The core concept
Red-light and near-infrared devices use specific bands of non-ionizing light. In photobiomodulation research, wavelength, dose, tissue target and protocol all matter. consumer marketing often compresses those variables into a few headline specifications.
What to compare
When reading a product specification sheet, note the wavelength distribution, irradiance measurement conditions, treatment distance guidance, exposure-time guidance, panel dimensions and control options. None should be interpreted in isolation.
Keep evidence tied to the use
Evidence for one wavelength, protocol or clinical context should not automatically be generalized to every home device or health claim. Our health-related pages use conservative language for that reason.
Why measurement distance changes the number
A panel can produce a different irradiance reading when the meter moves closer or farther away. Beam angle, LED spacing, optics, and the part of the treatment area being measured can also affect the result. That is why a single advertised number is hard to compare when brands use different test methods.
Peak output and useful coverage are different questions
A strong reading in the center of a panel does not tell you how evenly light reaches the edges of the treatment area. For a large panel, distribution can matter just as much as a peak measurement.
Questions worth asking
Find out the distance used for the published measurement, whether the company explains its test method, and whether the number represents a central reading or a broader average. Then read the device guidance for the recommended treatment distance.