How Adding 810 nm or 940 nm NIR Changes a Red-Light Panel's Useful Depth

Article author:

Evelyn Reed, M.S.

Adding 810 nm or 940 nm LEDs changes the spectrum a red-light panel emits, but it does not guarantee that a useful dose reaches a deeper tissue target. There is no fixed "penetration depth" for either wavelength, and the available evidence does not support a direct tissue-penetration ranking of 810 nm versus 940 nm.

For 940 nm, the accessible comparison with 850 nm suggests that higher water absorption can modestly limit its purely optical reach under some conditions and may create more warmth. That does not establish that 810 nm is deeper than 940 nm, or that either is automatically better than red light for a particular goal.

The practical question is not simply, "Which wavelength goes deepest?" It is: How much wavelength-specific light does the panel deliver at your treatment distance, over what area and time, and within a comfortable heat limit?

"Penetration Depth" Is Not One Measurement

Light particles scattering and fading gradually through layered skin, fat, and muscle

A panel advertisement may say that a wavelength "penetrates" a certain distance. Before using that claim to compare devices, it helps to ask what the word means.

What may be meant	What it tells you	What it does not tell you
Light enters and travels through tissue	Some photons can move beyond the skin surface.	How much light remains at a specified depth.
Fluence remains at depth	A measurable amount of optical energy is still present in deeper tissue.	Whether that amount is sufficient for a biological or clinical effect.
Useful dose at a target	The remaining light is adequate for a defined purpose under defined conditions.	This cannot be assumed from a wavelength label or a generic depth estimate.

This distinction matters because light is not either "present" or "absent" at one sharp boundary. Its intensity declines through tissue. A claim that light reaches a depth does not, by itself, show that enough wavelength-specific energy remains there to matter for the intended target.

The available material places roughly 650--950 nm within a lower-absorption optical window in biological tissue. That is useful context, not a universal depth guarantee. Transmission still depends on the wavelength, the tissue involved, the amount of light delivered, and the treatment setup.

For the accessible 850 nm and 940 nm comparison, relevant interactions include water, hemoglobin, myoglobin, and cytochrome-c oxidase. But the material does not provide tissue-specific absorption coefficients, fluence-at-depth measurements, or a threshold that would define a clinically useful dose.

What Adding 810 nm or 940 nm Actually Changes

Two near-infrared paths compared across matching tissue with subtle water and warmth cues

An added NIR channel can change the panel's spectral mix. Whether it meaningfully changes the dose delivered below the surface depends on how much of the panel's output is actually assigned to that channel.

810 nm: a label is not a depth result

The approved material does not provide a direct measured comparison of 810 nm with 940 nm, red wavelengths, or other wavelengths in tissue. In particular, findings for 850 nm should not be treated as substitute evidence for 810 nm.

That leaves a straightforward buying rule: do not infer an 810 nm advantage solely because a panel lists 810 nm LEDs. Ask how much 810 nm output the device produces at the distance you plan to use it.

940 nm: a water-and-warmth trade-off may matter

The accessible comparison characterizes 940 nm as having somewhat higher water absorption than 850 nm. It suggests that this may modestly reduce pure optical depth relative to 850 nm, particularly at very high power densities.

That comparison is limited:

It is 850 nm versus 940 nm, not 810 nm versus 940 nm.
It does not quantify absorption, remaining fluence, or useful dose at depth.
It does not establish a general ranking across skin, fat, muscle, or bone-adjacent tissue.
It does not show that 940 nm is ineffective, nor that 850 nm or 810 nm is universally preferable.

In other words, 940 nm should not be marketed---or purchased---as automatically "deeper" simply because it is a longer wavelength than 810 nm or 850 nm. Nor should its potentially greater warmth be treated as proof that it is reaching a deeper target.

Delivery Conditions Can Matter More Than the LED List

Technician measuring panel coverage, wavelength output, distance, and warmth on a torso target

A wavelength only contributes if the device delivers enough of it where and when you use the panel. Relevant comparison variables include power output, beam area, treatment distance, session duration, and pulsing capability.

For a panel buyer, that means total LED count and total wattage are incomplete specifications. A red-plus-NIR device may have many LEDs while allocating only a limited share of its output to 810 nm or 940 nm. Conversely, a smaller panel may provide more useful output at a chosen distance if its spectral distribution and coverage are well documented.

Distance and coverage

Distance affects the treatment geometry. As you move farther from a panel, the area covered and the light arriving at the body may change. Compare irradiance figures only when they are reported at the same stated test distance.

A useful specification should clarify:

the distance used for the measurement;
the treatment area or beam coverage;
whether the figure is an average, a center reading, or another measurement;
how evenly output is distributed across the usable area; and
how much output comes from red LEDs, 810 nm LEDs, and 940 nm LEDs separately.

Contact and non-contact setups also create different geometry. A manufacturer should provide instructions for the intended arrangement rather than expecting users to infer a distance or session length from a headline irradiance number.

Heat is a limit, not a performance signal

The accessible comparison associates 940 nm with mild warming and 850 nm with less warming. It also notes that water absorption can limit 940 nm penetration at very high power densities. However, it provides no temperature measurements, safe irradiance threshold, or wavelength-specific adverse-event comparison.

The practical takeaway is modest: warmth does not prove deeper delivery or a better result. If you are considering a 940 nm-equipped panel, treat thermal comfort as a real use constraint.

Start conservatively with lower power or shorter sessions, following the device instructions. Mild warmth may occur; burning is a sign to stop rather than push through the session. The available material does not establish a universal safe setting, session duration, or wavelength-specific dosing protocol.

A More Useful Panel-Comparison Checklist

Before paying extra for 810 nm or 940 nm, request documentation that answers these questions.

Ask for the measurements

Wavelength-specific irradiance: How much output comes from red, 810 nm, and 940 nm channels individually?
Named test distance: At what distance was each measurement taken?
Spectral distribution: What proportion of the output is assigned to each wavelength?
Coverage and uniformity: What area is measured, and how consistent is output across it?
Operating guidance: What distances, power settings, and session durations does the manufacturer document?
Thermal guidance: Does the manual explain how to reduce intensity or duration if the treatment area becomes uncomfortably warm?
Safety information: Are limitations, warnings, and use instructions easy to find?

Independent spectral and irradiance testing is more informative than a wavelength list, LED count, or total wattage claim. Pulsing capability may be listed as a feature, but the available evidence does not establish that pulsing increases useful deep-tissue dose.

What a specification can---and cannot---show

Documented wavelength-specific output can show:

that a panel emits the wavelengths it lists;
the relative contribution of its red and NIR channels;
how output changes at stated distances; and
whether the panel's coverage fits the area you intend to use.

It cannot, by itself, show:

a fixed penetration depth;
a useful dose at a specific internal target;
that 810 nm is superior to 940 nm, or vice versa;
a clinical outcome for a particular condition; or
that a warmer treatment is delivering more useful light.

The material available here also does not provide extractable human outcome results for a cited 940 nm surgical study. A study title or an isolated wavelength reference is not enough to support an outcome claim.

A Practical Decision Path

If your goal is primarily surface-oriented, choose red wavelengths as the starting point. Consider 810 nm or 940 nm as potentially useful additions only after confirming their wavelength-specific output, your intended treatment distance, coverage, session guidance, and heat constraints.

Do not buy a panel on a "penetration depth" claim alone. Compare BestQool panel specifications and instructions against this checklist, or contact support to verify the spectral mix, measured output, and recommended use before assuming that a listed wavelength delivers a particular result.