LEDs vs Laser Technology for Therapy
Understanding why coherent laser light delivers dramatically better results than LED-based devices—and what to watch out for when comparing specifications.
There's a wide range of LED (Light Emitting Diode) and SLD (Super Luminescent Diode) products created for the same applications as therapy lasers. These products can be successful in some applications, but at this point in time, most LED systems fall way short of true therapy laser results due to several major limitations.
Some manufacturers even have "laser" in their name yet use 90% LED technology. Please check the specs on any product before you buy—and remember that LEDs only deliver a small portion of energy into tissue compared to a true laser.
Why Energy Delivery Matters
When delivering energy to tissue, the entire process must minimize losses. Every system starts with available power, but as energy travels through a medium, there are losses. If energy converts to heat, it cannot convert to chemical energy—so most therapy devices try to minimize tissue heating.
This is what makes infrared lasers different from infrared saunas. Saunas are mainly photo-thermal. Better lasers are primarily photo-chemical. Higher wavelength lasers (980nm and above) suffer from this problem—much energy converts to heat, causing dilation and blood flow but not the photo-chemical reactions that drive cellular healing.
The Lake Analogy
Imagine throwing a handful of stones into a still lake at the same time (non-coherent light). The waves hit each other and energy is destroyed—only a small portion reaches the other side (deep tissue).
Now imagine throwing one rock, or timing multiple rocks to hit at the natural period of the waves (coherent light). This produces waves that travel across the entire lake. When peaks and valleys align, you get a rogue wave bigger than any single wave—additive interference. When out of phase, waves destroy each other.
Light reacts the same way. Non-coherent light is self-destructive and less efficient at traveling through tissue. That's why we prefer coherent laser light when pushing photonic energy through human tissue.
LED vs Laser: Direct Comparison
| Property | LED / SLD | Laser |
|---|---|---|
| Wavelength | 400nm+ narrow band Ranges from 600-700nm for "red" LEDs |
400nm+ monochromatic Precise, single wavelength |
| Divergence | High divergence Up to 120° spread common |
Low, controlled divergence ~7% spread, optimized for penetration |
| Super-Pulsing | No Can switch fast but not super-pulse |
Yes Enables safer high-power delivery |
| Coherent | No Random interference = inconsistent results |
Yes Spatially constant waves, non-interfering |
| Tissue Delivery Efficiency | 1–20% | ~90% |
Understanding LEDs
A light-emitting diode (LED) is a semiconductor light source with properties between an incandescent bulb and laser. When switched on, electrons recombine with electron holes, releasing energy as photons. The color defines the light properties and photon energy.
Early LEDs emitted low-intensity red light (610-760nm). Modern versions cover wider wavelengths including the infrared therapeutic window. However, LED light is non-coherent (radiating in all directions) and divergent.
Typical LEDs operate with 30-60mW of electrical power. They can switch fast but cannot be super-pulsed. Most LED devices are Class 1, though they can fall under laser limitations if power density is high enough.
The Misleading Spec Problem
One really misleading part of LED systems: many are rated on power consumption, not deliverable power output like lasers.
We tested all lasers we sell—they all produce rated power at the emitter head. When we tested a 50-LED array using the latest surface mount technology, the LEDs consumed close to 50 watts but produced less than 10% of rated light energy on our laser test rig.
We're not sure if companies cheat on specs to sell more systems or if all LEDs have such inefficiency, but watch out when shopping for wrap-around therapy devices or LED systems. Beyond not being coherent, these systems can deliver a small fraction of their stated power.
Understanding Laser Technology
LASER (Light Amplification by Stimulated Emission of Radiation) emits electromagnetic radiation via stimulated emission. Cold laser light has four key properties that make it superior for therapy:
Monochromatic
Single wavelength selected for optimal tissue penetration—no energy wasted across a spectrum.
Spatially Coherent
Energy doesn't destroy itself through out-of-phase interference. Waves work together, not against each other.
Controlled Divergence
Unlike hot lasers with almost no divergence, cold lasers use optics to diverge ~7%—pushing more energy in the needed direction.
Optically Optimized
Manipulated to maximize penetration depth while maintaining safety profiles.
What "Coherent Light" Really Means
In laser technology, coherent light means spatially constant waves of identical frequency and phase. The waves are non-interfering. When waves interfere, they can add together (constructive interference) or subtract (destructive interference) depending on relative phase.
Two waves are coherent if they have a constant relative phase. This differentiates lasers from light sources that emit incoherent beams with random phase varying over time and position.
Like other electrical transmission equipment (cell phones, walkie talkies), power is proportional to range—or in cold laser therapy, depth of penetration.
The 100-Watt Test
100W LED
Stand 20 feet away on a sunny day from a 100-watt LED light. You might not be able to tell if it's turned on or off.
So much energy is lost to divergence, non-coherence, and distribution over a wider wavelength band.
100W Laser
Stand 20 feet away from a 100-watt coherent, monochromatic, non-divergent laser and look right at it...
Don't actually do this. The concentrated energy delivery is powerful enough to cause serious damage—that's the difference.
What About SLDs?
Super Luminescent Diodes (SLDs) are similar to LEDs but have potential to be brighter. They're sometimes used in combination with lasers in therapy devices (like the TerraQuant/MR4 series) to provide supplemental wavelengths. However, they still lack the coherence and controlled divergence that makes true lasers superior for deep tissue penetration.
The Bottom Line
When LEDs Might Work
- Very superficial applications
- Large area coverage where depth doesn't matter
- When combined with true lasers for supplemental wavelengths
- Budget situations where some therapy is better than none
When You Need a Real Laser
- Deep tissue penetration required
- Consistent, repeatable results needed
- Professional clinical applications
- Treating joints, tendons, ligaments, deep muscles
- When dosage accuracy matters
Because lasers are coherent and have controlled divergence, they're the best at delivering photonic energy to deep tissue. There are still possibilities for LED systems—but if losses are too great, the system never delivers the needed dosage. Check the specs, test the output, and know what you're buying.
Frequently Asked Questions
Why do some LED devices claim to be "lasers"?
Marketing. Some manufacturers put "laser" in their product name while using 90% LED technology. Always check the actual specifications—look for true laser diodes, not just LEDs. If specs list "LED" anywhere, you're not getting a true laser.
Can LEDs be effective for any therapy applications?
Yes, for superficial applications where deep penetration isn't required. Red LED light (630-660nm) can be effective for skin conditions, wound healing on the surface, and cosmetic applications. They're also used as supplemental wavelengths alongside true lasers in some professional devices.
How can I tell if a device is a real laser or LED?
Check the specifications carefully. True lasers will list specific laser diode specifications with exact wavelengths and power ratings. LED devices often list power consumption rather than output. Ask for actual tested output power at the emitter head, not electrical consumption. If a company can't provide this, be suspicious.
What about those cheap LED wrap devices?
Be very cautious. Our testing showed LED arrays producing less than 10% of their rated power. Combined with the inherent inefficiency of non-coherent light delivery (1-20% tissue efficiency), you might be getting less than 2% of the advertised therapeutic effect. For serious therapy applications, invest in a real laser.
Why is 980nm wavelength problematic?
At 980nm and above, much of the energy converts to heat rather than driving photo-chemical reactions. This is why 980nm is used in surgical lasers—to cut and cauterize. For therapy, you want photo-chemical effects (cellular healing), not photo-thermal effects (heating). The 800-860nm range provides better balance of penetration depth and photo-chemical activity.
Ready to invest in real laser therapy?
We only sell true laser systems with tested, verified specifications. Let us help you find the right one.