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Difference between LED and LASER
Several types of devices are used to emit light. The two special devices that are used as the source of light in flashlights, traffic signals, medical instruments, etc. are LED and LASER. Both LED and LASER can emit electromagnetic radiation in the form of light. Although, these are different from each other.
In this article, we will highlight all the major differences between LED and LASER. Let's start with some basic information about LED and LASER so that it becomes easy to understand the differences between them.
What is LED?
LED stands Light Emitting Diode. The LED is a semiconductor device which emits light when an electric current flows through it. Basically, an LED is a PN junction diode in which electrons recombine with the holes to release energy in the form of photons of light.
An LED is an incoherent source of light which means its photons are out of phase. Also, it is not a monochromatic source of light, i.e. it generates a mixture of electromagnetic waves of different wavelengths and hence can consist of many colors. The working of LED is based on the principle of electro-luminance, i.e. lamination using charged particles (electrons and holes).
LEDs produce a divergent light beam, i.e. the light produced by the LED can travel in different directions randomly. The LED require little power for their operation. The LEDs do not require feedback.
The common applications of LEDs are in indicator lamps, area lighting, display screens, communication technology, vehicle headlamps, flashlights, etc.
What is LASER?
LASER stands for Light Amplification by Stimulated Emission of Radiation. A LASER is a device which emits light by the process of optical amplification based on the concept of stimulated emission of radiation.
In LASER, when the electrons in the atom of a lasing material absorbs energy from an electric current or a light source, they get excited. These excited electrons move from a low energy state to a high energy state. When these electrons return to their normal state, emit photons of light.
LASER has many unique properties such as monochromatic (i.e. one color light), non-divergent, coherent, etc. The LASER requires more power as compared to LED. Also, a proper feedback is required in the LASER.
The most common applications of LASER are in printing, optical memory drives, scanners, fiber optics, laser surgery, optical communication, measuring systems, etc.
Differences between LED and LASER
All the major differences between LED and LASER are listed in the following table −
| Basis of Difference | LED | LASER |
|---|---|---|
| Full form | LED stands for Light Emitting Diode. | LASER stands for Light Amplification by Stimulated Emission of Radiation. |
| Definition | A semiconductor device which produces light when an electric current flows through it is called LED or Light Emitting Diode. | A device which emits light by the optical amplification using stimulated emission of electromagnetic radiation is called LASER. |
| Working principle | The working of LED is based on the principle of electro-luminance. | The working of the LASER is based on the principle of stimulated emission. |
| Chromaticity | LED is usually a polychromatic, i.e. it produces a broader band of wavelengths. | LASER is a monochromatic source of light as it generates the light of single wavelength. |
| Coherence | LED is a non-coherent source of light, i.e. its photons are out of phase, | LASER is a coherent source of light, which means its photons are in phase. |
| Directionality | LED generates a divergent beam of light. Thus, the light produced by the LED can travel in all directions randomly. | LASER produces a non-divergent beam of light which is highly directional. |
| Optical spectral width | LED has a broader optical spectrum, usually ranging from 25 nm to 100 nm. | For LASER, the optical spectrum is much narrower, usually 0.01 nm to 5 nm. |
| Emission | LED involves spontaneous emission. | LASER involves stimulated emission. |
| Optical power output | LED has comparatively low optical output power. | LASER has high optical output power. |
| Temperature dependency | The operation of LED is less dependent on the temperature. | The operation of LASER is quite temperature dependent. |
| Conversion efficiency | LED has very low conversion efficiency, around 10% to 20%. | LASER has comparatively high conversion efficiency, around 30% to 70%. |
| Reliability | LEDs are highly reliable devices. | The reliability of LASER is moderate. |
| Drive circuit | LED has simple drive circuit. | The drive circuit of LASER is complex. |
| Impact on eyes | LED is considered for human eyes. | LASER is not safe for naked human eyes. Therefore, there must be rendered eye safe while looking the LASER. |
| Feedback | There is no need of feedback in LEDs. | A proper feedback is essential in LASER. |
| Power requirement | LEDs require comparatively less power for operation. | LASER requires more power than LEDs. |
| Response | LEDs have slow response. | LASER has comparatively faster response. |
| Cost | The cost of LED is low. | The cost of LASER is more than LED. |
| Applications | LEDs are used in several applications such as area illumination, communication over moderate distances at low data rate, automobile headlamps, display screens, etc. | LASER is used in optical communication, welding, metal cutting, medical surgery, etc. |
Conclusion
The most significant difference between LED and LASER is that the LED works on the principle of electro-luminance, whereas LASER works on the principle of stimulated emission.
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