What is the difference between Lasers and LEDs?

Question

What is the difference between Lasers and LEDs?

Answer 1

None of these are right. An LED wouldn't work without QM (Quantum mechanics).

A laser is a laser because the dominant process producing light is stimulated emission (StE). LEDs are dominantly spontaneous emission (SpE). As the name suggest SpE is light that just happens, it's spontaneous. StE on the other hand requires photons to seed it, one goes in two come out. Due to this the photons from StE are more "alike" as they are modelled on each other. The key value for a laser is it's threshold. This is the value above which it is a laser, i.e. when the StE process is strong enough to overcome the loss of light in the laser.



edit: sorry couldn't keep quiet, these answers are getting worse. Lasers do NOT have more power than LEDs, for the same size they have LESS power. They do however have higher spectral densities (i.e. more power per unit wavelength). They do NOT have to be collimated. The laser pointers everyone runs around with are only collimated because there is a lens on the front. The laser inside it isn't collimated at all.

Answer 2

Light Emitting Diodes (LEDs) are another form of light therapy that is a relatively recent development of the laser industry. LEDs are similar to lasers inasmuch as they have the same healing effects but differ in the way that the light energy is delivered. A significant difference between lasers and LEDs is the power output. The peak power output of LEDs is measured in milliwatts, while that of lasers is measured in watts. However, this difference when considered alone is misleading, since the most critical factor that determines the amount of energy delivered is the duty cycle of the device.

LED devices usually have a 50% duty cycle. That is, the LED pulse is "on" for 0.5 seconds and "off" for 0.5 seconds versus the 2 ten-millionths of a second burst from laser at 1 cycle per second (1hz). Moreover, LED is "on" 50% of the time and "off" 50% of the time regardless of what frequency setting (pulses per second) is used.

LEDs do not deliver enough power to damage the tissue, but they do deliver enough energy to stimulate a response from the body to heal itself. With a low peak power output but high duty cycle, the LEDs provide a much gentler delivery of the same healing wavelengths of light as does the laser but at a substantially greater energy output. For this reason, LEDs do not have the same risk of accidental eye damage that lasers do.

Lasers are also capable of a much faster pulse rate than LEDs, ... The primary physical difference between multimode and singlemode fiber is the core size ...









Moreover, LEDs are neither coherent nor collimated and they generate a broader band of wavelengths than do the single-wavelength laser. Non-collimation and the wide-angle diffusion of the LED confers upon it a greater ease of application, since light emissions are thereby able to penetrate a broader surface area. Moreover, the multiplicity of wavelengths in the LED, contrary to the single-wavelength laser, may enable it to affect a broader range of tissue types and produce a wider range of photochemical reactions in the tissue.







If LED light disperses over a greater surface area, it results in a faster treatment time for a given area than laser. The primary reason that BioPro 660 used LEDs over lasers is that LEDs are safer, more cost effective, provide a gentle but effective delivery of light and a greater energy output per unit of surface area in a given time duration.

Answer 3

the main difference between them is that LASERS have more intensity than LEDs.

LASERS prodoce a thin ray of light which travels in a specified path but LEDs split the they emit in all the directions.so there intensity is lesser than LASERS

Answer 4

Laser has quantum theory behind it, whereas LEDs are simple electrical parts.

Answer 5

laser is more coherent , more powerful and more parallel.