Understanding Beam Angle in Red Light Therapy

What is the best beam angle for red light therapy?

• 25° to 35° Beam Angle: The 25° to 35° beam angle is great for deep tissue penetration even at greater distances, to effectively stimulate cells while covering a generous area of skin or tissue. This range caters to both specific skin concerns and deeper muscle or joint issues, making it ideal for red light therapy panels.
• 60° Beam Angle: Straddles the line, potentially sacrificing therapeutic depth for broader coverage.
• 90° Beam Angle: Too diffuse, risking a significant drop in effectiveness by spreading the light too thinly.

What is the ideal distance from a red light therapy panel?

• 30° beam angle LEDs: a moderate distance (around 8 inches to 3 feet) provides a balance between intensity and coverage. At this range, the light is focused enough to provide therapeutic depth, yet spread out enough to cover a reasonable area.
• 60° beam angle LED: you might want to be closer, perhaps around 4 inches to 2 feet, to maximize the intensity without excessively diffusing the light. At this closer range, you harness more of the panel's power while still achieving a decent coverage area.
• 90° beam angle LED: it's advisable to be as close as 4 inches to 1 foot away. At this proximity, you ensure that the spread of the light doesn't dilute the intensity too much, which is essential to achieve the desired therapeutic effects.

Beam angle determines the level of intensity at which the beam of red light from each bulb in your at-home red light therapy panel connects with your skin. Our TotalSpectrum series of panels are designed with 30 degrees or lesser beam angles to maximise penetration of light into your skin, even at comfortable distances.

Technical Terms and Definitions

Lens

In an LED bulb, a lens is a piece of transparent plastic material that has two opposite regular curved surfaces used to focus the rays of light. These surfaces can be convex (curved outwardly, causing light rays to converge at a specific focal point) or concave (curved inwardly, causing parallel light rays to diverge away from a central focal point). Due to the brightness of LED bulbs, a lens is used to evenly distribute light. In the case of red light therapy, a convex lens is typically used to refract light waves.

Beam Angle

The beam angle is the angle between the two opposite directions over the beam axis for which the luminous intensity is half that of the maximum luminous intensity. Put more simply, the beam angle is the angle at which light is emitted from a source. To visualize this, picture a flashlight emitting a three-dimensional “cone” of light. At its source (the surface of the flashlight), it is the size of the flashlight’s diameter. As it is emitted, it radiates outwardly and the field becomes larger.

Inverse Square Law

The inverse square law dictates that a specified physical quantity is inversely proportional to the square of the distance from its source. In other words, the intensity of light at any given distance from a device equals the inverse of the square of the distance from the source. Intensity decreases the further away from the source you are. The inverse square law dictates that if the source is 2 times as far away, the light is ¼ as intense as at the source. If it’s 10 times farther away, the radiation exposure is 100 times less.

Minimum Usage Distance

This is the recommendation as to how far away from the device you should be during therapy. For most red light therapy panels, the minimum recommended distance is approximately four to six inches. You can find detailed instructions in our official usage guide for red light therapy.

Light Density (Intensity)

Light density simply means the intensity of light emitted from the surface of its source. The unit of measure for light density (L) is calculated in candela per square meter (cd/m²). One candela is the luminous intensity of a source that emits radiation at a frequency of 540 × 1012 Hz and has a radiant intensity of 1/683 watt per steradian, which is a measure of circular surface area.

Light Irradiance

Irradiance is the amount of light energy from its source hitting a square meter of its target each second. As opposed to light density, irradiance relies upon the energy connecting with the target rather than the energy level at its source. The unit of measure for irradiance is watts per square meter (Wm²). (Read more about irradiance in red light therapy.)

Light Refraction

Light refraction is the bending of light from one transparent substance into another. Refraction makes it possible for us to have light-altering lenses, magnifying glasses, prisms, and rainbows. Even our daily eyesight depends upon this bending of light.

Light Scatter

When light passes through one medium to another (air, for example) part of that light is absorbed by particles of the medium preceded by its ultimate source of absorption.

How Does Beam Angle Impact Treatment?

Red light therapy utilizes refractive lenses in its bulbs, providing maximum absorption of red light wavelengths into your body. Red light density varies in irradiance level based upon the beam angle of your device. Wider beam angles diversify (spread apart) red light waves more quickly due to the inverse square law. As beams of light diversify, they lose their intensity and intrinsic healing powers with increased distance between you and the device. Narrower beams offer less bodily coverage since they are straighter and cover less surface area from a distance, but they do offer more concentrated intensity from longer distances, improving benefits.

It could be more beneficial for light to reach your body more directly in the form of perpendicular (more narrowly angled) beams of light. Which is better? Greater bodily coverage with wider angled beams, or more targeted, straight light waves administered via lower angled beams? Light scatter and reflection decrease with a minimized distance, but light absorption is maximized at a greater distance. Therein lies the conundrum! The verdict is not yet in. But, each option offers its own unique treatment solutions.

The Most Common Beam Angles for Red Light Therapy Device Bulbs and Their Attributes

The beam angle of an LED determines the trade-off between coverage area and light intensity at a distance. Here’s a simple breakdown of what the most common angles mean for your therapy session.

90 Degrees: Wide Coverage, Low Intensity

Think of a 90-degree beam angle like a floodlight. It's designed to cover a very wide area. While this provides maximum surface coverage, the light energy spreads out very quickly and loses its power (irradiance) rapidly with distance. To receive a therapeutic dose, you would need to be extremely close to the panel. This angle is generally not ideal for deep tissue treatment, as the light becomes too diffuse to penetrate effectively from a comfortable distance.

60 Degrees: A Balance of Coverage and Power

A 60-degree beam angle is a common middle ground. It offers a good balance, providing a reasonably wide coverage area while maintaining better intensity at a distance compared to a 90-degree angle. This makes it a versatile choice, suitable for treating larger body parts like the back or legs from a moderate distance without a significant loss of therapeutic power.

30 Degrees: Focused Power, Optimal for Therapy

This is often considered the "gold standard" for high-quality red light therapy panels. A 30-degree angle acts more like a spotlight, concentrating the light energy into a more focused beam. This means the light maintains a high level of intensity even at a comfortable distance (like 6-12 inches), allowing it to penetrate deeper into tissues to reach muscles, joints, and ligaments. This angle minimizes "wasted" light that spills out to the sides, ensuring most of the therapeutic energy is directed at your body.

10 Degrees: Highly Specialized and Targeted

A 10-degree beam angle is extremely focused, similar to a laser pointer. While it delivers a very high intensity of light, the treatment area is incredibly small. This angle is not practical for therapy panels designed to treat areas larger than a few square inches. It is more commonly found in small, handheld "pen" devices intended for targeting very specific points.

To date, there is little evidence to support the supremacy of one lens beam angle over another. Consider your unique health and fitness goals when selecting a red light therapy device, bringing beam angle into the equation as you see fit.

Additional Resource Material

Not much research or reading material is currently available on optimal lens beam angles for red light therapy. Unless scientific studies begin to address the topic, it will remain up to you to determine how beam angle impacts your unique treatment needs. For now, here is some additional reference material to help you further understand the science behind LED lenses and light beam angles.

• sciencedots.com - Inverse Square Law
• sciencedirect.com - Beam Angle
• sciencelearn.org.nz - Reflection of Light
• sciencedirect.com - Light Irradiance
• gsu.edu - Refraction of Light
• physicsforums.com - What Is the Density of Light?
• Role of EMF in red light therapy

Until a better understanding of beam angle impact upon the success of red light therapy success is gained, it is best to focus on other parameters when selecting a device. Pay more attention to the light intensity at the recommended minimum usage distance. Personal objectives as to beam angle should be considered when selecting a red light therapy device. Until more concrete scientific evidence is available, however, the science behind the total therapeutic energy provided is a more reliable metric than beam angle.

Learn More About Choosing a Device

• The Importance of Power Density (Irradiance)
• Understanding EMF in Red Light Therapy
• Why Low Flicker is Crucial for Quality Devices
• Cheap vs. Expensive Red Light Therapy: A Buyer's Guide