LASER vs. LED: What’s the Difference? 4.88/5 (139)

I’ve always been fascinated by light.

When I was a kid, my first flashlight fascination soon developed into wiring electronic circuits and messing with LEDs. When I set out, at age 10, to build a robot, the first item I included was the lights. By the time high school came around, I was studying laser physics and wishing I could afford an actual Laser. I still remember the day I got to play with my first laser–it was an obsolete helium-neon beast that had been donated to our school. By today’s standards, it was quite primitive. But it would put a dot on a building 200 yards away and I was hooked.

Well, times have certainly changed. Lasers are now common, affordable, and widely available–but they’re still not very widely understood. And they’re often confused with LEDs. So here’s a quick, non-boring primer about lasers, LEDs and light.

Let’s start with some cool acronyms so we can get an idea of what we’re taking about.

LED stands for Light-emitting Diode. And it’s pretty much just that. A diode that emits light when electricity passes through it. Often in pretty colors.

LASER stands for Light Amplification by Stimulation of Emitted Radiation. This mouthful of gibberish pretty much means that a source of light is amplified within a gain medium and emitted in a specific way. Cool stuff happens in the process, which we’ll discuss in short order. But first, we’ve got to tackle the concept of color.

Take a look at the sun. OK, maybe don’t look directly at it, but consider it for a moment.

Sunlight appears to be white, but it’s actually made up of every color of light, including colors our eyes can’t see. That’s why sunlight can be separated into its constituent colors by a prism, or in the case of a rainbow, airborne water vapor. Included in sunlight is infrared light, which we cannot see, but we feel it as heat. Also included is invisible ultraviolet light, which is responsible for sunburns, faded upholstery, and germ-free drinking water. The point is there are many colors or wavelengths of light in sunlight.

Lasers, on the other hand, are monochromatic. This means that all the light produced by a laser is a single, specific wavelength. LEDs also tend to produce monochromatic, or nearly monochromatic light. In acupuncture, we select the color to use based on the effect we are hoping to achieve. The red colors tend to be tonifying, while blue colors tend to sedate.

So wavelength=color, and color=effect. Got it so far?

Are you coherent?

OK, our next step in this journey of discovery is the concept of coherence. To explain this one, I’m going to have to pull out a boating metaphor. Have you ever watched a rowing competition? You know, the sleek shells, the muscular guys, all rowing in perfect unison as they race along the water, while the coxswain calls out commands. One of the keys to winning is for all the rowers to work precisely together as one. This is a good metaphor for coherence.

Almost all forms of light are INcoherent. This means that each of the individual light waves pretty much does what it wants and ignores all the other light waves. Think of a rowing crew of drunken amateurs, some rowing one way, some rowing another, one playing the guitar, and one falling out of the boat. Get the picture? Though the boat may move, it won’t move powerfully or in a predictable direction.

Coherent light, on the other hand, features all the individual light waves precisely lined up with each other and working in perfect unison. They’re all going the same direction, and taking each “stroke” in the same way and at the same time. In other words, all the waves are “in phase.” Here’s an illustration:

Though the same amount of light is coming out of both light sources, the coherent light is much more concentrated and powerful because of its coherence.

It also stays in a single beam, rather than spreading out. That’s why a laser pointer will project a very small dot across a long distance. And that’s also why laser light is dangerous for our eyes. In nature, there is no such thing as coherent light; all coherent light is artificially made. Therefore, our eyes are not adapted to deal with the intense power of coherent light deposited in a small area on the retina, and, depending on the laser power, retinal burns can result. Hence the recommendation for safety glasses.

True Lasers?

OK, this brings me to one of the most common questions I get.

“Is this a ‘true laser’ or just a diode?”

Yep, not a week goes by that I don’t get asked that. And it’s a bit of a complicated question because of laser history. You see, in the early days, lasers consisted of large tubes, external light sources, fancy mirrors, and other tricks to get the light monochromatic and coherent. The first laser I ever touched was the size of a briefcase. But now, thanks to modern technology, laser light is produced by–wait for it–diodes. In fact, nearly ALL modern lasers are diode lasers. Therefore, the question about “true lasers” versus diodes is meaningless.

But wait, doesn’t the “D” in “LED” also stand for for Diode?

Yep.

And that’s where the confusion results. Diodes are the light source in LEDs AND in Lasers. So naturally, people confuse the two. But now YOU won’t because you know the difference in the light produced by each. All modern lasers are diodes. And yes, they are TRUE lasers, producing monochromatic, coherent light. Some folks hear the word, “diode” and immediately assume LED, not laser. Hence the confusion.

So When Would I Use Each?

OK, this brings us to the title of this post. Lasers vs. LEDs. When should you use a laser and when should you use an L.E.D.? It really depends on the target of your treatment and what you’re trying to accomplish.

Lasers concentrate all their power in a small point, which makes them ideal for laser acupuncture. And laser light is coherent, which also makes it ideal for this application. Lasers are used in fiber optic communication systems because coherent light can be transmitted over much greater distances than incoherent light. The coherent laser light can be transmitted hundreds, even thousands of miles through fiber optic cables without much loss. In the same way, laser light tends to penetrate easily to the meridians and travel along them, for energy-moving effects in the meridians, even at a distance from the point being treated.

So…if the meridians are fiber optic in nature (and there’s evidence they are) then coherent light is your best bet to penetrate, communicate, and move Chi.

Plus, it’s fast, painless, and effective! I get excited just thinking about it

LED’s, on the other hand, tend to distribute their power over a larger area, but without the traveling effect of laser. Therefore L.E.D. effects tend to remain local, affecting the local tissues that
are exposed to the light. Because they’re not coherent, they can safely use higher power without danger to eyes. Powerful L.E.D.’s in healing wavelengths are comfortable, safe, and produce very nice effects. In summary, LED’s are great for treating larger areas, and affecting local tissues.

Yep, I’m still fascinated with light.

Now, a word about safety:

Though Class IIIa lasers are generally considered “eye-safe,” this does NOT mean the lasers cannot damage the eye; rather, it means that you will most likely blink or look away before any real damage can be done.

However, out of an abundance of caution, many of our customers do choose to use laser safety glasses for their patients and themselves, just as an added layer of safety

We always want to promote and encourage the safest practices possible, and so if you are going to use laser safety glasses, you need to make sure they block the wavelengths that match your lasers. They are very specific, and if you have the wrong glasses, they will not work. Usually, you’ll need separate glasses for red and blue lasers because each set of glasses will only block one wavelength. This isn’t particularly convenient when you’re using two laser colors. Fortunately, I’ve designed a single set of glasses that blocks both blue and red wavelengths in the same lens. Click on the image for more information

I hope you’ve enjoyed learning a bit more about lasers vs. LEDs.