapping passes give each area time under the light. Rushing leaves gaps.
• Keep the teeth in contact. The tips should rest lightly on the scalp, not hover above the hair.
• Be consistent. Laser comb studies used regular sessions over months. Follow your device's instructions for timing.
If you're noticing sudden shedding, patches, itching or redness, see a board-certified dermatologist first.
How Reseen fits in
Weave, coming soon, is Reseen's handheld laser comb built around RootReach™: 36 light-guided teeth deliver 660nm red laser light right at the scalp. It's a cosmetic device designed to support scalp health for a healthier-looking scalp and fuller-looking hair. VIPE™ draws on the VCSEL chip expertise of Reseen's parent technology company, RAYSEES. Prefer hands-free? Halo, also coming soon, pairs 128 × 660nm red VCSEL lasers with 128 × 460nm blue LEDs in a wireless cap liner.
Frequently asked questions
Do laser combs work?
Several sham-controlled trials of laser combs, including a 2014 multicenter study in the American Journal of Clinical Dermatology, found greater increases in hair density with active combs than with sham devices in people with pattern hair loss. Results apply to the devices and populations studied, and individual results vary.
Laser comb vs. laser cap: which is better?
A 2021 JCAD meta-analysis found no significant difference in hair-density outcomes between comb- and helmet-type devices. The bigger difference is practical: combs target sections, caps cover the whole scalp hands-free. Pick the one you'll use consistently.
Does hair color affect red light therapy?
It can affect how much light reaches the scalp. Darker hair contains more melanin, which absorbs light, while lighter hair reflects and scatters more. Devices that part hair or deliver light at the skin surface reduce how much hair sits in the light's path.
Does the comb need to touch the scalp?
For a design like RootReach™, yes. Light exits at the tooth tips, so gentle contact keeps the light at skin level instead of letting it spread through an air gap or into surrounding hair.
Explore the science behind every term in the Reseen glossary.
Sources
1. A Systematic Review and Meta-analysis of Randomized Controlled Trials of United States FDA-Approved, Home-use, Low-Level Light/Laser Therapy Devices for Pattern Hair Loss: Device Design and Technology — Lueangarun S, et al.; Journal of Clinical and Aesthetic Dermatology, 2021
2. Efficacy and Safety of a Low-level Laser Device in the Treatment of Male and Female Pattern Hair Loss: A Multicenter, Randomized, Sham Device-controlled, Double-blind Study — Jimenez JJ, et al.; American Journal of Clinical Dermatology, 2014
3. Mechanisms and applications of the anti-inflammatory effects of photobiomodulation — Hamblin MR; AIMS Biophysics, 2017
4. Total internal reflection — Wikipedia
5. Laser hair removal — Wikipedia
6. Low-level laser therapy — Wikipedia
This article is for general education and is not medical advice. Reseen devices are cosmetic devices and are not intended to diagnose, treat, cure, or prevent any disease. Individual results vary. If you have a skin or scalp condition, talk to a board-certified dermatologist.