Advanced Intensity Analysis for Red Light Panels: Beam Angle, Coverage Area, and Isoirradiance Plots
What is the real intensity of a red light panel? How does Beam Angle really relate to the intensity distribution and coverage area?
Of course we can't talk about intensity without acknowledging the scam that most red light panel manufacturers are lying about intensity with cheap solar power meters.
But lets, just for this blog, imagine a world where manufacturers aren't lying about intensity. That we are all seeking the common goal of scientifically analyzing these panels so we can offer the most evidence-based understanding of these products.
How would we truly quantify the intensity output from a red light panel in an honest multiverse world? Lets take a look.
Beam Angle vs Lens Angle
We covered Beam Angles in a previous blog with some nice illustrations of the differences between narrow beam angles and wide beam angles.
However, we did not clearly separate the differences between Beam Angle of the entire panel, versus the Lens Angle of the individual LEDs.
Most companies are referring to the Lens Angle of the individual LEDs when they are making claims about having 30 degree, 60 degree, or 90 degree beam angles.
The Beam Angle for the entire panel is the aggregation of all of the LEDs in the arrangement on the panel, the lens angles, the spacing between the LEDs, and how all of the light converges together.
For example, our GembaRed OverClocked and Reboot panels use 60 degree lenses but according to our 3rd party lab the beam angle of the entire panel is only 20 degrees.
Obviously this makes a big difference in how we plan our coverage area for treatment. And we have seen many times how other brands are over-exaggerating their coverage area by referencing the lens angles and not the actual beam angle of the panel.
Intensity and Coverage Area
Most Red Light Panel companies will offer a single intensity number that represents the entire coverage area that they claim.
You might recognize a diagram like this being shown on many websites, which helps illustrate the intensity at various distances, as well as how the coverage expands with distance.
According to some companies, somehow a 3 foot tall panel emits 72 inches tall of coverage at only 18 inches away. This is only possible if they are confusing Beam Angle of the entire panel with Lens Angle of the individual LED lenses.
We can appreciate that many companies have claimed exorbitant coverage areas for their panels. For example, the PlatinumLED BioMax 600 currently claims to emit 130mW/cm^2 and a coverage area of 72 x 45 inches (6 foot by 3.75 foot) at 18 inches away.
With a blazing inferno of 130mW/cm^2 and a coverage area much larger than most humans, then there wouldn't be any need for additional "modular" panels.
Yet, most people who own the BioMax 600 quickly realize it actually emits a very narrow coverage area, and they do indeed need to purchase 3 more panels just to get the actual coverage that a single panel claimed to emit.
What Can We Learn From Lasers?
Lasers have been the forerunners of the Photobiomodulation (LLLT) industry, and we need to understand them but also appreciate the massive contextual differences between LED and Laser.
Lasers have a long history of having non-homogenous outputs. We can only "see" a small dot of a laser. And we falsely assume that the laser output is a perfect circle of even distribution.
We can't really tell by eye if a laser dot is a perfect circle or has an uniform distribution, even though that is what is commonly assumed.
For example, a 5mW laser with a 0.2 cm diameter. Typically researchers will simply divide 5 by pi*(0.2/2)^2 = 159 mW/cm^2.
(notice a 5mW laser is very low power [a typical pen laser], but companies can cherry pick this large intensity number to sell their falsely advertised intensity panels and imply that is a good idea to engulf an entire human body in the intensity of a laser)
With this simplistic math, the researchers have assumed that the Laser beam is perfectly distributed over the area of the circle. And that it is a perfect circle the first place.
In reality, it is widely accepted that this is not the case with most lasers. Lasers are known to emit a Gaussian Distribution where there is a hot spot in the very center and lesser intensity around the edges.
Then there are many lasers that don't even follow a Gaussian distribution, they have irregular distributions, or they aren't even perfect circles and are oval or irregularly shaped.
Researchers can employ not only power measurements, but devices called "beam profilers" that are designed to elucidate the true beam pattern of lasers. The Blog at Thor Photomedicine has much more detailed examples of laser beam profiles.
So even with a laser, we can start to appreciate the many layers of potential inaccuracies with assumptions about the intensity distribution.
Some studies have started to use truly uniform laser beams. The researchers note that they get much more consistent results with uniform beam distribution, rather than inconsistent results with Gaussian or haphazard distributions.
3rd Party Isoirradiance Plots
An advanced form of analysis that can be done by 3rd party test labs is called Iso-Irradiance plots. The lab measures the total power output and true beam angle output and can calculate these isoplots of intensity.
3rd Party Isoplot Analysis of the GembaRed Overclocked Panel at 6 inches away.
The picture above shows the isoline analysis for the GembaRed OverClocked panel at 6 inches away. Think of it like a topography map except for intensity.
At the center, the green oval shows us the average intensity of 40 mW/cm^2 in that area, reaching a maximum at the center of the panel of 47mW/cm^2.
The red boundary line the intensity drops to 20mW/cm^2. So we can see even at the perimeter of the panel the intensity has already dropped by nearly half.
Then outside the perimeter, the purple line drops to 10 mW/cm^2, then the next green line is 5 mW/cm^2, then the outer brown line is only 1mW/cm^2.
So we can see even though the panel width is about 9 inches, we really only get about 12 inches of coverage. But the intensity outside of the perimeter of the panel dramatically decreases.
Accurate intensity measurements are the basis for safe and effective red light therapy dosing.
Now that we know red light panels have a much more complex intensity distribution, how do we properly use this knowledge? Should we adjust our dosing strategy?
Probably not. But like how laser studies have evolved to preferring uniform distributions, perhaps red light panels should consider the intensity distribution as an important part of the design.
Eye safety is interesting, for example obviously we wouldn't want to put our face in the middle of a panel and stare directly at it, since that is the highest spot of intensity. If we position the height of our panels just a few inches below the eye-line, that will help ensure we don't get as much intensity as the rest of the body, while still enjoying a low beneficial dose of indirect light to the eyes.
Using just one intensity number to represent an entire coverage area rarely shows the entire story. Especially when companies use solar power meters, only advertise the intensity of a single hot spot, and make outrageous claims about coverage area.
Lens Angle and Beam Angle have big differences that manufacturers need to learn so they don't mis-calculate the coverage area. The Beam Angle of panels should be measured by an accredited 3rd party lab so we can calculate more accurate coverage areas.
The beam distribution issue is not new to the LLLT community. There have been similar issues with Laser dot assumptions, however with LED Panels the intensity distribution can be much more complex because they have many light sources over a wide area.
Advanced analysis by professional 3rd party labs provides intensity distributions of red light panels similar to how lasers should be analyzed with beam profilers. It really shows us the "full story" when it comes to intensity distribution and coverage area. This is possibly the best way to start to fully understand intensity output from these devices.
Joovv had briefly posted their own isoirradiance analysis plots in 2019, however they must have realized if anyone ever figured out how to read the plots then they would have incriminated themselves. Since their own 3rd party isoirradiance plots showed their panels had an average intenstiy of 20mW/cm^2 at 6 inches away. Don't worry, we have the screenshots.
We can see Joovv posted isoirradiance plots of their competitors (RedRush 360 and SaunaSpace) on Ben Greenfield's blog, but they cleverly didn't publish their own product analysis to continue to obscure the truth about their own panels. Joovv still displays the SaunaSpace graph on their own website, but is too cowardly to offer a plot of their own product as a fair comparison. Notice the pattern of Joovv hiding the truth about their own products while discrediting others?
Most red light panel companies seem to be on a quest to come up with the most misleading representations of intensity and often coverage area. But we present a potential world where we can do deep analysis of red light therapy panels so we can properly understand dosing, safety, and effectiveness.
So let us know what you prefer; challenging technical analysis or convenient marketing lies?