FlexArray™: The Laser Cap Liner That Fits the Hat You Already Wear

In short: FlexArray™ is the flexible light array inside Reseen's Halo. It puts 256 light points, 128 × 660nm red VCSEL lasers and 128 × 460nm blue LEDs, on a five-panel liner that bends to the shape of your head. It snaps magnetically into the Reseen cap or fits most standard baseball caps, so scalp care fits around your day.

The problem with one-shape-fits-all devices

Most people shopping for a laser cap for hair growth compare two numbers: price and diode count. The thing that often decides what reaches the scalp gets less attention: how the device sits on your head.

Heads aren't one shape. They vary in length, width, crown height and the slope from forehead to nape. A rigid helmet or dome cap is built around an average head. On a real one, some emitters sit close to the scalp while others hover farther off, often at the temples, hairline or back of the head.

Distance matters because light spreads as it travels. A 2025 pilot study of home-use light devices by Cronshaw and colleagues in Dentistry Journal (Photobiomodulation LED Devices for Home Use) found that for a wide-angle LED device:

"the irradiance varies dramatically with distance from the target surface" — Cronshaw et al., Dentistry Journal

Irradiance is light power per square centimeter. When the gap between emitter and skin varies across the head, so does the light each zone receives. That's why our scalp coverage guide treats evenness as seriously as reach.

The other problem: actually using it

The second issue is adherence. Light devices in research are used several times a week for months. A 2021 systematic review in the Journal of Clinical and Aesthetic Dermatology by Lueangarun and colleagues (home-use low-level light/laser therapy devices) analyzed the 32 home-use devices FDA-approved as of January 2020, grouped into four designs: sport caps, headbands, combs and helmets. Most were advised for use about 3 to 4 times per week, with sessions averaging about 30 minutes.

Format seems to shape whether people keep going. In a 2023 survey in the Journal of Cosmetic and Laser Therapy by Paiewonsky and colleagues (Photobiomodulation and alopecia), 86.4% of respondents preferred a hands-free device. And in a 48-week study of a home-use helmet device reported by Dermatology Times, adherence averaged more than 97%, which the report linked to convenience:

"likely reflecting the convenience of the helmet design" — Dermatology Times

Hands-free works. FlexArray asks a follow-up question: what if the hands-free device were also something you'd happily wear out the door?

How FlexArray works

A liner that bends instead of a shell that doesn't

FlexArray is built as five flexible panels rather than one rigid dome. Each panel can be molded and bent to follow the curve of your head, so the light points sit closer and more consistently around the scalp instead of following a fixed, average shape.

Why VCSEL makes a thin, flexible array possible

A flexible liner needs small, low-profile, cool-running light sources. That's where the VCSEL (vertical-cavity surface-emitting laser) comes in. As Wikipedia's VCSEL entry explains, VCSELs emit light perpendicular from the top surface of the chip, have a small active region that lowers the current needed to run them, produce a lower-divergence beam than edge-emitting lasers, and can be built in two-dimensional arrays.

For a wearable, those traits matter. Surface-emitting chips lie flat on a panel, low current keeps power draw modest for a wireless battery, and low output (under 5mW per emitter) keeps the light non-thermal. Our sister post on VIPE™ laser technology covers the photonic engine behind it. Reseen's parent company, RAYSEES, designs VCSEL semiconductor chips, which is where this platform comes from.

Magnetic snap-in, any-hat fit

The liner snaps magnetically into the Reseen cap. It also fits most standard baseball caps, so you can use a hat you already own. Darker caps are recommended because they help keep light focused inward rather than spilling through the fabric.

Smart wear detection

Halo starts when the liner makes proper contact with the scalp. No guessing whether it's seated right, and no light firing into the room.

Why 128 red lasers and 128 blue LEDs?

FlexArray pairs two light sources on purpose, each chosen for what it's meant to do.

• 660nm red VCSEL lasers. Red light around 660nm is the band most home scalp devices use. The Lueangarun review found all 32 devices used sources between 620 and 678nm. Lasers produce narrow-band light in a tighter beam. Reseen's VIPE™ emitters have a beam angle under 20°, compared with up to 120° for conventional LEDs, so more of the output is directed toward the scalp rather than scattered sideways.

• 460nm blue LEDs. Blue light acts near the surface of the skin. For surface-level light, a wider spread is fine, so LEDs are a sensible, efficient choice.

Halo has three preset modes:

Reading emitter counts honestly

Laser caps advertise diode counts because they're easy to compare. But more diodes isn't automatically better. The Lueangarun review found a median of 148 light sources per device (range 7 to 304), each under 5mW. A 2019 meta-analysis in Lasers in Medical Science by Liu and colleagues reported that device type did not affect effectiveness across the trials it pooled, and that lower treatment frequency performed better than higher.

When you compare a laser hat or red light therapy hat, ask:

1. How many are lasers and how many are LEDs? Some devices combine the two in one headline number. One device in the review listed 282 light sources: 82 laser diodes and 200 LEDs. Halo's 256 is 128 + 128, stated plainly.

2. What wavelength? Red sources typically fall around 620–680nm.

3. How close and even is the fit? Diodes that hover far from the scalp deliver less.

4. What dose per session? Research points to a dose window, not "more is better." See fluence.

5. Will you wear it? The best laser cap for hair growth on paper does little in a drawer.

Designed for wear-anywhere routines

Halo is wireless and charges by USB-C. There's no cord tethering you to a wall and no helmet to sit under. Wear it on a walk, at your desk or while you cook. In a familiar cap, it looks like a cap.

How Reseen fits in

Halo, coming soon, is Reseen's wireless cap liner built on FlexArray. It's a cosmetic device designed to support scalp health for a healthier-looking scalp and fuller-looking hair, in 10- and 15-minute sessions.

For targeted sections such as a part line or crown, Weave, also coming soon, is a handheld laser comb that delivers 660nm red laser light through light-guided teeth that touch the scalp. Read how it works in our RootReach™ technology post. Both run on VIPE™.

Frequently asked questions

Do laser caps work?

A 2019 meta-analysis of 11 double-blinded randomized trials found low-level laser therapy increased hair density in people with androgenetic alopecia compared with sham devices. Those findings apply to the specific devices and people studied. If you're noticing new or patchy hair loss, see a board-certified dermatologist first.

How many lasers should a laser cap have?

There's no magic number. Devices in a 2021 review ranged from 7 to 304 light sources. Wavelength, how close and evenly the emitters sit, dose per session and consistent use matter more than the headline count.

Can I put a laser liner in my own hat?

With Halo, yes. The FlexArray liner fits most standard baseball caps as well as the Reseen cap. Darker caps are recommended to keep light focused toward the scalp.

Laser cap vs red light hat: what's the difference?

"Red light hat" is often used for any red-light headwear, including LED-only designs. A laser cap uses laser diodes, which emit narrow-band light in a tighter beam. Many devices, Halo included, combine lasers and LEDs, so check the breakdown.

Why does Halo also have blue light?

Blue light acts near the skin's surface, so Halo uses 460nm blue LEDs in a dedicated Scalp Balance mode and a combined Deep Care mode. It's part of a cosmetic scalp-care routine, alongside the red lasers.

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. Photobiomodulation LED Devices for Home Use: Design, Function and Potential: A Pilot Study — Cronshaw M, et al.; Dentistry Journal (MDPI), 2025

3. Photobiomodulation and alopecia: a crowdsourced survey study on patient preferences — Paiewonsky B, et al.; Journal of Cosmetic and Laser Therapy, 2023

4. Twelve Months of LLLT Show Sustained Benefit in Alopecia — Dermatology Times, 2026 (reporting Shin JW, et al., Dermatologic Therapy, 2026)

5. Comparative effectiveness of low-level laser therapy for adult androgenic alopecia: a system review and meta-analysis of randomized controlled trials — Liu KH, et al.; Lasers in Medical Science, 2019

6. Vertical-cavity surface-emitting laser — 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.