Science guide · 7 min read

Red Light Therapy Terms Explained: Wavelength, Irradiance, and Dose

Understand the three measurement terms most often confused in product comparisons.

Answer in brief

Wavelength describes the type of light, irradiance describes power per area at a stated point, and dose combines irradiance with exposure time. These values are related but are not interchangeable.

Wavelength is not power

A nanometer value identifies a spectral location; it does not tell you how much light reaches a surface.

Irradiance needs distance

An irradiance number without measurement distance, instrument, and coverage context is difficult to compare.

Dose includes time

Dose calculations depend on measured irradiance and exposure duration. Follow verified device instructions instead of transferring values from another product.

Health information noticeThis educational content is not medical advice and does not diagnose, treat, cure, or prevent disease. Consult a qualified professional for individual medical questions.

Continue with a specific answer.

What do 660 nm and 850 nm mean?

Nanometers describe wavelength. 660 nm is visible red light, while 850 nm is near-infrared and mostly invisible. Device specifications should identify wavelengths separately and distinguish design targets from measured output.

Read the standalone answer

How often should I use a red light device?

Follow the instructions supplied with the specific device. Session time and frequency depend on measured output, distance, and intended routine; ALPHALUX will publish model-specific guidance only after verification.