Light and photobiomodulation
LED array
An LED array is a set of light-emitting diodes mounted together to cover an area. In photobiomodulation, arrays have largely replaced lasers because they are cheaper, safer and cover more skin. What reaches the skin depends on how the array is built as well as on the number of LEDs.
Also called LED panel, LED strip, light-emitting diode array
LEDs versus lasers. A laser produces coherent, single-wavelength light in a narrow beam. An LED produces incoherent light over a band typically tens of nanometres wide, spread over a wide angle. For photobiomodulation that difference has turned out not to matter much — one of the stated reasons the field renamed itself from LLLT to photobiomodulation was that LEDs produce comparable effects. LEDs are not assessed against laser safety standards; they are assessed as lamps under IEC 62471, which assigns a measured product to a risk group.
What the count describes. What reaches the skin depends on the power of each diode, the beam angle, the distance to the body and how the array is arranged. The Red Light sauna carries 750+ LEDs in total: 380+ at 850 nm near infrared, and 370+ high-density photobiomodulation LEDs in blue, green and red at 630 nm.
Arrangement. The strip design runs the full body length inside the sauna. The user’s head is outside, so the array is never in the user’s line of sight, and the lights switch off when the doors are opened.
Why it matters here
"750+ LEDs" is the headline number on the Red Light sauna. It describes the hardware; what reaches your skin also depends on how bright each diode is and how far away it sits.