Beam angle is the light spread over distance.
A narrow beam angle concentrates light, while a wide beam angle spreads the light.
At the same distance from the light source, the narrow beam has more energy.
Affect of Beam Angle on Photobiomodulation
Photobiomodulation (light therapy) is the use of red and infrared light to stimulate the body to heal itself.
The body responds to specific lightwaves. Not all red and infrared waves have the same healing effects.
The photobiomodulation treatment must use the right irradiance, also known as power density.
Wide beam angle lights lose more energy with distance than do narrow beam lights.
Therefore, you need to sit closer to a wide angle light than you do to a narrow beam light to get the same energy.
If you sit too close to a narrow beam, you might get too much energy, resulting in heating and even a burn.
If you sit too far away from a wide beam, your body will not get enough energy to promote healing.