10 ESSENTIALS: 01 – Coherence
Laser vs. LED Light
The difference between laser and LED light begins with precision. A true laser diode produces light within a narrow spectral range, allowing it to deliver a specific wavelength with a high degree of accuracy.
LED light is different. Its output is spread across a broader range of wavelengths. An LED may be identified by a peak wavelength, such as 635 nm, but that does not mean all of the light it produces is precisely 635 nm.
Its actual spectral output extends across a range around that peak. This difference is significant because wavelength matters in photobiomodulation (PBM). Different wavelengths interact differently with biological tissue and biological chromophores. If the wavelength matters, the precision of that wavelength matters, too.
Laser light is also coherent and highly directional. Its light waves maintain an organized relationship as they travel, while LED light is noncoherent and spreads more broadly from the source. These are fundamental differences in the light itself, not simply differences in power or brightness.
Precision at the Source
The Blue Honest PRO VX laser system uses 15 true laser diodes producing six specific wavelengths: 405, 470, 520, 635, 670 and 808 nm.
Each wavelength is generated by a laser diode, giving the system the wavelength precision and coherent light characteristics that distinguish a true laser from an LED-based light source.
Coherence, wavelength precision, and directionality all begin at the source.
When Light Enters Tissue
Once light enters biological tissue, photons can be reflected, scattered, or absorbed. Tissue composition, wavelength, beam geometry, irradiance, and other optical properties all influence how much light ultimately reaches a particular depth.
Laser light begins with different optical characteristics than LED light. Laser beams can be highly directional and collimated, while LED light is generally more divergent.
Research is examining how these characteristics influence the propagation of light within tissue. (1,2)
Wavelength is also critical. Shorter visible wavelengths are generally absorbed more strongly closer to the surface, while longer red and near-infrared wavelengths can penetrate more deeply. Research has demonstrated that penetration varies by wavelength and tissue type. (2,3)
This makes the 808 nm near-infrared wavelength an important part of the Blue Honest PRO VX spectrum. It provides a deeper-penetrating component alongside the visible wavelengths, which have their own optical and biological interactions.
Each wavelength retains its own optical characteristics. Infrared does not physically carry the other wavelengths deeper. Rather, combining visible and near-infrared wavelengths provides different absorption characteristics and penetration profiles across the spectrum.
And deeper does not automatically mean better. The objective is not simply to go as deep as possible, but to combine wavelengths with different characteristics within one system. If the wavelength matters, the accuracy of the wavelength matters too.
See the Full Picture
Choosing a laser involves more than any single specification. Explore all 10 Essentials and see how the pieces work together.
Explore the 10 Essentials →
Research & References
(1) Hashmi JT, Huang YY, Osmani BZ, Sharma SK, Naeser MA, Hamblin MR. Role of low-level laser therapy in neurorehabilitation. https://pubmed.ncbi.nlm.nih.gov/20662021/
(2) Kim HB, Baik KY, Seonwoo H, et al. Effects of pulsing of light on the dentinogenesis of dental pulp stem cells in vitro. Scientific Reports. 2018. https://www.nature.com/articles/s41598-018-19395-x
